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IPCC [Intergovernmental Panel on Climate Change]-September 1990
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IPCC [Intergovernmental Panel on Climate Change]-September 1990
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Kathleen McGinty's Files
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FOIA Number: 2012-0769-F
FOIA
MARKER
This is not a textual record. This is used as an
administrative marker by the William J. Clinton
Presidential Library Staff.
Collection/Record Group:
Clinton Presidential Records
Subgroup/Office of Origin:
Council on Environmental Quality
Series/Staff Member:
Kathleen (Katie) McGinty
Subseries:
OA/ID Number:
2616
FolderID:
Folder Title:
IPCC [Intergovernmental Panel on Climate Change] - September 1990
Stack:
Row:
Section:
Shelf:
Position:
S
61
5
7
2
02-05-92 11:15 AM
fill IPCC 1992 in
demake charge.
P02
02/05/92
10:15
CONGAL & INTERGOVERNMENTAL
022
LETTER SENT TO
ENTIRE SENATE
The Secretary of Energy
Washington, DO 20588
February 4, 1992
The Honorable Malcolm Wallop
Ranking Minority Member
Committee an Energy and Natural Resources
United States Senate
Washington, D.C. 20510
Dear Senstor Wallop:
As the Senate misses toward floor consideration of a 2106, I would like to take the
opportunity to share with you the Administration's position on annual lazy issues,
including off and gas development in the Archité National Wildlis Illenge (ANWR). global
climate change, alternative fuels (the Jeffords amendment), muslear Humaning wellown and
refhrm of the Public Unity Holding Company Act GUECAL
ABOTTO NATIONAL REFUGE (ANWR)
The Administration remains committed to the environmentally responsible development of
a small portion of the Arctic National Wildlife Refuge (ANWE). We vigardusly support
efforts to add to a. 2166 the ANWR provisions in a. 1940.
GLOBAL CLIMATE CHANGE
a. 2166 addresses issues related to posetble global elimate change in & STATEMENT consistent
with S. 894, which the Manate passed unanimously in the last Congress. Events since
passage of S. 824 would not justify a radioal departure in approach. In fact. the 1008
Update of the 1990 IPOO Edentific Assessment notes that baseline elimate modial
projections of potential future Northern Hemisphere warming have been significantly
reduced.
I understand that climate change language from e House energy subcommittee bill that
would establish a voluntary certification and registry scheme floor greenhouse gas
reductions may be offered as an amendment to B. 2166. We strongly oppose these
provisions for several reasons. First and foremost, such a program would work directly
against our economic interests by rewarding firms that reduce production or shift to
foreign sources of supply with potentially valuable "credits". Becond, the House
subcommittee language would enshrine outdated science in certified credits. The 1982
IPOC update, for example, reflects a changing understanding of the relative role of CFOs,
sulfur dioxide, nitrous oxides and carbon dioxide as influences on the climate system.
Third, the system itself would be an administrativo nightmare and a turget for extensive
litigation.
02-05-92 11:15 AM
P03
02/05/92
10:16
CONG/L 8 INTERGOVERNMENTAL
003
Basic and energy industries (and regions where they are concentrated) would be
particularly hard hit by policies spurred by this program. For examplo, in the "climate
policy sconario" in America's Energy Choices issued last year by a scalition of
environmental and other groups, coal use (and presumsbly coal employment) in 2030 is
reduced to only 15 percent of its projected level under Administration policies. On a more
general level, the same analysis suggests that limiting carbon emissions is easy - ifs
scenario combining slow economic growth and a continuing shift away from
manufacturing is assumed. This is certainly not the policy of the Administration for the
U.S. economy.
For these reasons, the House subcommittee approach is not as appropriate way to reflect
over the need to reduce greenhouse emissions. A far more effective approach to
reducing greenhouse gas amissions in the energy sector in to support the current
provisions of 8. 2166 related to climate. nuclear licensing and other related subjects.
ALTERNATIVE FUELS
We strongly oppose the Jeffords amendment. This amendment would mandate that 10%
of America's fuel supply be alternative or replacement fuels, and would require that DOB
establish an extensive regulatory apparatus to enforce this requirement. This
burdensome apparatus is counterproductive to meeting alternative fuel use objectives that
are almost certain to be achieved given other provisions of S. 2168 and the Clean Air Act
Amendments of 1990.
We are especially concerned that, by establishing 503 artificial distinction between all from
stripper operations and oil from other searces, the amendment will require allocation
regulations reminiscent of the costly and disruptive price and allocation controls used
during the 1970s. In addition, artificial distinctions based on the origin of fungible
products, such as oil and MTBE, mean that refiners would be required to track both the
sources and the makeup of refinery feedstocks, increasing consumer cost and reducing
consumer choice. This provision will also establish massive and unproductive new
paperwork requirements.
This smendment will increase gesoline prices. increase unemployment. and retard
economic growth. The Administration strongly opposes it.
NUCLEAR LICENSING REFORM
The Administration believes that the provisions of Title IX are essential to inspire
investment in new nuclear powerplants. The provisions of Title IX fully protect the
public's Interest and the Nuclear Regulatory Commission's authority to make safety
determinations, but have also been carefully selected to provide prospective nuclear plant
owners and investors with definition of the new licensing process to make it sufficiently
predictable.
The Administration will oppose any changes in the language of TYUe 1X that might lessen
the predictability of the new process, particularly any changes In the post-construction
safety determination and hearing provisions that are of fundamental importance in
reducing the uncortainty associated with 10 CFR Part 32.
02-05-92 11:15 AM
P04
W
PUBLIC HOLDING COMPANY ACT REFORM
I would usge you to support the 8. 2166 title amending the Public Utility Holding
Company Act (PUHCA). PUHCA reform is a vital part of the President's National Energy
Strategy. It will stimulate sconomic growth, create jobs, encourage Innovation, and save
consumers billions of dollars.
It is good for the economy and good for consumers because It permits utilities to buy
electricity from the lowest comb suppliers. Twenty six aut of filly states now encourage
competition in electric power generation, but PUHCA discourage the most promising
companies from competing. B. 2166 would end these restrictions and allow the most
competitive suppliers to build and operate power plants in as many service areas as state
utility commissions permit. The net result of PUHCA reform will be Lower cost power and
stronger incentives for innovation in the multibillion dollar electric power, industry.
PUHCA reform, is proposed in B. 2166, does not force anyone to do anything. It does not
deregulate the electric utility business and It does not restructure the industry. It morely
permits utilities and etate regulators to Invite the best builders of povice plants to do
business to a new area without running afoul of a UT-year old law whose Sumero did not
foresse today's competitive opportunities. It also would allow American power suppliers
to compete in a huge electric power market around the globe.
Opponents of competition in electric generation argus that, If there must be PUNCA
reform, the bill should be amended to include provisions such as a restriction on debt of
competing power producers. You should ase opposition to PUHOA reform for what it is -
an attempt to straightjacket competitors if they cannot be kept out of the maximet
altogether. The Administration will Hikewise oppose other PUNCA amendments which
would sectously weeken the PUECA title in S. 2166.
We approciate your consideration of the concerns outlined above and look forward to
working with you to ennet comprehensive energy legislation.
Sincerely,
Jan James Admiral, D. U.S. D. Watkins Navy Nath. (Retired)
some language;
Industrial energy audits ;
EADC.
Dept. of inmal Commiss a lab for prysols in 1976 6
make auditar
in the K then in
do nt P.E.
1
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WMO
UNEP
INTERGOVERNMENTAL PANEL ON
CLIMATE CHANGE
POLICYMAKERS
SUMMARY
OF THE
SCIENTIFIC ASSESSMENT OF
CLIMATE CHANGE
Report to IPCC from Working Group 1
June 1990
Prepared by the IPCC Group at the Meteorological Office, Bracknell, UK
Executive Summary
We are certain of the following:
there is a natural greenhouse effect which already keeps the Earth warmer than it
would otherwise be.
emissions resulting from human activities are substantially increasing the
atmospheric concentrations of the greenhouse gases: carbon dioxide, methane,
chlorofluorocarbons (CFCs) and nitrous oxide. These increases will enhance the
greenhouse effect, resulting on average in an additional warming of the Earth's
surface. The main greenhouse gas, water vapour, will increase in response to
global warming and further enhance it.
We calculate with confidence that:
some gases are potentially more effective than others at changing climate, and
their relative effectiveness can be estimated. Carbon dioxide has been
responsible for over half the enhanced greenhouse effect in the past, and is likely
to remain so in the future.
atmospheric concentrations of the long-lived gases (carbon dioxide, nitrous oxide
and the CFCs) adjust only slowly to changes in emissions. Continued emissions of
these gases at present rates would commit us to increased concentrations for
centuries ahead. The longer emissions continue to increase at present day rates,
the level. greater reductions would have to be for concentrations to stabilise at a given
the long-lived gases would require immediate reductions in emissions from
human activities of over 60% to stabilise their concentrations at today's levels;
methane would require a 15-20% reduction.
1
Based on current model results, we predict:
under the IPCC Business-as-Usual (Scenario A) emissions of greenhouse
gases, a rate of increase of global mean temperature during the next century of
about 0.3°C per decade (with an uncertainty range of 0.2°C to 0.5°C per decade);
this is greater than that seen over the past 10,000 years. This will result in a likely
increase in global mean temperature of about 1°C above the present value by
2025 and 3°C before the end of the next century. The rise will not be steady
because of the influence of other factors.
under the other IPCC emission scenarios which assume progressively
increasing levels of controls, rates of increase in global mean temperature of about
0.2°C per decade (Scenario B), just above 0.1°C per decade (Scenario C) and
about 0.1°C per decade (Scenario D).
that land surfaces warm more rapidly than the ocean, and high northern latitudes
warm more than the global mean in winter.
regional climate changes different from the global mean, although our
confidence in the prediction of the detail of regional changes is low. For example,
temperature increases in Southern Europe and central North America are
predicted to be higher than the global mean, accompanied on average by reduced
summer precipitation and soil moisture. There are less consistent predictions for
the tropics and the southern hemisphere.
under the IPCC Business as Usual emissions scenario, an average rate of global
mean sea level rise of about 6cm per decade over the next century (with an
uncertainty range of 3 - 10 cm per decade), mainly due to thermal expansion of the
oceans and the melting of some land ice. The predicted rise is about 20cm in
global mean sea level by 2030, and 65cm by the end of the next century. There will
be significant regional variations.
There are many uncertainties in our predictions particularly with
regard to the timing, magnitude and regional patterns of climate
change, due to our incomplete understanding of:
sources and sinks of greenhouse gases, which affect predictions of future
concentrations
clouds, which strongly influence the magnitude of climate change
oceans, which influence the timing and patterns of climate change
polar ice sheets which affect predictions of sea level rise
These processes are already partially understood, and we are confident that the
uncertainties can be reduced by further research. However, the complexity of the
system means that we cannot rule out surprises.
2
Our Judgement is that:
Global - mean surface air temperature has increased by 0.3°C to 0.6°C over the
last 100 years, with the five global-average warmest years being in the 1980s.
Over the same period global sea level has increased by 10-20cm. These increases
have not been smooth with time, nor uniform over the globe.
The size of this warming is broadly consistent with predictions of climate models,
but it is also of the same magnitude as natural climate variability. Thus the
observed increase could be largely due to this natural variability; alternatively this
variability and other human factors could have offset a still larger human-induced
greenhouse warming. The unequivocal detection of the enhanced greenhouse
effect from observations is not likely for a decade or more.
There is no firm evidence that climate has become more variable over the last
few decades. However, with an increase in the mean temperature, episodes of
high temperatures will most likely become more frequent in the future, and cold
episodes less frequent.
Ecosystems affect climate, and will be affected by a changing climate and by
increasing carbon dioxide concentrations. Rapid changes in climate will change
the composition of ecosystems; some species will benefit while others will be
unable to migrate or adapt fast enough and may become extinct. Enhanced levels
of carbon dioxide may increase productivity and efficiency of water use of
vegetation. The effect of warming on biological processes, although poorly
understood, may increase the atmospheric concentrations of natural greenhouse
gases.
To Improve our predictive capability, we need:
to understand better the various climate-related processes, particularly
those associated with clouds, oceans and the carbon cycle
to improve the systematic observation of climate-related variables on a
global basis, and further investigate changes which took place in the past
to develop improved models of the earth's climate system.
to increase support for national and international climate research
activities, especially in developing countries
to facilitate international exchange of climate data
Introduction: what is the issue ?
There is concern that human activities may be inadvertently changing the climate of
the globe through the enhanced greenhouse effect, by past and continuing
emissions of carbon dioxide and other gases which will cause the temperature of
the Earth's surface to increase - popularly termed the "global warming". If this
occurs, consequent changes may have a significant impact on society.
The purpose of the Working Group I report, as determined by the first meeting of
IPCC, is to provide a scientific assessment of:
1) the factors which may affect climate change during the next century
especially those which are due to human activity.
2) the responses of the atmosphere - ocean - land - ice system.
3) current capabilities of modelling global and regional climate changes and
their predictability.
4) the past climate record and presently observed climate anomalies.
On the basis of this assessment, the report presents current knowledge regarding
predictions of climate change (including sea level rise and the effects on
ecosystems) over the next century, the timing of changes together with an
assessment of the uncertainties associated with these predictions.
This Policymakers Summary aims to bring out those elements of the main report
which have the greatest relevance to policy formulation, in answering the following
questions:
What factors determine global climate?
What are the greenhouse gases, and how and why are they increasing?
Which gases are the most important?
How much do we expect the climate to change?
How much confidence do we have in our predictions?
Will the climate of the future be very different ?
Have human activities already begun to change global climate?
How much will sea level rise?
What will be the effects on ecosystems?
What should be done to reduce uncertainties, and how long will this take?
This report is intended to respond to the practical needs of the policymaker. It is
neither an academic review, nor a plan for a new research programme.
Uncertainties attach to almost every aspect of the issue, yet policymakers are
4
looking for clear guidance from scientists; hence authors have been asked to
provide their best-estimates wherever possible, together with an
assessment of the uncertainties.
This report is a summary of our understanding in 1990. Although continuing
research will deepen this understanding and require the report to be updated at
frequent intervals, basic conclusions concerning the reality of the enhanced
greenhouse effect and its potential to alter global climate are unlikely to change
significantly. Nevertheless, the complexity of the system may give rise to surprises.
What factors determine global climate ?
There are many factors, both natural and of human origin, that determine the
climate of the earth. We look first at those which are natural, and then see how
human activities might contribute.
What natural factors are important?
The driving energy for weather and climate comes from the sun. The Earth
intercepts solar radiation (including that in the short-wave, visible, part of the
spectrum); about a third of it is reflected, the rest is absorbed by the different
components (atmosphere, ocean, ice, land and biota) of the climate system. The
energy absorbed from solar radiation is balanced (in the long term) by outgoing
radiation from the Earth and atmosphere; this terrestrial radiation takes the form of
long-wave invisible infra-red energy, and its magnitude is determined by the
temperature of the Earth-atmosphere system.
There are several natural factors which can change the balance between the
energy absorbed by the Earth and that emitted by it in the form of longwave infra-
red radiation; these factors cause the radiative forcing on climate. The most
obvious of these is a change in the output of energy from the Sun. There is direct
evidence of such variability over the 11-year solar cycle, and longer period
changes may also occur. Slow variations in the Earth's orbit affect the seasonal
and latitudinal distribution of solar radiation; these were probably responsible for
initiating the ice ages.
One of the most important factors is the greenhouse effect; a simplified
explanation of which is as follows. Shortwave solar radiation can pass through the
clear atmosphere relatively unimpeded. But long-wave terrestrial radiation emitted
by the warm surface of the Earth is partially absorbed and then re-emitted by a
number of trace gases in the cooler atmosphere above. Since, on average, the
outgoing long wave radiation balances the incoming solar radiation, both the
atmosphere and the surface will be warmer than they would be without the
greenhouse gases.
The main natural greenhouse gases are not the major constituents, nitrogen and
oxygen, but water vapour (the biggest contributor), carbon dioxide, methane,
nitrous oxide, and ozone in the troposphere (the lowest 10-15km of the
atmosphere) and stratosphere.
5
solar radiation
SUN
is reflected by the earth
and the atmosphere
solar
radiation
some of the infra-red
passes
radiation is absorbed
through
ATMOSPHERE
and re-emitted by the
the clear
greenhouse gases.
atmosphere
The effect of this is to
warm the surface and
the lower atmosphere
EARTH
infra-red
most solar
radiation is absorbed
radiation is
by the earth's surface and
emitted from
warms it
the earth's
surface
A simplified diagram Illustrating the greenhouse effect
Aerosols (small particles) in the atmosphere can also affect climate because they
can reflect and absorb radiation. The most important natural perturbations result
from explosive volcanic eruptions which affect concentrations in the lower
stratosphere. Lastly, the climate has its own natural variability on all timescales
and changes occur without any external influence.
How do we know that the natural greenhouse effect is real?
The greenhouse effect is real; it is a well understood effect, based on established
scientific principles. We know that the greenhouse effect works in practice, for
several reasons.
Firstly, the mean temperature of the Earth's surface is already warmer by about
33°C (assuming the same reflectivity of the earth) than it would be if the natural
greenhouse gases were not present. Satellite observations of the radiation emitted
from the earth's surface and through the atmosphere demonstrate the effect of the
greenhouse gases.
Secondly, we know the composition of the atmospheres of Venus, Earth and Mars
are very different, and their surface temperatures are in general agreement with
greenhouse theory.
Thirdly, measurements from ice cores going back 160,000 years show that the
earth's temperature closely paralleled the amount of carbon dioxide and methane
in the atmosphere. Although we do not know the details of cause and effect,
calculations indicate that changes in these greenhouse gases were part, but not
all, of the reason for the large (5-7°C) global temperature swings between ice ages
and interglacial periods.
AT
Depth (m)
500
C
1000
1500
2000
2
0
-2
-4
-6
CH4
-8
(ppbv)
-10
700
600
500
1990
level
400
of CO2
CO2
CO2
ppmv
ppmv
300
300
280
280
260
260
240
240
220
220
200
200
180
180
0
40
80
120
160
Age (kyr BP)
Analysis of air trapped in Antarctic Ice cores shows that methane and carbon
dioxide concentrations were closely correlated with the local temperature over the
last 160,000 years. Present day concentrations of carbon dioxide are Indicated.
How might human activities change global climate ?
Naturally occurring greenhouse gases keep the Earth warm enough to be
habitable. By increasing their concentrations, and by adding new greenhouse
gases like chlorofluorocarbons (CFCs), humankind is capable of raising the global-
average annual-mean surface-air temperature (which, for simplicity, is referred to
as the "global temperature"), although we are uncertain about the rate at which this
will occur. Strictly, this is an enhanced greenhouse effect - above that occurring
due to natural greenhouse gas concentrations; the word "enhanced" is usually
omitted, but it should not be forgotten. Other changes in climate are expected to
result, for example changes in precipitation, and a global warming will cause sea
levels to rise; these are discussed in more detail later.
There are other human activities which have the potential to affect climate. A
change in the albedo (reflectivity) of the land, brought about by desertification or
deforestation affects the amount of solar energy absorbed at the Earth's surface.
7
Human-made aerosols, from sulphur emitted largely in fossil fuel combustion, can
modify clouds and this may act to lower temperatures. Lastly, changes in ozone
in the stratosphere due to CFCs may also influence climate.
What are the greenhouse gases and why are they
increasing?
We are certain that the concentrations of greenhouse gases in the atmosphere
have changed naturally on ice-age time-scales, and have been increasing since
pre-industrial times due to human activities. The table below summarizes the
present and pre-industrial abundances, current rates of change and present
atmospheric lifetimes of greenhouse gases influenced by human activities. Carbon
dioxide, methane, and nitrous oxide all have significant natural and human
sources, while the chlorofluorocarbons are only produced industrially.
SUMMARY OF KEY GREENHOUSE GASES AFFECTED BY HUMAN ACTIVITIES
Carbon
Methane
CFC-11
CFC-12
Nitrous
Dioxide
Oxide
Atmospheric
concentration
ppmv
ppmv
pptv
pptv
ppbv
Pre-industrial
(1750-1800)
280
0.8
0
0
288
Present day (1990)
353
1.72
280
484
310
Current rate of change
1.8
0.015
9.5
17
0.8
per year
(0.5%)
(0.9%)
(4%)
(4%)
(0.25%)
Atmospheric lifetime
(50-200)+
10
65
130
150
(years)
ppmv = parts per million by volume;
ppby = parts per billion (thousand million) by volume;
pptv = parts per trillion (million million) by volume.
t The way in which CO₂ is absorbed by the oceans and biosphere is not simple and a single
value cannot be given; refer to the main report for further discussion.
Two important greenhouse gases, water vapour and ozone, are not included in the
table above. Water vapour has the largest greenhouse effect, but its concentration
in the troposphere is determined internally within the climate system, and, on a
global scale, is not affected by human sources and sinks. Water vapour will
increase in response to global warming and further enhance it; this process is
included in climate models. The concentration of ozone is changing both in the
stratosphere and the troposphere due to human-made emissions, but it is difficult to
quantify the changes from present observations.
For a thousand years prior to the industrial revolution, abundances of the
greenhouse gases were relatively constant. However, as the world's population
increased, as the world became more industrialized and as agriculture developed,
the abundances of the greenhouse gases increased markedly. The figures below
illustrate this for carbon dioxide, methane, nitrous oxide and CFC-11.
360
CARBON DIOXIDE
340
CO2 CONCENTRATION (ppm)
320
300
280
260
1750
1800
1850
1900
1950
2000
YEAR
1800
METHANE
1600
CH4 CONCENTRATION (ppb)
1400
1200
1000
800
600
1750
1800
1850
1900
1950
2000
YEAR
Concentrations of carbon dioxide and methane after remaining relatively constant
up to the 18th century, have risen sharply since then due to man's activities.
Since the industrial revolution the combustion of fossil fuels and deforestation have
led to an increase of 26% in carbon dioxide concentration in the atmosphere. We
know the magnitude of the present day fossil-fuel source, but the input from
deforestation cannot be estimated accurately. In addition, although about half of
the emitted carbon dioxide stays in the atmosphere, we do not know well how
much of the remainder is absorbed by the oceans and how much by terrestrial
biota. Emissions of chlorofluorocarbons, used as aerosol propellants, solvents,
refrigerants and foam blowing agents, are also well known; they were not present
in the atmosphere before their invention in the 1930s.
9
310
NITROUS OXIDE
N2O CONCENTRATION (ppb)
300
290
280
1750
1800
1850
1900
1950
2000
YEAR
0.3
CFC11
CFC11 CONCENTRATION (ppb)
0.2
0.1
0.0
1750
1800
1850
1900
1950
2000
YEAR
Concentrations of nitrous oxide have Increased since the mid-18th century,
especially In the last few decades. CFCs were not present in the atmosphere
before the 1930s
The sources of methane and nitrous oxide are less well known. Methane
concentrations have more than doubled because of rice production, cattle rearing,
biomass burning, coal mining and ventilation of natural gas; also, fossil fuel
combustion may have also contributed through chemical reactions in the
atmosphere which reduce the rate of removal of methane. Nitrous oxide has
increased by about 8% since pre-industrial times, presumably due to human
activities; we are unable to specify the sources, but it is likely that agriculture plays
a part.
The effect of ozone on climate is strongest in the upper troposphere and lower
stratosphere. Model calculations indicate that ozone in the upper troposphere
should have increased due to human-made emissions of nitrogen oxides,
hydrocarbons and carbon monoxide. While at ground level ozone has increased in
the northern hemisphere in response to these emissions, observations are
insufficient to confirm the expected increase in the upper troposphere. The lack of
10
adequate observations prevents us from accurately quantifying the climatic effect of
changes in tropospheric ozone.
In the lower stratosphere at high southern latitudes ozone has decreased
considerably due to the effects of CFCs, and there are indications of a global-scale
decrease which, while not understood, may also be due to CFCs. These observed
decreases should act to cool the earth's surface, thus providing a small offset to the
predicted warming produced by the other greenhouse gases. Further reductions in
lower stratospheric ozone are possible during the next few decades as the
atmospheric abundances of CFCs continue to increase.
Concentrations, lifetimes and stabilisation of the gases
In order to calculate the atmospheric concentrations of carbon dioxide which will
result from human-made emissions we use computer models which incorporate
details of the emissions and which include representations of the transfer of carbon
dioxide between the atmosphere, oceans and terrestrial biosphere. For the other
greenhouse gases, models which incorporate the effects of chemical reactions in
the atmosphere are employed.
The atmospheric lifetimes of the gases are determined by their sources and sinks
in the oceans, atmosphere and biosphere. Carbon dioxide, chlorofluorocarbons
and nitrous oxide are removed only slowly from the atmosphere and hence,
following a change in emissions, their atmospheric concentrations take decades to
centuries to adjust fully. Even if all human-made emissions of carbon dioxide were
halted in the year 1990, about half of the increase in carbon dioxide concentration
caused by human activities would still be evident by the year 2100.
In contrast, some of the CFC substitutes and methane have relatively short
atmospheric lifetimes so that their atmospheric concentrations respond fully to
emission changes within a few decades.
To illustrate the emission-concentration relationship clearly, the effect of
hypothetical changes in carbon dioxide fossil fuel emissions is shown below: (a)
continuing global emissions at 1990 levels; (b) halving of emissions in 1990; (c)
reductions in emissions of 2% per year (pa) from 1990 and (d) a 2% pa increase
from 1990-2010 followed by a 2% pa decrease from 2010.
Continuation of present day emissions are committing us to increased future
concentrations, and the longer emissions continue to increase, the greater would
reductions have to be to stabilise at a given level. If there are critical concentration
levels that should not be exceeded, then the earlier emission reductions are made
the more effective they are.
11
100% 1990
EMISSIONS
(a)
500
CO2 CONCENTRATION (ppm)
(b)
400
50% of 1990
EMISSIONS
300
1980
2000
2020
2040
2060
2080
2100
YEAR
500
2%pa DECREASE
CO2 CONCENTRATION (ppm)
FROM 2010
(d)
400
(c)
2%pa DECREASE
FROM 1990
300
1980
2000
2020
2040
2060
2080
2100
YEAR
The relationship between hypothetical fossil fuel emissions of carbon dioxide and
Its concentration In the atmosphere is shown In the case where (a) emissions
continue at 1990 levels, (b) emissions are reduced by 50% In 1990 and continue at
that level, (c) emissions are reduced by 2% pa from 1990, and (d) emissions, after
Increasing by 2% pa until 2010, are then reduced by 2% pa thereafter.
The term "atmospheric stabilisation" is often used to describe the limiting of the
concentration of the greenhouse gases at a certain level. The amount by which
human-made emissions of a greenhouse gas must be reduced in order to stabilise
at present day concentrations, for example, is shown in the box below. For most
gases the reductions would have to be substantial.
STABILISATION OF ATMOSPHERIC CONCENTRATIONS
Reductions in the human-made emissions of greenhouse gases required to
stabilise concentrations at present day levels:
Carbon Dioxide
>60%
Methane
15 - 20%
Nitrous Oxide
70 - 80%
CFC-11
70 - 75%
CFC-12
75 - 85%
HCFC-22
40 - 50%
Note that the stabilisation of each of these gases would have different effects on climate, as
explained in the next section.
How will greenhouse gas abundances change in the future?
We need to know future greenhouse gas concentrations in order to estimate future
climate change. As already mentioned, these concentrations depend upon the
magnitude of human-made emissions and on how changes in climate and other
environmental conditions may influence the biospheric processes that control the
exchange of natural greenhouse gases, including carbon dioxide and methane,
between the atmosphere, oceans and terrestrial biosphere - the greenhouse gas
"feedbacks".
Four scenarios of future human-made emissions were developed by Working
Group III. The first of these assumes that few or no steps are taken to limit
greenhouse gas emissions, and this is therefore termed Business-as-Usual (BaU).
(It should be noted that an aggregation of national forecasts of emissions of carbon
dioxide and methane to the year 2025 undertaken by Working Group III resulted in
global emissions 10-20% higher than in the BaU scenario.) The other three
scenarios assume that progressively increasing levels of controls reduce the
growth of emissions; these are referred to as scenarios B, C, and D. They are
briefly described in the Annex. Future concentrations of some of the greenhouse
gases which would arise from these emissions are shown below.
13
900
BUSINESS-
CARBON DIOXIDE concentration (ppmv)
800
AS-USUAL
700
600
SCENARIO B
500
400
SCENARIOS C and D
300
1980
2000
2020
2040
2060
2080
2100
YEAR
4000
BUSINESS
concentration (ppbv)
3500
AS-USUAL
3000
SCENARIO.B
2500
2000
SCENARIO C
METHANE
1500
SCENARIO D
1000
1980
2000
2020
2040
2060
2080
2100
YEAR
700
BUSINESS-
600
AS-USUAL
CFC11 concentration (pptv)
500
SCENARIO B
400
300
200
100
SCENARIOS
Cand D
0
1980
2000
2020
2040
2060
2080
2100
YEAR
Atmospheric concentrations of carbon dioxide, methane and CFC-11 resulting from
the four IPCC emissions scenarios
11
Greenhouse gas feedbacks
Some of the possible feedbacks which could significantly modify future
paragraphs. greenhouse gas concentrations in a warmer world are discussed in the following
The net emissions of carbon dioxide from terrestrial ecosystems will be elevated if
higher temperatures increase respiration at a faster rate than photosynthesis, or if
plant populations, particularly large forests, cannot adjust rapidly enough to
changes in climate. A net flux of carbon dioxide to the atmosphere may be
particularly evident in warmer conditions in tundra and boreal regions where there
are large stores of carbon. The opposite is true if higher abundances of carbon
dioxide in the atmosphere enhance the productivity of natural ecosystems, or if
there is an increase in soil moisture which can be expected to stimulate plant
growth in dry ecosystems and to increase the storage of carbon in tundra peat. The
extent to which ecosystems can sequester increasing atmospheric carbon dioxide
remains to be quantified.
If the oceans become warmer, their net uptake of carbon dioxide may decrease
because of changes in (i) the chemistry of carbon dioxide in seawater (ii) biological
activity in surface waters and (iii) the rate of exchange of carbon dioxide between
the surface layers and the deep ocean. This last depends upon the rate of
formation of deep water in the ocean which, in the North Atlantic for example, might
decrease if the salinity decreases as a result of a change in climate.
Methane emissions from natural wetlands and rice paddies are particularly
sensitive to temperature and soil moisture. Emissions are significantly larger at
higher temperatures and with increased soil moisture; conversely, a decrease in
soil moisture would result in smaller emissions. Higher temperatures could
increase the emissions of methane at high northern latitudes from decomposable
organic matter trapped in permafrost and methane hydrates.
As illustrated earlier, ice core records show that methane and carbon dioxide
interglacials. concentrations changed in a similar sense to temperature between ice ages and
Although many of these feedback processes are poorly understood, it seems likely
that, overall, they will act to increase, rather than decrease, greenhouse gas
concentrations in a warmer world.
Which gases are the most important?
We are certain that increased greenhouse gas concentrations increase radiative
forcing. We can calculate the forcing with much more confidence than the climate
change that results because the former avoids the need to evaluate a number of
poorly understood atmospheric responses. We then have a base from which to
calculate the relative effect on climate of an increase in concentration of each
gas in the present-day atmosphere, both in absolute terms and relative to carbon
dioxide. These relative effects span a wide range; methane is about 21 times more
effective, molecule-for-molecule, than carbon dioxide, and CFC-11 about 12 000
times more effective. On a kilogram-per-kilogram basis, the equivalent values are
15
58 for methane and about 4000 for CFC-11, both relative to carbon dioxide. Values
for other greenhouse gases are to be found in the full report.
The total radiative forcing at any time is the sum of those from the individual
greenhouse gases. We show in the figure below how this quantity has changed in
the past (based on observations of greenhouse gases) and how it might change in
the future (based on the four IPCC emissions scenarios). For simplicity, we can
express total forcing in terms of the amount of carbon dioxide which would give that
forcing; this is termed the equivalent carbon dioxide concentration.
Greenhouse gases have increased since pre-industrial times (the mid-18th
century) by an amount that is radiatively equivalent to about a 50% increase in
carbon dioxide, although carbon dioxide itself has risen by only 26%; other gases
have made up the rest.
10
BUSINESS
AS USUAL
1120
8
FORCING (watts/metre2)
B
6
C
4
560
SCENARIO D
2
EQUIVALENT CO2
CONCENTRATION (ppm)
0
280
1900
1950
2000
2050
2100
YEAR
Radiative forcing, also expressed as equivalent carbon dioxide concentrations,
resulting from the four IPCC emissions scenarios
The contributions of the various gases to the total increase in climate forcing during
the 1980s is shown below as a pie diagram; carbon dioxide is responsible for
about half the decadal increase. (Ozone, the effects of which may be significant, is
not included)
CFCs
11 and 12
OTHER
CFCs
CARBON
DIOXIDE
55%
NITROUS
OXIDE
METHANE
The contribution from each of the human-made greenhouse gases to the change in
radiative forcing from 1980 to 1990. The contribution from ozone may also be
significant, but cannot be quantified at present.
How can we evaluate the effect of different greenhouse gases?
To evaluate possible policy options, it is useful to know the relative radiative effect
(and, hence, potential climate effect) of equal emissions of each of the greenhouse
gases. The concept of relative Global Warming Potentials (GWP) has been
developed to take into account the differing times that gases remain in the
atmosphere.
This index defines the time-integrated warming effect due to an instantaneous
release of unit mass (1 kg) of a given greenhouse gas in today's atmosphere,
relative to that of carbon dioxide. The relative importances will change in the future
as atmospheric composition changes because, although radiative forcing
increases in direct proportion to the concentration of CFCs, changes in the other
greenhouse gases (particularly carbon dioxide) have an effect on forcing which is
much less than proportional.
The GWPs in the following table are shown for three time horizons, reflecting the
need to consider the cumulative effects on climate over various time scales. The
longer time horizon is appropriate for the cumulative effect; the shorter timescale
will indicate the response to emission changes in the short term. There are a
number of practical difficulties in devising and calculating the values of the GWPs,
and the values given here should be considered as preliminary. In addition to
these direct effects, there are indirect effects of human-made emissions arising
from chemical reactions between the various constituents. The indirect effects on
stratospheric water vapour, carbon dioxide and tropospheric ozone have been
included in these estimates.
The table indicates, for example, that the effectiveness of methane in influencing
climate will be greater in the first few decades after release, whereas emission of
the longer-lived nitrous oxide will affect climate for a much longer time. The
lifetimes of the proposed CFC replacements range from 1 to 40 years; the longer
lived replacements are still potentially effective as agents of climate change. One
example of this, HCFC-22 (with a 15 year lifetime), has a similar effect (when
released in the same amount) as CFC-11 on a 20 year timescale; but less over a
500 year timescale.
GLOBAL WARMING POTENTIALS
The warming effect of an emission of 1kg of each gas relative to that of CO₂
I
These figures are best estimates calculated on the basis of the present day atmospheric composition
Time Horizon
20 yr
100 yr
500 yr
Carbon dioxide
1
1
1
Methane (including indirect)
63
21
9
Nitrous oxide
270
290
190
CFC-11
4500
3500
1500
CFC-12
7100
7300
4500
HCFC-22
4100
1500
510
Global Warming Potentials for a range of CFCs and potential replacements are given in the full text
The table shows carbon dioxide to be the least effective greenhouse gas per
kilogramme emitted, but its contribution to global warming, which depends on the
product of the GWP and the amount emitted, is largest. In the example in the box
below, the effect over 100 years of emissions of greenhouse gases in 1990 are
shown relative to carbon dioxide. This is illustrative; to compare the effect of
different emission projections we have to sum the effect of emissions made in
future years
THE RELATIVE CUMULATIVE CLIMATE EFFECT OF 1990 MAN-MADE
EMISSIONS
GWP
1990
Relative
(100yr
emissions
contribution
horizon)
(Tg)
over 100yr
Carbon dioxide
1
26000t
61%
Methane*
21
300
15%
Nitrous oxide
290
6
4%
CFCs
Various
0.9
11%
HCFC-22
1500
0.1
0.5%
Others*
Various
8.5%
*These values include the indirect effect of these emissions on other greenhouse gases via chemical
reactions in the atmosphere. Such estimates are highly model dependent and should be considered
preliminary and subject to change. The estimated effect of ozone is included under "others". The
gases included under "others" are given in the full report.
t 26 000 Tg (teragrams) of carbon dioxide = 7 000 Tg (=7 Gt) of carbon
18
There are other technical criteria which may help policymakers to decide, in the
event of emissions reductions being deemed necessary, which gases should be
considered. Does the gas contribute in a major way to current, and future, climate
forcing? Does it have a long lifetime, so earlier reductions in emissions would be
more effective than those made later? And are its sources and sinks well enough
known to decide which could be controlled in practice? The table below illustrates
these factors.
MAJOR
LONG
SOURCES
GAS
CONTRIBUTOR?
LIFETIME?
KNOWN?
Carbon dioxide
yes
yes
yes
Methane
yes
no
semi-quantitatively
Nitrous oxide
not at
yes
qualitatively
present
CFCs
yes
yes
yes
HCFCs, etc
not at
mainly no
yes
present
Ozone
possibly
no
qualitatively
How much do we expect climate to change?
It is relatively easy to determine the direct effect of the increased radiative forcing
due to increases in greenhouse gases. However, as climate begins to warm,
various processes act to amplify (through positive feedbacks) or reduce (through
negative feedbacks) the warming. The main feedbacks which have been identified
are due to changes in water vapour, sea-ice, clouds and the oceans.
The best tools we have which take the above feedbacks into account (but do not
include greenhouse gas feedbacks) are three-dimensional mathematical models of
the climate system (atmosphere-ocean-ice-land) known as General Circulation
Models (GCMs). They synthesise our knowledge of the physical and dynamical
processes in the overall system and allow for the complex interactions between the
various components. However, in their current state of development, the
descriptions of many of the processes involved are comparatively crude. Because
of this, considerable uncertainty is attached to these predictions of climate change,
which is reflected in the range of values given; further details are given in a later
section.
The estimates of climate change presented here are based on
i. the "best estimate" of equilibrium climate sensitivity (i.e the equilibrium
temperature change due to a doubling of carbon dioxide in the atmosphere)
19
obtained from model simulations, feedback analyses and observational
considerations (see box: "What tools do we use?")
ii. a "box diffusion upwelling" ocean-atmosphere climate model which
translates the greenhouse forcing into the evolution of the temperature response
for the prescribed climate sensitivity. (This simple model has been calibrated
against more complex atmosphere-ocean coupled GCMs for situations where the
more complex models have been run).
What tools do we use to predict future climate, and how do we use them?
The most highly developed tool which we have to predict future climate is known as a general
circulation model or GCM. These models are based on the laws of physics and use
descriptions in simplified physical terms (called parameterisations) of the smaller-scale processes
such as those due to clouds and deep mixing in the ocean. In a climate model an atmospheric
component, essentially the same as a weather prediction model, is coupled to a model of the
ocean, which can be equally complex.
Climate forecasts are derived in a different way from weather forecasts. A weather prediction model
gives a description of the atmosphere's state up to 10 days or so ahead, starting from a detailed
description of an initial state of the atmosphere at a given time. Such forecasts describe the
movement and development of large weather systems, though they cannot represent very small
scale phenomena; for example, individual shower clouds.
To make a climate forecast, the climate model is first run for a few (simulated) decades. The statistics
of the model's output is a description of the model's simulated climate which, if the model is a good
one, will bear a close resemblance to the climate of the real atmosphere and ocean. The above
exercise is then repeated with increasing concentrations of the greenhouse gases in the model.
The differences between the statistics of the two simulations ( for example in mean temperature and
interannual variability) provide an estimate of the accompanying climate change.
The long term change in surface air temperature following a doubling of carbon dioxide
(referred to as the climate sensitivity) is generally used as a benchmark to compare models. The
range of results from model studies is 1.9 to 5.2°C. Most results are close to 4.0°C but recent
studies using a more detailed but not necessarily more accurate representation of cloud processes
give results in the lower half of this range. Hence the models results do not justify altering the
previously accepted range of 1.5 to 4.5°C.
Although scientists are reluctant to give a single best estimate in this range, it is neccessary for the
presentation of climate predictions for a choice of best estimate to be made. Taking into account the
model results, together with observational evidence over the last century which is suggestive of the
climate sensitivity being in the lower half of the range, (see section: "Has man already begun to
change global climate?") a value of climate sensitivity of 2.5°C has been chosen as the best
estimate. Further details are given in Section 5 of the report.
In this Assessment, we have also used much simpler models, which simulate the behaviour of
GCMs, to make predictions of the evolution with time of global temperature from a number of
emission scenarios. These so-called box-diffusion models contain highly simplified physics but give
similar results to GCMs when globally averaged.
A completely different, and potentially useful, way of predicting patterns of future climate is to
search for periods in the past when the global mean temperatures were similar to those we expect in
future, and then use the past spatial patterns as analogues of those which will arise in the future.
For a good analogue, it is also necessary for the forcing factors (for example, greenhouse gases,
orbital variations) and other conditions (for example, ice cover, topography, etc.) to be similar; direct
comparisons with climate situations for which these conditions do not apply cannot be easily
interpreted. Analogues of future greenhouse-gas-changed climates have not been found.
We cannot therefore advocate the use of paleo-climates as predictions of regional climate change
due to future increases in greenhouse gases. However, paleo-climatological information can
provide useful insights into climate processes, and can assist in the validation of climate models.
How quickly will global climate change ?
a. If emissions follow a Business-as-Usual pattern
Under the IPCC Business-as-Usual (Scenario A) emissions of greenhouse gases,
the average rate of increase of global mean temperature during the next century is
estimated to be about 0.3°C per decade (with an uncertainty range of 0.2°C to
0.5°C). This will result in a likely increase in global mean temperature of about 1°C
above the present value (about 2°C above that in the pre-industrial period) by 2025
and 3°C above today's (about 4°C above pre-industrial) before the end of the next
century.
The projected temperature rise out to the year 2100, with high, low and best-
estimate climate responses, is shown in the diagram below. Because of other
factors which influence climate, we would not expect the rise to be a steady one
7
BUSINESS
6
HIGH ESTIMATE
AS-USUAL
REALISED TEMPERATURE RISE
5
4
BEST ESTIMATE
3
above 1765 (°C)
LOW ESTIMATE
2
1
0
1850
1900
1950
2000
2050
2100
YEAR
Simulation of the Increase In global mean temperature from 1850-1990 due to
observed increases In greenhouse gases, and predictions of the rise between
1990 and 2100 resulting from the Business-as-Usual emissions.
The temperature rises shown above are realised temperatures; at any time we
would also be committed to a further temperature rise toward the equilibrium
temperature (see box: "Equilibrium and Realised Climate Change"). For the BaU
"best estimate" case in the year 2030, for example, a further 0.9°C rise would be
expected, about 0.2°C of which would be realised by 2050 (in addition to changes
due to further greenhouse gas increases); the rest would become apparent in
decades or centuries.
Even if we were able to stabilise emissions of each of the greenhouse gases at
present day levels from now on, the temperature is predicted to rise by about 0.2°C
per decade for the first few decades.
The global warming will also lead to increased global average precipitation and
diminish. evaporation of a few percent by 2030. Areas of sea-ice and snow are expected to
21
b. If emissions are subject to controls
Under the other IPCC emission scenarios which assume progressively increasing
levels of controls, average rates of increase in global mean temperature over the
1
next century are estimated to be about 0.2°C per decade (Scenario B), just above
0.1°C per decade (Scenario C) and about 0.1°C per decade (Scenario D). The
results are illustrated below, with the Business-as-Usual case for comparison. Only
the best-estimate of the temperature rise is shown in each case.
5
BUSINESS
4
AS-USUAL
REALISED TEMPERATURE
RISE above 1765(°C)
3
SCENARIO B
SCENARIO C
2
SCENARIO D
1
0
1850
1900
1950
2000
2050
2100
YEAR
Simulations of the Increase In global mean temperature from 1850-1990 due to
observed Increases in greenhouse gases, and predictions of the rise between
1990 and 2100 resulting from the IPCC Scenario B,C and D emissions, with the
Business-as-Usual case for comparison.
The indicated range of uncertainty in global temperature rise given above reflects a
subjective assessment of uncertainties in the calculation of climate response, but
does not include those due to the transformation of emissions to concentrations,
nor the effects of greenhouse gas feedbacks.
22
Equilibrium and realised climate change
When the radiative forcing on the earth-atmosphere system is changed, for example by increasing
greenhouse gas concentrations, the atmosphere will try to respond (by warming) immediately. But
the atmosphere is closely coupled to the oceans, so in order for the air to be warmed by the
greenhouse effect, the oceans also have to be warmed; because of their thermal capacity this takes
decades or centuries. This exchange of heat between atmosphere and ocean will act to slow down
the temperature rise forced by the greenhouse effect.
in a hypothetical example where the concentration of greenhouse gases in the atmosphere,
following a period of constancy, rises suddenly to a new level and remains there, the radiative
forcing would also rise rapidly to a new level. This increased radiative forcing would cause the
atmosphere and oceans to warm, and eventually come to a new, stable, temperature. A commitment
to this equilibrium temperature rise is incurred as soon as the greenhouse gas concentration
changes. But at any time before equilibrium is reached, the actual temperature will have risen by
only part of the equilibrium temperature change, known as the realised temperature change.
Models predict that, for the present day case of an increase in radiative forcing which is
approximately steady, the realised temperature rise at any time is about 50% of the committed
temperature rise if the climate sensitivity (the response to a doubling of carbon dioxide) is 4.5°C and
about 80% if the climate sensitivity is 1.5°C. If the forcing were then held constant, temperatures
would continue to rise slowly, but it is not certain whether it would
take decades or centuries for most of the remaining rise to equilibrium to occur
Forcing stablisation
Forcing
Forcing
0
50
100
150
0
100
200
300
Years
Years
Equilibrium
4
4
Equilibrium
°C
°C
temperature
uncertainty
3
3
Slow rise toward
Realised
2
equilibrium
2
temperature
1
1
0
o
0
50
100
150
0
100
200
300
Years
Years
What will be the patterns of climate change by 2030?
Knowledge of the global mean warming and change in precipitation is of limited
use in determining the impacts of climate change, for instance on agriculture. For
this we need to know changes regionally and seasonally.
Models predict that surface air will warm faster over land than over oceans, and a
minimum of warming will occur around Antarctica and in the northern North Atlantic
region.
There are some continental-scale changes which are consistently predicted by the
highest resolution models and for which we understand the physical reasons. The
warming is predicted to be 50-100% greater than the global mean in high northern
latitudes in winter, and substantially smaller than the global mean in regions of sea
ice in summer. Precipitation is predicted to increase on average in middle and
high latitude continents in winter (by some 5 - 10% over 35-55°N).
Five regions, each a few million square kilometres in area and representative of
different climatological regimes, were selected by IPCC for particular study (see
map below). In the box below are given the changes in temperature, precipitation
and soil moisture, which are predicted to occur by 2030 on the Business-as-Usual
scenario, as an average over each of the five regions. There may be considerable
variations within the regions. In general, confidence in these regional estimates is
low, especially for the changes in precipitation and soil moisture, but they are
examples of our best estimates. We cannot yet give reliable regional predictions at
the smaller scales demanded for impacts assessments.
4
2
3-
5
Map showing the locations and extents of the five areas selected by IPCC
24
ESTIMATES FOR CHANGES BY 2030
(IPCC Business-as-Usual scenario; changes from pre Industrial)
The numbers given below are based on high resolution models, scaled to be consistent with our
best estimate of global mean warming of 1.8°C by 2030. For values consistent with other estimates
of global temperature rise, the numbers below should be reduced by 30% for the low estimate or
increased by 50% for the high estimate. Precipitation estimates are also scaled in a similar way.
Confidence in these regional estimates is low.
Central North America (35°-50°N 85°-105°W)
The warming varies from 2 to 4°C in winter and 2 to 3°C in summer.
Precipitation increases range from 0 to 15% in winter whereas there are
decreases of 5 to 10% in summer. Soil moisture decreases in summer by 15 to
20%.
Southern Asia (5°-30°N 70°-105°E)
The warming varies from 1 to 2°C throughout the year. Precipitation changes
little in winter and generally increases throughout the region by 5 to 15% in
summer. Summer soil moisture increases by 5 to 10%.
Sahel (10°-20°N 20°W-40°E)
The warming ranges from 1 to 3°C. Area mean precipitation increases and area
mean soil moisture decreases marginally in summer. However, throughout the
region, there are areas of both increase and decrease in both parameters
throughout the region.
Southern Europe (35°-50°N 10°W- 45°E)
The warming is about 2°C in winter and varies from 2 to 3°C in summer. There
is some indication of increased precipitation in winter, but summer precipitation
decreases by 5 to 15%, and summer soil moisture by 15 to 25%.
Australia (12°-45°S 110°-155°E)
The warming ranges from 1 to 2°C in summer and is about 2°C in winter.
Summer precipitation increases by around 10%, but the models do not produce
consistent estimates of the changes in soil moisture. The area averages hide
large variations at the sub-continental level.
How will climate extremes and extreme events change?
Changes in the variability of weather and the frequency of extremes will generally
have more impact than changes in the mean climate at a particular location. With
the possible exception of an increase in the number of intense showers, there is no
clear evidence that weather variability will change in the future. In the case of
temperatures, assuming no change in variability, but with a modest increase in the
mean, the number of days with temperatures above a given value at the high end
of the distribution will increase substantially. On the same assumptions, there will
be a decrease in days with temperatures at the low end of the distribution. So the
number of very hot days or frosty nights can be substantially changed without any
change in the variability of the weather. The number of days with a minimum
threshold amount of soil moisture (for viability of a certain crop, for example) would
be even more sensitive to changes in average precipitation and evaporation.
If the large scale weather regimes, for instance depression tracks or anticyclones,
shift their position, this would effect the variability and extremes of weather at a
particular location, and could have a major effect. However, we do not know if, or
in what way, this will happen.
Will storms increase in a warmer world?
Storms can have a major impact on society. Will their frequency, intensity or
location increase in a warmer world?
Tropical storms, such as typhoons and hurricanes, only develop at present over
seas that are warmer than about 26°C. Although the area of sea having
temperatures over this critical value will increase as the globe warms, the critical
temperature itself may increase in a warmer world. Although the theoretical
maximum intensity is expected to increase with temperature, climate models give
no consistent indication whether tropical storms will increase or decrease in
frequency or intensity as climate changes; neither is there any evidence that this
has occurred over the past few decades.
Mid-latitude storms, such as those which track across the North Atlantic and
North Pacific, are driven by the equator-to-pole temperature contrast. As this
contrast will probably be weakened in a warmer world (at least in the northern
hemisphere), it might be argued that mid-latitude storms will also weaken or
change their tracks, and there is some indication of a general reduction in day-to-
day variability in the mid-latitude storm tracks in winter in model simulations,
though the pattern of changes vary from model to model. Present models do not
resolve smaller-scale disturbances, so it will not be possible to assess changes in
storminess until results from higher resolution models become available in the next
few years.
Climate change in the longer term
The foregoing calculations have focussed on the period up to the year 2100; it is
clearly more difficult to make calculations for years beyond 2100. However, while
the timing of a predicted increase in global temperatures has substantial
uncertainties, the prediction that an increase will eventually occur is more certain.
Furthermore, some model calculations that have been extended beyond 100 years
suggest that, with continued increases in greenhouse climate forcing, there could
be significant changes in the ocean circulation, including a decrease in North
Atlantic deep water formation.
Other factors which could influence future climate
Variations in the output of solar energy may also affect climate. On a decadal
time-scale solar variability and changes in greenhouse gas concentration could
give changes of similar magnitudes. However the variation in solar intensity
changes sign so that over longer timescales the increases in greenhouse gases
are likely to be more important. Aerosols as a result of volcanic eruptions can
lead to a cooling at the surface which may oppose the greenhouse warming for a
few years following an eruption. Again, over longer periods the greenhouse
warming is likely to dominate.
26
Human activity is leading to an increase in aerosols in the lower atmosphere,
mainly from sulphur emissions. These have two effects, both of which are difficult to
quantify but which may be significant particularly at the regional level. The first is
the direct effect of the aerosols on the radiation scattered and absorbed by the
atmosphere. The second is an indirect effect whereby the aerosols affect the
microphysics of clouds leading to an increased cloud reflectivity. Both these effects
might lead to a significant regional cooling; a decrease in emissions of sulphur
might be expected to increase global temperatures.
Because of long-period couplings between different components of the climate
system, for example between ocean and atmosphere, the earth's climate would still
vary without being perturbed by any external influences. This natural variability
could act to add to, or subtract from, any human-made warming; on a century
timescale this would be less than changes expected from greenhouse gas
increases.
How much confidence do we have in our
predictions?
Uncertainties in the above climate predictions arise from our imperfect knowledge
of:
future rates of human-made emissions
how these will change the atmospheric concentrations of greenhouse
gases
the response of climate to these changed concentrations
Firstly, it is obvious that the extent to which climate will change depends on the rate
at which greenhouse gases (and other gases which affect their concentrations) are
emitted. This in turn will be determined by various complex economic and
sociological factors. Scenarios of future emissions were generated within IPCC
WGIII and are described in the annex.
Secondly, because we do not fully understand the sources and sinks of the
greenhouse gases, there are uncertainties in our calculations of future
concentrations arising from a given emissions scenario. We have used a number
of models to calculate concentrations and chosen a best estimate for each gas. In
the case of carbon dioxide, for example, the concentration increase between 1990
and 2070 due to the Business-as-Usual emissions scenario spanned almost a
factor of two between the highest and lowest model result (corresponding to a
range in radiative forcing change of about 50%)
Furthermore, because natural sources and sinks of greenhouse gases are
sensitive to a change in climate, they may substantially modify future
concentrations (see earlier section: "Greenhouse gas feedbacks"). It appears that,
as climate warms, these feedbacks will lead to an overall increase, rather than
decrease, in natural greenhouse gas abundances. For this reason, climate change
is likely to be greater than the estimates we have given.
Thirdly, climate models are only as good as our understanding of the processes
which they describe, and this is far from perfect. The ranges in the climate
predictions given above reflect the uncertainties due to model imperfections; the
largest of these is cloud feedback (those factors affecting the cloud amount and
distribution and the interaction of clouds with solar and terrestrial radiation), which
leads to a factor of two uncertainty in the size of the warming. Others arise from the
transfer of energy between the atmosphere and ocean, the atmosphere and land
surfaces, and between the upper and deep layers of the ocean. The treatment of
sea-ice and convection in the models is also crude. Nevertheless, for reasons
given in the box below, we have substantial confidence that models can predict at
least the broad-scale features of climate change.
Furthermore, we must recognise that our imperfect understanding of climate
processes (and corresponding ability to model them) could make us vulnerable to
surprises; just as the human-made ozone hole over Antarctica was entirely
unpredicted. In particular, the ocean circulation, changes in which are thought to
have led to periods of comparatively rapid climate change at the end of the last ice
age, is not well observed, understood or modelled.
Confidence in predictions from climate models
What confidence can we have that climate change due to increasing greenhouse gases will look
anything like the model predictions? Weather forecasts can be compared with the actual weather
the next day and their skill assessed; we cannot do that with climate predictions. However, there are
several indicators that give us some confidence in the predictions from climate models.
When the latest atmospheric models are run with the present atmospheric concentrations of
greenhouse gases and observed boundary conditions their simulation of present climate is
generally realistic on large scales, capturing the major features such as the wet tropical
convergence zones and mid-latitude depression belts, as well as the contrasts between summer
and winter circulations. The models also simulate the observed variability; for example, the large
day-to-day pressure variations in the middle latitude depression belts and the maxima in
interannual variability responsible for the very different character of one winter from another both
being represented. However, on regional scales (2,000km or less), there are significant errors in
all models.
Overall confidence is increased by atmospheric models' generally satisfactory portrayal of aspects
of variability of the atmosphere, for instance those associated with variations in sea surface
temperature. There has been some success in simulating the general circulation of the ocean,
including the patterns (though not always the intensities) of the principal currents, and the
distributions of tracers added to the ocean.
Atmospheric models have been coupled with simple models of the ocean to predict the equilibrium
response to greenhouse gases, under the assumption that the model errors are the same in a
changed climate. The ability of such models to simulate important aspects of the climate of the last
ice age generates confidence in their usefulness. Atmospheric models have also been coupled
with multilayer ocean models (to give coupled ocean-atmosphere GCMs) which predict the gradual
response to increasing greenhouse gases. Although the models so far are of relatively coarse
resolution, the large scale structures of the ocean and the atmosphere can be simulated with some
skill. However, the coupling of ocean and atmosphere models reveals a strong sensitivity to small
scale errors which leads to a drift away from the observed climate. As yet, these errors must be
removed by adjustments to the exchange of heat between ocean and atmosphere. There are
similarities between results from the coupled models using simple representations of the ocean and
those using more sophisticated descriptions, and our understanding of such differences as do
occur gives us some confidence in the results.
Will the climate of the future be very different?
When considering future climate change, it is clearly essential to look at the record
of climate variation in the past. From it we can learn about the range of natural
climate variability, to see how it compares with what we expect in the future, and
also look for evidence of recent climate change due to man's activities.
Climate varies naturally on all time scales from hundreds of millions of years down
to the year to year. Prominent in the Earth's history have been the 100,000 year
glacial-interglacial cycles when climate was mostly cooler than at present. Global
surface temperatures have typically varied by 5-7°C through these cycles, with
large changes in ice volume and sea level, and temperature changes as great as
10-15°C in some middle and high latitude regions of the northern hemisphere.
Since the end of the last ice age, about 10,000 years ago, global surface
temperatures have probably fluctuated by little more than 1°C. Some fluctuations
have lasted several centuries, including the Little Ice Age which ended in the
nineteenth century and which appears to have been global in extent.
The changes predicted to occur by about the middle of the next century due to
increases in greenhouse gas concentrations from the Business-as-Usual
emissions will make global mean temperatures higher than they have been in the
last 150,000 years.
The rate of change of global temperatures predicted for Business-as-Usual
emissions will be greater than those which have occured naturally on earth over
the last 10,000 years, and the rise in sea level will be about three to six times faster
than that seen over the last 100 years or so.
Has man already begun to change the global
climate?
The instrumental record of surface temperature is fragmentary until the mid-
nineteenth century, after which it slowly improves. Because of different methods of
measurement, historical records have to be harmonised with modern observations,
introducing some uncertainty. Despite these problems we believe that a real
warming of the globe of 0.3°C - 0.6°C has taken place over the last century; any
bias due to urbanisation is likely to be less than 0.05°C.
Moreover since 1900 similar temperature increases are seen in three independent
data sets: one collected over land and two over the oceans. The figure below
shows current estimates of smoothed global mean surface temperature over land
and ocean since 1860. Confidence in the record has been increased by their
similarity to recent satellite measurements of mid-tropospheric temperatures.
0.5
0.4
0.3
TEMPERATURE CHANGE (°C)
0.2
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
1850
1900
1950
2000
YEAR
Global mean combined land-air and sea-surface temperatures, 1861 - 1989, relative
to the average for 1951-80.
Although the overall temperature rise has been broadly similar in both
hemispheres, it has not been steady, and differences in their rates of warming have
sometimes persisted for decades. Much of the warming since 1900 has been
concentrated in two periods, the first between about 1910 and 1940 and the other
since 1975; the five warmest years on record have all been in the 1980s. The
northern hemisphere cooled between the 1940s and the early 1970s when
southern hemisphere temperatures stayed nearly constant. The pattern of global
warming since 1975 has been uneven with some regions, mainly in the northern
hemisphere, continuing to cool until recently. This regional diversity indicates that
future regional temperature changes are likely to differ considerably from a global
average.
The conclusion that global temperature has been rising is strongly supported by
the retreat of most mountain glaciers of the world since the end of the nineteenth
century and the fact that global sea level has risen over the same period by an
average of 1 to 2mm per year. Estimates of thermal expansion of the oceans, and
of increased melting of mountain glaciers and the ice margin in West Greenland
over the last century, show that the major part of the sea level rise appears to be
related to the observed global warming. This apparent connection between
observed sea level rise and global warming provides grounds for believing that
future warming will lead to an acceleration in sea level rise.
The size of the warming over the last century is broadly consistent with the
predictions of climate models, but is also of the same magnitude as natural climate
variability. If the sole cause of the observed warming were the human-made
greenhouse effect, then the implied climate sensitivity would be near the lower end
of the range inferred from the models. The observed increase could be largely due
to natural variability; alternatively this variability and other man-made factors could
have offset a still larger man-made greenhouse warming. The unequivocal
detection of the enhanced greenhouse effect from observations is not likely for a
decade or more, when the committment to future climate change will then be
considerably larger than it is today.
Global-mean temperature alone is an inadequate indicator of greenhouse-gas-
induced climatic change. Identifying the causes of any global-mean temperature
change requires examination of other aspects of the changing climate, particularly
its spatial and temporal characteristics - the man-made climate change "signal".
Patterns of climate change from models such as the northern hemisphere warming
faster than the southern hemisphere, and surface air warming faster over land than
over oceans, are not apparent in observations to date. However, we do not yet
know what the detailed "signal" looks like because we have limited confidence in
our predictions of climate change patterns. Furthermore, any changes to date
could be masked by natural variability and other (possibly man-made) factors, and
we do not have a clear picture of these.
How much will sea level rise ?
Simple models were used to calculate the rise in sea level to the year 2100 ; the
results are illustrated below. The calculations necessarily ignore any long-term
changes, unrelated to greenhouse forcing, that may be occurring but cannot be
detected from the present data on land ice and the ocean. The sea-level rise
expected from 1990-2100 under the IPCC Business as Usual emissions scenario
is shown below. An average rate of global mean sea level rise of about 6cm per
decade over the next century (with an uncertainty range of 3 - 10 cm per decade).
The predicted rise is about 20cm in global mean sea level by 2030, and 65cm by
the end of the next century. There will be significant regional variations.
The best estimate in each case is made up mainly of positive contributions from
thermal expansion of the oceans and the melting of glaciers Although, over the
next 100 years, the effect of the Antarctic and Greenland ice sheets is expected to
be small, they make a major contribution to the uncertainty in predictions.
120
BUSINESS
HIGH ESTIMATE
100
AS-USUAL
SEA LEVEL RISE (cm)
80
BEST ESTIMATE
60
40
LOW ESTIMATE
20
0
1980
2000
2020
2040
2060
2080
2100
YEAR
Sea level rise predicted to result from Business-as-Usual emissions, showing the
best-estimate and range
31
Even if greenhouse forcing increased no further, there would still be a commitment
to a continuing sea level rise for many decades and even centuries, due to delays
in climate, ocean and ice mass responses. As an illustration, if the increases in
greenhouse gas concentrations were to suddenly stop in 2030, sea level would go
on rising from 2030 to 2100, by as much again as from 1990-2030, as shown in the
diagram below.
40
SEA LEVEL RISE (cm)
30
commitment
20
10
FORCING STABILISED
IN 2030
0
1980
2000
2020
2040
2060
2080
2100
YEAR
Commitment to sea level rise In the year 2030. The curve shows the sea level rise
due to Business-as-Usual emissions to 2030, with the additional rise that would
occur In the remainder of the century even If climate forcing was stabilised In 2030.
Predicted sea level rises due to the other three emissions scenarios are shown
below, with the Business-as-Usual case for comparison; only best-estimate
calculations are shown.
80
BUSINESS
60
AS-USUAL
SEA LEVEL RISE (cm)
SCENARIO B
40
SCENARIO C
SCENARIO D
20
0
1980
2000
2020
2040
2060
2080
2100
YEAR
Model estimates of sea-level rise from 1990-2100 due to all four emissions
scenarlos.
32
The West Antarctic Ice Sheet is of special concern. A large portion of it, containing
an amount of ice equivalent to about 5m of global sea level, is grounded far below
sea level. There have been suggestions that a sudden outflow of ice might result
from global warming and raise sea level quickly and substantially. Recent studies
have shown that individual ice streams are changing rapidly on a decade-to-
century timescale; however this is not necessarily related to climate change. Within
the next century, it is not likely that there will be a major outflow of ice from West
Antarctica due directly to global warming.
Any rise in sea level is not expected to be uniform over the globe. Thermal
expansion, changes in ocean circulation, and surface air pressure will vary from
region to region as the world warms, but in an as yet unknown way. Such regional
details await further development of more realistic coupled ocean atmosphere
models. In addition, vertical land movements can be as large or even larger than
changes in global mean sea level; these movements have to be taken into account
when predicting local change in sea level relative to land.
The most severe effects of sea-level rise are likely to result from extreme events (for
example, storm surges) the incidence of which may be affected by climatic change.
What will be the effect of climate change on
ecosystems ?
Ecosystem processes such as photosynthesis and respiration are dependent on
climatic factors and carbon dioxide concentration in the short term. In the longer
term, climate and carbon dioxide are among the factors which control ecosystem
structure, i.e., species composition, either directly by increasing mortality in poorly
adapted species, or indirectly by mediating the competition between species.
Ecosystems will respond to local changes in temperature (including its rate of
change), precipitation, soil moisture and extreme events. Current models are
unable to make reliable estimates of changes in these parameters on the required
local scales.
Photosynthesis captures atmospheric carbon dioxide, water and solar energy and
stores them in organic compounds which are then used for subsequent plant
growth, the growth of animals or the growth of microbes in the soil. All of these
organisms release carbon dioxide via respiration into the atmosphere. Most land
plants have a system of photosynthesis which will respond positively to increased
atmospheric carbon dioxide ("the carbon dioxide fertilization effect") but the
response varies with species. The effect may decrease with time when restricted
by other ecological limitations, for example, nutrient availability. It should be
emphasized that the carbon content of the terrestrial biosphere will increase only if
the forest ecosystems in a state of maturity will be able to store more carbon in a
warmer climate and at higher concentrations of carbon dioxide. We do not yet know
if this is the case.
The response to increased carbon dioxide results in greater efficiencies of water,
light and nitrogen use. These increased efficiencies may be particularly important
during drought and in arid/semi-arid and infertile areas.
Because species respond differently to climatic change, some will increase in
abundance and/or range while others will decrease. Ecosystems will therefore
change in structure and composition. Some species may be displaced to higher
latitudes and altitudes, and may be more prone to local, and possibly even global,
extinction; other species may thrive.
As stated above, ecosystem structure and species distribution are particularly
sensitive to the rate of change of climate. We can deduce something about how
quickly global temperature has changed in the past from paleoclimatological
records. As an example, at the end of the last glaciation, within about a century,
temperature increased by up to 5°C in the North Atlantic region, mainly in Western
Europe. Although during the increase from the glacial to the current interglacial
temperature simple tundra ecosystems responded positively, a similar rapid
temperature increase applied to more developed ecosystems could result in their
instability.
DEFORESTATION AND REFORESTATION
Man has been deforesting the Earth for millennia. Until the early part of the
century, this was mainly in temperate regions, more recently it has been
concentrated in the tropics. Deforestation has several potential impacts on
climate: through the carbon and nitrogen cycles (where it can lead to changes in
atmospheric carbon dioxide concentrations), through the change in reflectivity of
terrain when forests are cleared, through its effect on the hydrological cycle
(precipitation, evaporation and runoff) and surface roughness and thus
atmospheric circulation which can produce remote effects on climate.
It is estimated that each year about 2 Gt of carbon (GtC) is released to the
atmosphere due to tropical deforestation. The rate of forest clearing is difficult to
estimate; probably until the mid-20th century, temperate deforestation and the
loss of organic matter from soils was a more important contributor to atmospheric
carbon dioxide than was the burning of fossil fuels. Since then, fossil fuels have
become dominant; one estimate is that around 1980, 1.6 GtC was being released
annually from the clearing of tropical forests, compared with about 5 GtC from the
burning of fossil fuels. If all the tropical forests were removed, the input is
variously estimated at from 150 to 240 GtC; this would increase atmospheric
carbon dioxide by 35 to 60 ppmv.
To analyse the effect of reforestation we assume that 10 million hectares of forests
are planted each year for a period of 40 years, ie 4 million km2 would then have
been planted by 2030, at which time 1GtC would be absorbed annually until
these forests reach maturity. This would happen in 40-100 years for most forests.
The above scenario implies an accumulated uptake of about 20GtC by the year
2030 and up to 80GtC after 100 years. This accumulation of carbon in forests is
equivalent to some 5-10% of the emission due to fossil fuel burning in the
Business-as-Usual scenario.
Deforestation can also alter climate directly by increasing reflectivity and
decreasing evapotranspiration. Experiments with climate models predict that
replacing all the forests of the Amazon Basin by grassland would reduce the
rainfall over the basin by about 20%, and increase mean temperature by several
degrees.
34
What should be done to reduce uncertainties, and
how long will this take ?
Although we can say that some climate change is unavoidable, much uncertainty
exists in the prediction of global climate properties such as the temperature and
rainfall. Even greater uncertainty exists in predictions of regional climate change,
and the subsequent consequences for sea level and ecosystems. The key areas of
scientific uncertainty are:
clouds: primarily cloud formation, dissipation, and radiative properties,
which influence the response of the atmosphere to greenhouse forcing;
oceans: the exchange of energy between the ocean and the
atmosphere, between the upper layers of the ocean and the deep ocean,
and transport within the ocean, all of which control the rate of global
climate change and the patterns of regional change;
greenhouse gases: quantification of the uptake and release of the
greenhouse gases, their chemical reactions in the atmosphere, and how
these may be influenced by climate change.
polar ice sheets: which affect predictions of sea level rise
important. Studies of land surface hydrology, and of impact on ecosystems, are also
To reduce the current scientific uncertainties in each of these areas will require
internationally coordinated research, the goal of which is to improve our capability
to observe, model and understand the global climate system. Such a program of
research will reduce the scientific uncertainties and assist in the formulation of
sound national and international response strategies.
Systematic long-term observations of the system are of vital importance for
understanding the natural variability of the Earth's climate system, detecting
whether man's activities are changing it, parametrising key processes for models,
and verifying model simulations. Increased accuracy and coverage in many
observations are required. Associated with expanded observations is the need to
develop appropriate comprehensive global information bases for the rapid and
efficient dissemination and utilization of data. The main observational
requirements are:
(i) the maintenance and improvement of observations (such as those from
satellites) provided by the World Weather Watch Programme of WMO
(ii) the maintenance and enhancement of a programme of monitoring, both
from satellite-based and surface-based instruments, of key climate
elements for which accurate observations on a continuous basis are
required, such as the distribution of important atmospheric constituents,
clouds, the earth's radiation budget, precipitation, winds, sea surface
temperatures and terrestrial ecosystem extent, type and productivity.
(iii) the establishment of a global ocean observing system to measure changes
in such variables as ocean surface topography, circulation, transport of
heat and chemicals, and sea-ice extent and thickness.
(iv) the development of major new systems to obtain data on the oceans,
atmosphere and terrestrial ecosystems using both satellite-based
instruments and instruments based on the surface, on automated
instrumented vehicles in the ocean, on floating and deep sea buoys, and
on aircraft and balloons.
(v) the use of paleoclimatological and historical instrumental records to
document natural variability and changes in the climate system, and
subsequent environmental response.
The modelling of climate change requires the development of global models
which couple together atmosphere, land, ocean and ice models and which
incorporate more realistic formulations of the relevant processes and the
interactions between the different components. Processes in the biosphere (both
on land and in the ocean) also need to be included. Higher spatial resolution than
is currently generally used is required if regional patterns are to be predicted.
These models will require the largest computers which are planned to be available
during the next decades.
Understanding of the climate system will be developed from analyses of
observations and of the results from model simulations. In addition, detailed
studies of particular processes will be required through targetted observational
campaigns. Examples of such field campaigns include combined observational
and small scale modelling studies for different regions, of the formation, dissipation,
radiative, dynamical and microphysical properties of clouds, and ground-based
(ocean and land) and aircraft measurements of the fluxes of greenhouse gases
from specific ecosystems. In particular, emphasis must be placed on field
experiments that will assist in the development and improvement of sub-grid-scale
parametrizations for models.
The required program of research will require unprecedented international
cooperation, with the World Climate Research Programme (WCRP) of the World
Meteorological Organization and International Council of Scientific Unions (ICSU),
and the International Geosphere-Biosphere Programme (IGBP) of ICSU both
playing vital roles. These are large and complex endeavours that will require the
involvement of all nations, particularly the developing countries. Implementation of
existing and planned projects will require increased financial and human
resources; the latter requirement has immediate implications at all levels of
education, and the international community of scientists needs to be widened to
include more members from developing countries.
The WCRP and IGBP have a number of ongoing or planned research programs,
that address each of the three key areas of scientific uncertainty. Examples
include:
clouds:
International Satellite Cloud Climatology Project (ISCCP);
Global Energy and Water Cycle Experiment (GEWEX).
oceans:
World Ocean Circulation Experiment (WOCE);
Tropical Oceans and Global Atmosphere (TOGA).
trace gases:
Joint Global Ocean Flux Study (JGOFS);
International Global Atmospheric Chemistry (IGAC).
Past Global Changes (PAGES)
36
As research advances, increased understanding and improved observations will
lead to progressively more reliable climate predictions. However considering the
complex nature of the problem and the scale of the scientific programmes to be
undertaken we know that rapid results cannot be expected. Indeed further
scientific advances may expose unforeseen problems and areas of ignorance.
Timescales for narrowing the uncertainties will be dictated by progress over the
next 10-15 years in two main areas:
Use of the fastest possible computers, to take into account coupling of the
atmosphere and the oceans in models, and to provide sufficient resolution
for regional predictions.
Development of improved representation of small scale processes within
climate models, as a result of the analysis of data from observational
programmes to be conducted on a continuing basis well into the next
century.
37
Annex
EMISSIONS SCENARIOS FROM WORKING GROUP III OF
THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
The Steering Group of the Response Strategies Working Group requested the USA
and the Netherlands to develop emissions scenarios for evaluation by the IPCC
Working Group I. The scenarios cover the emissions of carbon dioxide (CO₂),
methane (CH₄), nitrous oxide (N₂O), chlorofluorocarbons (CFCs), carbon
monoxide (CO) and nitrogen oxides (NOx) from the present up to the year 2100.
Growth of the economy and population was taken common for all scenarios.
Population was assumed to approach 10.5 billion in the second half of the next
century. Economic growth was assumed to be 2-3% annually in the coming
decade in the OECD countries and 3-5 % in the Eastern European and developing
countries. The economic growth levels were assumed to decrease thereafter. In
order to reach the required targets, levels of technological development and
environmental controls were varied.
In the Business-as-Usual scenario (Scenario A) the energy supply is coal
intensive and on the demand side only modest efficiency increases are achieved.
Carbon monoxide controls are modest, deforestation continues until the tropical
forests are depleted and agricultural emissions of methane and nitrous oxide are
uncontrolled. For CFCs the Montreal Protocol is implemented albeit with only
partial participation. Note that the aggregation of national projections by IPCC
Working Group III gives higher emissions (10 - 20%) of carbon dioxide and
methane by 2025.
In Scenario B the energy supply mix shifts towards lower carbon fuels, notably
natural gas. Large efficiency increases are achieved. Carbon monoxide controls
are stringent, deforestation is reversed and the Montreal Protocol implemented with
full participation.
In Scenario c a shift towards renewables and nuclear energy takes place in the
second half of next century. CFCs are now phased out and agricultural emissions
limited.
For Scenario D a shift to renewables and nuclear in the first half of the next
century reduces the emissions of carbon dioxide, initially more or less stabilizing
emissions in the industrialized countries. The scenario shows that stringent
controls in industrialized countries combined with moderated growth of emissions
in developing countries could stabilize atmospheric concentrations. Carbon
dioxide emissions are reduced to 50% of 1985 levels by the middle of the next
century.
BUSINESS
AS-USUAL
20
CO2 EMISSIONS (GtC/year)
10
SCENARIO B
SCENARIO C
SCENARIO D
0
1980
2000
2020
2040
2060
2080
2100
YEAR
1100
BUSINESS
1000
AS-USUAL
METHANE EMISSIONS (Gt/year)
900
800
SCENARIO B
700
600
SCENARIO C
500
SCENARIO D
400
1980
2000
2020
2040
2060
2080
2100
YEAR
Emissions of carbon dioxide and methane (as examples) to the year 2100, In the
four scenarios developed by IPCC Working Group 3.
IPCC FIRST ASSESSMENT REPORT
OVERVIEW
31 AUGUST 1990
1
PREFACE
TO THE IPCC OVERVIEW
The IPCC First Assessment Report consists of
this IPCC Overview,
the Policymakers Summaries of the three IPCC
Working Groups (concerned with assessment
respectively of the science, impacts and response
strategies) and the IPCC Special Committee on the
Participation of Developing Countries, and
the three reports of the Working Groups.
The Overview brings together material from the four
Policymakers Summaries. It presents conclusions, proposes lines
of possible action (including suggestions as to the factors which
might form the basis for negotiations) and outlines further work
which is required for a more complete understanding of the
problems of climate change resulting from human activities.
Because the Overview cannot reflect all aspects of the
problem which are presented in the three full reports of the
Working Groups and the four Policymakers Summaries, it should be
read in conjunction with them.
The issues, options and strategies presented in the Report
are intended to assist policymakers and future negotiators in
their respective tasks. Further consideration of the Report
should be given by every government as it cuts across different
sectors in all countries. It should be noted that the Report
reflects the technical assessment of experts rather than
government positions, particularly those governments that could
not participate in all Working Groups of IPCC.
1
This Overview reflects the conclusions of the reports of (i)
the three IPCC Working Groups on science, impacts, and response
strategies, and (11) the Policymakers Summaries of the IPCC
Working Groups and the IPCC Special Committee on the
Participation of Developing Countries.
1. SCIENCE
This section is structured similarly to the Policymakers
Summary of Working Group I.
We are certain of the following:
There is a natural greenhouse effect which already keeps the
Earth warmer than it would otherwise be.
Emissions resulting from human activities are substantially
increasing the atmospheric concentrations of the greenhouse
gases, carbon dioxide, methane, chlorofluorocarbons (CFCs)
and nitrous oxide. These increases will enhance the
greenhouse effect, resulting on average in an additional
warming of the Earth's surface. The main greenhouse gas,
water vapour, will increase in response to global warming
and further enhance it.
We calculate with confidence that:
Some gases are potentially more effective than others at
changing climate, and their relative effectiveness can be
estimated. Carbon dioxide has been responsible for over
half of the enhanced greenhouse effect in the past, and is
likely to remain so in the future.
Atmospheric concentrations of the long-lived gases (carbon
dioxide, nitrous oxide and the CFCs) adjust only slowly to
changes of emissions. Continued emissions of these gases
at present rates would commit us to increased concentrations
for centuries ahead. The longer emissions continue to
increase at present-day rates, the greater reductions would
have to be for concentrations to stabilize at a given level.
For the four scenarios of future emissions which IPCC has
developed as assumptions (ranging from one where few or no
steps are taken to limit emissions, viz., Scenario A or
Business as Usual Scenario, through others with increasing
levels of controls respectively called Scenarios B, C and
D), there will be a doubling of equivalent carbon dioxide
concentrations from pre-industrial levels by about 2025,
2040 and 2050 in Scenarios A, B, and C respectively (see the
section "Which gases are the most important?" in the
Policymakers Summary of Working Group I for a description
of the concept of equivalent carbon dioxide). See the
Appendix for a description of the IPCC emissions scenarios.
2
Stabilization of equivalent carbon dioxide concentrations
at about twice the pre-industrial level would occur under
Scenario D towards the end of the next century. Immediate
reductions of over 60% in the net (sources minus sinks)
emissions from human activities of long-lived gases would
achieve stabilization of concentration at today's levels;
methane concentrations would be stabilized with a 15-20%
reduction.
The human-caused emissions of carbon dioxide are much
smaller than the natural exchange rates of carbon dioxide
between the atmosphere and the oceans, and between the
atmosphere and the terrestrial system. The natural exchange
rates were, however, in close balance before human-induced
emissions began; the steady anthropogenic emissions into
the atmosphere represent a significant disturbance of the
natural carbon cycle.
Based on current model results, we predict:
An average, rate of increase of global mean temperature
during the next century of about 0.3'C per decade (with an
uncertainty range of 0.2 - 0.5°C per decade) assuming the
IPCC Scenario A (Business as Usual) emissions of greenhouse
gases; this is a more rapid increase than seen over the
past 10,000 years. This will result in a likely increase
in the global mean temperature of about 1°C above the
present value by 2025 (about 2°C above that in the pre-
industrial period), and 3°C above today's value before the
end of the next century (about 4°C above pre-industrial).
The rise will not be steady because of other factors.
Under the other IPCC emissions scenarios which assume
progressively increasing levels of controls, rates of
increase in global mean temperature of about 0.2'C per
decade (Scenario B), just above 0.1°C per decade (Scenario
C) and about 0.1°C per decade (Scenario D). The rise will
not be steady because of other factors.
Land surfaces warm more rapidly than the oceans, and higher
northern latitudes warm more than the global mean in winter.
The oceans act as a heat sink and thus delay the full effect
of a greenhouse warming. Therefore, we would be committed
to a further temperature rise which would progressively
become apparent in the ensuing decades and centuries.
Models predict that as greenhouse gases increase, the
realized temperature rise at any given time is between 50
and 80% of the committed temperature rise.
Under the IPCC Scenario A (Business as Usual) emissions, an
average rate of global mean sea-level rise of about 6 cm per
decade over the next century (with an uncertainty range of
3 - 10 cm per decade), mainly due to thermal expansion of
the oceans and the melting of some land ice. The predicted
rise is about 20 cm in global mean sea level by 2030, and
3
65 cm by the end of the next century. There will be
significant regional variations.
With regard to uncertainties, we note that:
There are many uncertainties in our predictions particularly
with regard to the timing, magnitude and regional patterns
of climate change, especially changes in precipitation.
-
These uncertainties are due to our incomplete
understanding of sources and sinks of greenhouse
gases and the responses of clouds, oceans and
polar ice sheets to a change of the radiative
forcing caused by increasing greenhouse gas
concentrations.
-
These processes are already partially understood,
and we are confident that the uncertainties can
be reduced by further research. However, the
complexity of the system means that we cannot rule
out surprises.
our judgement is that:
Global mean surface air temperature has increased by 0.3 to
0.6°C over the last 100 years, with the five global-average
warmest years being in the 1980's. Over the same period
global sea-level increased by 10 to 20 cm. These increases
have not been smooth in time, nor uniform over the globe.
The size of the warming over the last century is broadly
consistent with the prediction by climate models, but is
also of the same magnitude as natural climate variability.
If the sole cause of the observed warming were the human-
made greenhouse effect, then the implied climate sensitivity
would be near the lower end of the range inferred from
models. Thus the observed increase could be largely due to
this natural variability; alternatively this variability
and other human factors could have offset a still larger
human-induced greenhouse warming. The unequivocal detection
of the enhanced greenhouse effect from observations is not
likely for a decade or more.
Measurements from ice cores going back 160,000 years show
that the Earth's temperature closely paralleled the amount
of carbon dioxide and methane in the atmosphere. Although
we do not know the details of cause and effect, calculations
indicate that changes in these greenhouse gases were part,
but not all, of the reasons for the large (5-7°C) global
temperature swings between ice ages and interglacial
periods.
Natural sources and sinks of greenhouse gases are sensitive
to a change in climate. Although many of the response
(feedback) processes are poorly understood, it appears that,
as climate warms, these feedbacks will lead to an overall
increase, rather than a decrease, in natural greenhouse gas
4
abundances. For this reason, climate change is likely to
be greater than the estimates given above.
2. IMPACTS
The report on impacts of Working Group II is based on the
work of a number of subgroups, using independent studies which
have used different methodologies. Based on the existing
literature, the studies have used several scenarios to assess the
potential impacts of climate change. These have the features of:
1) an effective doubling of CO₂ in the atmosphere between
now and 2025 to 2050;
ii) a consequent increase of global mean temperature in
the range of 1.5°C to 4' - 5'C;
iii) an unequal global distribution of this temperature
increase, namely a smaller increase of half the global
mean in the tropical regions and a larger increase of
twice the global mean in the polar regions; and
iv) a sea-level rise of about 0.3 - 0.5 m by 2050 and about
1 m by 2100, together with a rise in the temperature
of the surface ocean layer of between 0.2' and 2.5°C.
These scenarios pre-date, but are in line with, the
assessment of Working Group I which, for Scenario A (Business as
Usual) has estimated the magnitude of sea-level rise at about
20 cm by 2030 and about 65 cm by the end of the next century.
Working Group I has also predicted the increase in global mean
temperatures to be about 1°C above the present value by 2025 and
3°C before the end of the next century.
Any predicted effects of climate change must be viewed in
the context of our present dynamic and changing world. Large-
scale natural events such as El Niño can cause significant
impacts on agriculture and human settlement. The predicted
population explosion will produce severe impacts on land use and
on the demands for energy, fresh water, food and housing, which
will vary from region to region according to national incomes and
rates of development. In many cases, the impacts will be felt
most severely in regions already under stress, mainly the
developing countries. Human-induced climate change due to
continued uncontrolled emissions will accentuate these impacts.
For instance, climate change, pollution and ultraviolet-B
radiation from ozone depletion can interact, reinforcing their
damaging effects on materials and organisms. Increases in
atmospheric concentrations of greenhouse gases may lead to
irreversible change in the climate which could be detectable by
the end of this century.
Comprehensive estimates of the physical and biological
effects of climate change at the regional level are difficult.
5
Confidence in regional estimates of critical climatic factors
is low. This is particularly true of precipitation and soil
moisture, where there is considerable disagreement between
various general circulation model and palaeoanalog results.
Moreover, there are several scientific uncertainties regarding
the relationship between climate change and biological effects
and between these effects and socioeconomic consequences.
This impact study part of the Overview does not attempt to
anticipate any adaptation, technological innovation or any other
measures to diminish the adverse effects of climate change that
will take place in the same time frame. This is especially
important for heavily managed sectors, e.g., agriculture,
forestry and public health.
Finally, the issue of timing and rates of change need to be
considered; there will be lags between:
i) emissions of greenhouse gases and doubling of
concentrations;
ii) doubling of greenhouse gas concentrations and change
in climate;
iii) changes in climate and resultant physical and
biological effects; and
iv) changes in physical and ecological effects and
resultant socioeconomic (including ecological)
consequences. The shorter the lags, the less the
ability to cope and the greater the socioeconomic
impacts.
There is uncertainty related to these time lags. The
changes will not be steady and surprises cannot be ruled out.
The severity of the impacts will depend to a large degree on the
rate of climate change.
Despite these uncertainties, Working Group II has been able
to reach some major conclusions. These are presented below.
2.1 Agriculture and forestry
Sufficient evidence is now available from a variety of
different studies to indicate that changes of climate would have
an important effect on agriculture and livestock. Studies have
not yet conclusively determined whether, on average, global
agricultural potential will increase or decrease. Negative
impacts could be felt at the regional level as a result of
changes in weather and pests associated with climate change, and
changes in ground-level ozone associated with pollutants,
necessitating innovations in technology and agricultural
management practices. There may be severe effects in some
regions, particularly decline in production in regions of high
present-day vulnerability that are least able to adjust. These
include Brazil, Peru, the Sahel Region of Africa, Southeast Asia,
6
and the Asian region of the USSR and China. There is a
possibility that potential productivity of high and mid
latitudes may increase because of a prolonged growing season, but
it is not likely to open up large new areas for production and
it will be mainly confined to the Northern Hemisphere.
Patterns of agricultural trade could be altered by decreased
cereal production in some of the currently high-production areas,
such as western Europe, southern USA, parts of South America and
western Australia. Horticultural production in mid-latitude
regions may be reduced. On the other hand, cereal production
could increase in northern Europe. Policy responses directed to
breeding new plant cultivars, and agricultural management
designed to cope with changed climate conditions, could lessen
the severity of regional impacts. On the balance, the evidence
suggests that in the face of estimated changes of climate, food
production at the global level can be maintained at essentially
the same level as would have occurred without climate change;
however, the cost of achieving this is unclear. Nonetheless,
climate change may intensify difficulties in coping with rapid
population growth. An increase or change in UV-B radiation at
ground level resulting from the depletion of stratospheric ozone
will have a negative impact on crops and livestock.
The rotation period of forests is long and current forests
will mature and decline during a climate in which they are
increasingly more poorly adapted. Actual impacts depend on the
physiological adaptability of trees and the host-parasite
relationship. Large losses from both factors in the form of
forest declines can occur. Losses from wildfire will be
increasingly extensive. The climate zones which control species
distribution will move poleward and to higher elevations.
Managed forests require large inputs in terms of choice of
seedlot and spacing, thinning and protection. They provide a
variety of products from fuel to food.
The degree of dependency on products varies among countries,
as does the ability to cope with and to withstand loss. The most
sensitive areas will be where species are close to their
biological limits in terms of temperature and moisture. This is
likely to be, for example, in semi-arid areas. Social stresses
can be expected to increase and consequent anthropogenic damage
to forests may occur. These increased and non-sustainable uses
will place more pressure on forest investments, forest
conservation and sound forest management.
2.2 Natural terrestrial ecosystems
Natural terrestrial ecosystems could face significant
consequences as a result of the global increases in the
atmospheric concentrations of greenhouse gases and the associated
climatic changes. Projected changes in temperature and
precipitation suggest that climatic zones could shift several
hundred kilometres towards the poles over the next fifty years.
Flora and fauna would lag behind these climatic shifts, surviving
in their present location and, therefore, could find themselves
7
in a different climatic regime. These regimes may be more or
less hospitable and, therefore, could increase productivity for
some species and decrease that of others. Ecosystems are not
expected to move as a single unit, but would have a new structure
as a consequence of alterations in distribution and abundance of
species.
The rate of projected climate changes is the major factor
determining the type and degree of climatic impacts on natural
terrestrial ecosystems. These rates are likely to be faster
than the ability of some species to respond and responses may
be sudden or gradual.
Some species could be lost owing to increased stress leading
to a reduction of global biological diversity. Increased
incidence of disturbances such as pest outbreaks and fire are
likely to occur in some areas and these could enhance projected
ecosystem changes.
Consequences of CO2 enrichment and climate change for
natural terrestrial ecosystems could be modified by other
environmental factors, both natural and man-induced (e.g. by air
pollution).
Most at risk are those communities in which the options for
adaptability are limited (e.g. montane, alpine, polar, island
and coastal communities, remnant vegetation, and heritage sites
and reserves) and those communities where climatic changes add
to existing stresses. The socioeconomic consequences of these
impacts will be significant, especially for those regions of the
globe where societies and related economies are dependent on
natural terrestrial ecosystems for their welfare. Changes in the
availability of food, fuel, medicine, construction material and
income are possible as these ecosystems are changed. Important
fibre products could also be affected in some regions.
2.3 Hydrology and water resources
Relatively small climate changes can cause large water
resource problems in many areas, especially arid and semi-arid
regions and those humid areas where demand or pollution has led
to water scarcity. Little is known about regional details of
greenhouse-gas-induced hydrometeorological change. It appears
that many areas will have increased precipitation, soil moisture
and water storage, thus altering patterns of agricultural,
ecosystem and other water use. Water availability will decrease
in other areas, a most important factor for already marginal
situations, such as the Sahelian zone in Africa. This has
significant implications for agriculture, for water storage and
distribution, and for generation of hydroelectric power. In some
limited areas, for example, under an assumed scenario of a 1°C
to 2'C temperature increase, coupled with a 10% reduction in
precipitation, a 40-70% reduction in annual runoff could occur.
Regions such as southern Asia, that are dependent on unregulated
river systems, are particularly vulnerable to hydrometeorological
change. On the other hand, regions such as the western USSR and
8
western United States that have large regulated water resource
systems are less sensitive to the range of hydrometeorological
changes in the assumed scenario. In addition to changes in water
supply, water demand may also change through human efforts to
conserve, and through improved growth efficiency of plants in a
higher CO, environment. Net socioeconomic consequences must
consider both supply and demand for water. Future design in
water resource engineering will need to take possible impacts
into account when considering structures with a life span to the
end of the next century. Where precipitation increases, water
management practices, such as urban storm drainage systems, may
require upgrading in capacity. Change in drought risk represents
potentially the most serious impact of climate change on
agriculture at both regional and global levels.
2.4 Human settlements, energy, transport, and industrial
sectors, human health and air quality
The most vulnerable human settlements are those especially
exposed to natural hazards, e.g. coastal or river flooding,
severe drought, landslides, severe wind storms and tropical
cyclones. The ,most vulnerable populations are in developing
countries, in the lower-income groups: residents of coastal
lowlands and islands, populations in semi-arid grasslands, and
the urban poor in squatter settlements, slums and shanty towns,
especially in megacities. In coastal lowlands such as in
Bangladesh, China and Egypt, as well as in small island nations,
inundation due to sea-level rise and storm surges could lead to
significant movements of people. Major health impacts are
possible, especially in large urban areas, owing to changes in
availability of water and food and increased health problems due
to heat stress spreading of infections. Changes in precipitation
and temperature could radically alter the patterns of vector-
borne and viral diseases by shifting them to higher latitudes,
thus putting large populations at risk. As similar events have
in the past, these changes could initiate large migrations of
people, leading over a number of years to severe disruptions of
settlement patterns and social instability in some areas.
Global warming can be expected to affect the availability
of water resources and biomass, both major sources of energy in
many developing countries. These effects are likely to differ
between and within regions with some areas losing and others
gaining water and biomass. Such changes in areas which lose
water may jeopardize energy supply and materials essential for
human habitation and energy. Moreover, climate change itself is
also likely to have different effects between regions on the
availability of other forms of renewable energy such as wind and
solar power. In developed countries some of the greatest impacts
on the energy, transport and industrial sectors may be determined
by policy responses to climate change such as fuel regulations,
emission fees or policies promoting greater use of mass transit.
In developing countries, climate-related changes in the
availability and price of production resources such as energy,
water, food and fibre may affect the competitive position of many
industries.
9
Global warming and increased ultraviolet radiation resulting
from depletion of stratospheric ozone may produce adverse impacts
on air quality such as increases in ground-level ozone in some
polluted urban areas. An increase of ultraviolet-B radiation
intensity at the Earth's surface would increase the risk of
damage to the eye and skin and may disrupt the marine food chain.
2.5 Oceans and coastal zones
Global warming will accelerate sea-level rise, modify ocean
circulation and change marine ecosystems, with considerable
socioeconomic consequences. These effects will be added to
present trends of rising sea-level, and other effects that have
already stressed coastal resources, such as pollution and over-
harvesting. A 30-50 cm sea-level rise (projected by 2050) will
threaten low islands and coastal zones. A 1 m rise by 2100 would
render some island countries uninhabitable, displace tens of
millions of people, seriously threaten low-lying urban areas,
flood productive land, contaminate fresh water supplies and
change coastlines. All of these impacts would be exacerbated if
droughts and storms become more severe. Coastal protection would
involve very significant costs. Rapid sea-level rise would
change coastal ecology and threaten many important fisheries.
Reductions in sea ice will benefit shipping, but seriously impact
on ice-dependent marine mammals and birds.
Impacts on the global oceans will include changes in the
heat balance, shifts in ocean circulation which will affect the
capacity of the ocean to absorb heat and CO2 and changes in
upwelling zones associated with fisheries. Effects will vary by
geographic zones, with changes in habitats, a decrease in
biological diversity and shifts in marine organisms and
productive zones, including commercially important species. Such
regional shifts in fisheries will have major socioeconomic
impacts.
2.6 Seasonal snow cover, ice and permafrost
The global areal extent and volume of elements of the
terrestrial cryosphere (seasonal snow cover, near-surface layers
of permafrost and some masses of ice) will be substantially
reduced. These reductions, when reflected regionally could have
significant impacts on related ecosystems and social and economic
activities. Compounding these impacts in some regions is that,
as a result of the associated climatic warming positive
feedbacks, the reductions could be sudden rather than gradual.
The areal coverage of seasonal snow and its duration are
projected to decrease in most regions, particularly at mid
latitudes, with some regions at high latitudes possibly
experiencing increases in seasonal snow cover. Changes in the
volume of snow cover, or the length of the snow cover season,
will have both positive and negative impacts on regional water
resources (as a result of changes in the volume and the timing
of runoff from snowmelt), on regional transportation (road,
marine, air and rail), and on recreation sectors.
10
Globally, the ice contained in glaciers and ice sheets is
projected to decrease, with regional responses complicated by the
effect of increased snowfall in some areas which could lead to
accumulation of ice. Glacial recession will have significant
implications for local and regional water resources, and thus
impact on water availability and on hydroelectric power
potential. Glacial recession and loss of ice from ice sheets
will also contribute to sea-level rise. Permafrost, which
currently underlies 20-25% of the land mass of the Northern
Hemisphere, could experience significant degradation within the
next 40-50 years. Projected increases in the thickness of the
freeze-thaw (active) layer above the permafrost and a recession
of permafrost to higher latitudes and altitudes could lead to
increases in terrain instability, erosion and landslides in those
areas which currently contain permafrost. As a result, overlying
ecosystems could be significantly altered and the integrity of
man-made structures and facilities reduced, thereby influencing
existing human settlements and development opportunities.
3.
RESPONSE STRATEGIES
The consideration of climate change response strategies
presents formidable difficulties for policymakers.
The
information available to make sound policy analyses is inadequate
because of :
(a) uncertainty with respect to how effective specific response
options or groups of options would be in actually averting
potential climate change;
(b) uncertainty with respect to the costs, effects on economic
growth, and other economic and social implications of
specific response options or groups of options.
The IPCC recommends a programme for the development and
implementation of global, comprehensive and phased action for
the resolution of the global warming problem under a flexible and
progressive approach.
A major dilemma of the issue of climate change due to
increasing emission of greenhouse gases in the atmosphere is that
actions may be required well before many of the specific issues
that are and will be raised can be analyzed more thoroughly by
further research.
The CFCs are being phased out to protect the stratospheric
ozone layer. This action will also effectively slow down the
rate of increase of radiative forcing of greenhouse gases in the
atmosphere. Every effort should be made to find replacements
that have little or no greenhouse warming potential or ozone
depletion potential rather than the HCFCs and HFCs that are now
being considered.
11
The single largest anthropogenic source of radiative forcing
is energy production and use. The energy sector accounts for an
estimated 46% (with an uncertainty range of 38-54%) of the
enhanced radiative forcing resulting from human activities.
It is noted that emissions due to fossil fuel combustion
amounts to about 70-90% of the total anthropogenic emissions of
CO2 into the atmosphere, whereas the remaining 10-30% is due to
human use of terrestrial ecosystems. A major decrease of the
rate of deforestation as well as an increase in afforestation
would contribute significantly to slowing the rate of CO2
concentrations increase in the atmosphere; but it would be well
below that required to stop it. This underlines that when
forestry measures have been introduced, other measures to limit
or reduce greenhouse emissions should not be neglected.
3.1 Roles of industrialized and developing countries
Industrialized and developing countries have a common but
varied responsibility in dealing with the problem of climate
change and its adverse effects. The former should take the lead
in two ways:
1. A major part of emissions affecting the atmosphere at
present originates in industrialized countries where the
scope for change is greatest. Industrialized countries
should adopt domestic measures to limit climate change by
adapting their own economies in line with future agreements
to limit emissions.
11. To co-operate with developing countries in international
action, without standing in the way of the latter's
development by contributing additional financial resources,
by appropriate transfer of technology, by engaging in close
co-operation in scientific observation, analysis and
research, and finally by means of technical co-operation
geared to forestalling and managing environmental problems.
*
Sustainable development' in industrialized as well as
developing countries requires proper concern for environmental
protection as the basis for continued economic growth.
Environmental considerations must be systematically integrated
into all plans for development. The right balance must be struck
between economic growth and environmental objectives.
*
Emissions from developing countries are growing in order to
meet their development requirements and thus, over time, are
likely to represent an increasingly significant percentage of
1
Sustainable development is development that meets the
needs of the present without compromising the ability of future
generations to meet their own needs and does not imply in any way
encroachment upon national sovereignty. (Annex II to decision
15/2 of the 15th session of the UNEP Governing Council, Nairobi,
May 1989).
12
global emissions. As the greenhouse gas emissions in developing
countries are increasing with their population and economic
growth, rapid transfer, on a preferential basis, to developing
countries, of technologies which help to monitor, limit or adapt
to climate change, without hindering their economic development,
is an urgent requirement. Developing countries should, within
the limits feasible, take measures to suitably adapt their
economies. Recognizing the poverty that prevails among the
populations of developing countries, it is natural that achieving
economic growth is given priority by them. Narrowing the gap
between the industrialized and developing world would provide a
basis for a full partnership of all nations in the world and
would assist developing countries in dealing with the climate
change issue.
3.2 Options
*
The climate scenario studies of Working Groups I and III
outline control policies on emissions that would slow global
warming from the presently predicted value of about 0.3°C per
decade to about 0.1°C per decade (see Appendix).
*
The potentially serious consequences of climate change give
sufficient reasons to begin adopting response strategies that can
be justified immediately even in the face of significant
uncertainties. The response strategies include:
-
phasing out of CFC emissions and careful assessment of
the greenhouse gas potential of proposed substitutes;
-
efficiency improvements and conservation in energy
supply, conversion and end use, in particular through
improving diffusion of energy-efficient technologies,
improving the efficiency of mass-produced goods,
reviewing energy-related price and tariff systems to
better reflect environmental costs;
-
sustainable forest management and afforestation;
-
use of cleaner, more efficient energy sources with
lower or no emissions of greenhouse gases;
-
review of agriculture practices.
*
There is no single quick-fix technological option for
limiting greenhouse gas emissions. Phased and flexible response
strategies should be designed to enhance relevant technological
research, development and deployment, including improvement and
reassessment of existing technologies. Such strategies should
involve opportunities for international co-operation.
A
comprehensive strategy addressing all aspects of the problem and
reflecting environmental, economic and social costs and benefits
is necessary.
*
Because a large, projected increase in world population will
be a major factor in causing the projected increase in global
13
greenhouse gases, it is essential that global climate change
strategies take into account the need to deal with the issue of
the rate of growth of the world population.
Subject to their particular circumstances, individual
nations, or groups of nations, may wish to consider taking steps
now to attempt to limit, stabilize or reduce the emission of
greenhouse gases resulting from human activities and prevent the
destruction and improve the effectiveness of sinks. One option
that governments may wish to consider is the setting of targets
for CO₂ and other greenhouse gases.
A large number of options were preliminarily assessed by
IPCC Working Group III. It appears that some of these options
may be economically and socially feasible for implementation in
the near-term while others, because they are not yet technically
or economically viable, may be more appropriate for
implementation in the longer term. In general, the Working Group
found that the most effective response strategies, especially in
the short term, are those which are:
beneficial for reasons other than climate change and
justifiable in their own right, for example increased
energy efficiency and lower greenhouse gas emission
technologies, better management of forests, and other
natural resources, and reductions in emissions of CFCs
and other ozone depleting substances that are also
radiatively important gases;
economically efficient and cost effective, in
particular those that use market-based mechanisms;
able to serve multiple social, economic and
environmental purposes;
flexible and phased, so that they can be easily
modified to respond to increased understanding of
scientific, technological and economic aspects of
climate change;
compatible with economic growth and the concept of
sustainable development;
administratively practical and effective in terms of
application, monitoring and enforcement;
reflecting obligations of both industrialized and
developing countries in addressing this issue, while
recognizing the special needs of developing countries,
in particular in the areas of financing and technology.
The degree to which options are viable will also vary
considerably depending on the region or country involved. For
each country, the implications of specific options will depend
on its social, environmental and economic context. Only through
careful analysis of all available options will it be possible to
14
determine which are best suited to the circumstances of a
particular country or region. Initially, the highest priority
should be to review existing policies with a view to minimizing
conflicts with the goals of climate change strategies. New
policies will be required.
In the long-term perspective, work should begin on defining
criteria for selection of appropriate options which would reflect
the impacts of climate change and its costs and benefits on the
one hand, and social and economic costs and benefits of the
options on the other.
Consideration of measures for reducing the impacts of global
climate change should begin as soon as possible, particularly
with regard to disaster preparedness policies, coastal zone
management and control measures for desertification, many of
these being justified in their own right. Measures to limit or
adapt to climate change should be as cost-effective as possible
while taking into account important social implications.
Limitation and adaptation should be considered as an integrated
package.
*
Assessing areas at risk from sea-level rise and developing
comprehensive management plans to reduce future vulnerability of
populations and coastal developments and ecosystems as part of
coastal zone management plans should begin as soon as possible.
Environmental objectives can be pursued through regulations
and/or through market based economic instruments. The latter,
through their encouragement of flexible selection of abatement
measures, tend to encourage innovation and the development of
improved technologies and practices for reducing emissions and
therefore frequently offer the possibility of achieving
environmental improvements at lower costs than through regulatory
mechanisms. It is not likely, however, that economic instruments
will be applicable to all circumstances.
Three factors are considered as potential barriers to the
operation of markets and/or the achievement of environmental
objectives through market mechanisms. These are:
1)
information problems, which can often cause markets to
produce less effective or unfavourable environmental
outcomes;
ii) existing measures and institutions, which can encourage
individuals to behave in environmentally damaging ways;
and
iii) balancing competing objectives (social, environmental
and economic).
An initial response strategy may therefore be to address
information problems directly and to review existing measures
which may be barriers. For example, prior to possible adoption
of a system of emission charges, countries should examine
15
existing subsidies and tax incentives on energy and other
relevant greenhouse gas producing sectors.
*
With respect to institutional mechanisms for providing
financial co-operation and assistance to developing countries,
a two track approach was considered:
1)
one track built on work underway or planned in existing
institutions. Bilateral donors could further integrate
and reinforce the environmental components of their
assistance programmes and develop cofinancing
arrangements with multilateral institutions while
ensuring that this does not impose inappropriate
environmental conditions.
11) parallel to this track the possibility of new
mechanisms and facilities was considered. Some
developing and industrialized countries suggested that
new mechanisms directly related to a future climate
convention and protocols that might be agreed upon,
such as a new international fund, were required.
Governments should undertake now:
accelerated and co-ordinated research programmes to
reduce scientific and socioeconomic uncertainties with
a view towards improving the basis for response
strategies and measures;
review of planning in the fields of energy, industry,
transportation, urban areas, coastal zones and resource
use and management;
encouragement of beneficial behavioral and structural
(e.g. transportation and housing infrastructure)
changes;
expansion of the global ocean observing and monitoring
systems.
It should be noted that no detailed assessments have been
made as of yet of the economic costs and benefits, technological
feasibility or market potential of the underlying policy
assumptions.
4.
PARTICIPATION OF DEVELOPING COUNTRIES
It is obvious that the impact on and the participation by
the developing countries in the further development of a future
strategy is essential. The IPCC has attempted to address this
specific issue by establishing a Special Committee on the
Participation of Developing Countries and requested it to
identify factors inhibiting the full participation of the
developing countries in IPCC and recommend remedial measures
where possible. The Committee stressed that full participation
16
includes not only the physical presence at meetings but also the
development of national competence to address all issues of
concern such as the appreciation of the scientific basis of
climate change, the potential impacts on society of such change
and evaluations of practical response strategies for
national/regional applications.
The factors that kept developing countries from fully
participating were identified by the Special Committee as:
insufficient information;
insufficient communication;
limited human resources;
institutional difficulties;
limited financial resources.
On some of these factors, the IPCC Working Groups have
developed policy options which are to be found in their
respective reports.
Developing countries will, in some cases, need additional
financial resources for supporting their efforts to promote
activities which contribute both to limiting greenhouse gas
emissions and/or adapting to the adverse effects of climate
change, while at the same time promote economic development.
Areas of co-operation could include, inter alia:
efficient use of energy resources, the use of fossil
fuels with lower greenhouse gas emission rates or non-
fossil sources, the development of clean and renewable
energy sources, such as: biomass, windpower, wave-
power, hydroelectric and solar, wherever applicable;
increased rational utilization of forest products,
sound forest management practices and agricultural
techniques which reduce the negative effects on
climate;
facilitating the development and transfer of clean and
safe technologies in areas which could include:
-
the building and manufacturing industries;
-
public transport systems;
-
industry;
measures which enhance the capacity of developing
countries to develop programmes to address climate
change, including research and development activities
and public awareness and education programmes, such as:
-
the development of the human resources necessary
to tackle the problem of climate change and its
adverse effects;
17
-
the provision of study and training programmes in
subjects and techniques related to climate change;
-
the provision of skilled personnel and the
material necessary to organize education
programmes to develop locally the skills necessary
to assess climate change and combat its adverse
effects;
-
the development of climate-related research
programmes organized on a regional basis;
facilitating the participation of developing countries
in fora and organizations such as: the International
Geosphere-Biosphere Programme, the Land-Ocean Inter-
actions in the Coastal Zone, the Biosphere Aspects of
the Hydrological Cycle, the Global Change Impact on
Agriculture and Society, the World Climate Programme,
the Man and the Biosphere Programme;
facilitating participation by developing countries in
international fora on global climate change such as the
IPCC;
strengthening existing education and research
institutions and the development of new ones at
national and regional levels.
*
Further, co-operation and assistance for adaptive measures
would be required, noting that for some regions and countries,
adaptation rather than limitation activities are potentially most
important.
*
The IPCC concludes that the recommendations of the Special
Committee need not and should not await the outcome of future
negotiations on a climate convention. It appeals to the
multilateral and bilateral funding organizations to implement its
recommendations. It further appeals to governments for
continuing and increased contributions to the IPCC Trust Fund on
an urgent basis.
5.
INTERNATIONAL CO-OPERATION AND FUTURE WORK
*
The measures noted above require a high degree of interna-
tional co-operation with due respect for national sovereignty of
states. The international negotiations on a framework convention
should start as quickly as possible after presentation of this
Report in line with Resolution SS II/3 Climate.C. (August 1990)
of the UNEP Governing Council and Resolution 8 (EC-XLII, June
1990) of the WMO Executive Council. Many, essentially develop-
ing, countries stressed that the negotiations must be conducted
in the forum, manner and with the timing to be decided by the UN
General Assembly.
18
This convention, and any additional protocols that might be
agreed upon, would provide a firm basis for effective co-
operation to act on greenhouse gas emissions and adapt to any
adverse effects of climate change. The convention should
recognize climate change as a common concern of mankind and, at
a minimum, contain general principles and obligations. It should
be framed in such a way as to gain the adherence of the largest
possible number and most suitably balanced range of countries
while permitting timely action to be taken.
Key issues for negotiations will include the criteria,
timing, legal form and incidence of any obligations to control
the net emissions of greenhouse gases, how to address equitably
the consequences for all, any institutional mechanisms including
research and monitoring that may be required, and in particular,
the requests of the developing countries for additional financial
resources and for the transfer of technology on a preferential
basis. The possible elements of a framework convention on
climate change were identified and discussed by Working Group III
in its legal measures topic paper, appended to its Policymakers
Summary.
The IPCC recommends that research regarding the science of
climate change in general, technological development and the
international economic implications, be intensified.
Because climate change would affect, either directly or
indirectly, almost every sector of society, broad global
understanding of the issue will facilitate the adoption and the
implementation of such response options as deemed necessary and
appropriate. Further efforts to achieve such global understand-
ing are urgently needed.
APPENDIX
Emissions scenarios developed by IPCC
The IPCC used two methods to develop scenarios of future
emissions:
One method used global models to develop four scenarios
which were subsequently used by Working Group I to develop
scenarios of future warming. All of these four scenarios
assumed the same global economic growth rates taken from the
World Bank projections and the same population growth
estimates taken from the United Nations studies. The
anthropogenic emissions of carbon dioxide and methane from
these scenarios are shown in Figures 1 and 2 below.
The second method used studies of the energy and agriculture
sectors submitted by over 21 countries and international
organizations to estimate CO2 emissions.
Both scenario approaches indicate that CO₂ emissions will
grow from about 7 Btc (billion or 1000 million tonnes carbon) per
year now to 12-15 Btc per year by the year 2025. Scenario A
(Business as Usual) includes a partial phase-out of CFCs under
the Montreal Protocol and lower CO₂ and CH, emissions than the
Reference Scenario. The Reference Scenario developed through
country and international studies of the energy and agriculture
groups, includes higher CO₂ emissions and assumed a total CFC
phase-out. The results indicate that the CO₂ equivalent
concentrations and their effects on global climate are similar.
Figure 1. Projected Man-Made CO2 Emissions
(Billion or 1000 million tonnes carbon per year)
BUSINESS
AS-USUAL
20
(SCENARIO A)
MAN-MADE CARBON DIOXIDE
EMISSIONS (BtC/year)
10
SCENARIO B
SCENARIO C
SCENARIO D
0
1980
2000
2020
2040
2060
2080
2100
YEAR
Figure 2. Projected Man-Made Methane Emissions
(Million tonnes carbon per year)
900
BUSINESS
AS-USUAL
800
(SCENARIO A)
MAN-MADE METHANE
EMISSIONS (MtC/year)
700
600
SCENARIO B
500
SCENARIO C
400
SCENARIO D
300
1980
2000
2020
2040
2060
2080
2100
YEAR
Method 1²
Scenario A (Business as Usual) assumes that few or no steps
are taken to limit greenhouse gas emissions. Energy use and
clearing of tropical forests continue and fossil fuels, in
particular coal, remain the world's primary energy source. The
Montreal Protocol comes into effect but without strengthening and
with less than 100 percent compliance. Under this scenario, the
equivalent of a doubling of pre-industrial CO₂ levels occurs,
according to Working Group I, by around 2025.
Scenario B (Low Emissions Scenario) assumes that the energy
supply mix of fossil fuels shifts towards natural gas, large
2 All of the scenarios assumed some level of compliance with
the Montreal Protocol but not with all of the (June 1990)
amendments agreed to in London. The London amendments to the
Montreal Protocol, when fully implemented, would result in a
virtually complete elimination of production of fully halogenated
CFCs, halons, carbon tetrachloride and methyl chloroform early
in the 21st century. The Parties of the Protocol also call for
later elimination of HCFCs. Thus, the assumptions of Scenarios
A and B overestimate the radiative forcing potential of CFCs and
halons. Additionally, the UN has provided recent population
projections that estimate higher population than used in the
global model scenarios (Scenarios A through D); use of these
newer projections would increase future CO2 emissions.
Additionally, the Reference Scenario CO₂ emissions are higher
than Scenario A (Business as Usual), suggesting Scenario A
(Business as Usual) may be an underestimate.
efficiency increases are achieved, deforestation is reversed and
emissions of CFCs are reduced by 50% from their 1986 levels.
This results in an equivalent doubling of pre-industrial carbon
dioxide by about 2040.
Scenario C (Control Policies Scenario) assumes that a shift
towards renewable energies and safe nuclear energy takes place
in the latter part of the next century, CFC gases are phased out
and agricultural emissions (methane and nitrous oxide) are
limited; an equivalent doubling of pre-industrial carbon dioxide
will occur in about 2050.
Scenario D (Accelerated Policies Scenario) assumes that a
rapid shift to renewable energies and safe nuclear energy takes
place early in the next century, stringent emission controls in
industrial countries and moderate growth of emissions in
developing countries. This scenario, which assumes carbon
dioxide emissions are reduced to 50% of 1985 levels, stabilizes
equivalent carbon dioxide concentrations at about twice the pre-
industrial levels towards the end of the next century.
Method 2 (see fpotnote 2 on previous page)
Using the second method, the so-called Reference Scenario
was developed by the Energy and Industry Subgroup and Agriculture
and Forestry Subgroup of Working Group III. Under the Reference
Scenario, global CO₂ emissions from all sectors grow from
approximately 7.0 Btc (per year) in 1985 to over 15 Btc (per
year) in 2025. The energy contribution grows from about 5 Btc
(per year) to over 12 Btc (per year). Primary energy demand more
than doubles between 1985 and 2025 with an average growth rate
of 2.1%. The per capita energy emissions in the industrialized
countries increase from 3.1 tonnes carbon (TC) in 1985 to 4.7 TC
in 2025; for the developing countries, they rise from 0.4 TC in
1985 to 0.8 TC in 2025.
Summary
All of the above scenarios provide a conceptual basis for
considering possible future patterns of emissions and the broad
responses that might affect those patterns. No full assessment
was made of the total economic costs and benefits, technological
feasibility, or market potential of the underlying policy
assumptions. Because of the inherent limitations in our ability
to estimate future rates of population and economic growth,
individual behaviour, technological innovation, and other factors
which are crucial for determining emission rates over the course
of the next century, there is some uncertainty in the projections
of greenhouse gas emissions. Reflecting these inherent
difficulties, the IPCC's work on emissions scenarios are the best
estimates at this time covering emissions over the next century,
but continued work to develop improved assumptions and methods
for scenario estimates will be useful to guide the development
of response strategies.
Intergovernmental Panel on
Climate Change
Policymakers Summary
of the
Potential Impacts of Climate Change
Report from Working Group II to IPCC
June 1990
Recommendations for action
26
Potential impacts of climate change on human settlement, the energy, transport
and industrial sectors, human health and air quality
27
Major findings
27
Principal issues
27
Human settlement
28
Energy
29
Transport
30
Industry
30
Human health
31
Air pollution
32
Ultraviolet-B radiation
32
Recommendations for action
32
Potential impacts of climate change on the world ocean and coastal zones
33
Major findings
33
Impacts of sea-level rise on coastal zones
34
Threatened populations in low-lying areas and island nations
34
Alteration of the biophysical properties of estuaries and wetlands
35
Inundation and recession of barrier islands, coral atolls and other
shorelines
36
Impacts on the World Ocean
37
Recommendations for action
38
Impacts of climate change on seasonal snow cover, ice and permafrost, and
socioeconomic consequences
38
Major findings
39
Principal issues
40
Seasonal snow cover
40
Ice sheets and glaciers
41
Permafrost
42
Recommendations for action
44
Summary of major future actions
45
Concluding remarks
46
Tables
Table 1. Palaeoclimate analogs used by Soviet scientists
10
Table 2. Estimates for regional changes by Working Group I
10
iii
Executive summary
The IPCC Working Groups on scientific
scenario (scenario A in Working Group
analysis (Working Group I), impacts
I Report) has estimated the magnitude
(Working Group II) and response
of sea-level rise at about 20 cm by 2030
strategies (Working Group III) were
and about 65 cm by the end of the next
established in November 1988 and
century. Working Group I has also
proceeded to work in parallel under
predicted the increase in global mean
instructions from IPCC. The respon-
temperatures to be about 1° C'above the
sibility of Working Group II is to
present value by 2025 and 3°C before
describe the environmental and socio-
the end of the next century.
economic implications of possible
climate changes over the next decades
Any predicted effects of climate change.
caused by increasing concentrations of
must be viewed in the context of our
greenhouse gases.
present dynamic and changing world.
Large-scale natural events such as El
The report of Working Group II is based
Niño can cause significant impacts on
on the work of a number of subgroups,
agriculture and human settlement. The
using independent studies which have
predicted population explosion will
used different methodologies. Based on
produce severe impacts on land use and
the existing literature, the studies have
on the demands for energy, fresh water,
used several scenarios to assess the
food and housing, which will vary from
potential impacts of climate change:
region. to region according to national
These have the features of:
incomes and rates of development. In
many cases, the impacts will be felt most
(i) an effective doubling of CO₂ in the
severely in regions already under stress,
atmosphere between now and 2025 to
mainly the developing countries.
2050 for a "business-as-usual" scenario;
Human-induced climate change due to
continued uncontrolled emissions will
(ii) a consequent increase of global
accentuate these impacts. For instance,
mean temperature in the range of 1.5°C
climate change, pollution and ultra-
to 4°-5°C;
violet-B radiation from ozone depletion
can interact, reinforcing their damaging
(iii) an unequal global distribution of
effects on materials and organisms.
this temperature increase, namely a
Increases in atmospheric concentrations
smaller increase of half the global mean
of greenhouse gases may lead to irrever-
in the tropical regions and a larger
sible change in the climate which could
increase of twice the global mean in the
be detectable by the end of this century.
polar regions; and
Comprehensive estimates of the physical
(iv) a sea-level rise of about 0.3-0.5 m
and biological effects of climate change
by 2050 and about 1 m by 2100, together
at the regional level are difficult.
with a rise in the temperature of the
Confidence in regional estimates of
surface ocean layer of between 0.2° and
critical climatic factors is low. This is
2.5°C.
particularly true of precipitation and soil
moisture, where there is considerable
These scenarios pre-date, but are in line
disagreement between various general
with, the recent assessment of Working
circulation model and palaeoanalog
Group I which, for a "business-as-usual"
results. Moreover, there are several
scientific uncertainties regarding the
Agriculture and forestry
relationship between climate change and
biological effects and between these
Sufficient evidence is now available from
effects and socioeconomic consequences.
a variety of different studies to indicate
that changes of climate would have an
This report does not attempt to antici-
important effect on agriculture and live-
pate any adaptation, technological
stock. Studies have not yet conclusively
innovation or any other measures to
determined whether, on average, global
diminish the adverse effects of climate
agricultural potential will increase or
change that will take place in the same
decrease. Negative impacts could be felt
time frame. This is especially important
at the regional level as a result of
for heavily managed sectors, eg agri-
changes in weather and pests associated
culture, forestry and public health. This
with climate change, and changes in
is one of the responsibilities of Working
ground-level ozone associated with
Group III.
pollutants, necessitating innovations in
technology and agricultural management
Finally, the issue of timing and rates of
practices. There may be severe effects
change need to be considered; there will
in some regions, particularly decline in
be lags between:
production in regions of high present-day
vulnerability that are least able to adjust.
i) emissions of greenhouse gases and
These include Brazil, Peru, the Sahel
doubling of concentrations;
Region of Africa, Southeast Asia, the
Asian region of the USSR and China.
ii) doubling of greenhouse gas concen-
There is a possibility that potential
trations and changes in climate;
productivity of high and mid latitudes
may increase because of a prolonged
iii) changes in climate and resultant
growing season, but it is not likely to
physical and biological effects; and
open up large new areas for production
and it will be mainly confined to the
iv) changes in physical and ecological
Northern Hemisphere.
effects and resultant socioeconomic
(including ecological) consequences.
Patterns of agricultural trade could be
The shorter the lags, the less the ability
altered by decreased cereal production
to cope and the greater the socio-
in some of the currently high-production
economic impacts.
areas, such as Western Europe, southern
US, parts of South America and western
There is uncertainty related to these
Australia. Horticultural production in
time lags. The changes will not be
mid-latitude regions may be reduced.
steady and surprises cannot be ruled out.
On the other hand, cereal production
The severity of the impacts will depend
could increase in northern Europe.
to a large degree on the rate of climate
Policy responses directed to breeding
change.
new plant cultivars, and agricultural
management designed to cope with
Despite these uncertainties, Working
changed climate conditions, could lessen
Group II has been able to reach some
the severity of regional impacts. On
major conclusions, which are:
balance, the evidence suggests that in
the face of estimated changes of climate,
food production at the global level can
be maintained at essentially the same
2
level as would have occurred without
the associated climatic changes. Pro-
climate change; however, the cost of
jected changes in temperature and pre-
achieving this is unclear. Nonetheless,
cipitation suggest that climatic zones
climate change may intensify difficulties
could shift several hundred kilometres
in coping with rapid population growth.
towards the poles over the next fifty
An increase or change in UV-B radia-
years. Flora and fauna would lag behind
tion at ground level resulting from the
these climatic shifts, surviving in their
depletion of stratospheric ozone will
present location and, therefore, could
have a negative impact on crops and
find themselves in a different climatic
livestock.
regime. These regimes may be more or
less hospitable and, therefore, could
The rotation period of forests is long
increase productivity for some species
and current forests will mature and
and decrease that of others. Ecosystems
decline during a climate in which they
are not expected to move as a single
are increasingly more poorly adapted.
unit, but would have a new structure as
Actual impacts depend on the physio-
a consequence of alterations in distri-
logical adaptability of trees and the host-
bution and abundance of species.
parasite relationship. Large losses from
both factors in the form of forest
The rate of projected climate changes is
declines can occur. Losses from wildfire
the major factor determining the type
will be increasingly extensive. The
and degree of climatic impacts on
climate zones which control species
natural terrestrial ecosystems. These
distribution will move poleward and to
rates are likely to be faster than the
higher elevations. Managed forests
ability of some species to respond and
require large inputs in terms of choice of
responses may be sudden or gradual.
seedlot and spacing, thinning and
protection. They provide a variety of
Some species could be lost owing to
products from fuel to food. The degree
increased stress leading to a reduction in
of dependency on products varies among
global biological diversity. Increased
countries, as does the ability to cope
incidence of disturbances such as pest
with and to withstand loss. The most
outbreaks and fire are likely to occur in
sensitive areas will be where species are
some areas and these could enhance
close to their biological limits in terms of
projected ecosystem changes.
temperature and moisture. This is likely
to be, for example, in semi-arid areas.
Consequences of CO2 enrichment and
Social stresses can be expected to
climate change for natural terrestrial
increase and consequent anthropogenic
ecosystems could be modified by other
damage to forests may occur. These
environmental factors, both natural and
increased and non-sustainable uses will
man-induced (eg by air pollution).
place more pressure on forest invest-
ments, forest conservation and sound
Most at risk are those communities in
forest management.
which the options for adaptability are
limited (eg montane, alpine, polar, island
Natural terrestrial ecosystems
and coastal communities, remnant vege-
tation, and heritage sites and reserves)
Natural terrestrial ecosystems could face
and those communities where climatic
significant consequences as a result of
changes add to existing stresses.
the global increases in the atmospheric
concentrations of greenhouse gases and
3
The socioeconomic consequences of
In addition to changes in water supply,
these impacts will be significant,
water demand may also change through
especially for those regions of the globe
human efforts to conserve, and through
where societies and related economies
improved growth efficiency of plants in
are dependent on natural terrestrial
a higher CO₂ environment. Net socio-
ecosystems for their welfare. Changes in
economic consequences must consider
the availability of food, fuel, medicine,
both supply and demand for water.
construction materials and income are
Future design in water resource
possible as these ecosystems are
engineering will need to take possible
changed. Important fibre products could
impacts into account when considering
also be affected in some regions.
structures with a life span to the end of
the next century. Where precipitation
Hydrology and water resources
increases, water management practices,
such as urban storm drainage systems,
Relatively small climate changes can
may require upgrading in capacity.
cause large water resource problems in
Change in drought risk represents
many areas, especially arid and semi-arid
potentially the most serious impact of
regions and those humid areas where
climate change on agriculture at both
demand or pollution has led to water
regional and global levels.
scarcity. Little is known about regional
details of greenhouse-gas-induced hydro-
Human settlements, energy,
meteorological change. It appears that
transport, and industrial sectors,
many areas will have increased precipi-
human health and air quality
tation, soil moisture and water storage,
thus altering patterns of agricultural,
The most vulnerable human settlements
ecosystem and other water use. Water
are those especially texposed to natural
availability will decrease in other areas,
hazards, eg coastal or river flooding,
a most important factor for already
severe drought, landslides, severe wind
marginal situations, such as the Sahelian
storms and tropical cyclones. The most
zone in Africa. This has significant
vulnerable populations are in developing
implications for agriculture, for water
countries, in the lower income groups,
storage and distribution, and for
residents of coastal lowlands and islands,
generation of hydroelectric power. In
populations in semi-arid grasslands, and
some limited areas, for example, under
the urban poor in squatter settlements,
the assumed scenario of a 1°C to 2°C
slums and shanty towns, especially in
temperature increase, coupled with a
megacities. In coastal lowlands such as
10% reduction in precipitation, a 40-70%
in Bangladesh, China and Egypt, as well
reduction in annual runoff could occur.
as in small island nations, inundation
Regions such as Southeast Asia, that are
due to sea-level rise and storm surges
dependent on unregulated river systems,
could lead to significant movements of
are particularly vulnerable to hydro-
people. Major health impacts are
meteorological change. On the other
possible, especially in large urban areas,
hand, regions such as the western USSR
owing to changes in availability of water
and western United States that have
and food and increased health problems
large regulated water resource systems
due to heat stress spreading of infec-
are less sensitive to the range of
tions. Changes in precipitation and
hydrometeorological changes in the
temperature could radically alter the
assumed greenhouse scenario.
patterns. of vector-borne and viral
diseases by shifting them to higher
4
latitudes, thus putting large populations
Oceans and coastal zones
at risk. As similar events have in the
past, these changes could initiate large
Global warming will accelerate sea-level
migrations of people, leading over a
rise, modify ocean circulation and
number of years to severe disruptions of
change marine ecosystems, with con-
settlement patterns and social instability
siderable socioeconomic consequences.
in some areas.
These effects will be added to present
trends of rising sea-level, and other
Global warming can be expected to
effects that have already stressed coastal
affect the availability of water resources
resources, such as pollution and over-
and biomass, both major sources of
harvesting. A 30-50 cm sea-level rise
energy in many developing countries.
(projected by 2050) will threaten low
These effects are likely to differ between
islands and coastal zones. A 1 m rise
and within regions with some areas
by 2100 would render some island
losing and others gaining water and
countries uninhabitable, displace tens of
biomass. Such changes in areas which
millions of people, seriously threaten
lose water may jeopardise energy supply
low-lying urban areas, flood productive
and materials essential for human
land, contaminate fresh water supplies
habitation and energy. Moreover,
and change coastlines. All of these
climate change itself is also likely to
impacts would be exacerbated if
have different effects between regions on
droughts and storms become more
the availability of other forms of
severe. Coastal protection would involve
renewable energy such as wind and solar
very significant costs. Rapid sea-level
power. In developed countries some of
rise would change coastal ecology and
the greatest impacts on the energy,
threaten many important fisheries.
transport and industrial sectors may be
Reductions in sea ice will benefit
determined by policy responses to
shipping, but seriously impact on ice-
climate change such as fuel regulations,
dependent marine mammals and birds:
emission fees or policies promoting
greater use of mass transit. In
Impacts on the global oceans will include
developing countries, climate-related
changes in the heat balance, shifts in
changes in the availability and price of
ocean circulation which will affect the
production resources such as energy,
capacity of the ocean to absorb heat and
water, food and fibre may affect the
CO₂, and changes in upwelling zones
competitive position of many industries.
associated with fisheries. Effects will
vary by geographic zones, with changes
Global warming and increased ultra-
in habitats, a decrease in biological
violet radiation resulting from depletion
diversity and shifts in marine organisms
of stratosphere ozone may produce
and productive zones, including commer-
adverse impacts on air quality such as
cially important species. Such regional
increases in ground-level ozone in some
shifts in fisheries will have major
polluted urban areas. An increase of
socioeconomic impacts.
UV-B radiation intensity at the earth's
surface would increase the risk of
Seasonal snow cover, ice and
damage to the eye and skin and may
permafrost
disrupt the marine food chain.
The global areal extent and volume of
elements of the terrestrial cryosphere
(seasonal snow cover, near-surface layers
5
of permafrost and some masses of ice)
which currently contain permafrost. As
will be substantially reduced. These
a result, overlying ecosystems could be
reductions, when reflected regionally,
significantly altered and the integrity of
could have significant impacts on related
man-made structures and facilities
ecosystems and social and economic
reduced, thereby influencing existing
activities. Compounding these impacts
human settlements and development
in some regions is that, as a result of the
opportunities.
associated climatic warming positive
feedbacks, the reductions could be
Future action
sudden rather than gradual.
The results of the Working Group II
The areal coverage of seasonal snow and
studies highlight our lack of knowledge,
its duration are projected to decrease in
particularly at the regional level and in
most regions, particularly at mid-
areas most vulnerable to climate change.
latitudes, with some regions at high
Further national and international
latitudes possibly experiencing increases
research is needed on:
in seasonal snow cover. Changes in the
volume of snow cover, or the length of
regional effects of climate change on
the snow cover season, will have both
crop yields, livestock productivity and
positive and negative impacts on
production costs;
regional water resources (as a result of
changes in the volume and the timing of
identification of agricultural
runoff from snowmelt); on regional
management practices and tech-
transportation (road, marine, air and
nology appropriate for changed
rail); and on recreation sectors.
climate;
Globally, the ice contained in glaciers
factors influencing distribution of
and ice sheets is projected to decrease,
species and their sensitivity to climate
with regional responses complicated by
change;
the effect of increased snowfall in some
areas which could lead to accumulation
initiation and maintenance of
of ice. Glacial recession will have
integrated monitoring systems for
significant implications for local and
terrestrial and marine ecosystems;
regional water resources, and thus
impact on water availability and on
intensive assessment of water
hydroelectric power potential. Glacial
resources and water quality, especially
recession and loss of ice from ice sheets
in arid and semi-arid developing
will also contribute to sea-level rise.
countries and their sensitivity to
climate change;
Permafrost, which currently underlies
20-25% of the land mass of the Northern
regional predictions of changes in soil
Hemisphere, could experience significant
moisture, precipitation, surface and
degradation within the next 40-50 years.
subsurface runoff regimes and their
Projected increases in the thickness of
interannual distributions as a result of
the freeze-thaw (active) layer above the
climate change;
permafrost and a recession of permafrost
to higher latitudes and altitudes could
assessment of vulnerability of
lead to increases in terrain instability,
countries to gain or loss of energy
erosion and landslides in those areas
resources, particularly biomass and
6
hydroelectric power in developing
countries;
adaptability of vulnerable human
populations to heat stress and vector-
borne and viral diseases;
global monitoring of sea-level
changes, particularly for island
countries;
identification of populations and
agricultural and industrial production
at risk in coastal areas and islands;
better understanding of the nature
and dynamics of ice masses and their
sensitivity to climate change;
integration of climate change impact
information into the general planning
process, particularly in developing
countries; and
development of methodology to assess
sensitivity of environments and
socioeconomic systems to climate
change.
Some of these topics are already
being covered by existing and
proposed programs and these will
need continuing support.
In
particular, there are three core
projects of the International
Geosphere-Biosphere Program,
namely:
Land-Ocean Interactions in the
Coastal Zone
Biosphere Aspects of the
Hydrological Cycle
Global Change Impact on
Agriculture and Society
that will provide valuable data in the
coming years.
7
Scenarios
Any changes which take place as the
between now and 2025 to 2050 for a
results of increasing emissions must be
'business-as-usual' scenario, with no
viewed against a background of changes
changes to present policy;
which are already occurring and which
will continue to occur as a result of
(ii) an increase of mean global
other factors such as:
temperature in the range 1.5° C to 4.5° C
corresponding to the effective doubling
Natural changes - these include long-
of CO₂;
term changes which are driven by
solar and tectonic factors, and short-
(iii) an unequal global distribution of
to-medium term changes which are
this temperature increase, namely half
driven by ocean and atmospheric
the global mean in the tropical regions
circulation patterns.
and twice the global mean in the polar
regions;
Population increase - the predicted
world population is expected to be
(iv) a sea-level rise of about 0.3 to 0.5
above 10 billion by the middle of the
m by 2050 and about 1 m by 2100,
next century; this growth will be
together with a rise in temperature of
unevenly distributed on a regional
the surface ocean layer of between 0.2°
basis and will impact on already
and 2.5°.
vulnerable areas.
These scenarios can be compared with
Land use changes - the clearing of
the recent assessment of Working
forests for new agricultural
Group I which, for a 'business as usual'
production, together with more
scenario, has predicted the increase in
intensive use of existing agricultural
global temperatures to be about 1°C
land, will contribute to land
above the present value by 2025 and
degradation and increase demands for
3°C before the end of next century.
water resources.
However, it has also estimated the
magnitude of sea-level rise to be about
In an ideal world, Working Group I
20 cm by 2030 and about 65 cm by the
would have had the time to produce
end of next century. Nevertheless, the
scenarios for emission-induced climate
impacts based on 1-2 m rise serve as a
change which could have been used as a
warning of the consequences of
basis for the analyses of this Working
continued uncontrolled emissions.
Group. However, this was precluded
because work proceeded in parallel. As
The smaller rise does not lessen the
a result, and in order to complete its
anxiety, for their continued existence, of
work in time, Working Group II has
the small island countries, particularly
used a number of scenarios based on
the Pacific and Indian Oceans and the
existing models in the literature.
Caribbean, or of the larger populations
in low-lying coastal areas such as
The scenarios generally have the
Bangladesh. It is difficult to predict the
following features:
regional effects of sea-level rise with any
certainty. Significant variations of sea-
(i) an effective doubling of CO2 in the
level already occur for a variety of
atmosphere over pre-industrial levels
reasons, while there are considerable
8
shifts in land levels associated with
in producing its predictions of temper-
tectonic plate movements which can also
ature rise and precipitation changes. In
lead to rises and falls.
its report, estimates for 2030 have been
given for central North America,
The scenarios of Working Group II are
southern Asia, Sahel, southern Europe
derived both from General Circulation
and Australia. These are reproduced in
Models and from palaeoanalog tech-
Table 2 and are broadly similar to those
niques. Palaeoclimate analogs are
used by Working Group II.
proposed by Soviet scientists as a means
by which climate changes can be
Despite the current uncertainties, both
assessed. The methodology assumes that
techniques have been used by Working
past warm geologic intervals provide
Group II in the development of regional
insight into possible future climate
impacts to assist policy makers. There
conditions. The General Circulation
are problems with prediction of regional
Models, developed by Western scientists,
precipitation since there is disagreement
are based on three-dimensional
between various general circulation
mathematical representations of the
model outputs as a result of simplifi-
physical processes in the atmosphere and
cations to the representation of complex
the interactions of the atmosphere with
physical processes. Current research is
the earth's surface and the oceans.
seeking to improve the general circu-
There is considerable scientific debate
lation model approach and to increase
about the merits and demerits of each of
resolution to enable better regional
these; as discussed in the report of
predictions. There are also problems
Working Group I.
with the palaeoanalog approach which
yields differing scenarios for precipi-
The palaeoclimate scenarios used by
tation from the general circulation
Soviet scientists are based on three
model approach. This leads to different
warm geological periods with estimated
assessments of impact on water
future levels of concentration of CO₂
resources and agriculture. Soviet
applied to them. The details of these
scientists are working to validate their
are shown in Table 1. While these are
techniques and improve regional
superficially similar to the predictions of
scenarios.
the general circulation model approach
for different CO₂ concentrations, the
It should be noted that, in many
factors which caused the climate changes
situations, the overall impact is
in geologic times are not clear. Never-
determined more by the changes in the
theless, they have been used to make
magnitude and frequency of extreme
predictions of climate change of regions
events than by changes in the average.
in the USSR.
This is especially the case for tropical
storms and droughts. The assessment of
The General Circulation Models are, in
Working Group I of possible climate
their current state of development,
changes suggests a low probability of
comparatively crude in their description
increased frequency of extreme events.
of many of the processes involved.
However, it is entirely possible that shifts
However they can be used to simulate
in climate regimes will result in changes
regional changes resulting from a range
in frequency in certain regions.
of concentrations of CO₂ in the atmo-
sphere. Working Group I has favoured
the general circulation model approach
9
Table 1 Palaeoclimate analogs used by Soviet scientists
Period
Analogue
Temperature
Past co₂ concn.
Assumed co₂
(year)
(difference from
(ppm)
concn. (ppm)
present)
Holocene
2000
+1
280
380
Optimum
Eemian
2025
+2
280
420
Interglacial
Pliocene
2050
+4
500-600
560
Table 2 Estimates for regional changes by Working Group I
(IPCC Business-as-Usual scenario; changes from pre-industrial)
The estimates are based on high resolution models, scaled to give a global mean warming of 1.8°C
consistent with the best estimate (2.5°C) of climate response to greenhouse gases. With the low
estimate value of 1.5°C, these values should be reduced by 30%; with a high estimate of 4.5°C, they
should be increased by 50%. Confidence on these estimates is low.
Central North America (35° -50° N 85°-105°W)
The warming varies from 2° to 4°C in winter and 2° to 3°C in summer. Precipitation increase range
*
from 0% to 15% in winter, whereas there are decreases of 5% to 10% in summer. Soil moisture
decreases in summer by 15% to 20%.
Southern Asia (5°-30°N 70°-105°E)
The warming varies from 1° to 2°C throughout the year. Precipitation changes little in winter and
generally increases throughout the region by 5% to 15% in summer. Summer soil moisture increases
by 5% to 10%.
Sahel 20°W-40°E)
The warming ranges from 1° to 3°C. Area mean precipitation increases and area mean soil moisture
decreases marginally in summer. However, there are areas of both increase and decrease in both
parameters throughout the region, which differ from model to model.
Southern Europe (30°-50°N 10°W-45°E)
The warming is about 2°C in winter and varies from 2° to 3°C in summer. There is some indication
of increased precipitation in winter, but summer precipitation decreases by 5% to 15%, and summer
soil moisture by 15% to 25%.
Australia (12° -45° S.110°-155" E)
The warming ranges from 1° to 2° in summer and is about 2°C in winter. Summer precipitation
increases by around 10%, but the models do not produce consistent estimates of the changes in soil
moisture. The area averages hide large variations at the subcontinental level.
10
An issue of importance not considered in
any detail is the impact of possible
response strategies (developed by
Working Group III) on the scenarios
used here. Thus, a major change in
energy production from fossil fuel to
nuclear or renewable energy sources
could drastically alter our assessments.
Further, changes in agricultural practice
could dramatically alter yields of
particular crops in certain regions.
These impacts of response strategies
require much additional work.
Despite all these uncertainties, it is
possible to make assessments of
potential impacts of climate change by
considering the sensitivity of natural
systems to significant variations. These
are summarised in the following sections
under: agriculture and forestry;
terrestrial ecosystems; hydrology and
water resources; human settlement,
energy, transport, industry, human health
and air quality; world ocean and coastal
zones; seasonal snow cover, ice and
permafrost.
11
Summary of findings
the same level as would have
occurred without climate change; but
Potential impacts of climate
the cost of achieving this is unclear.
Nonetheless, climate changes may
change on agriculture, land use
intensify difficulties in coping with
and forestry
rapid population growth.
Potential impacts on agriculture
Principal issues
Major findings
Magnitudes of possible dislocation
Sufficient evidence is now available
Under the estimate of changes in pro-
from a variety of different studies to
ductive potential for the changes of
indicate that changes of climate would
climate outlined in this report, the cost
have an important effect on agri-
of producing some mid-latitude crops,
culture, including livestock. Yet the
such as maize and soybean, could
fact that there are major uncer-
increase, reflecting a small net decrease
tainties regarding likely effects in
in the global food production capability
specific regions should be a cause for
of these crops. Rice production could,
concern. Studies have not yet
however, increase if available moisture
conclusively determined whether, on
increased in Southeast Asia, but these
average, global agricultural potential
effects may be limited by increased
will increase or decrease.
cloudiness and temperature. The
average global increase in overall pro-
Negative impacts could be felt at the
duction costs due to climate change
regional level as a result of changes in
could thus be small.
weather, diseases, pests and weeds
associated with climate change,
Much depends on the possible benefits
necessitating innovation in technology
of the so-called 'direct' effects of
and agriculture management
increased CO₂ on crop yield. If plant
practices. There may be severe
productivity were substantially enhanced
effects in some regions, particularly in
and more moisture were available in
regions of high present-day vulner-
some major production areas, then world
ability that are least able to adjust
production of staple cereals could
technologically to such effects.
increase relative to demand. If, on the
contrary, there is little beneficial direct
There is a possibility that potential
CO₂ effect and climate changes are
productivity of high and mid-latitudes
negative for agricultural potential in all
may increase because of a prolonged
or most of the major food-exporting
growing season, but it is not likely to
areas, then the average costs of world
open up large new areas for
agricultural production due to climate
production, and will be largely
change could increase significantly.
confined to the Northern Hemi-
sphere.
Most vulnerable regions and sectors
On balance, the evidence is that in
On the basis of both limited resource
the face of estimated changes of
capacity in relation to present-day
climate, food production at the global
population and possible future
level can be maintained at essentially
diminution of the agricultural resource
12
base as a consequence of reduced crop-
could be severe. In addition, relatively
water availability, two broad sets of
small decreases in rainfall, changes in
regions appear most vulnerable to
rainfall distribution or increases in
climate change: (i) some semi-arid,
evapotranspiration could markedly
tropical and subtropical regions (such as
increase the probability, intensity and
western Arabia, the Maghreb, western
duration of drought in currently drought-
West Africa, Horn of Africa and
prone (and often food-deficient) regions.
southern Africa, eastern Brazil), and (ii)
Increase in drought risk represents
some humid tropical and equatorial
potentially the most serious impact of
regions (such as Southeast Asia and
climate change on agriculture at both
Central America).
the regional and global level.
In addition, certain regions that are
Effects on crop growth potential, land
currently net exporters of cereals could
degradation, pests and diseases
also be characterised by reduced produc-
tive potential as a result of climate
Higher levels of atmospheric CO₂ are
changes. Any decrease in production in
expected to enhance the growth rate of
these regions could markedly affect
some staple cereal crops, such as wheat
future global food prices and patterns of
and rice, but not of others such as millet,
trade. These regions might include, for
sorghum and maize. The use of water
example, Western Europe, southern US,
by crop plants may also be more
parts of South America, and Western
efficient under higher CO₂ levels. How-
Australia.
ever, it is not clear how far the poten-
tially beneficial 'direct' effects of
Effect of altered climate extremes
enhanced atmospheric CO₂ will be mani-
fested in the farmer's field.
Relatively small changes in the mean
values of rainfall and temperature can
Warming is dikely to result in a poleward
have a marked effect on the frequency
shift of thermal limits of agriculture,
of extreme levels of available warmth
which may increase productive potential
and moisture. For example, the number
in high-latitude regions. But soils and
of very hot days which can cause
terrain may not enable much of this
damaging heat stress to temperate crops
potential to be realised. Moreover,
and livestock could increase significantly
shifts of moisture limits in some semi--
in some regions as a result of a 1°C to
arid and sub-humid regions could lead to
2°C increase in mean annual temper-
significant reductions of potential with
atures. Similarly, reduction in average
serious implications for regional food
levels of soil moisture as a result of
supplies in some developing countries.
higher rates of evapotranspiration could
Horticultural production in mid-latitude
increase substantially the number of days
regions may be reduced owing to insuf-
below a minimum threshold of water
ficient accumulated winter chilling. The
availability for given crops.
impact of climate change will be far
greater for long-lived horticultural fruit
Although at present we know little about
crops, with long establishment periods,
how the frequency of extreme events
than for annual crops where new
may alter as a result of climate change,
cultivars can quickly replace others.
the potential impact of concurrent
drought or heat stress in the major
Temperature increases may extend the
food-exporting regions of the world
geographic range of some insect pests,
13
diseases and weeds, allowing their
however, to assume that crop-water
expansion to new regions as they warm
availability could decrease in some
and become suitable habitats. Changes
regions. Under these circumstances
in temperature and precipitation may
there could be substantial regional
also influence soil characteristics.
dislocation of access to food.
Regional impacts
Adaptation in agriculture
Impacts on potential yields are likely to
In some parts of the world, climatic
vary greatly according to types of climate
limits to agriculture are estimated to
change and types of agriculture.
shift poleward by 200-300 km per degree
of warming. The warming-induced
In the northern mid-latitude regions,
upwards shift in thermal zones above
where summer drying may reduce pro-
mountain slopes could be in the order of
ductive potential (eg in the south and
150-200 m.
central US and in southern Europe),
yield potential is estimated to fall by
Agriculture has an ability to adjust,
10-30% under an equilibrium 2 X CO₂
within given economic and technological
climate by the middle of the next
constraints, to a limited rate and range
century. Towards the northern edge of
of climate change. This capability varies
current core producing regions, however;
greatly between regions and sectors, but
warming may enhance productive
no thorough analysis of adaptive capacity
potential in climatic terms. When
has yet been conducted for the
combined with direct CO2 effects,
agriculture sector.
increased climatic potential could be
substantial - though in actuality it may
In some currently highly variable
be limited by soils, terrain and land use.
climates, farmers may be more adaptable
than those in regions of more equable
There are indications that warming could
climate. But in developing economies,
lead to an overall reduction of cereal
and particularly in some marginal types
production potential in North America
of agriculture, this intrinsic adaptive
and to southern Europe, but increased
capability may be much lower. It is
potential in northern Europe. Warming
important to establish in more detail the
could allow increased agricultural output
nature of this adaptability and thus help
in regions near the northern limit of
to determine critical rates and ranges of
current production in the USSR and
climatic change that would exceed those
North America, but output in the
that could be accommodated by adjust-
southern areas of these regions could
ments within the system.
only increase if corresponding increases
in soil moisture were to occur; this is at
Recommendations for action
present uncertain.
This study has emphasised the
Little is known about likely impacts in
inadequacy of our present knowledge. It
semi-arid and humid tropical regions,
is clear that more information on
because production potential here
potential impacts would help to identify
largely depends on crop-water avail-
the full range of potentially useful
ability, and the regional pattern of
responses and assist in determining
possible changes in precipitation is
which of these may be most valuable.
unclear at present. It is prudent,
14
Some priorities for future research may
recommended that national and inter-
be summarised as follows:
national centres of agricultural
research consider the potential value
Improved knowledge is needed of
of new research programs aimed at
effects of changes in climate on crop
identifying or developing cultivars and
yields and livestock productivity in
management practices appropriate for
different regions and under varying
altered climates.
types of management. To date, less
than a dozen detailed regional studies
Further information is needed on the
have been completed, and these are
range of potentially effective policy
insufficient as a basis for generalising
responses at regional, national and
about effects on food production at
international levels (eg reallocation of
the regional or world scale. Further
land use, plant breeding, improved
research in vulnerable regions in
agricultural extension schemes, large-
particular should be encouraged.
scale water transfers etc).
Improved understanding of the effects
Potential impacts on managed
of changes in climate on other
forests and the forest sector
physical processes is needed: for
example on rates of soil erosion and
All impacts referred to in this section
salinisation; on soil nutrient
reflect the current uncertainty in the
depletion; on pests, diseases and soil
extent of warming, and levels and
microbes, and their vectors; on
distribution of precipitation. They
hydrological conditions as they affect
reflect the consensus that anthropogenic
irrigation water availability.
change is occurring; the direction is
towards higher temperatures, with the
An improved ability is required to
extent affected by latitude and
'scale-up' our understanding of effects
continentality.
on crops and livestock, effects on
farm production, on village
The distinction between managed and
production, and on national and
unmanaged forests is often unclear, but
global food supply. This is parti-
it is taken here to be one of degree in
cularly important because policies
the intensity of human intervention. In
must be designed to respond to
managed forests, harvesting takes place
impacts at the national and global
and the forests are renewed, replaced or
levels. Further information is needed
restructured in such a way that actual
on the effects of changes in climate
physical inputs are needed to achieve
on social and economic conditions in
goals.
rural areas (eg employment and
income, equity considerations, farm
infrastructure, and support services).
Managed forests are quite distinct from
the unmanaged forests. They supply a
wide variety of products and are found
Further information is needed on the
in a wide variety of countries with
range of potentially effective technical
different social, physical and political
adjustments at the farm and village
environments. The intensity of forest
level (eg irrigation, crop selection,
fertilising etc) and on the economic
management may not necessarily parallel
the degree of economic development;
and political constraints on such
different countries depend to different
adjustments. In particular, it is
degrees on the products from forests.
15
Therefore the severity of the impacts will
with moving processing facilities and
vary among countries as will the ability
infrastructure as the wood supply zones
to respond. In tropical countries the
move northward. The most important
managed forests characteristically
feature of these costs and disruptions
employ exotic species, whereas in the
from a global point of view is that the
northern countries greater reliance is
changes will differ among countries and
placed on indigenous species.
that some countries are better able than
others to cope with the impacts.
Biophysical effects on forest ecosystems
Major forest-type zones and species
Impacts on forest ecosystems will be at
ranges could shift significantly as a result
the tree and microsite levels, at the
of climate change. Results of several
stand/watershed level and at the
Northern Hemisphere studies show that
regional level. Impacts on individual
both high-latitude and low-latitude
trees include tolerance of drought and
boundaries of temperate and northern
winds, the possible effects of altered
forests (and tree species) may shift
seasonality (active VS dormant stages),
hundreds of kilometres poleward. In
altered photosynthetic rates and
contrast, studies in the Southern Hemi-
increased water use efficiency. At the
sphere suggest that Australian species
microsite level, moisture may be limited
could adapt and grow at temperatures
and biological soil processes may be
much warmer than those of their natural
enhanced. Forest renewal will be
distribution.
adversely affected if there is a shortage
of moisture at the critical establishment
At the stand level, the following effects
phase.
of climate change on forests are likely:
increased mortality owing to physical
On stand levels, insects and diseases can
stress; increased susceptibility to and
be expected to cause significant losses to
infestations of insects and diseases;
forests and these losses can be expected
increased susceptibility to and incidences
to increase with increasing change. Fire
of fire; changed stand growth rates, both
severity will increase, and while managed
increases and decreases; more difficult
forests may have less fuel available than
stand establishment by both natural and
unmanaged ecosystems, this will not
artificial regeneration; and changed
lessen the incidence of fire, nor will it
composition of species.
affect the weather conditions giving rise
to the rates of spread or the extent of
Two broad types of forests are likely to
the areas burned. Developed countries
be sensitive to a changing climate: (i)
can barely cope with the current state
boreal forests, where stands are mainly
and the extent of areas burned seem to
even-aged and often temperature-
be rising. The incidence of fire may be
limited, and where temperature changes
less in the tropics as the climate there
are expected to be large; and (ii) forests
changes less, but many plantations are in
in arid and semi-arid regions where
semi-arid zones and will be suffer
increased temperatures and stable or
adverse impacts. Costs associated with
decreasing precipitation could render
flooding, resulting from rising sea-levels
sites inhospitable to the continued
and disruption of weather patterns, can
existence of current forest stands.
be expected. There will be problems in
However, there could be compensating
using the lower quality wood grown
effects of faster growth owing to higher
under stress and large costs associated
ambient CO2.
16
Socioeconomic implications
under new climates will have no regard
for non-ecological boundaries such as
All countries use forests for heating,
watersheds, ownerships, parks, nature
cooking and food. The degree to which
reserves and recreation areas.
people are dependent on these, however,
varies widely. Forest ecosystem changes
It is concluded that climate change could
and tree distribution have no regard for
more likely exacerbate most current and
political or administrative boundaries.
near-term issues and tensions rather than
Managed forests have, by definition, high
relieve them. This finding is very
levels of investment in them; some
dependent on the assumption that during
countries are better able than others to
the next 30-50 years, in response to
tolerate the risk to, and possible loss, of
climate change, forests everywhere in the
these investments.
world will be prone to some measure
and form of decline. These changes will
Intensively managed forests have high
be taking place at the same time as a
inputs from choice of species, sites,
substantial increase in population with
spacing, tending, thinning, fertilisation
increased demands: If, on the other
and protection. These interventions are
hand, forests in some regions are largely
costly and some countries may not be
unaffected by climate change, or actually
able to supply the inputs necessary to
experience increased growth rates, then
establish, maintain and protect the
perhaps most of the issues and tensions
investments.
could be at least partly relieved.
Increased protection costs will be
Adaptation
unevenly borne and could encourage
poorer countries to accelerate harvesting,
Much can be done to reduce the suscep-
reduce rotation periods and engage in
tibility of socioeconomic systems to
other practices, which may not be
climate-induced forest declines.
sustainable. More data are needed on
Appropriate measures include the whole
these secondary and insidious effects of
array of forest-management tools, to be
climate change. Associated disruptions
chosen and implemented as local con-
in the social fabric of many countries
ditions warrant, but some may be
may impact adversely on forests, as
detrimental to other indicators, for
instances of arson or other damage as do
example, wildlife or recreation.
now.
For wood supply, the forest-products
The socioeconomic implications of shifts
industry can move processing technology
in the ranges of tree species will be
towards new kinds and qualities of fibre,
influenced by the fact that climate will
and plan new mills in areas improving in
probably change much faster than tree
wood-supply potential. Governments
species can naturally respond (eg
can support efforts in economic
through migration).
diversification in forest-based
communities, and engage in improved
Moreover, new sites may not be
long-range planning for future changes in
hospitable, having evolved over
land potential for forestry. The
thousands of years under other climatic
provision of recreational facilities is
and vegetative regimes. The suitability
another example of an important forest-
of new ranges and the actual compo-
based economic sector. Governments
sition and growth patterns of forests
and private firms must anticipate how
17
forested landscapes might change, and
which are biologically sustainable, even
plan accordingly to divest themselves of
if the eventual changes are minimal.
the old facilities and invest in the new.
Examining biogeochemical changes on a
Recommendations for action
global scale is complex enough; adding
humans as a variable factor complicates
The ability to deal with climate change
the issue even more. Nevertheless,
and the forest sector is related to the
humans are the critical element in the
amount of knowledge available. There
study of ecological systems. We must
are uncertainties to be considered: for
consider the institutional imperatives and
instance, in the future, will the same
the economic and political influences on
tensions and issues have similar high
people in different nations, together with
priority? Studies of the socioeconomic
the cultural diversity that distinguishes
impacts must be global in scope, inter-
and may dominate our actions.
national in organisation, institutional in
focus and historical in breadth. We
The nature and temporal/spatial distri-
need regional climate scenarios and
bution of climate change itself is highly
better information on stand-level
uncertain, as are the various ways by
responses, the biological relationship
which a changing climate could influence
between species and sites and the
forests and their growing sites, and the
inherent variability of species. Changing
various repercussions this might have on
climates demonstrate the need for
our uses of forests. Moreover, the
strategies in active management in the
means by which society might cope with
forest sector. Even better knowledge is
the changing environmental and socio-
needed of the potential role of forest
economic conditions; in a context in
management in mitigating impacts and
which those conditions are rapidly
exploiting opportunities from climate
changing quite independently of climate
change.
change, are largely unexplored so far.
A major impact, of which there is
The following major research and assess-
evidence now, will be considerable
ment initiatives should be developed and
apprehension on the part of the general
pursued in the near future (early 1990s)
public, particularly those dependent on
to begin to shed light on the impacts
the forest sector for their livelihood.
discussed in this section: (i) more secure
Public cooperation in the implemen-
regional climate scenarios; (ii)
tation of decisions will be required for
simulation of impacts of climate change
dealing with a problem which has
on managed forest stands; (iii) modelling
biological rather than ideological
studies for better understanding of
solutions.
matches between species and sites; (iv)
analyses of the potential role of forest
Research on the socioeconomic impacts
management in mitigating undesirable
of climate change must focus on the
impacts and capitalising on desirable
transitional climates occurring over the
impacts of climate change; (v) regional
next several decades, not only at specific
analyses of potential disruption of
points in time. This reflects the way
wildlife habitat and the recreational
people live - in specific localities and in
potential of forests due to forest-
real time. It makes sense to prepare for
structure changes brought on by climate
serious impacts by implementing policies
change; (vi) regional analyses of
potential socioeconomic repercussions of
18
fluctuations in timber supply due to
where the land is classified as polar
climate change on rural communities,
desert, tundra and boreal forest.
industrial concerns, markets and trade in
forest products, and governments. (vii)
Ecosystems are not expected to move
synthesis studies of the policy
as a single unit, but would have a new
possibilities for the forest sector to
structure as a consequence of
prepare for climate change; and (viii)
alterations in species distributions and
periodical assessment of the destruction
abundance.
of tropical forests using remote sensing.
Some species could be lost owing to
Potential impacts of climate
increased stresses leading to a
change on natural terrestrial
reduction in global biological
ecosystems and the socioeconomic
diversity, whereas other species may
thrive as stresses decrease.
consequences
Most sensitive are those communities
Major findings
in which the options for adaptability
Global increases in the atmospheric
are limited (eg montane, alpine,
polar, island and coastal com-
concentration of greenhouse gases
munities, remnant vegetation, and
and related climatic changes will have
heritage sites and reserves) and those
significant consequences for natural
communities where climatic change
terrestrial ecosystems and related
add to existing stresses.
socioeconomic systems.
Increased incidents of disturbances
Climatic zones could shift several
such as pest outbreaks and fire are
hundred kilometres towards the poles.
likely to occur in some areas and
Flora and fauna would lag behind
these climatic shifts, surviving in their
these could enhance projected
ecosystem changes.
present location; they would therefore
find themselves in a different climatic
The direct effects of increased
regime.
atmospheric concentrations of CO2
may increase plant growth, water use
The rate of projected climatic changes
efficiency and tolerance to salinity,
is the major factor determining the
though this positive effect could be
type and degree of climatic impacts
reduced over time by ecosystem feed-
on natural terrestrial ecosystems.
backs. Enhanced levels of air
These rates are likely to be faster
pollution could also reduce this
than the ability of some species to
positive effect.
respond and these responses may be
sudden or gradual.
Socioeconomic consequences of these
impacts will be significant, especially
New climatic regimes may be less-
hospitable under some circumstances
for those regions of the globe where
societies and related economies are
(eg towards lower latitudes and lower
dependent on natural terrestrial
altitudes) and may be more
hospitable under others (eg towards
ecosystems for their welfare. Changes
in the availability of food, fuel,
higher latitudes). Vegetation zone
medicine, construction materials and
changes are projected to be greatest
income are possible as these
19
ecosystems are affected. Important
specialised organisms with specific
fibre products, recreation and tourism
niches;
industries could also be affected in
some regions.
poor dispersers;
Principal issues
more slowly reproducing species; and
The projected changes in climate will
localised populations of annual
present these ecosystems with a climate
species.
warmer than that experienced during
their recent evolution and there will be
This would suggest that montane and
warming at a rate 15-40 times faster than
alpine, polar, island and coastal
past glacial-interglacial transitions. This
communities, and heritage sites and
combination of relatively large and fast
reserves are particularly at risk, since
changes in climate will cause disruption
their component species may not be able
of ecosystems, allowing some species to
to survive or adapt to climate change
expand their ranges while others will
because of the limited number of
become less viable and, in some cases,
adaptive options available to them.
may disappear.
Changes in the boundaries of vegetation
Current knowledge does not allow a
zones
comprehensive and detailed analysis of
all aspects of the impacts of climate
Projected changes in global temperature
change on natural terrestrial ecosystems.
of 1.5° -4.5° C and changes in precipi-
It is possible, however, to make some
tation will result in the movement of the
plausible implications. All estimates
boundaries of vegetation zones, and will
presented below are based on scenarios
impact on their floristic composition and
of enhanced atmospheric concentrations
associated animal species. Boundaries
of greenhouse gases and related changes
(eg boreal-tundra, temperate forests,
in global climate. It is impossible to
grasslands etc) are expected to shift
evaluate the consequences of change in
several hundreds of kilometres over the
climatic variability since the required
next 50 years. Real rates of the move-
climatic analyses are not available.
ment of species, however, will be
restricted by limits on their ability to
Particularly sensitive species
disperse and the presence of barriers to
dispersion; they will, therefore, average
The species which are particularly
approximately 10-100 m/year.
sensitive to climatic changes are:
Both coniferous and broad-leaved
species at the edge of (or beyond)
thermophilic tree species will find
their optimal range;
favourable environments much further
poleward than their current limits. In
geographically localised species (eg
the northern parts of the Asian USSR,
those found on islands, on mountain
the boundary of the zone will move
peaks, in remnant vegetation patches
northward 40°-50° of latitude (500-600
in rural areas, and in parks and
km). The tundra zone is expected to
reserves);
disappear from the north of Eurasia.
genetically impoverished species;
20
Expected changes in precipitation will
evapotranspiration, as well as indirectly
allow species to extend their boundaries
by altering sea and lake levels which
equatorward. As a result, broad-leaved
influence water levels in coastal and
species range will expand and these
shoreline ecosystems.
ecosystems will be more maritime in
terms of species composition. The forest
The seasonality of rainfall also affects its
steppe subzone in the European USSR
impact. A lengthening of the dry season
will change while in southern portions of
or, conversely, an increase in ground-
western Siberia the forest-steppe
water table levels could both accentuate
boundary could move up to 200 km.
salinisation problems. In Mediterranean
and semi-arid climates, where evapotran-
In the semi-arid, arid and hyper-arid
spiration exceeds precipitation for long
ecoclimatic zones of the Mediterranean,
periods and increased percolation from
greenhouse-gas-induced climate change
vegetation clearing or excessive irrigation
will reduce plant productivity and result
may have raised the water table, surface
in desertification of the North African
soil salinisation can be a major problem.
and Near Eastern steppes owing to
Such salinisation can kill all but the most
increased evapotranspiration. The upper
halophytic. vegetation, increase soil
limit of the deserts would migrate under
erosion and reduce water quality.
the influence of climate change and most
Salinisation is already a problem in
likely extend into the area that currently
many Mediterranean and semi-arid
corresponds to the lower limits of the
regions, (eg coastal Western Australia,
Semi-Arid Zone (ie foothills of the high,
the Mediterranean, subtropical Africa)
Mid and Tell Atlas and Tunisian Dorsal
and is a major cause of increased
in Northern Africa, and of the main
desertification.
mountain ranges of the Near-Middle
East: Taurus, Lebanon, Alaoui,
Greenhouse-gas-induced climatic
Kurdistan, Zagros and Alborz).
changes will affect the structure and
composition of natural terrestrial
The impact of climate changes on the
ecosystems as a result of altered
present tropical and temperate rainforest
relationships within these ecosystems,
is uncertain. For example, almost all of
perhaps leading to the introduction of
Tasmania is expected to become, at best,
new species.
climatically 'marginal' in terms of
temperate rainforests, largely owing to a
Given the new associations of species
rise in winter temperatures suggested by
that could occur as climate changes,
climate scenarios. This increase in
:
many. species will face 'exotic'
temperature is unlikely to have a direct
competitors for the first time. Local
effect on the forest, but may facilitate
extinctions may occur as climate change
the invasion of less frost-tolerant species.
causes increased frequencies of droughts
and fires, and invasion of species. One
Changes within ecosystems
species that might spread, given such
conditions, is Melaleuca quinquenervia, a
Projected greenhouse-gas-induced
bamboo-like Australian plant. This
climate changes will profoundly affect
species has already invaded the Florida
hydrologic relationships in natural
Everglades, forming dense monotypic
terrestrial ecosystems, both directly by
stands where drainage and frequent fires
altering inputs of precipitation, runoff,
have dried the natural marsh community.
soil moisture, snow cover and melt, and
21
Pests and pathogens, in some cases, are
which would tend to accelerate changes
expected to increase their ranges as a
in ecosystem composition under con-
result of climate change and, in the case
ditions of changing climate.
of insects, their population densities.
This could place at risk the health of
In areas with a distinct wet and dry
ecosystems, and thereby play an
season (parts of the tropic, and all of the
important role in determining future.
Mediterranean-climate regions), change
vegetation and animal distributions
in the amount of precipitation in rainy
months could alter fuel loads by
Pest outbreaks can also be expected as a
influencing growth. The altered fuel
result of the increased stress and
loads, along with changes in precipi-
mortality of standing vegetation resulting
tation, could affect fire intensities during
from a combination of climate-driven
the dry season. A shift towards a slightly
stressors. An example from New
wetter climate during the summer rainy
Zealand concerns hard beech
season could increase fuel loadings in
(Nothofagus truncata). A 3°C rise in
most of the subtropical and temperate
temperature would increase annual
woodlands of Mexico, which would
respiratory carbon losses by 30%; such a
suggest increased fire frequencies.
loss exceeds the total annual amount
allocated to stem and branch growth for
Global biological diversity is expected to
this species. With insufficient reserves
decrease with possible socioeconomic
to replace current tissue, the tree is
consequences as a result of climate
weakened, and becomes more suscep-
change; however, some local increases
tible to pathogens and insects.
may also result, especially over the
Following repeated drought episodés,
longer term. The resulting impacts on
several (Nothofagus) species succumbed
biological diversity are dependent on the
to defoliation insects. This would be
balance between changes in species
exacerbated by non-induced climate
interactions and adaptation through
change.
migration.
Since wetlands, particularly seasonal
Warming could set off a chain of
wetlands in warmer regions, provide
extinctions by eliminating keystone
habitat for the breeding and growth of
herbivores or their functional
vectors of a number of serious diseases
counterparts in other ecosystems. For
such as malaria, filariasis and schisto-
example, in the 100 years following the
somiasis, an increase in average temper-
disappearance of elephants in the
ature and any change in the distribution
Hluhluwe Game reserve in Natal,
of seasonal wetlands will alter the
several species of antelope have been
temporal and spatial distribution of these
extirpated and populations of open
diseases.
country grazers, such as wildebeest and
waterbuck, have been greatly reduced.
Higher temperatures and changed
precipitation may well lead to increased
The direct effects of increased
drought frequency and fire risk in many
atmospheric concentrations of CO₂ may
forested areas. Coupled with probably
increase the rate of plant growth;
increased fuel density because of the
however, man-induced changes in the
direct effects of increased ambient CO₂
chemical composition of the atmosphere
on forest understorey, this could lead to
(eg ozone) and ecosystem feedbacks
increased exposure of forests to fire,
22
could reduce this positive effect over.
initiating and supporting regional
time.
national and international research
and impacts programs; and
Recommendations for action
educating resource managers and the
While the specific impacts of global
public about the potential
warming on any one region or a single
consequences of climatic change for
species are to some degree matters of
natural terrestrial ecosystems.
conjecture, there are some clear
conclusions that can be made. Natural
Potential impacts of climate
terrestrial ecosystems will change in
change on hydrology and water
make-up and shift in location, and those
resources
species which can adapt and shift will
survive. The sensitive species, especially
those for which options are limited, will
Major findings
dwindle and disappear.
For many watersheds worldwide,
Examination of the environmental
especially those in arid and semi-arid
impacts of climate change on natural
regions, runoff is very sensitive to
terrestrial ecosystems and the associated
small changes and variations in
socioeconomic consequences is in its
climate. For example, 1°C to 2°C
infancy. The studies that have been
temperature increase coupled with a
carried out are limited; only specific
10% reduction in precipitation could
regions and sectors have been examined.
conceivably produce a 40-70%
Further limiting this work is that, for the
reduction in annual runoff.
most part, existing studies have taken a
narrow view of the problem and not
Based on empirical data and
looked at it from a multi-disciplinary
hydrological models, annual runoff
perspective. In addition, most of the
appears to be more sensitive to
studies have examined the effects of
changes in precipitation than to
climate change on current social,
changes in temperature. However, in
economic and environmental systems
regions where seasonal snowfall and
and have not considered social and
snowmelt are a major part of the total
economic adjustments nor impacts and
water supply, the monthly distribution
of runoff and soil moisture is more
consequences during ecosystem
transitional periods.
sensitive to temperature than to
precipitation.
These limitations can be addressed by:
The construction of hypothetical
assembling relevant inventories of
scenarios provides a range of runoff
species and ecosystems;
responses and the characteristics of
those responses for particular areas.
initiating and maintaining integrated
However, credible forecasts for any
monitoring programs;
specific region, sufficient to designate
either direction or magnitude of
gathering information on relative
change, are not yet available. We can
species and ecosystems sensitivities to
conduct warm sensitivity analysis
climate change;
using General Circulation Models
while the scientific basis slowly
improves.
23
Vulnerabilities in present water uses
In many instances it can be expected
(ie where demand exceeds firm yield)
that changes in hydrologic extremes in
and conflicts among current uses are
response to global warming will be more
likely to be exacerbated by global
significant than changes in hydrologic
warming in most arid and semi-arid
mean conditions. Thus, attention must
regions.
be focused on changes in the frequency
and magnitude of floods and droughts in
The regions that appear to be at
evaluating the societal ramifications of
greatest risk, in terms of serious
water resource changes.
threats to sustaining the population
are: Africa - Maghreb, Sahel, the
Initial water resource planning and
north of Africa, southern Africa; Asia
policy making will continue to be
- western Arabia, Southeast Asia, the
implemented even in the face of
Indian subcontinent; North America -
uncertainty about global change.
Mexico, Central America, southwest
Clarification and specification of the
US; South America - parts of eastern
useful information about the various
Brazil; Europe - Mediterranean zone.
methods for estimating future change
must be made available to the
The relative degree of water
management community.
management (storage versus mean
annual flow) is a primary determinant
Regional impacts
in adapting to changes in the mean
annual variability.
Continental/national
It is essential that future design of
Based on palaeoclimatic analogs coupled
water resource engineering take into
with physically based water-balance
account that climate is a
models, annual runoff over the whole of
non-stationary process, and that
the USSR is projected to rise, although
structures with a design life of 50 to
runoff is expected to decrease slightly in
more than 100 years should be
the forest steppe and southern forest
designed to accommodate climatic
zones. In any case, winter runoff is
and hydrometeorological conditions
expected to increase in the regions with
which may exist over the entire life of
snowfall and snowmelt. Serious flooding
the structure.
problems could arise in many northern
rivers of the USSR.
Principal issues
An assessment of all the river basins in
If worthwhile estimates of water
the US shows that the arid and semi-arid
resources conditions, appropriate for
regions of the US would be most
planning and policy formulation, are to
severely affected by global warming,
be produced, then studies must include
even though there is a high degree of
estimates on the frequency, intensity and
water control. The competing uses of
duration of potential future hydrologic
agricultural irrigation, municipal water
events. This is especially critical for
supply, and generation of hydroelectric
evaluating effects on agriculture, the
power, have stressed even the present
design of water resource management
system. All other regions in the US will
systems, and for producing reasonably
probably suffer adverse water-resource
accurate water supply estimates.
impacts to some degree, whether for
generation of hydroelectric power,
24
municipal water supply shortages, or
sensitive to climatic conditions, especially
agricultural irrigation.
precipitation. Research suggests, for
example, that a 20% to 30% decrease in
An assessment of the general circulation
precipitation could lead to a 15% to
model studies for the nations of the
59% reduction in runoff. As for
European Economic Community (EEC)
potential changes in water resources in
indicates that precipitation and runoff
the future, it can be said that the
may increase in the northern nations,
situation is very uncertain. Therefore,
possibly causing flooding problems in
additional comprehensive studies of this
low-lying countries. The Mediterranean
problem, which is very important for the
countries of the EEC may experience a
region, are required.
decline in runoff, thereby increasing the
already serious and frequent water
A study of the Sacramento-San Joaquin
supply shortages occurring in that region.
River basin showed how a highly
It is most probable that agriculture will
managed water resource system,
suffer the most adverse effects.
dependent on snowmelt-generated
runoff, would be affected by global
In Japan, prolonged periods of droughts
warming. Air temperature increases
and shorter periods of intense precipi-
changed the timing and increased the
tation may be likely. Current storage
magnitude of snowmelt-generated runoff
capacity is limited and a large proportion
by 16% to 81%, severely stressing the
of the population is located on flood-
flood-control capabilities of existing
plains. Water demand can be expected
reservoirs. However, summer runoff
to increase, which will seriously stress
decreases of 30% to 68%, coupled with
the existing water management system.
soil moisture decreases of 14% to 36%
and a doubling of water demand by the
An increase in precipitation and
year 2020, suggest that serious water use
consequent flooding, along with
conflicts and periodic shortages are a
overloads of stormwater/sewerage
distinct possibility for this system.
systems leading to degradation of surface
water quality, is possible in News
In the Murray-Darling basinof Australia,
Zealand.
the use of spatial analogs indicates that
precipitation could decrease by 40% to
The UK can expect an increase in mean
50%. However, based on general
annual runoff over most of the country,
circulation model outputs, the
but with a stronger seasonal variation in
summer-dominant rainfall area of
peak flows, imposing the need for
Australia will possibly expand to
redesigning existing water management
encompass 75% of the continent by
systems.
2035. Runoff could double on the
Darling River.
River basins and critical environments
A water supply-demand stochastically-
Runoff in the Volga River basin, after
based sensitivity analysis was conducted
undergoing an initial decrease through
for the Delaware River basin, a highly
the year 2000, is expected to increase
urbanised watershed in the northeastern
after that year.
US. Basin-wide estimates of annual
runoff indicate a possible decrease of
Studies indicate that hydrological
9% to 25%. Also, the probability of
conditions in the Sahelian zone are very
drought increases substantially
25
throughout the basin. The Delaware
mation on both the frequency and
River supplies a large percentage of New
magnitude of events. Increased
York City's water supply, which is
understanding of relations between
already operating below its safe yield.
climatic variability and hydrologic
Reduced flows in the Delaware River
response must be developed. Such work
would threaten the city of Philadelphia's
should include the development of
water supply intakes in the estuarine
methods for translating climate model
portion of the river through upstream
information into a form that provides
movement of the freshwater-saltwater
meaningful input data to watershed and
interface.
water resource system models.
Large lakes/seas
Areas particularly vulnerable to even
small changes, in climate must be
The Caspian Sea is the largest closed
identified worldwide. Vulnerabilities
water body in the world. It receives
must be ascertained considering both
nearly 80% of its runoff from the Volga
natural and anthropogenic conditions
River and will respond to the initial
and potential changes.
decrease in projected Volga River flows
to the year 2000, but will increase
Intensive assessments of water resource
thereafter. This will greatly improve the
sensitivities are necessary in developing
severely degraded water quality and
countries, especially those located in
ecological conditions in the Sea.
environmentally sensitive arid and
semi-arid regions, where the potential
Based on general circulation model
for conflicts associated with low water
results, the Great Lakes are expected to
resource system development and rapidly
incur net basin runoff decreases of 23%
increasing water demands is high.
to 51% under an effective doubling of
CO₂ scenario. Generation of hydro-
Studies are needed that produce
electric power, the very important
improved procedures for operating water
commercial navigational uses, and lake
management systems in consideration of
water quality which is due to thermal
climate uncertainty. A related aspect of
stratification, are expected to be
this work is the development of design
adversely affected.
criteria for engineered structures that
specifically incorporate estimates of
The Aral Sea would continue to
climatic variability and change.
experience water-quality degradation by
polluted irrigation return flows, as the
Very little is currently known about the
precipitation-runoff increases projected
effects of climate change on water
for the area would not be enough to
quality. Although concerns about water
compensate for increased expansion of
quality are becoming increasingly
irrigated agriculture.
important, the separation of human-
induced versus climate-induced changes
Recommendations for action
in water quality is a very difficult
problem. Specifically, there is an
The most essential need is for more
immediate need to identify those aspects
reliable and detailed (both in space and
of this problem that hold the most
time) estimates of future climatic
promise for yielding credible evaluations
conditions. These estimates must be
of climatic effects on water quality.
regionally specific and provide infor-
26
Potential impacts of climate
change will also affects the regional
change on human settlement, the
distribution of other renewable energy
energy, transport and industrial
resources such as wind and solar
sectors, human health and air
power.
quality
Vector-borne and viral diseases such
as malaria, schistosomiasis and
Major findings
dengue can be expected under
warmer climatic conditions to shift to
Throughout the world the most
higher latitudes.
vulnerable populations are farmers
engaged in subsistence agriculture,
Should severe weather, such as
residents of coastal lowlands and
tropical cyclones, occur more
islands, populations in semi-arid
frequently or become more intense as
grasslands and the urban poor in
a result of climate changes, human
slums in shanty towns, especially in
settlement and industry may be
megacities those with several
seriously affected, with large loss of
millions of inhabitants.
human life.
Climate change and even a modest
Principal issues
global sea-level rise can be expected
to prove disruptive to human
settlement in many vulnerable coastal
The impact on developing countries,
many of which lack resources for
areas of some island nations and
communities where drought, floods
adaptation, may be particularly
and changed agricultural growing
disruptive. Understanding likely impacts
conditions have affected water
of climate change on human settlement,
energy, transport, industry and human
resources, energy, public health and
sanitation, and industrial or
health in such countries should be a high
agricultural production.
priority, together with reinforcing
indigenous capability to design and
Global warming can be expected to
implement strategies to reduce adverse
cause a significant shift in the
impacts of climate change.
permafrost zone; such rapid change
will prove quite. disruptive to roads,
The impacts of climate change on
human settlement and related
railways, buildings, oil and gas
pipelines, mining facilities and
socioeconomic activity, including the
infrastructure in the permafrost
energy, transport and industry sectors,
region.
will differ regionally, depending on
regional distribution of changes in
Global warming can be expected to
temperature, precipitation, soil moisture,
patterns of severe storm, and other
affect. the availability of water
possible manifestations of climate
resources and biomass, both major
change. As the general circulation
energy sources in a large number of
developing countries. Such changes
model scenarios provided by Working
in areas which lose water may
Group I have indicated, changes in some
jeopardise energy supply and
of these climatic characteristics may
materials essential for human
differ considerably among regions. In
habitation and energy. Climate
addition, the vulnerability to change in
climate of human settlement and related
27
economic activity varies considerably
sea-level rise. Coastal areas of such
among regions and within regions. For
industrialised nations as the United
example, coastal areas may generally be
States and Japan will also be threatened,
more vulnerable to climate change than
although these nations are expected to
inland areas within the same region.
have the requisite resources to cope with
this challenge. The Netherlands has
Development of effective strategies to
demonstrated how a small country can
respond to climate change will require
effectively marshall resources to deal
much better capability to predict and
with such a threat.
detect regional climate change and
occurrence of severe meteorological
Besides flooding of coastal areas, human
phenomena. A major issue is that of
settlement may be jeopardised by
timing. For example, a sea-level rise of
drought, which could impair food
0.5 m over 50 years would have substan-
supplies and the availability of water
tially different impacts than the same
resources. Water shortages caused by
rise over 100 years. Not only are
irregular rainfall may especially affect
present-value costs for adaptation
developing countries, as seen in the case
measures vastly different, but also much
of the Zambezi river basin. Biomass is
of the present-day infrastructure would
the principal source of energy for most
have undergone replacement in the
of the countries of sub-Saharan Africa,
longer time period.
and changed moisture conditions in
some areas, reducing this biomass, could
Human settlement
pose grave problems for domestic energy
production and construction of shelter.
A principal difficulty in determining the
impact of climate change on human
Although there has been only a handful
habitat is the fact that many other
of city-specific studies, they suggest that
factors, largely independent of climate
climate change could prove costly to
change, are also important. One can
major urban areas in developed nations.
reliably predict that certain developing
A study has projected that an effective
countries will be extremely/vulnerable to
CO2 doubling could produce a major
climate changes because they are already
water shortfall for New York City equal
at the limits of their capacity to cope
to 28% to 42% of the planned supply in
with climatic events. These include
the Hudson River Basin, requiring a $3
populations in low-lying coastal regions
billion project to skim Hudson River
and islands, subsistence farmers,
flood waters into additional reservoirs.
populations in semi-arid grasslands, and
the urban poor.
Although in the permafrost region global
warming may result in expansion of
The largest impacts on humanity of
human settlement poleward, thawing of
climate change may be on human settle-
the permafrost may also disrupt
ment, with the existence of entire
infrastructure and transport and
countries such as the Maldives, Tuvalu,
adversely affect stability of existing
and Kiribati imperilled by a rise of only
buildings and conditions for future
a few metres in sea-levels and populous
construction.
river delta and coastal areas of such
countries as Egypt, Bangladesh, India,
The gravest effects of climate change
China and Indonesia, threatened by
may be those on human migration as
inundation from even a moderate global
millions are displaced by shoreline
28
erosion, coastal flooding and severe
countries. This could become an
drought. Many areas to which they flee
increasingly important concern in
are likely to have insufficient health and
developing countries, many of which are
other support services to accommodate
facing serious economic pressures from
the new arrivals. Epidemics may sweep
the need to import conventional energy
through refugee camps and settlements,
resources.
spilling over into surrounding
communities. In addition, resettlement
Developing countries, including many in
often causes psychological and social
Africa, depend significantly on
strains, and this may affect the health
hydroelectric power. By changing water
and welfare of displaced populations.
resource availability, climate change may
make some present hydroelectric power
Energy
facilities obsolete and future energy
planning more troubled, although others
Among the largest potential impacts of
may benefit from increased runoff.
climate change on the developing world
are the threats in many areas to biomass,
Major studies to date of the likely
a principal source of energy in most
impact of global warming on the energy
sub-Saharan African nations and many
sector in developed countries are
other developing countries. More than
confined largely to six countries: Canada,
90% of the energy in some African
the Federal Republic of Germany,
countries depends on biomass energy
Japan, the UK, the USSR and the US.
(fuelwood). Owing to uncertainties in
Generally, they show differing overall
water resource projections derived from
aggregate impacts, depending on how
current climate models, it is very difficult
much energy use is related to residential
to provide reliable regional projections
and office heating and cooling. Climate
of future moisture conditions in these
warming will increase energy consump-
countries. Drier conditions could be
tion for air-conditioning and, conversely,
expected in some countries or regions,
lower it for heating.
and in those situations energy resources
could be severely impaired. There could
In addition, the energy sector may be
be possible compensating effects of
affected by response strategies against
faster growth of fuelwood due to higher
global warming, such as a policy on
ambient CO2. Analysis of this situation
emission stabilisation. This may be
should be a top priority for energy
among the most significant energy sector
planners.
impacts in many developed countries,
enhancing opportunities for technologies
In addition to affecting the regional
that produce low quantities of green-
distribution of water and biomass,
house gases. Controversy on the way to
climate-related changes in cloud cover,
obtain CO₂-free energy has already risen,
precipitation and wind circulation
particularly the options of increased
intensity will affect the distribution of
reliance on nuclear power or hydro-
other forms of potential renewable
electric power, weighed against related
energy such as solar and wind power.
safety and environmental concerns.
Understanding these impacts on hydro,
Energy sector changes in both
biomass, solar and wind energy is
developing and developed countries may
particularly important because renewable
have broad economic impacts affecting
energy sources are playing a significant
regional employment, migration and
role in the energy planning of many
patterns of living.
29
Transport
costs could prove very costly in such
exposed coastal areas. Reduced snow
Generally, the impacts of climate change
and ice and lessened threat of frost
on the transport sector appear likely to
heaves should generally produce highway
be quite modest, with two exceptions.
maintenance savings as suggested by a
Ultimately, the greatest impact of
study of Cleveland, Ohio, US.
climate change on the transport sector in
developed countries would appear to be
Impacts on railways appear likely to be
changes produced by regulatory policies
modest, although heat stress on tracks
or consumer shifts designed to reduce
could increase summertime safety
transport-related emissions of green-
concerns on some railways and reduce
house gases. Because of the importance
operational capability during unusually
of the transport sector as a source of
hot periods. Dislocations due to
greenhouse. gases, it is already being
flooding may increase.
targeted as a major source of potential
reductions in greenhouse gas emissions,
There has been little analysis of likely
with potentially added constraints on
impacts on ocean transport. The
private automobile traffic, automotive
greatest effect would appear likely to be
fuel and emissions, and increased use of
some jeopardy to shipping infrastructure
efficient public transport.
such as ports and docking facilities,
threatened both by sea-level rise and
A second large impact on the transport
storm surge. Some climate projections
sector concerns inland shipping, where
indicate the possibility that tropical
changes in water levels of lakes and
cyclone intensity may increase. This
rivers may seriously affect navigation and
could have adverse implications for
the costs of barge and other transport.
ocean shipping and infrastructure. On
Studies to date, focused entirely on the
the other hand, decreased sea ice could
Great Lakes region of Canada and the
provide greater access to northern ports
US, have shown quite, large potential
and even enable regular use of the
impacts. Climate scenarios have shown
Arctic Ocean for shipping. Moderate
a likely drop of lake levels of as much as
sea-level rise could also increase the
2.5 m resulting from an effective CO
allowable draught for ships using shallow
doubling. Such changes could increase
channels.
shipping costs, but the shipping season
could be longer than at present due to
There is a strong need for analysis of
decreased ice. Lake and river levels
likely impacts of climate change for the
may rise in some other regions with
transport sector in developing countries,
potentially enhanced opportunities for
as efficiency of the transport sector is
shipping.
likely to be an essential element in the
ability of countries to respond to climate
Generally, impacts on roads appear
change.
likely to be quite modest, except in
coastal areas where highways or bridges
Industry
may be endangered by sea-level rise or
in mountainous regions where potentially
Studies of likely impacts of climate
increased intensity in rainfall might pose
change on the industrial sector tend to
the risk of mudslides. Studies in
be concentrated heavily on certain
Atlantic Canada and Greater Miami,
sectors such as recreation and only on a
US, indicate that highway infrastructure
handful of developed countries,
30
principally Australia, Canada, Japan, the
With sufficient lead time, industry may
UK and the US. There is very little
be able to adjust to many of the changes
analysis of the likely impacts of climate
accompanying global warming.
change on industry in developing
Shortages of capital in developing
countries, although there is some
countries which may be vulnerable to
evidence to suggest that industry of
flood, drought or coastal inundation may,
developing countries may be particularly
however, constrain such industry's ability
vulnerable to climate change. An
to design effective response strategies.
especially important factor is the likely
change in the production map of primary
Human health
products as a result of climate change.
Humans have a great capacity to adapt
Changes in the regional and global
to climatic conditions. However,
availability and cost of food and fibre
adaptations have occurred over many
may significantly affect the competi-
thousands of years. The rate of
tiveness and viability of such derivative
projected climatic changes suggest that
industries as food processing, forest and
the cost of future adaptation may be
paper products, textiles and clothing.
significant.
Climate change may be expected to have
impacts on the availability and cost of
A greater number of heatwaves could
food, fibre, water and energy which
increase the risk of excess mortality.
would differ markedly from region to
Increased heat stress in summer is likely
region.
to increase heat-related deaths and
illnesses. Generally, the increase in
Just as the motor vehicle and the energy
heat-related deaths would be likely to
sectors are likely to be influenced by
exceed the number of deaths avoided by
regulatory decisions and shifts in
reduced severe cold in winter. Global
consumer patterns emanating from
warming and stratospheric ozone
concerns about limiting greenhouse gas
depletion appear likely to worsen air
emissions, heavy manufacturing may face
pollution conditions, especially in many
readjustment to new situations such as
heavily populated and polluted urban
transboundary siting constraints and
areas. Climate change-induced
international mechanisms for develop-
alterations in photochemical reaction
ment and transfer of new technology.
rates among chemical pollutants in the
Efficiency in the use of energy may
atmosphere may increase oxidant levels,
become an even more significant com-
adversely affecting human health.
petitive factor in steel, aluminium and
other metal industries, and automotive
There is a risk that increased
manufacturing. Public concerns about
ultraviolet-B radiation resulting from
limiting greenhouse gas emissions may
depletion of the stratospheric ozone
also create opportunities for energy
layer could raise the incidence of skin
conservation or for industries based on
cancer, cataracts and snow blindness.
'clean technology'. Studies of likely
The increased skin cancer risks are
impacts of climate change on industry
expected to rise most among fair-skinned
tend to be clustered in the recreational
Caucasians in high-latitude zones.
sector, where direct impacts of climate
change are more ascertainable.
Another major effect of global warming
may be the movement poleward in both
hemispheres of vector-borne diseases
31
carried by mosquitoes and other
change their distribution patterns and
parasites. Parasitic and viral diseases
transformation rates in regional or local
have the potential for increase and
sectors. A change in aerosol formation
reintroduction in many countries.
by atmospheric conversion from NOₓ,
and SO₂ and windblown dust from arid
Changes in water quality and availability
land could lead to changes in visibility
may also affect human health. Drought-
and albedo. Material damage caused by
induced famine and malnutrition have
acidic and other types of air pollutants
enormous consequences for human
may be aggravated by higher levels of
health and survival.
humidity.
The potential scarcity in some regions of
Ultraviolet-B radiation
biomass used for cooking, and the
growing difficulty in securing safe
Besides the human health implications of
drinking water because of drought, may
increased ultraviolet-B radiation already
increase malnutrition in some developing
discussed, such radiation may also signi-
countries.
ficantly affect terrestrial vegetation,
marine organisms, air quality and
Air pollution
materials. Increased ultraviolet-B
radiation may adversely affect crop
SOx NOₓ and auto-exhaust controls are
yields. There are some indications that
already being implemented to improve
increased solar ultraviolet-B radiation
air quality in urban areas in some
which penetrates into the ocean surface
developed countries. Concerns about
zone where some marine organisms live,
possible energy penalties and overall
may adversely affect marine phyto-
implications of such control measures for
plankton, potentially reducing marine
greenhouse gas emissions will need to be
productivity and affecting the global food
incorporated in future planning.
supply. Increased ultraviolet-B radiation
Moreover, global warming and strato-
can also be expected to accelerate
spheric ozone depletion appear likely to
degradation of plastic and other coating
aggravate tropospheric ozone problems
used outdoors. The enhanced green-
in polluted urban areas. The tropo-
house effect is expected to decrease
spheric temperature rise induced by the
stratospheric temperatures and this may
enhanced greenhouse effect could
affect the state of the stratospheric
change homogeneous and heterogeneous
ozone layer.
reaction rates, solubility to cloud wäter,
emission from marine, soil and vege-
Recommendations for action
tative surfaces, and deposition to plant
surfaces of various atmospheric gases,
Assessment of the vulnerability of
including water vapour and methane. A
countries, especially in the developing
change in water vapour concentration
world, to gain or loss of energy
will lead to changes in the concentration
resources such as hydroelectric power,
of HO, radicals and H₂O₂, which are
biomass, wind and solar, and an
important for the oxidation of SO₂ and
examination of available substitutes
NO, in the atmosphere. The predicted
under new climate conditions, should
change of the patterns of cloud cover,
be a high priority.
stability in the lower atmosphere,
circulation and precipitation, could
Research is critically needed into the
concentrate or dilute pollutants, and
adaptability of vulnerable human
32
populations, especially the elderly and
greenhouse effect, which have been
the sick, to the occurrence of
considered by the IPCC, will be added to
increased heat stress as well as the
these present trends.
potential for vector-borne and viral
diseases to shift geographically.
A 20-30 cm sea-level rise (projected by
the year 2050) poses problems for the
Policy makers should give priority to
low-lying island countries and coastal
the identification of population and
zones, destroying productive land and
agricultural and industrial production
the freshwater, lens. Protecting these
at risk in coastal areas subject to
areas entails considerable cost.
inundation from sea-level rise of
various magnitudes and to storm
A 1 m sea-level rise (the maximum
surge.
projected by the year 2100) would
eliminate several sovereign states,
It is important that developing
displace populations, destroy low-lying
countries have the capability to assess
urban infrastructure, inundate productive
climate change impacts and to
lands, contaminate freshwater supplies
integrate this information into their
and alter coastlines. These effects could
planning. The world community
not be prevented except at enormous
should assist countries in conducting
cost. The severity would vary among
such assessments and work to create
coastal regions and would depend on the
indigenous climate-change impact
actual rate of rise.
assessment capabilities in such
countries.
Coastal ecology is affected by the rate of
sea-level rise. Too rapid a rise could
Potential impacts of climate
reduce or eliminate many coastal eco-
change on the world ocean and
systems, drown coral reefs, reduce
coastal zones
biological diversity and disrupt the life
cycles of many economically and
Major findings
culturally important species.
The projected global warming will cause
Erosion of wetlands and increasing
sea-level rise, modify ocean circulation,
availability of organic matter from
sea-level rise can increase estuarine and
and cause fundamental changes to
marine ecosystems, with considerable
near-shore productivity for some
decades.
socioeconomic consequences.
Sea-level is already rising on average of
Global warming will change the thermal
over 6 cm per 50 years, with important
budget of the World Ocean and shift the
regional variations because of local
global ocean circulation. Changes in
geological movements. The Greenland
ocean circulation, including high-latitude
and perhaps the Antarctic ice sheets may
deep water formation, will affect the
still be responding to changes since the
capacity of the ocean as a sink of
last glaciation. Fisheries and various
atmospheric heat and CO2. Upwellings
of nutrient-rich waters associated with
coastal resources are presently under
growing stress from pollution, exploita-
major fisheries are also expected to
tion and development, creating serious
change, causing a decrease in primary
problems for populations dependent on
production in open ocean upwelling
them. Impacts from the enhanced
zones and an increase in primary
33
production in coastal upwelling zones.
range and estuarine salt-front intrusion;
The expected impacts will include
increases in sedimentation in the zone of
chemical changes in biogeochemical
tidal excursion; and increase in the
cycles such as the global carbon cycle
potential for salt water contamination of
which affects the rate of accumulation of
coastal freshwater acquifers. The
atmospheric CO2.
predicted changes in climate may also
affect the frequency and intensity of
Adverse ecological and biological
coastal storms and hurricanes, which are
consequences will vary by geographic
the major determinants of coastal
zones of the world's oceans. The loss of
geomorphic features and extreme high
habitat will cause changes in biological
sea-level events.
diversity, redistribution of marine
organisms and a shift in the ocean
The socioeconomic impacts of these
production zones.
direct physical effects are uncertain and
more difficult to assess, and are region-
A simultaneous rise in both water
and site-specific. There are three
temperature and sea-level may lead to
general impact categories that
the redistribution of commercially
encompass the physical effects:
important species and benthic organisms.
Changes in fisheries production may well
threatened populations in low-lying
balance globally in the long term, but
areas and island nations.
there could be important regional shifts
in areas of fisheries, with major
alteration and degradation of the
socioeconomic impacts.
biophysical properties of beaches,
estuaries and wetlands.
Shipping and ocean transportation will
benefit from less sea ice and small
inundation, erosion and recession of
increases in depth in harbours, but some
barrier beaches and shoreline.
ice-dependent marine mammals and
birds will lose migratory and hunting
routes and the essential habitats.
Threatened populations in low-lying
areas and island nations
Increase in ultraviolet-B radiation can
have widespread effects on biological
The most important socioeconomic
and chemical processes, on life in the
impact of sea-level rise is the inundation
upper layer of the open ocean, on corals,
of intensely utilised and densely
and on wetlands. These impacts are of
populated coastal plains. A 1 m rise
concern but not well understood.
would produce a coastline recession of
several kilometres in a number of
Impacts of sea-level rise on coastal
countries. Other countries have a
zones
substantial proportion of land area
between 1 m and 5 m above sea-level,
The magnitude and rate of sea-level rise
with high density coastal populations.
will determine the ability of social and
For example, a 1 m sea-level rise could
natural ecosystems to adapt to the rise.
inundate 12-15% of Egypt's arable land
Direct effects of the rise are straight-
and 14% of Bangladesh's net cropped
forward: inundation of low-lying coastal
area, displacing millions of inhabitants.
areas; erosion and recession of sandy.
shorelines and wetlands; increased tidal
34
Sea-level rise would also expose a
hydrologic and hydraulic regime or
greater proportion of low-lying areas to
would migrate inland through adjacent
coastal storm flooding from storm
lowlands not impeded by protective
surges. Densely populated urban areas
structures. The value of these wetlands
could be protected at great cost, but less
as habitat for wildlife would be impaired
densely populated areas stretched out
during the transitional period and their
along the coastline could not be
biodiversity may decrease. Although
protected. In these situations, large-
many wetlands have kept pace or have
scale resettlement might. be necessary.
increased in area under the historic rate
Another consequence of sea-level rise is
of sea-level- rise owing to sediment
greater incursion of salt water into
entrapment and peat formation, vertical
freshwater estuarine areas, along with
accretion of wetlands has not been
larger tidal excursion. This would
observed to occur at rates comparable to
reduce the freshwater portion of
those projected for sea-level rise in the
estuarine rivers, especially during
next century.
drought periods, adversely affecting
municipal and industrial freshwater
Wetlands are vital to the ecology and
supplies, and could contaminate coastal
economy of coastal areas. Their
groundwater acquifers, which also supply
biological productivity is equal to or
water for municipal purposes in many
exceeds that of any other natural or
areas. Many estuarine areas across the
agricultural system, although little of that
world, with large population centres,
productivity may be available to marsh
would be affected, particularly those
animals and coastal fisheries. Over half
where a decrease in net freshwater
the species of commercially important
runoff is also projected as a consequence
fishes in the southeastern US use salt
of global warming.
marshes as nursery grounds. Wetlands
also serve as sinks for pollutants and
Finally, as sea-level rises, much of the
provide a degree of protection from
infrastructure in low-lying urban areas
floods, storms and high tides. Based on
would be affected, requiring major
these functions, marshes can provide a
engineering design adjustments and
present value to society of as much as
investments. In particular, stormwater
$US5500/acre or over $US10,000/ha.
drainage and sewerage systems of many
cities will be affected. Coastal pro-
Coastal wetlands and estuaries are
tection structures, highways, power plants
important to many species. If sea-level
and bridges may require redesign and
rise is too rapid, natural succession of
reinforcement to withstand increased
the coastal ecology will not take place
flooding, erosion, storm surges, wave
and will lead to great disruption in life
attack and sea-water intrusion.
cycles. In the short term, production of
fisheries could rise as marshes flood, die
Alteration of the biophysical properties
and decompose, thus improving fisheries
of estuaries and wetlands
habitat in some cases and providing
more nutrients. Further nutrients will
An accelerated rise in sea-level could
become available from the leaching of
severely redistribute coastal wetlands.
soils and peat which become more
Salt, brackish and fresh marshes as well
frequently flooded. This temporary
as mangrove and other swamps would be
increase in productivity appears to be
lost to inundation and erosion; others
happening now in the southeast US
would transform and adapt to the new
where sea-level rise is compounded by
35
land subsidence. However, this
important ecological habitats with high
temporary benefit for fisheries may be
biodiversity. Unlike continental areas
balanced by negative impacts on birds
with receding coastlines, where areas for
and other wildlife as the habitat area is
resettlement are available landward of
decreased. In the longer term, by 2050
the coasts, coral islands have very
the overall impact on fisheries and
limited possibilities. If the rate of
wildlife is likely to be negative.
sea-level rise exceeds the maximum rate
of vertical coral growth (8 mm/yr), then
While considering potential changes in
inundation and erosive processes begin
the biogeochemical cycles of chemicals
to dominate, leading to the demise of
from sea-level rise, it should be noted
the coral atoll. However, if the rate of
that (i) growth of nitrogen and
sea-level rise is small, then coral growth
phosphorus concentrations on a regional
may be able to keep pace. Although
scale (in subpolar and mid latitudes, in
there are engineering solutions for
the Bering Sea in particular) would
retarding erosion and protecting against
result from flooding of coastal areas and
storm damage of continental coasts,
from soil erosion; and (ii) many
coral atolls cannot be effectively
pesticides which are presently held in
protected.
sediments could be released into the
marine environment by coastal flooding.
Barrier beaches are important for human
use, both for subsistence and recreation,
The combination of climatic changes will
and as protection for lagoons and
cause coastal ecosystems to move inland,
mainland areas from coastal storms.
unless humankind intervenes, and
Coastal areas have always been
poleward. Also, if sea-level rise is rapid,
hazardous. Societies have adapted to or
as predicted, productivity will probably
sought to control the most extreme
fall, but there may be some decades
conditions resulting from natural climate
during which wetlands-based productivity
variability. The loss of habitable coastal
increases before it falls. Once the ocean
areas, which are typically densely
begins to stabilise at its new level (if this
populated will undoubtedly lead to
were to occur in the foreseeable future),
targe-scale resettlement. Since most
productivity will begin to decrease.
commercial and subsistence fisheries are
de facto located in the very same
Inundation and recession of barrier
vulnerable areas, the impacts are
islands, coral atolls and other shorelines
twofold: reduction in ecological
(wetlands) habitat that sustains fish
Sea-level rise would cause inundation
populations, coupled with increased
and recession of all types of shorelines,
threats to habitable coastal areas. Many
especially low-lying coastal areas. Many
areas. around the globe, comprising
beaches have very small gradients of
thousands of kilometres of shoreline and
1:100 or less. A 1 m rise in sea-level
affecting millions of people would be
would inundate 100 m of beach.
adversely affected by a rise of 1 m, or
Additional shoreline recession would
even 0.5 m. For the most part,
result from normal erosive processes
prevention of the primary physical
including storm surges and wave attack.
effects is not economical for most of the
The potential destruction of coral atolls
threatened coastline. Therefore, the
is perhaps most significant, because
prospect for adverse impacts should be
these island areas serve both as
considered to be extremely important
contained human habitats as well as
and virtually irreversible.
36
Impacts on the World Ocean
regions would determine the future
productivity of the oceans.
Global climate warming can change the
physical, chemical and biological
According to the results of numerical
processes in the oceans, and affect
experiments with the use of General
productivity of the oceans and fisheries.
Circulation Models of the atmosphere-
Effective CO₂ doubling could lead to an
ocean system, as well as palaeo-
increase of sea-surface temperature by
oceanographical data, the global
0.2° -2° C and to changed heat balance
warming would be accompanied by a
components. Impacts will differ among
weakening of the intensity of oceanic
geographic zones.
upwellings because of a decrease in the
meridional temperature gradient. This
In addition, an increase in atmospheric
process will involve a decrease in the
CO₂ could cause an increase in sea-
productivity of these ecosystems.
water acidity up to 0.3 pH and elevation
However, some increase in the intensity
of the lysocline (because of solution of
of coastal upwellings as a result of
additional amounts of CaCO₃). These
increasing temperature difference
processes might be accompanied by a
between land and water surface, would
decrease in the stability of the complexes
partially compensate for the reduction of
of trace metals with aquatic humus,
oceanic upwellings. Besides, an increase
strengthening the toxic impacts of these
in the temperature at high latitudes will
substances on marine organisms as well
be accompanied by an increase in their
as a change in the conditions of
productivity. As a result of the above
accumulation of deposits.
changes, a redistribution of productive
zones will probably occur. This could
Coastal ecosystems will be exposed to
lead to disturbances in the trophic
the most severe impact owing to a water
structure of marine ecosystems and to a
temperature increase and, especially, to
change in the conditions of the
sea-level rise. Disturbances by hydro-
formation of the stocks of commercial
logical and hydrochemical conditions in
fishes.
these regions will be accompanied by a
shift of feeding zones of many commer-
An increase in the zone of the area of
cial fish species and benthic organisms,
warm equatorial and tropical waters
a change in the trophic structure of
would cause the movement of pelagic
coastal communities and, as a conse-
and benthic communities of these areas
quence, a decrease in their productivity.
to the boreal and temperate regions.
At the first stage, as the flux of nutrient
This circumstance might significantly
increases, in the process of land flooding,
affect the structure of world fisheries.
a certain increase in the productivity of
Under conditions of climate warming,
coastal areas might be observed.
the. intensification of biodegradation
processes will occur by up to 30-50% in
A change in heat balance and the circu-
the zone of high latitudes. This factor,
lation system in the oceans will produce
along with the expected increase of
a direct effect on the productivity of
ultraviolet-B radiation, resulting from the
marine ecosystems. Taking into consi-
depletion of the ozone layer, could
deration the fact that 45% of the total
accelerate bacterial and photochemical
annual production is in the zones of
degradation of pollutants and reduction
oceanic and coastal upwellings and
of their 'residence time' in the marine
subpolar regions, a change in these
environment. Ecological and biological
37
consequences of climate changes will
may prove to be beneficial by increasing
vary among geographic zones. A
the allowable draught of ships in shallow
regional approach is needed to study the
ports and channels.
biogeochemical carbon cycle, especially
in the most productive and vulnerable
Recommendations for action
ecosystems of the ocean.
Identification and assessment of the
The highly productive subpolar and
risks to coastal areas and islands and
polar ecosystems of the Bering Sea,
living resources of a 0.3-0.5 m rise in
Arctic Seas and Southern Ocean are
sea-level.
important to study because the
high-latitude areas will see the greatest
Assessment of potential leaching of
changes. These areas are important to
toxic chemicals with sea-level rise.
the total global carbon cycle in the
ocean, in climate-forming processes, in
Improvement of the methods for
fisheries, and in marine mammal and
analysing the major components of
bird production.
oceanic branch of carbon cycle (the
carbonate system and organic
International investigations, for example
carbon).
those planned for the region of the
Bering Sea, will contribute to the
Assessment of the possible impacts of
determination of the role of subpolar
increased UV-B radiation from strato-
ecosystems in the formation of earth's
spheric ozone depletion on oceanic
climate, as well as to a more compre-
and estuarine ecosystems.
hensive study of possible ecological
impacts of global warming on the ocean,
Determination of ecological impacts
in particular on fisheries.
of Arctic and Antarctic sea ice
reductions.
Many fisheries and marine mammal
populations are heavily stressed from
Development of methodologies to
fishing pressure. Climate changes will
assess the impacts on living marine
increase stress and the chance of
resources, and socioeconomic impacts,
collapse. However, for some species, the
of changes in the ocean and coastal
new climate may be more advantageous
zone.
to their well-being.
Development and implementation of
One benefit of warming will be the
multinational systems to detect and
reduction of sea ice and thus improved
monitor expected environmental and
access for shipping. However, there are
socioeconomic impacts of ocean and
ecological concerns. Land animals use
coastal zone changes.
sea ice for migratory and hunting routes,
while for many species of marine
mammals (eg seals, polar bears,
penguins) sea ice is an essential part of
their habitat. Thus, reduction of the
amount or duration of ice can cause
difficulties for such animals. Moderate
rises in sea-level, provided they are
insufficient to threaten port installations,
38
Impacts of climate change on
decrease.
Regional responses,
seasonal snow cover, ice and
however, are complicated by the
permafrost, and socioeconomic
effect of increased snowfall in some
areas which could lead to accumu-
consequences
lation of ice. Glacial recession will
have significant implications for local
Major findings
and regional water resources and thus
impact on -water availability and on
The global areal extent and volume of
hydroelectric power potential.
the terrestrial cryosphere (seasonal
Enhanced melt rates of glaciers may
snow cover, near-surface layers of
initially increase the flow of melt-
permafrost and some masses of ice)
waters; however, flows will decrease
will be substantially reduced. These
and eventually be lost as glacial ice
reductions, when reflected regionally,
mass decreases. Glacial recession
could have significant impacts on
and loss of ice from ice sheets will
related ecosystems and social and
also contribute to sea-level rise.
economic activities.
Degradation of permafrost is expected
Thawing and reduction in the areal
with an increase in the thickness of
extent of the terrestrial cryosphere
the seasonal freeze-thaw (active) layer
can enhance global warming (positive
and a recession of permafrost to
feedback on climate warming)
higher latitudes and higher altitudes.
through changes in the global and
The thickness of the active layer is
local radiation and heat balances, and
expected to increase by 1 m over the
the release of greenhouse gases. This
next 40-50 years. Although major
positive feedback could increase the
shifts are expected in climatic zones,
rate of global warming and, in some
recession of permafrost will signi-
regions, could result in changes that
ficantly lag behind, receding only
are sudden rather than gradual. The
25-50 km during the next 40-50 years.
possibility of relatively rapid changes,
These changes could lead to increases
increases the potential significance of
in terrain instability, erosion and
the associated impacts.
landslides in those areas which are
currently underlaid by permafrost.
The areal coverage of seasonal snow
and its duration are projected to
The socioeconomic consequences of
decrease in most regions, particularly
these changes in permafrost could be
at mid latitudes, with some regions at
significant. Ecosystems which are
high latitudes in the Arctic and
underlaid by permafrost could be
Antarctic possibly experiencing
substantially altered owing to terrain
increases in seasonal snow cover.
disturbances and changes in the
availability of water. The integrity of
Decreases in seasonal snow cover can
existing and planned structures and
have both positive and negative socio-
associated facilities and infrastructure
economic consequences owing to
could be reduced by changes in the
impacts on regional water resources,
underlying permafrost. Retrofitting
winter transportation and winter
or redesigning would be required at a
recreation.
minimum; however, in some situations
the associated terrain disruptions
Globally, the ice contained in glaciers
and/or costs (environmental, social
and ice sheets is projected to
39
and economic) may be too large,
these elements and degradation of
necessitating abandonment. Develop-
permafrost as a result of climatic
ment opportunities could also be
warming can enhance warming through
affected in areas where the risks
changes in surface characteristics and
associated with developing in an area
release of greenhouse gases.
susceptible to permafrost degradation
are assessed as too high.
The impacts of socioeconomic conse-
quences of changes in the terrestrial
The terrestrial cryosphere, because of
cryosphere will depend to a large extent
its relative responsiveness to climate
on the rate at which the changes occur.
and climatic changes, provides an
Where the rate of change is quick or
effective means of monitoring and
sudden, environment and associated
detecting climatic change.
social and economic systems will have
little time to adapt. Under these
Lack of sufficient data and gaps in
circumstances the impacts and socio-
the understanding of associated
economic consequences could be large.
processes limits more quantitative
assessments at this time.
Seasonal snow cover
Principal issues
General Circulation Models indicate that
in most parts of the Northern and
The terrestrial component of the cryo-
Southern Hemispheres the area of snow
sphere consists of seasonal snow cover,
cover is expected to decrease as a result
mountain glaciers, ice sheets, and frozen
of increased temperature and, in most
ground, including permafrost and
regions, a corresponding decrease in
seasonally frozen ground. These
total mass of the snow. Areas where
elements of the terrestrial cryosphere
snow cover is projected to increase
currently cover approximately 41 million
include latitudes south of 60°S and
km², with seasonal snow cover covering
higher élevations of inland Greenland
as much as 62% of the Eurasian
and Antarctica (though the latter is, and
continent and virtually all of North
will remain, largely a cold desert).
America north of 35° latitude.
A reduction in the areal snow coverage
Projected changes in climate will
and in the length of the snow cover
dramatically reduce the areal extent and
season will result in a positive climatic
volume of these elements of the terres-
feedback, increasing global warming as a
trial cryosphere. This has implications
result of the greater amount of solar
not only with respect to changes in the
radiation that a snow-free surface can
availability of fresh water, changes in
absorb relative to one that is snow-
sea-level and in terrain characteristics,
covered.
but also for societies and related
economic systems which have come to
Loss of snow cover has both negative
depend on, or are limited by, the
and positive. socioeconomic conse-
existence of a terrestrial cryosphere.
quences. Decreases in snow cover will
result in increased risks of damages and
Feedback mechanisms are an important
losses for those systems which rely on
factor in understanding the impacts of
snow as protection (ie insulation) from
climatic change on the terrestrial
cold winter climates. Included are
cryosphere. Reduced areal coverage of
agricultural crops such as winter wheat,
40
trees and shrubs, hibernating animals,
time. Increased temperatures generally
and construction and maintenance of
result in increased ablation and, hence,
municipal infrastructures.
a decrease in ice mass. Conversely,
increased snowfall usually increases ice
Reductions in both the temporal and
mass. Since projected changes in
spatial coverage of seasonal snow cover
climate for some ice-covered regions
will have significant ramifications for
include both increases in temperature
water resources as the amount of water
and snowfall, understanding the impact
available for consumptive (eg potable
of climatic changes on glaciers and ice
and irrigation water) and non-
sheets must consider the combined
consumptive (eg hydroelectric power and
impact.
waste management) uses decreases.
Particularly sensitive are those areas
The bulk of the earth's ice mass is stored
such as the Alps and Carpathians, the
in the Antarctic ice sheet, divided-
Altai mountains of Central Asia, the Syr
between an eastern portion resting on
Dar'ya and Amu Dar'ya region of the
continental crust and a large western
USSR, the Rocky Mountains and the
portion which is underlaid both by
North American Great Plains, all of
continental crust and ocean. Much of
which are dependent on snowmelt for
the remaining ice mass is contained in
the majority of their spring and summer
the Greenland ice sheet, with smaller
water resources.
quantities stored in glaciers throughout
the world.
Changes in snow cover will also affect
tourism and recreation-based industries
Although observed data are limited, it is
and societies, particularly winter
estimated that both Antarctic and
recreation sports such as skiing.
Greenland ice sheets are at present
Projected climate change could eliminate
roughly in equilibrium, with annual gains
a $50 million per annum ski industry in
close to annual losses. There is some
Ontario, Canada.
evidence that suggests that the Green-
land ice sheet has been thickening since
From a positive impacts perspective,
the late 1970s, which has been attributed
reductions of seasonal snow cover will
to new snow accumulations on the ice
reduce expenditures on snow removal
sheet.
and will increase access opportunities
and ease transportation problems. A
Greenhouse-gas-induced climatic change
reduction in snow cover, however, will
will tend gradually to warm these sheets
also have adverse impacts for transpor-
and bring them out of balance with the
tation in those areas which rely on snow
new climate regime. Change in ice-sheet
roads in winter. Inability to use snow
volume is likely to be slow, however,
roads will result in the necessity of using
with significant loss unlikely to occur
other more costly methods of
until after 2100. Calculations for
transportation.
Greenland suggest that a 3% loss of ice
volume in the next 250 years is possible,
Ice sheets and glaciers
based on the projected changes in
climate. In the case of the Antarctic ice
The relationships between climate and
sheet the situation is more complex.
ice sheets and glaciers are complex, and
The mass of the eastern ice sheet is
because of relatively limited monitoring
expected to remain virtually the same or
and research, not fully understood at this
increase slowly as a result of expected
41
increases in precipitation and temper-
air to melt glacial ice and snow, thereby
atures. In contrast, the western ice
reducing the degree of warming.
sheet, like other marine ice sheets is
inherently unstable. Climatic warming
The melting of glaciers will also alter
could cause groundline retreat and rapid
regional hydrologic cycles. In New
dispersal of ice into the surrounding
Zealand it has been estimated that a
ocean by way of relatively fast-flowing
3°C increase in temperature would, in
ice streams. These changes in behaviour
the short term, increase glacier-fed river
could lead to collapse of a portion of the
flow in some western rivers, increasing
western Antarctic ice sheet which,
hydroelectric power generation by 10%.
depending on the amount of ice
Another effect of glacier retreat is
involved, could have a dramatic impact
possible increased debris flows. Large
on sea-level and the surrounding
amounts of debris masses on steep
environment.
slopes will become exposed as a result of
glacial retreat and, therefore, would be
The response of glaciers to climatic
unstable and vulnerable to the effects of
change will depend on their type and
erosion. Landslides would result,
geographic location. In general,
leading to burial of structures, traffic
however, they have been shrinking for
routes and vegetation. Obstructions of
the last 100 years and are expected to
river flows and increased sediment loads
continue to do so in response to pro-
resulting in changes in water quantity (eg
jected changes in climate. In Austria a
local floods and reduced flows down-
3°C warming by 2050 is projected to
stream) and water quality would also be
cause a reduction by about one-half in
likely to occur as a result of debris flows.
the extent of alpine glaciers. Melting of
glaciers in the Soviet arctic archipelagoes
Permafrost
may result in their disappearance in
150-250 years. In contrast, an assess-
Permafrost is the part of the terrestrial
ment of mountain glaciers in the
cryosphere consisting of ground (soil and
temperate zone of Eurasia indicates that
rock) that remains at or below freezing
up to 2020 these glaciers will, in general,
throughout the year. It usually contains
remain essentially unchanged, with
ice which can take a variety of forms
increased precipitation compensating for
from ice held in soil pores to massive
increased melt.
bodies of more or less pure ice many
metres thick. The presence of this ice in
Ice sheet and glacier melting will result
the ground makes it behave uniquely as
in higher sea-levels. Observations over
an earth material, and makes its
the last century indicate that levels have
properties vulnerable to climatic
been rising between 1-3 mm/year
warming.
primarily as a result of mass loss from
alpine glaciers. Current projections
At present about 20-25% of the land
suggest an accelerated rise with green-
surface of the earth contains permafrost,
house gas warming to a most probable
primarily in the polar regions but also in
rise of 65 cm by the end of the next
the alpine areas at lower latitudes. It
century.
occupies approximately 10.7 million km²
in the USSR, 5 million km² in Canada, 2
Glacial melting can act as a negative
million km² in China and 1.5 million km²
feedback to regional and global
in Alaska. Present and past climate is
warming, with heat extracted from the
the major determinant of permafrost
42
occurrence and characteristics; however,
Slope failures, thermokarst and loss of
a variety of other factors is also
near-surface moisture, as the increased
important, for example, the properties of
depth of the active layer moved limited
the soil, and overlying terrain, vegetation
water supplies further from the surface,
and snow cover.
would have detrimental effects on vege-
tation and could lead to significant
Permafrost is usually present where the
decreases in plant populations. In the
mean annual air temperature is less than
longer term, permafrost degradation
-1°C. At temperatures near this value it
would allow the growth of deeper
is discontinuous in extent (discontinuous
rooted, broadleaved species and the
permafrost zone). Both its extent and
establishment of denser forest of coni-
thickness increase at progressively higher
ferous species. Wildlife could also be
latitudes where temperatures are lower:
affected through changes in terrain,
It has been found to extend to depths of
surface hydrology and food availability.
approximately 1000 m or more in parts
Loss of species and habitats can be
of Canada, approximately 1500 m in the
expected, especially where wetlands dry
USSR and 100-250 m in China.
out or areas are flooded as a result of
melt.
Permafrost can also exist in seabeds.
There is extensive ice-bound material in
Assessment of the effects of climate
the continental shelf beneath the Arctic
change on permafrost in any particular
Ocean; however, this permafrost is
location must consider factors other than
commonly relict (ie it formed under past
temperature, eg changes in summer
conditions and would not form under
rainfall and snow cover. In general,
current ones).
however, the projected warming during
the next several decades would signi-
Permafrost is to a large extent inherently
ficantly deepen the active layer and
unstable since it exists so close to its
initiate a northward retreat of perma-
melting point. Most responsive to
frost. It is expected that a 2°C global
changes in climate would be those
warming would shift the southern
portions nearest the surface. Climate
boundary of the climatic zone currently
warming would thicken the active layer,
associated with permafrost over most of
leading to a decrease in soil stability.
Siberia north and northeast by at least
This permafrost degradation would lead
500-700 km. The southern extent of
to thaw settlement of the surface
permafrost will lag behind this, moving
(thermokarst), ponding of surface water,
only 25-50 km in the next 40-50 years
slope failures (landslides) and increased
(up to 10% reduction in an area
soil creep. This terrain instability would
underlaid by continuous permafrost).
result in major concerns for the integrity
The depth of the active layer is expected
and stability of roads, pipelines, airfields,
to increase by 1 m during the next 40-50
dams, reservoirs and other facilities in
years. Projected changes in permafrost
areas which contain permafrost. Terrain
in Canada are of similar magnitude.
instability of the surface layer can also
occur as a result of permafrost degra-
The melting of permafrost would result
dation in alpine areas, such as the Alps.
in the release of methane and, to a
This instability could result in dangerous
lesser extent, CO₂ from previously frozen
debris falls from thawed rocks and
biological material and from gas
mudflows.
hydrates. The extent to which this will
enhance the greenhouse effect is
43
uncertain, but could be about 1°C by
concurrent monitoring of those
the middle of the next century.
facilities, structures and natural
resources that are at risk owing to
The socioeconomic impacts of perma-
projected changes in the terrestrial
frost degradation will be mixed.
cryosphere;
Maintenance costs of existing northern
facilities such as buildings, roads and
establishment of new guidelines and
pipelines will tend to rise with abandon-
procedures for design and construc-
ment and relocation needed in some
tion practices that -consider the
cases. Change in current construction
impacts of climatic changes on
practices will be necessary, as may be
permafrost;
changes in sanitary waste disposal.
Benefits from climate warming and
research, including international
permafrost melt are likely for agri-
cooperative efforts, on the relation-
culture, forestry, and hunting and
ships between components of the
trapping.
terrestrial cryosphere and climate in
conjunction with other determining
Recommendations for action
factors, including feedback
mechanisms;
Projected greenhouse-gas-induced
changes in climate will lead to ablation
refinement of existing climate-
of global ice masses. Uncertainty exists,
terrestrial cryosphere models;
however, regarding how this global
response will be reflected at the
impacts assessments nationally and
regional/local level and how the
regionally that will provide data and
individual ice masses and seasonal ice
information on the impacts of climate
and snow will respond. The most impor-
change on areas in which components
tant effects of climatic change at high
of the terrestrial cryosphere occur and
latitudes and elevated regions will be on
the resulting socioeconomic conse-
and through changes in the terrestrial
quences;
cryosphere. Furthermore, the terrestrial
cryosphere is particularly suited for early
assessment of the needs for protected
detection of the effects of climate
areas (natural reserves) for affected
change. These two points necessitate a
species and habitats; and
better understanding of the nature and
dynamics of these ice masses and the
development and distribution of
factors that control them. This will
relevant educational material and
require:
information on climatic changes, their
impacts on the terrestrial cryosphere
establishment or enhancement of
and socioeconomic consequences, as
integrated, systematic observation
well as a wider distribution of
programs commensurate with
research results.
research on the use of more efficient
ground-based systems and remote
sensing technologies designed to
provide baseline information and
trends;
44
Summary of major future
a global monitoring of sea-level
actions
changes, particularly for island
countries;
The results of the Working Group II
identification of populations and
studies highlight our lack of knowledge,
agricultural and industrial production
particularly at the regional level and in
at risk in coastal areas and islands;
areas most vulnerable to climate change.
Further national and international
better understanding of the nature
research is needed on:
and dynamics of ice masses and their
sensitivity to climate change;
regional effects of climate change on
crop yields, livestock productivity and
integration of climate change impact
production costs;
information into the general planning
process, particularly in developing
identification of agricultural manage-
countries; and
ment practices and technology
appropriate for changed climate;
development of methodology to assess
sensitivity of environments and
factors influencing distribution of
socioeconomic systems to climate
species and their sensitivity to climate
change.
change;
Some of these topics are already
initiation and maintenance of
being covered by existing and
integrated monitoring systems for
proposed programs and these will
terrestrial and marine ecosystems;
need continuing support. In
particular, there are three core
intensive assessment of water
projects of the International
resources and water quality, especially
Geosphere-Biosphere Program,
in arid and semi-arid developing
namely:
countries and their sensitivity to
climate change;
Land-Ocean Interactions in the
Coastal Zone
regional predictions of changes in soil
moisture, precipitation, surface and
Biosphere Aspects of the
subsurface runoff regimes and their
Hydrological Cycle
interannual distributions as a result of
climate change;
Global Change Impact on
Agriculture and Society
assessment of vulnerability of
countries to gain or loss of energy
that will provide valuable data in the
resources, particularly biomass and
coming years.
hydroelectric power in developing
countries;
adaptability of vulnerable human
populations to heat stress and vector-
borne and viral diseases;
45
Concluding remarks
slowly but steadily while others such as
shifts in climate zones - which will affect
Human-induced climate change can have
the occurrence of such events as floods,
profound consequences for the world's
droughts and severe storms - may occur
social, economic and natural systems.
unpredictably. Regions and nations
Each country should take steps to
differ considerably in their vulnerability
understand the impacts on its population
to such changes and subsequent impacts.
and land resources resulting from such a
Generally human activity in developing
change, and the consequences of sea-
countries is more vulnerable than that in
level rise, the changed character of
developed countries to the disruption
átmospheric circulation and the resulting
associated with climate change. Global
changes in typical weather patterns,
warming and its impact must not widen
reduction of freshwater resources,
the gap between developed and
increased ultraviolet-B radiation and
developing countries.
spreading of pests and diseases. These
can affect the potential of food and
The capacity of developing nations to
agricultural production and adversely
adapt to likely climate changes and to
affect human health and well-being.
minimise their own contributions to it
through greenhouse gas emissions, is
Too rapid a change in climate may not
constrained by their limited resources, by
allow species to adapt and, thus,
their debt problems and by their
biodiversity could be reduced. This
difficulties in developing their economies
reduction could occur equally as well in
on a sustainable and equitable basis.
the cryosphere regions, where melting of
These countries will need assistance in
sea ice could accelerate, and in the
developing and implementing
equatorial regions where sea surface
appropriate response options (including
temperatures could increase. Traditional
consideration of technological
cost-benefit analyses do not allow for
development and transfer, additional
assessment of these risks. Although
financial assistance, public education and
substantial scientific uncertainty remains
information). As they possess greater
concerning the precise time, location and
resources to cope with climate change,
nature of particular impacts, it is
developed countries must recognise the
inevitable, under the scenario developed
need to assist developing countries to
by Working Group I, that in the absence
assess and deal with the potential
of major preventive and adaptive actions
impacts of climate change.
by humanity, significant and potentially
disruptive changes in the earth's
environment will occur.
The world community recognises the
need to undertake certain actions to
reduce and mitigate the impact of
climate change. Specific measures
should follow the assessments of poten-
tial impact on the biosphere and on
human activity, and a comparison of the
net costs of adaptation and mitigation
measures. Some of these impacts, such
as sea-level rise, are likely to proceed
46
WMO
UNEP
INTERGOVERNMENTAL PANEL ON
CLIMATE CHANGE
POLICYMAKERS
SUMMARY
OF THE
FORMULATION OF RESPONSE STRATEGIES
Report Prepared for IPCC
by Working Group III
June 1990
1
REPORT OF WORKING GROUP III OF THE
2
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
3
(RESPONSE STRATEGIES WORKING GROUP)
4
5
POLICYMAKERS SUMMARY
6
7
TABLE OF CONTENTS
8
9
Page
10
11
EXECUTIVE SUMMARY
i
12
13
1.
RSWG CHAIRMAN'S INTRODUCTION
1
14
15
2.
SOURCES OF ANTHROPOGENIC GREENHOUSE GASES
3
16
17
3.
FUTURE EMISSIONS OF GREENHOUSE GASES
5
18
19
3.1 Emissions scenarios
6
20
3.2 Reference scenario
10
21
22
4.
RESPONSE STRATEGIES FOR ADDRESSING GLOBAL
23
CLIMATE CHANGE
12
24
25
5.
OPTIONS FOR LIMITING GREENHOUSE GAS EMISSIONS
13
26
27
5.1 Limitation of net emissions from the
28
energy sector
14
29
5.2 Limitation of net emissions from the
30
industry sector
22
31
5.3 Limitation of net emissions from the
32
agriculture sector
23
33
5.4 Limitation of net emissions from
34
forestry and other activities
24
35
36
6.
FURTHER WORK ON GREENHOUSE GAS EMISSION LIMITATION
37
GOALS
26
38
39
7.
MEASURES FOR ADAPTING TO GLOBAL CLIMATE CHANGE
27
40
41
7.1 Coastal zone management
27
42
7.2 Resource use and management
30
43
44
8.
MECHANISMS FOR IMPLEMENTING RESPONSE STRATEGIES
33
45
46
8.1 Public information and education
33
47
8.2 Technology development and transfer
34
48
8.3
Economic measures
36
49
8.4
Financial mechanisms
38
50
8.5 Legal and institutional mechanisms
41
51
52
9.
THE SPECIAL CIRCUMSTANCES OF THE DEVELOPING COUNTRIES
42
53
54
ANNEX I
SUMMARY OF THE REMARKS OF THE CHAIRMAN,
55
MR. J. RIPERT, OF THE IPCC SPECIAL COMMITTEE ON
56
THE PARTICIPATION OF DEVELOPING COUNTRIES
44
57
58
LIST OF ACRONYMS AND CHEMICAL SYMBOLS
46
1
i
2
3
4
EXECUTIVE SUMMARY
5
6
Working Group III (Response Strategies Working Group) was tasked
7 to formulate appropriate response strategies to global climate change.
8 This was to be done in the context of the work of Working Group I
9 (Science) and Working Group II (Impacts) which concluded that:
10
11
"We are certain emissions resulting from human activities are
12
substantially increasing the atmospheric concentrations of the
13
greenhouse gases: carbon dioxide, methane, chlorofluoro-carbons
14
(CFCs) and nitrous oxide. These increases will enhance the
15
greenhouse effect, resulting on average in an additional warming
16
of the Earth's surface.
17
18
"The longer emissions continue at present day rates, the greater
19
reductions would have to be for concentrations to stabilize at
20
a given level.
21
22
"The long-lived gases would require immediate reductions in
23
emissions from human activities of over 60% to stabilize their
24
concentrations at today's levels.
25
26
"Based on current model results, we predict under the IPCC
27
Business-as-Usual emissions of greenhouse gases, a rate of
28
increase of global mean temperature during the next century of
29
about 0.3°C per decade (with an uncertainty range of 0.2°C to
30
0.5°C per decade), greater than that seen over the past 10,000
31
years; under the same scenario, we also predict an average rate
32
of global mean sea level rise of about 6 cm per decade over the
33
34
decade). next century (with an uncertainty range of 3 - 10 cm per
35
36
"There are many uncertainties in our predictions particularly
37
with regard to the timing, magnitude and regional patterns of
38
climate change.
39
40
"Ecosystems affect climate, and will be affected by a changing
41
climate and by increasing carbon dioxide concentrations. Rapid
42
changes in climate will change the composition of ecosystems;
43
some species will benefit while others will be unable to migrate
44
or adapt fast enough and may become extinct. Enhanced levels
45
of carbon dioxide may increase productivity and efficiency of
46
water use of vegetation.
47
48
"In many cases, the impacts will be felt most severely in
49
regions already under stress, mainly the developing countries.
50
51
"The most vulnerable human settlements are those especially
52
exposed to natural hazards, e.g., coastal or river flooding,
53
severe drought, landslides, severe storms and tropical
54
cyclones".
55
56
1
ii
2
3
4
Any responses will have to take into account the great diversity
5
of different countries' situations and their responsibility for and
6
negative impacts on different countries and consequently would require
7 a wide variety of responses. Developing countries for example are at
8 widely varying levels of development and face a broad range of
9 different problems. They account for 75% of the world population and
10 their primary resource bases differ widely. Nevertheless, they are
11 most vulnerable to the adverse consequences of climate change because
12 of limited access to the necessary information, infrastructure, and
13 human and financial resources.
14
15 Main findings
16
17
1)
Climate change is a global issue; effective responses would
18
require a global effort which may have a considerable impact
19
on humankind and individual societies.
20
21
2)
Industrialized countries and developing countries have a common
22
responsibility in dealing with problems arising from climate
23
change.
24
25
3)
Industrialized countries have specific responsibilities on two
26
levels:
27
28
a) major part of emissions affecting the atmosphere at present
29
originates in industrialized countries where the scope for
30
change is greatest. Industrialized countries should adopt
31
domestic measures to limit climate change by adapting their own
32
economies in line with future agreements to limit emissions;
33
34
b) to co-operate with developing countries in international
35
action, without standing in the way of the latter's development,
36
by contributing additional financial resources, by appropriate
37
transfer of technology, by engaging in close co-operation
38
concerning scientific observation, by analysis and research, and
39
finally by means of technical co-operation geared to
40
forestalling and managing environmental problems.
41
42
4)
Emissions from developing countries are growing and may need
43
to grow in order to meet their development requirements and
44
thus, over time, are likely to represent an increasingly
45
significant percentage of global emissions. Developing
46
countries have the responsibility, within the limits feasible,
47
to take measures to suitably adapt their economies.
48
49
5)
Sustainable development requires the proper concern for
50
environmental protection as the necessary basis for continuing
51
economic growth. Continuing economic development will
52
increasingly have to take into account the issue of climate
53
change. It is imperative that the right balance between
54
economic and environmental objectives be struck.
55
56
1
iii
2
3
4
6)
Limitation and adaptation strategies must be considered as an
5
integrated package and should complement each other to minimize
6
net costs. Strategies that limit greenhouse gases emissions
7
also make it easier to adapt to climate change.
8
9
7)
The potentially serious consequences of climate change on the
10
global environment give sufficient reasons to begin by adopting
11
response strategies that can be justified immediately even in
12
the face of significant uncertainties.
13
14
8)
A well-informed population is essential to promote awareness
15
of the issues and provide guidance on positive practices. The
16
social, economic and cultural diversity of nations will require
17
tailored approaches.
18
19 A flexible and progressive approach
20
21
Greenhouse gas emissions from most sources are likely to
22. increase significantly in the future if no response measures are taken.
23 Although some controls have been put in place under the Montreal
24 Protocol for CFCs and halons, emissions of CO₂, CH4, N₂O and other gases
25 such as several CFC-substitutes will grow. Under these scenarios, it
26 is estimated that CO₂ emissions will increase from approximately 7
27 billion (or 1000 million) tonnes carbon (Btc) in 1985 to between 11-15
28 Btc by 2025. Similarly, man-made methane emissions are estimated to
29 increase from about 300 teragrams (Tg) to over 500 Tg by the year 2025.
30 Based on these projections, Working Group I estimated that global
31 warming of 0.3°C/decade could occur.
32
33
The climate scenario studies of Working Group I further suggest
34, that control policies on emissions can indeed slow global warming,
35 perhaps from 0.3°C/decade to 0.1°C/decade. The social, economic and
36 environmental costs and benefits of these control policies have not
37 been fully assessed. It must be emphasized that implementation of
38 measures to reduce global emissions are very difficult as energy use,
39 forestry, and land use patterns are primary factors in the global
40 economy. To take maximum advantage of our increasing understanding of
41 scientific and socio-economic aspects of the issue, a flexible and
42 progressive approach is required. Subject to their particular
43 circumstances, individual nations may wish to consider taking steps now
44 to attempt to limit; stabilize or reduce the emission of greenhouse
45 gases resulting from human activities and prevent the destruction and
46 improve the effectiveness of sinks. One option that governments may
47- wish to consider is the setting of targets for CO₂ and other greenhouse
48 gases.
49
50
Because large, projected increase in world population will be
51 a major factor in causing the projected increase in global greenhouse
52 gases, it is essential that global climate change strategies include
53 strategies and measures to deal with the rate of growth of the world
54 population.
55
56
1
iv
2
3
4
Shorter-term
5
6
The Working Group has identified measures at the national,
7
regional and international levels as applicable which, while helping
8 to tackle climate change, can yield other benefits.
9
10
Limitation
11
12
-
Improved energy efficiency reduces emissions of carbon
13
dioxide, the most significant greenhouse gas, while
14
improving overall economic performance and reducing other
15
pollutant emissions and increasing energy security.
16
17
-
Use of cleaner energy sources and technologies reduces
18
carbon dioxide emissions, while reducing other pollutant
19
emissions that give rise to acid rain and other damaging
20
effects.
21
22
-
Improved forest management and, where feasible, expansion
23
of forest areas as possible reservoirs of carbon.
24
25
-
Phasing out of CFCs under the Montreal Protocol, thus
26
removing some of the most powerful and long-lived
27
greenhouse gases, while also protecting the stratospheric
28
ozone layer.
29
30
-
Agriculture, forestry and other human activities are also
31
responsible for substantial quantities of greenhouse gas
32
emissions. In the short term, reductions can be achieved
33
through improved livestock waste management, altered use
34
and formulation of fertilizers, and other changes to
35
agricultural land use, without affecting food security, as
36
well as through improved management in landfill and
37
wastewater treatment.
38
39
Adaptation
40
41
-
Developing emergency and disaster preparedness policies and
42
programmes.
43
44
-
Assessing areas at risk from sea-level rise and developing
45
comprehensive management plans to reduce future
46
vulnerability of populations and coastal developments and
47
ecosystems as part of coastal zone management plans.
48
49
-
Improving the efficiency of natural resource use, research
50
on control measures for desertification and enhancing
51
adaptability of crops to saline regimes.
52
53
1
<
2
3
4
Longer-term
5
6
Governments should prepare for more intensive action which is
7
detailed in the report. To do so, they should undertake now:
8
9
-
Accelerated and coordinated research programmes to reduce
10
scientific and socio-economic uncertainties with a view
11
towards improving the basis for response strategies and
12
measures.
13
14
-
Development of new technologies in the fields of energy,
15
industry and agriculture.
16
17
-
Review planning in the fields of of energy, industry,
18
transportation, urban areas, coastal zones and resource use
19
and management.
20
-
Encourage beneficial behavioral and structural (e.g.
21
transportation and housing infrastructure) changes.
22
23
-
Expand the global ocean observing and monitoring systems.
24
25
It should be noted that no detailed assessments have been made
26 as of yet of the economic costs and benefits, technological feasibility
27 or market potential of the underlying policy assumptions.
28
29 International cooperation
30
31
The measures noted above require a high degree of international
32 cooperation with due respect for national sovereignty of states. The
33 international negotiation on a framework convention should start as
34 quickly as possible after the completion of the IPCC First Assessment
35 Report. This, together with any additional protocols that might be
36 agreed upon, would provide a firm basis for effective cooperation to
37 act on greenhouse gas emissions and adapt to any adverse effects of
38 climate change. The convention should, at a minimum, contain general
39 principles and obligations. It should be framed in such a way as to
40 gain the adherence of the largest possible number and most suitably
41 balanced range of countries while permitting timely action to be taken.
42
43
Key issues for negotiation will include the criteria, timing,
44 legal form and incidence of any obligations to control the net
45 emissions of greenhouse gases, how to address equitably the
46 consequences for all, any institutional mechanisms that may be
47 required, the need for research and monitoring, and in particular, the
48 request of the developing countries for additional financial resources
49 and for the transfer of technology on a preferential basis.
50
51
1
vi
2
3
4
Further consideration
5
6
The issues, options and strategies presented in this document
7 are intended to assist policymakers and future negotiators in their
8 respective tasks. Further consideration of the summary and the
9 underlying reports of Working Group III should be given by every
10 government as they cut across different sectors in all countries. It
11 should be noted that the scientific and technical information contained
12 in the policymakers summary and the underlying reports of Working Group
13 III do not necessarily represent the official views of all governments,
14 particularly those that could not participate fully in all Working
15 Groups.
16
17
18
19
20
1
1 1.
RSWG CHAIRMAN'S INTRODUCTION
2
3
The First Plenary Meeting of Working Group III of the IPCC, the
4 Response Strategies Working Group (RSWG), was held in Washington, 30
5 January - 2 February 1989. This meeting was largely organizational
6 (see Figure 1), and it was not until after a subsequent RSWG Officers
7 Meeting in Geneva, 8-12 May 1989, that the real work by the four RSWG
8 subgroups, the Emissions Scenarios Task Force (Task A), and
9 "Implementation Measures" Topic Coordinators (Task B) began.
10
11
The Second RSWG Plenary Session was held in Geneva,
12 from 2 to 6 October 1989, to discuss the implementation measures: 1)
13 public education and information; 2) technology development and
14 transfer; 3) financial measures; 4) economic measures; and 5) legal
15 measures, including elemements of a framework climate convention. A
16 consensus was reached on five topical papers dealing with these
17 measures, with the understanding that they would be "living documents"
18 subject to further modification as new information and developments
19 might require.
20
21
The Third Plenary Meeting of RSWG, held in Geneva, 5-9 June
22 1990, achieved three objectives:
23
24
1)
It reached consensus on the attached "policy summary", the first
25
interim report of the RSWG.
26
27
2)
It completed final editing and accepted the reports of the four
28
RSWG subgroups, of the coordinators of Task A, and of the
29
coordinators of the five Task B topical papers. These documents
30
comprise the underlying material for the consensus report of
31
this meeting, the policymakers summary; they are not themselves
32
the product of a RSWG plenary consensus although many
33
governments participated in their formulation.
34
35 Finally,
36
37
3)
The Working Group agreed to submit comments on its suggested
38
future work programme to the RSWG Chairman by 1 July 1990, for
39
transmission to the Chair of the IPCC. There was general
40
agreement that the work of the RSWG should continue.
41
42
The primary task of the RSWG was, in the broad sense, technical,
43 not political. The charge of IPCC to RSWG was to lay out as fully and
44 fairly as possible a set of response policy options and the factual
45 basis for those options.
46
47
Consistent with that charge, it was not the purpose of the RSWG
48 to select or recommend political actions, much less to carry out a
49 negotiation on the many difficult policy questions that attach to the
50 climate change issue, although clearly the information might tend to
51 suggest one or another option. Selection of options for implementation
52 is appropriately left to the policymakers of governments and/or
53 negotiation of a convention.
54
IPCC
RESPONSE STRATEGIES
WORKING GROUP
STEERING
"Task A":
COMMITTEE
Emissions
"Task B":
Implementation
Scenarios
Mechanisms:
Legal Measures (U.K., Canada, Malta)
Financial Measures (France, Neth.)
2
Economic Measures (Australia, N.Z.)
Technology Measures (Japan, India)
Public Education Measures (U.S., PRC)
Energy and
Agriculture
Coastal Zone
Resource Use
Industry
and Forestry
Management
Management
Subgroup
Subgroup
Subgroup
Subgroup
(Japan and
(FRG and
(N. Zealand &
(France, India,
China)
Zimbabwe)
Netherlands)
and Canada)
Figure 1.
4
CONTRIBUTION TO RADIATIVE FORCING
BY SECTOR
1980s
Other (3%)
Agriculture (9%)
Forestry (18%)
Energy (46%)
CFCs (24%)
Figure 2.
3
1
The work of RSWG continues. The Energy and Industry Subgroup
2 has, since the June RSWG Plenary Meeting, held another very productive
3 meeting in London, the results of which are not reflected in this
4
report.
5
6
Two specific items of unfinished business submitted to RSWG by
7 the Ministers at the November 1989 meeting in Noordwijk are the
8 consideration of the feasibility of achieving: (1) targets to limit
9 or reduce CO₂ emissions, including e.g. a 20 percent reduction of CO₂
10 emission levels by the year 2005; (2) a world net forest growth of 12
11 million hectares a year in the beginning of the next century. The RSWG
12 hopes to complete this analysis before the Second World Climate
13 Conference in November of this year.
14
15
The subgroup chairs and topic coordinators took the
16 responsibility for completing their individual reports and, along with
17 their respective governments, contributed generously of their time and
18 resources to that end.
19
20
21
The RSWG Policymakers Summary is the culmination of the first
22 year of effort by this body. The RSWG has gone to considerable lengths
23 to insure that the summary accurately reflects the work of the various
24 subgroups and tasks. Given the very strict time schedule under which
25 the RSWG was asked to work, this first report can only be a beginning.
26
27
2.
SOURCES OF ANTHROPOGENIC GREENHOUSE GASES
28
29
A wide range of human activities result in the release of
30 greenhouse gases, particularly CO₂, CH₄, CFCs and N₂O, into the
31 atmosphere. Anthropogenic emissions can be categorized as arising from
32 energy production and use, non-energy industrial activities (primarily
33 the production and use of CFCs), agricultural systems, and changes in
34 land-use patterns (including deforestation and biomass burning). The
35 relative contributions of these activities to radiative forcing during
36 the 1980s are discussed in the text and shown below in Figure 2 (see
37 Working Group I report for further explanation of the radiative forcing
38 of the various greenhouse gases).
39
40
IPCC Working Group I calculated that the observed increases in
41 the atmospheric concentrations of CO₂, CH₄, CFCs and N₂O during the
42 1980s, which resulted from human activities, contributed to the
43 enhanced radiative forcing by 56%, 15%, 24% and 5%, respectively.
44
45 Energy
46
47
The single largest anthropogenic source of radiative forcing is
48 energy production and use. The consumption of energy from fossil fuels
49 (coal, petroleum and natural gas excluding fuel wood) for industrial
50 commercial, residential, transportation and other purposes results in
51 large emissions of CO₂ accompanied by much smaller emissions of CH₄ from
52 coal mining and the venting of natural gas; the energy sector accounts
53 for an estimated 46% (with an uncertainty range of 38-54%) of the
54 enhanced radiative forcing resulting from human activities.
5
1
Natural fluxes of CO₂ into the atmosphere are large (200 Bt/yr¹),
2 but inputs of man made sources are large enough to significantly
3 disturb the atmospheric balance.
4
5
Industry
6
7
The production and use of CFCs and other halocarbons in various
8 industrial processes comprise about 24% of the enhanced radiative
9
forcing.
10
11 Forestry
12
13
Deforestation, biomass burning including fuel wood, and other
14 changes in land-use practices, release CO2, CH4, and N₂O into the
15 atmosphere and together comprise about 18% (with an uncertainty range
16 of 9-26%) of the enhanced radiative forcing.
17
18 Agriculture
19
20
Methane releases from rice cultivation and from livestock
21 systems, and nitrous oxide released during the use of nitrogeneous
22 fertilizers together comprise about 9% (with an uncertainty range of
23 4-13%) of the enhanced radiative forcing.
24
25 Other sources
26
27
Carbon dioxide from cement manufacturing and methane from land-
28 fills together comprise about 3% (with an uncertainty range of 1-4%)
29 of the enhanced radiative forcing.
30
31
Estimates of current greenhouse gas emissions are not precise
32 because of uncertainties regarding both total emissions and emissions
33 from individual sources. Global emissions from certain sources are
34 particularly difficult to determine, e.g., CO₂ emission from
35 deforestation, CH4 emission from rice cultivation, livestock systems,
36 biomass burning, coal mining and venting of natural gas, and N₂O
37 emissions from all sources. The range of such estimates can be quite
38 large, typically, a factor of 1.5 for methane from livestock, a factor
39 of 4 for CO₂ from deforestation, and upto a factor of 7 for rice.
40
41 3.
FUTURE EMISSIONS OF GREENHOUSE GASES
42
43
Greenhouse gas emissions from most sources are likely to
44 increase significantly in the future if no policy measures are taken.
45 As economic and population growth continue, in particular in the
46 developing countries, there is expected to be an increase in energy
47 use, industrial and agricultural activity, deforestation, and other
48 activities which result in a net increase of greenhouse gas emissions.
49 Although some controls have been put in place under the Montreal
50 Protocol for certain CFCs and halons, emissions of CO₂, methane,
51 nitrous oxide, and other greenhouse gases are likely to increase under
52 current patterns of economic activity and growth.
53
54
1
Billion (or 1000 million) tonnes per year.
6
1
However, because of the inherent limitations in our ability to
2 estimate future rates of population and economic growth, etc, there
3 is some uncertainty in the projections of greenhouse gas emissions,
4 individual behavior, technological innovation, and other factors which
5 are crucial for determining emission rates over the course of the next
6 century. This lends uncertainty to projections of greenhouse gas
7 emissions over several decades or longer. Reflecting these inherent
8 difficulties, the RSWG's work on emissions scenarios are the best
9 estimates at this time covering emissions over the next century but
10 further work needs to be done.
11
12
The RSWG used two methods to develop scenarios of future
13 emissions as discussed in Sections 3.1. and 3.2. One method used
14 global models to develop four scenarios which were subsequently used
15 by Working Group I to develop estimates of future warming. The second
16 method used studies of the energy and agriculture sectors submitted by
17 over 21 countries and international organizations to estimate
18 emissions. These latter studies were aggregated into a reference
19 scenario. Both approaches show that emissions of CO₂ and CH4 will
20 increase in the future. Both approaches indicate that CO₂ emissions
21 will grow from approximately 7 BtC to between 11-15 Btc by the year
22 2025.
23
24
3.1
Emissions scenarios
25
26
One of the RSWG's first tasks was to prepare some initial
27 scenarios of possible future greenhouse gas emissions for the use of
28 the three IPCC Working Groups. An experts' group was formed which
29 looked at four hypothetical future patterns of greenhouse gas emissions
30 and their effect on the atmosphere. The cumulative effect of these
31 emissions was calculated using the concept of equivalent CO₂
32 concentrations (e.g. the contributions of all greenhouse gases to
33 radiative forcing are converted into- their equivalent in terms of CO₂
34 concentrations). Global economic growth rates were taken from World
35 Bank projections and population estimates were taken from UN studies
36 and assumed equal for all scenarios.
37
38
The first of the scenarios, called the Business-as-Usual or the
39 2030 High Emissions Scenario, assumes that few or no steps are taken
40 to limit greenhouse gas emissions. Energy use and clearing of tropical
41 forests continue and fossil fuels, in particular coal, remain the
42 world's primary energy source. The Montreal Protocol comes into effect
43 but without strengthening and with less than 100 percent compliance.
44 Under this scenario, the equivalent of a doubling of pre-industrial CO₂
45 levels occurs, according to Working Group I, by around 2025.
46
47
The estimated anthropogenic contributions to radiative forcing
48 in 2025 are shown in Figure 3 and the corresponding data are shown in
49 Table 1. The RSWG attempted to synthesize and compare the results of
50 the Reference scenario and the Business-as-Usual Scenario (2030 High
51 Emissions). See Figure 4. The figure shows the equivalent CO₂
52 concentrations for the Business-as-Usual Scenario (which includes the
53 Montreal Protocol and lower CO₂ and CH₄ emissions) and the Reference
54 Scenario developed by the agriculture and energy groups (higher CO₂
7
CONTRIBUTION TO RADIATIVE FORCING BY SECTOR:
2025 EMISSIONS
(Based on Global Warming Potentials For 100-Year Time Horizon)
Other (3%)
CFCs (3%)
Forestry (15%)
Agriculture
(14%)
Energy (65%)
Figure 3.
8
1
2
TABLE 1
3
4
Anthropogenic Greenhouse Gas Emissions From Working Group III Scenarios
5
6
AFOS/EIS
2030 High Emissions
7
Reference Scenario
Scenarios
8
9
1985
2025
1985
2025
10
11
CO₂ Emissions (BtC)
12
13
Energy
5.1
12.4
5.1
9.9
14
Deforestation
1.7**
2.6
0.7*
1.4
15
Cement
0.1
0.2
0.1
0.2
16
17
Total
6.9
15.2
5.9
11.5
18
19
CH4 Emission (TgCH₄) ***
20
21
Coal Mining
44
126
35
85
22
Natural Gas
22
59
45
74
23
Rice
110
149
110
149
24
Enteric Ferm.
75
125
74
125
25
Animal Wastes
37
59
-
-
26
Landfills
30
60
40
71
27
28
Subtotal
318
577
304
503
29
30
Biomass Burning
55
77
31
Natural
179
179
32
33
Total
541
761
34
35
N₂O (TgN)
12.5
16.4
36
37
CO (TgC)
537
781
38
NOₓ (TgN)
51
68
39
40
CFCs (Gg)
41
42
CFC11
278
245
43
CFC12
362
303
44
HCFC
97
1340
45
Halon 1211
1.4
18.6
46
Halon 1301
2.1
7.4
47
48
*
Assuming low biomass per hectare and deforestation rates.
49
**
Midrange estimates for deforestation and biomass consistent with
50
preferred value from Working Group I.
51
*** Differences in the 1985 emissions figures are due to differences
52
in definitions and qualifying the emissions from these particular
53
sources.
EIS/AFOS Reference Scenario--Task A: Business as Usual
CO2 Equivalent Concentrations
(ppm)
1,400
1,200
1,000
EIS/AFOS Reference Scenario
800
6
600
400
Task A: 2030 High Emissions
200
2000
2020
2040
2060
2080
2100
Figure 4.
10
1 emissions/CFC phaseout). The results indicate that the CO₂ equivalent
2 concentrations and thus the effect on the global climate are similar
3 for both scenarios.
4
5
The second of the scenarios, the 2060 Low Emissions Scenario,
6 assumes that a number of environmental and economic concerns result in
7 steps to reduce the growth of greenhouse gas emissions. Energy
8 efficiency measures, which might only be possible with government
9 intervention, are implemented, emissions controls are adopted globally,
10 and the share of the world's primary energy provided by natural gas
11 increases. Full compliance with the Montreal Protocol is achieved and
12 tropical deforestation is halted and reversed. Under this scenario,
13 the cumulative effect of such measures is a CO₂ equivalent doubling
14 around 2060.
15
16
The remaining two scenarios reflect futures where steps in
17 addition to those in the 2060 Low Emissions Scenario are taken to
18 reduce greenhouse gas emissions. These steps include rapid utilization
19 of renewable energy sources, stregthening of the Montreal Protocol, and
20 adoption of agricultural policies to reduce emissions from livestock
21 systems, rice paddies, and fertilizers.
22
23
All of the above scenarios provide a conceptual basis for
24 considering possible future patterns of emissions and the broad
25 responses that might affect those patterns. However, they represent
26 assumptions rather than cases derived from specific studies. In
27 addition, no full assessment was made as yet of the total economic
28 costs and benefits, technological feasibility, or market potential of
29 the underlying policy assumptions.
30
31
3.2
Reference scenario
32
33
Table 2 shows the results of the EIS Reference Scenario (for CO₂
34 emissions from the energy sector only) divided by region. The table
35 is incomplete and does not include CO₂ emissions from non-energy
36 sources nor other greenhouse gases and sinks. While it is not directly
37 a measure of a region's climate forcing contribution, this table does
38 portray a future where, in the absence of specific policy measures,
39 global emissions of one major gas, CO2, grow from 5.15 Btc in 1985, to
40 7.30 BtC in 2000 and 12.43 Btc in 2025. Primary energy demand more
41 than doubles between 1985 and 2025, an average annual growth rate of
42 2.1%.
43
44
The annual rate of growth in CO₂ emissions varies between 0.7%
45 in Western Europe, 1.3% in North America and the Pacific OECD
46 Countries, and 3.6% in developing countries. The share of emissions
47 between regions varies over time.
48
49
Under this scenario, the per capita emissions in the
50 industrialized countries increase from 3.1 tonnes carbon (TC) per
51 capita in 1985 to 4.7 TC per capita in 2025. For the developing
52 countries, the per capita emissions rise from 0.4 TC per capita in 1985
53 to 0.8 TC per capita in 2025.
54
55
11
1
TABLE 2
2
3
GROSS CO₂ EMISSIONS FROM THE ENERGY SECTOR*
4
5
(From the Reference Scenario)
6
7
CO₂ Emissions in the Reference Scenario (billion tonnes carbon/year)
8
9
1985
oto
2000
or
2025
o\o
10
11
Global Totals
5.15
(100)
7.30
(100)
12.43
(100)
12
13
Industrialized
3.83
(74)
4.95
(68)
6.95
(56)
14
15
North America
1.34
(26)
1.71
(23)
2.37
(19)
16
Western Europe
0.85
(16)
0.98
(13)
1.19
(10)
17
OECD Pacific
0.31
(6)
0.48
(7)
0.62
(5)
18
Centrally Planned Europe
1.33
(26)
1.78
(24)
2.77
(22)
19
20
Developing
1.33
(26)
2.35
(32)
5.48
(44)
21
22
Africa
0.17
(3)
0.28
(4)
0.80
(6)
23
Centrally Planned Asia
0.54
(10)
0.88
(12)
1.80
(14)
24
Latin America
0.22
(4)
0.31
(4)
0.65
(5)
25
Middle East
0.13
(3)
0.31
(4)
0.67
(5)
26
South and East Asia
0.27
(5)
0.56
(8)
1.55
(12)
27
28
1985
2000
2025
29
30
PC**
CI***
PC
CI
PC
CI
31
32
Global Totals
1.06
15.7
1.22
15.8
1.56
16.0
33
34
Industrialized
3.12
16.3
3.65
16.1
4.65
16.0
35
36
North America
5.08
15.7
5.75
15.8
7.12
16.6
37
Western Europe
2.14
15.6
2.29
15.1
2.69
14.6
38
OECD Pacific
2.14
16.1
3.01
16.1
3.68
14.8
39
Non OECD Europe
3.19
17.5
3.78
16.9
5.02
16.4
40
41
Developing
0.36
14.2
0.51
15.2
0.84
16.0
42
43
Africa
0.29
12.3
0.32
13.2
0.54
15.2
44
Centrally Planned Asia
0.47
17.3
0.68
18.8
1.15
19.6
45
Latin America
0.55
11.5
0.61
11.4
0.91
11.8
46
Middle East
1.20
16.7
1.79
16.1
2.41
15.5
47
South and East Asia
0.19
12.3
0.32
14.3
0.64
15.6
48
49
*
This table presents regional CO₂ emissions and does not include
50
CFCs, CH₄, 03, N₂O, or sinks. Climate change critically depends
51
on all GHG from all economic sectors. This table should be
52
interpreted with care.
53
54
**
PC - Per capita carbon emissions in tonnes carbon per person.
55
56
CI - Carbon Intensity in kilograms carbon per gigajoule.
12
1
The Reference Scenario sets out an example of the scope of the
2 reductions in total global emissions which might be necessary to
3 stabilize or reduce CO₂ emissions. The stabilization of global
4 emissions at 1985 levels would require reductions of 29% by 2000 and
5 59% by 2025. A reduction of global emissions to 20% below 1985 levels
6 would require reductions of 44% in 2000 and 67% by 2025.
7
8
The carbon intensity figures show, for each region, the amount
9 of carbon emitted per unit of energy consumed. The contribution of
10 energy consumption in a region to global warming is largely a function
11 of its carbon intensity, total fuel use, and of the efficiency with
12 which it consumes fossil fuels. Carbon intensity for industrialized
13 countries changes from 16.3 tonnes carbon per gigajoule (TC-GJ) in 1985
14 to 15.5 in 2025. In the developing world the change is from 14.2 TC-GJ
15 to 15.6.
16
17
4.
RESPONSE STRATEGIES FOR ADDRESSING GLOBAL CLIMATE CHANGE
18
19
Because climate change could potentially result in significant
20 impacts on the global environment and human activities, it is important
21 to begin considering now what measures might be taken in response.
22 Working Group 1 found that under a "Business-as-Usual" scenario global
23 average temperature could rise by 0.3 degrees centigrade per decade;
24 it also found that under the Accelerated Control Policies Scenario
25 (scenario D) with extremely stringent emissions reductions the
26 temperature rise could perhaps be reduced to 0.1 degree centigrade per
27 decade. The RSWG identified a wide range of options for the
28 international community to consider. These include measures both to
29 limit net greenhouse gas emissions and to increase the ability of
30 society and managed ecosystems to adapt to a changing climate.
31
32
Strategies which focus only on one group of emission sources,
33 one type of abatement option or one particular greenhouse gas will not
34 achieve this. Policy responses should, therefore, be balanced against
35 alternative abatement options among the energy, industry, forestry and
36 agricultural sectors, and adaptation options and other policy goals
37 where applicable at both national and international levels. Ways
38 should be sought to account for other countries, and intergenerational
39 issues, when making policy decisions.
40
41
The consideration of climate change response strategies,
42 however, presents formidable difficulties for policymakers. On the
43 one hand, the information available to make sound policy analyses is
44 inadequate because of: (a) remaining scientific uncertainties regarding
45 the magnitude, timing, rate, and regional consequences of potential
46 climate change; (b) uncertainty with respect to how effective specific
47 response options or groups of options would be in actually averting
48 potential climate change; and (c) uncertainty with respect to the
49 costs, effects on economic growth, and other economic and social
50 implications of specific response options or groups of options. The
51 potentially serious consequences of climate change on the global
52 environment, however, give sufficient reasons to begin by adopting
53 response strategies that can be justified immediately even in the face
54 of such significant uncertainties.
55
13
1
Recognizing these factors, a large number of options were
2 preliminarily assessed. It appears that some of these options may be
3 economically and socially feasible for implementation in the near-term
4 while others, because they are not yet technically or economically
5 viable, may be more appropriate for implementation in the longer-term.
6 In general, the RSWG found that the most effective response strategies,
7 especially in the short-term, are those which are:
8
9
-
beneficial for reasons other than climate change and justifiable
10
in their own right, for example increased energy efficiency and
11
lower greenhouse gas emission technologies, better management
12
of forests and other natural resources, and reductions in
13
emissions of CFCs and other ozone depleting substances that are
14
also radiatively important gases;
15
16
-
economically efficient and cost effective, in particular those
17
that use market-based mechanisms;
18
19
-
able to serve multiple social, economic, and environmental
20
purposes;
21
22
-
flexible and phased, so that they can be easily modified to
23
respond to increased understanding of scientific, technological
24
and economic aspects of climate change;
25
26
-
compatible with economic growth and the concept of sustainable
27
development;
28
29
-
administratively practical and effective in terms of
30
application, monitoring, and enforcement; and
31
32
-
reflecting obligations of both industrialized and developing
33
countries in addressing this issue, while recognizing the
34
special needs of developing countries, in particular in the
35
areas of financing and technology.
36
37
The degree to which options are viable will also vary
38 considerably depending on the region or country involved. For each
39 country, the implications of specific options will depend on its
40 social, environmental, and economic context. Only through careful
41 analysis of all available options will it be possible to determine
42 which are best suited to the circumstances of a particular country or
43 region. Initially, the highest priority should be to review existing
44 policies with a view to minimizing conflicts with the goals of climate
45 change strategies. New policies will be required.
46
47
5.
OPTIONS FOR LIMITING GREENHOUSE GAS EMISSIONS
48
49
The RSWG reviewed potential measures for mitigating climate
50 change by limiting net emissions of greenhouse gases from the energy,
51 industry, transportation, housing and building, forestry, agriculture,
52 and other sectors. These measures include those which limit emissions
53 from greenhouse gas sources (such as energy production and use), those
54 which increase the use of natural sinks (such as immature forests and
55 other biomass) for sequestering greenhouse gases, as well as those
56 measures aimed at protecting reservoirs such as existing forests.
14
1 While RSWG was not mandated to consider the role of the oceans, Working
2 Group I noted that oceans also play an equally important role as sinks
3 and reservoirs for carbon dioxide. A discussion of both short and
4 long-term options for each major emissions sector is provided below.
5
6
It also should be recognized that the large, projected increase
7 in the world population, to as much as ten billion people during the
8 next century, will be a major factor in causing the projected increase
9 in global greenhouse gases. This is because larger populations will
10 be accompanied by increased consumption of energy and of food, more
11 land clearing, and other activities, all of which will cause an
12 increase in net greenhouse gas emission. It is essential, therefore,
13 that policies designed to deal effectively with the issue of potential
14 global climate change include strategies and measures to reduce the
15 rate of growth of the world population.
16
17
5.1
Limitation of net emissions from the energy sector
18
19
The energy sector plays a vitally important role in economic
20 well-being and development for all nations. At the same time, because
21 energy production and use accounts for approximately one half of the
22 radiative forcing from human activities, energy policies need to ensure
23 that continued economic growth occurs in a manner that, globally,
24 conserves the environment for future generations. However, there is
25 no single, quick-fix technological option for limiting greenhouse gas
26 emissions from energy sources. A comprehensive strategy is necessary
27 which deals with improving efficiency on both the demand and supply
28 sides as a priority and emphasizes technological research, development,
29 and deployment.
30
31
The RSWG recognizes the particular difficulties which will be
32 faced by countries, particularly developing countries, whose economy
33 is heavily dependent on the production and/or export of fossil fuels,
34 as a consequence of actions taken by other countries to limit or reduce
35 energy related greenhouse gas emissions. These difficulties should be
36 taken into account when elaborating international strategies.
37
38
Various potential options have been identified for reducing
39 greenhouse gas emissions from energy systems. The most relevant
40 categories of options appear to be:
41
42
-
efficiency improvements and conservation in energy supply,
43
conversion, and end use;
44
45
-
fuel substitution by energy sources which have lower or no
46
greenhouse gas emissions;
47
48
-
reduction of greenhouse gas emissions by removal, recirculation
49
or fixation;
50
51
-
management and behavioural changes (e.g. increased work in homes
52
through information technology) and structural changes (e.g.
53
modal shift in transport).
54
55
From an analysis of the technologies in these categories, it
56 appears that some technologies are available now or in the short-term
15
1 while others need further development to lower costs or to improve
2
their environmental characteristics.
3
4
Tables 3 and 4 provide various examples of technological options
5 within each of the broad categories defined above, and their possible
6 application in the short, medium, and longer-term. This distinction
7 among time frames is used in order to reflect the remaining
8 technological needs in each category and to assist in formulating
9 technological strategies. Short-term technologies are those which
10 apparently are or will be both technically and economically ready for
11 introduction and/or demonstration up to the year 2005 and beyond.
12 Mid-term technologies are those which, while technically available now,
13 are not yet economic and thus may not be implemented until the period
14 from 2005 to 2030. Longer-term technologies are not yet available but
15 may emerge after 2030 as a result of research and development. Such
16 time frames could be influenced by such factors as the pace of the
17 technological changes and economic conditions.
18
19
The technical, economic, and market potential of technological
20 options will vary depending upon the sector in which they are to be
21 applied. The technical potential of an energy technology is its
22 capacity to reduce potential emissions, irrespective of the costs
23 involved, and is largely a function of technical feasibility and
24 resource availability. Economic potential refers to whether the
25 application of the options is economically efficient and cost-effective
26 - it may be significantly less than technical potential where there are
27 positive resource costs. Market potential refers to whether the
28 consumer or user is likely to adopt the option - it might be even less
29 than economic potential due to market imperfections, attitudes to risk,
30 and the presence of non-monetary costs.
31
32
There is, in general, extensive information available on the
33 technical potential of the many technological options listed. For
34 example:
35
36
-
in the Transportation sector, vehicle efficiency improvements
37
have very high technical potential (e.g. 50 percent improvement
38
from the average vehicle on the road in some countries) ;
39
40
-
in the Electricity Generation sector, efficiency improvements
41
of .15 to 20 percent could be achieved for retrofits of coal
42
plants and up to 65 percent for new generation versus average
43
existing coal plants; fuel substitution could achieve 30 percent
44
(for oil to natural gas) to 40 percent (for coal to natural gas)
45
reduction in emissions of CO₂;
46
47
-
in the Buildings sector, new homes could be roughly twice as
48
energy efficient and new commercial buildings up to 75 percent
49
as energy efficient as existing buildings; retrofitting existing
50
homes could average 25 percent improvement and existing
51
commercial buildings around fifty percent;
52
53
-
in the Industry sector, the technical potential for efficiency
54
improvements ranges from around 15 percent in some sub-sectors
55
to over 40 percent in others (i.e. the best available technology
56
versus the stock average).
TABLE 3
Examples of Short-Term Options
I. IMPROVE EFFICIENCY IN THE PRODUCTION, CONVERSION AND USE OF ENERGY
Electricity Generation
Industry Sector
Transport Sector
Building Sector
Improved efficiency in
Promotion of further
electricity generation
1
Improved fucl efficiency of
efficiency improvements in
Improved heating and cooling
road vehicles;
-
Repowering of existing
production process;
equipment and systems;
facilities with high
Materials recycling
-
Electronic engine
efficiency systems;
(particularly energy-
Improvement of energy
Introduction of
management and
intensive materials);
efficiency of air
-
transmission control
integrated gasification
Substitution with lower
conditioning:
systems;
-
combined cycle systems;
Promotion of
energy intensity materials;
-
advanced vehicle
Introduction of
introduction of area
-
Improved electromcchanical
design;
atmospheric fluidised
drives and motors;
heating and cooling
-
regular vehicle
bed combustion;
Thermal process
including use of heat
maintenance:
Introduction of
optimisation, including
pumps:
-
pressurised fluidised bcd
higher capacity
-
Improved burner
energy cascading and co-
trucks;
combustion with
generation.
efficiency;
-
improved efficiency
-
combined cycle power
Improved operation and
Use of heat pumps 111
in transport facilities;
systems;
maintenance.
buildings:
-
regenerating units;
-
Improvement of boiler
Use of advanced
efficiency.
electronic energy
Technology development in
:
management control
Improved system for co-
public transportation;
systems.
generation of electricity and
-
Intra-city modal shift
stcam.
Improved space conditioning
(e.g. car to bus or
efficiency in house/burking:
Improved operation and
metro);
-
advanced train
-
maintenance.
Improved heat efficiency
control system to
through highly efficient
increase traffic
Introduction of photovoltaics,
insulating materials:
especially for local electricity
density on urban rail
-
Better building design
lines;
generation.
(orientation, window,
-
High-speed inter-city
building. envelope, etc.):
Introduction of fuel cells.
trains;
-
Improved air-to-air heat
.
Better intermodal
exchangers.
integration.
Improved lighting efficiency.
Reduced size and weight,
Improved appliance efficiency
with use of lightweight
Improved operation and
composite materials and
maintenance
structural ceramics;
Improved efficiency of cook
improved aerodynamics,
stoves (in developing
combustion chamber
countries).
components, better
lubricants and tyre design,
etc.).
Driver behaviour, traffic
management, and vehic le
maintenance.
TABLE 3 (CONTINUED)
II. NON FOSSIL AND LOW EMISSION ENERGY SOURCES
Electricity Generation
Other Sectors
- Construction of small-scale and large-scale hydro projects;
. Expansion of conventional nuclear power plants;
Substitution of natural gas and biomass for heating oil and coal:
Solar heating.
-
Construction of gas-fired power plants;
Technologies for producing and utilising alternative fuels;
- Standardised design of nuclear power plants to improve economics
-
and safety;
Improved storage and combustion systems for natural gas;
introduction of flexible-fuel and alcohol fuel vehicles.
- Development of geothermal energy projects;
- Introduction of wind turbines;
* Expansion of sustainable biomass combustion.
,
Replacement of scrubbers and other energy consuming control technology
with more energy efficient emission control.
17
III. REMOVAL, RECIRCULATION OR FIXATION
Energy/Industry
Landfills
Recovery and use of leaked or released CH4 from fossil fuel storage, coal
mining;
Recycle and incineration of waste materials to reduce CII, emissions:
Improved maintenance of oil and natural gas and oil production and
Use or Haring of CH4 emissions;
distribution systems to reduce CH₁ leakage;
Improved maintenance of landfill to decrease CH₄ emissions
Improved emission control of CO, so,, NO, and VOCs to protect sinks of
greenhouse gases.
TABLE 4
Examples of Medium-/Long-Term Options
1. IMPROVE EFFICIENCY IN THE PRODUCTION, CONVERSION AND THE USE OF ENERGY
Electricity Generation
Industry Sector
Transport Sector
Building Sector
Advanced technologies for
Increased use of less
Improved fuel efficiency of
Improved energy storage
storage of intermitient energy;
energy-intensive materials;
road vehicles;
systems;
Advanced batteries;
Advanced process
Improvements in aircraft
Compressed air energy storage;
technologies;
and ship design:
Use of information
Superconducting energy storage;
Use of biological
technology to anticipate
phenomena in processes;
-
Advanced propulsion
and satisfy energy
Localised process energy
concepts;
needs;
conversion;
-
Ultra high-bypass
:
Use of hydrogen to
Use of fuel cells for CO-
aircraft engines;
store energy for use in
generation.
-
Contra-rotating ship
buildings.
propulsion.
Improved building systems,
New Building materials
18
for better insulation at
reduced cost;
Windows which adjust
opacity to maximise
solar gain.
New food storage systems
which eliminate refrigeration
requirements.
TABLE 4 (CONTINUED)
II. NON FOSSIL AND LOW EMISSION ENERGY SOURCES
Electricity Generation
Other Sectors
Nuclear power plants:
Other technologies for producing and utilising alternative fuels:
Passive safety features to improve reliability and acceptability.
-
Improved storage and combustion systems for hydrogen;
Control of gases boiled off from cryogenic fuels;
Solar power technologies:
Improvements in performance of metal hydrides:
-
High-yicld processes to convert lingo-cellulosic biomass into
Solar thermal;
alcohol fuels;
Solar photovoltaic (especially for local electricity generation).
Introduction of electric and hybrid vehicles;
Reduced re-charging time for advanced batteries.
Advanced fuel cell technologies.
III. REMOVAL, RECIRCULATION OR FIXATION
Improved combustion conditions to reduce N₂O emissions.
Treatment of exhaust gas to reduce N₂O emissions.
CO2 separation and geological and marine disposal.
20
1
The constraints to achieving the technical potential in these
2
sectors can be generally categorized as:
3
4
-
capital costs of more efficient technologies vis-à-vis the cost
5
of energy;
6
7
-
relative prices of fuels (for fuel substitution) ;
8
9
-
lack of infrastructure;
10
11
-
remaining performance drawbacks of alternative technologies;
12
13
-
replacement rates;
14
15
-
reaching the large number of individual decision-makers
16
involved.
17
18
Each of these constraints may be more or less significant
19 depending on the sector in question. While not a constraint,
20 behavioural changes (e.g., improved driver behaviour, better vehicle
21 maintenance and turning off unused lights) can make significant
22 contributions to emissions reduction in all sectors. Achieving such
23 changes requires the engagement of both the energy supplier and the
24 consumer. Likewise, improvements in operational practices on the part
25 of industry and government (e.g. better traffic management or boiler
26 operation) offer significant potential but require increased attention.
27 Transport and housing policies (e.g. promotion of public transport,
28 home insulation) could also reduce greenhouse gas emissions. A more
29 comprehensive assessment of the measures to overcome these constraints
30 is contained in section 8 of this report.
31
32
Factors external to the energy sector also significantly
33 constrain potential. These include the difficulty of:
34
35
-
making basic changes in the structure of economies (e.g.
36
development of new transportation and housing infrastructure) ;
37
38
-
making fundamental changes in attitudinal and social factors
39
(e.g. preferences for smaller and higher efficiency vehicles)
40
41
The challenge to policymakers is to enhance the market uptake
42 of technological options and behavioral and operational changes as
43 well as to address the broader issues outside the energy sector in
44 order to capture more of the potential that exists.
45
46 Options and strategies
47
48
Tables 3 and 4 summarize the technological, regulatory, and
49 institutional approaches which could form elements of strategies to
50 control greenhouse gases.
51
52
A list of options recommended by EIS as measures for addressing
53 greenhouse gas emissions is given below. Countries are encouraged to
54 evaluate the social, economic and environmental consequences of these
55 options.
56
21
1
taking steps now 2 to attempt to limit, stabilize or reduce the
2
emission of energy related greenhouse gases and prevent the
3
destruction and improve the effectiveness of sinks. One option
4
that governments may wish to consider is the setting of targets
5
for CO₂ and other greenhouse gases;
6
7
-
adopting a flexible progressive approach, based on the best
8
available scientific, economic and technological knowledge, to
9
action needed to respond to climate change;
10
11
-
drawing up specific policies and implementing wide-ranging
12
comprehensive programmes which cover all energy-related
13
greenhouse gases;
14
15
-
starting with implementing strategies which have multiple
16
social, economic and environmental benefits, are cost effective,
17
are compatible with sustainable development and make use of
18
market forces in the best way possible;
19
20
-
intensifying international, multilateral and bilateral co-
21
operation in developing new energy strategies to cope with
22
climate change. In this context, industrialized countries are
23
encouraged to promote the development and the transfer of energy
24
efficient and clean technologies to other countries;
25
26
-
increasing public awareness of the need for external
27
environmental costs to be reflected in energy prices, markets
28
and policy decisions to the extent that they can be determined;
29
30
-
increasing public awareness of energy efficiency technologies
31
and products and alternatives, through public education and
32
information (e.g. labelling). ;
33
34
-
strenghtening research and development and international
35
collaboration in energy technologies, and economic and energy
36
policy analysis, which are relevant for climate change;
37
38
-
encouraging the participation of industry, the general public,
39
and NGOs in the development and implementation of strategies to
40
limit greenhouse gas emissions.
41
42
Short-term strategy options
43
44
Short-term strategies for all individual nations include:
45
46
-
improving diffusion of energy efficient and alternate energy
47
technologies which are technically and commercially proven;
48
49
50
2
There was significant concern expressed at the RSWG
51
meeting about the immediacy implied by the word now in option
52
one, when implemention could only be considered at a rate
53
consistent with countries' level of knowledge and particular
54
circumstances.
22
1
-
improving energy efficiency of mass produced goods including
2
motor vehicles and electrical appliances and equipment and
3
buildings (e.g., through improved standards)
4
5
-
developing, diffusing and transfering technologies to limit
6
energy related greenhouse gas emissions;
7
8
-
reviewing energy-related price and tariff systems and policy
9
decisions on energy planning to better reflect environmental
10
costs.
11
12 Long-term strategy options
13
14
Over the longer term, sustainable development will remain a
15 central theme of policies and strategies. Specific approaches within
16 a sustainable development policy framework will evolve as our
17 understanding of climate change and its implications improves.
18
19
Long-term strategies for all individual nations include:
20
21
-
accelerating work to improve the long-term potential of
22
efficiency in the production and use of energy; encouraging a
23
relatively greater reliance on no or lower greenhouse gas
24
emissions energy sources and technologies; and enhancing natural
25
and man-made means to sequester greenhouse gases;
26
27
-
further reviewing, developing and deploying policy instruments,
28
which may include public information, standards, taxes and
29
incentives, tradeable permits, and environmental impact
30
assessments, which will induce sustainable energy choices by
31
producers and consumers without jeopardizing energy security and
32
economic growth;
33
34
-
developing methodologies to evaluate the trade off between
35
limitation and adaptation strategies and establishing changes
36
in infrastructure (e.g. pipelines, electrical grids, dams)
37
needed to limit or adapt to climate change.
38
39
5.2
Limitation of net emissions from the industry sector
40
41
The most significant source of greenhouse gases associated
42 with industrial activity not related to energy use is the production
43 and use of CFCs and other halocarbons. CFCs represent a very important
44 source of greenhouse gas emissions and account for about 24% of the
45 total contributions to the enhanced radiative forcing for the period
46 of the 1980s. While the RSWG did not consider control strategies for
47 these gases since the issue is already addressed under the Montreal
48 Protocol on Substances that Deplete the Ozone Layer, it noted that the
49 review of the Montreal Protocol now underway should take into account
50 the global warming potential of potential CFC substitutes.
51
52
The RSWG did develop future emission scenarios for CFCs and
53 HCFC-22 (HCFC-22 was used as a surrogate for a potential mix of HCFCs
54 and HFCs substitutes). The potential impact of such substitutes on
55 radiative forcing was assessed by Working Group I. For a given
56 emission rate, HCFCs and HFCs are less effective greenhouse gases than
23
1 the CFCs because of their shorter lifetimes. The growth rates assumed
2 in the IPCC scenarios will result in the atmospheric concentrations of
3 HFCs and HCFCs becoming comparable to the CFCs during the next several
4 decades assuming that the CFCs had continued to be used at current
5 rates. Assuming the IPCC scenarios for HFCs and HCFCs, Working Group
6 I calculated that these gases would contribute up to 10% of the total
7
additional radiative forcing for the period 2000-2050.
8
9
5.3
Limitation of net emissions from the agriculture sector
10
11
About 9 percent of anthropogenic greenhouse gas emissions can
12 be attributed to the agricultural sector, in particular livestock
13 systems, rice cultivation, and the use of nitrogenous fertilizers.
14 Limitation of emissions from this sector presents a challenge because
15 the processes by which greenhouse gases, in particular methane and
16 nitrous oxide, are released in agricultural activities are not well
17 understood. In addition, response options in the agricultural sector
18 must be designed to ensure maintenance of food supply. There appear,
19 however, to be a number of short-term response options, some
20 economically beneficial in their own right, which could contribute to
21 a limitation of net emissions from agricultural sources. Where
22 appropriate the removal of subsidies, incentives and regulatory
23 barriers that encourage greenhouse gas emissions from the agricultural
24 sector would be both environmentally and economically beneficial. In
25 addition, there are a number of promising technologies and practices
26 which, in the longer term, could significantly reduce greenhouse gas
27
emissions.
28
29 Short-term options:
30
31
Livestock systems: Methane emissions could be reduced through
32
improved management of livestock wastes, expansion of
33
supplemental feeding practices, and increased use of production
34
and growth enhancing agents with safeguards for human health.
35
36
Fertilizer use: Nitrous oxide emissions may be reduced by using
37
existing improved fertilizer formulations, judicious use of
38
animal manures and compost, and improved application technology
39
and practices.
40
41
Marginal lands: Areas marginally suitable for annual cropping
42
systems may be shifted to perennial cover crops for fodder,
43
pastoral land uses or forests if soils are suitable. Such
44
actions would increase carbon uptake, both in the vegetation and
45
soil, and would yield other benefits.
46
47
Sustainable agricultural practices: Where possible, minimum or
48
no-till systems should be introduced for those countries
49
currently using tillage as part of the annual cropping sequence,
50
thus maintaining and increasing soil organic matter.
51
52 Longer-term options:
53
54
Rice cultivation: A comprehensive approach, including management
55
of water regimes, improvement of cultivars, efficient use of
56
fertilizers, and other management practices, could lead to a 10
24
1
to 30 percent reduction in methane emissions from flooded rice
2
cultivation although substantial research is necessary to
3
develop and demonstrate these practices. It is estimated that
4
at least 20 years would be needed to introduce such practices.
5
Adaptable alternative crops research is needed to provide a more
6
diverse crop base for rice growing regions.
7
8
Livestock: Through a number of technologies it appears that
9
methane emissions may be reduced from livestock systems by up
10
to 25 - 75 percent per unit of product in dairy and meat
11
production, although many uncertainties exist.
12
13
Fertilizers: Fertilizer-derived emissions of nitrous oxide
14
potentially can be reduced (although to what extent is
15
uncertain) through changes in practices such as using
16
fertilizers with controlled nitrogen conversion rates, improving
17
fertilizer-use efficiency, and adopting alternative agricultural
18
systems where possible.
19
20
Desertification: Enhanced research on control mesures.
21
22
23
5.4
Limitation of net emissions from forestry and other activities
24
25
Forestry and related aspects of land use cannot be considered
26 in isolation, and solutions must be based on an integrated approach
27 which links forestry to other policies, such as those concerned with
28 poverty and land resources, which should be supported by strong
29 institutions in order to enhance overall forest management. The forest
30 crisis is rooted in the agricultural sector and in people's needs for
31 employment and income. Deforestation will be stopped only when the
32 natural forest is economically more valuable for the people who live
33 in and around the forests than alternative uses for the same land.
34
35
Forestry practices and other human activities associated with
36 land use, such as biomass burning and landfills, account for about 18
37 percent of anthropogenic greenhouse gas emissions. A number of short
38 and long-term response options for limiting net emissions from these
39 sectors have been identified.
40
41 Short-term options:
42
43
1.
Improvement of forest-management and reduction of deforestation
44 and forest degradation which should be supported by:
45
46
-
reduction of air pollution which contributes to forest
47
degradation;
48
49
-
elimination of inappropriate economic incentives and subsidies
50
that contribute to forest loss, where appropriate;
51
52
-
integration of forest conservation requirements and sustainable
53
developement in all relevant sectors of national development
54
planning and policy taking account of the interests of local
55
communities;
56
25
1 -
co-ordinated remote sensing, data collection and analyses to
2
provide the required data;
3
4
-
a meeting of interested countries from the developing and the
5
industrialized worlds and of appropriate international agencies
6
to identify possible key elements of a world forest conservation
7
protocol in the context of a climate convention process that
8
also addresses energy supply and use, and practical means of
9
implementing it. Such a meeting should also develop a framework
10
and methodology for analysing the feasibility of the Noordwijk
11
remit including alternative targets, as well as the full range
12
of costs and benefits;
13
14
-
strengthening Tropical Forestry Action Plan (TFAP) and in the
15
light of the independent review which is being undertaken, the
16
International Tropical Timber Organization (ITTO), and other
17
international organizations whose objective is to help
18
developing countries in achieving conservation, and sustainable
19
development and management of forests;
20
21
-
an assessment of incentives and disincentives for sustainable
22
forest management, for example, the feasibility of labelling;
23
24
-
introduction of sustainable forest harvesting and management;
25
26
-
development of enhanced regeneration methods;
27
28
-
development and implementation of (large-scale) national
29
afforestation and forest conservation plans, where feasible.
30
31
2.
Where appropriate expand forest areas, especially by
32 afforestation, agroforestry and regreening of available surplus
33 agricultural, urban and marginal lands.
34
35
3.
Where appropriate strengthen and improve the use of forest
36 products and wood through measures such as substituting a portion of
37 fossil energy sources by wood or other sustainably managed biomass;
38 partial replacement of high energy input materials by wood; further
39 recycling of forest products; and, improved efficiency of use of fuel
40 wood.
41
42
4.
Development of methane recovery systems for landfill and waste
43 water treatment facilities and their use, in particular, in
44 industrialized countries.
45
46 Longer-term options:
47
48
1.
Maintain the health and the continuance of existing forests as
49 major natural carbon reservoirs, especially through the development and
50
implementation of
51
52
-
silvicultural adjustment and stress management strategies;
53
54
-
special forest protection strategies (developed under climate
55
change scenarios) ;
56
26
1
-
environmentally sound treatment practices for peatlands;
2
3
-
standardisation of methods of forest inventory and bio-
4
monitoring to facilitate global forest management.
5
6 2.
Expand forest biomass, especially of intensively managed
7 temperate forests, by silviculture measures and genetically improved
8 trees.
9
10
3.
With regard to waste management, use of gas collection and
11 flaring to reduce methane emissions from landfills and development of
12 biogas plants to reduce methane emissions from wastewater treatment.
13 Demonstration, training and technology transfer are necessary to
14 realise these potentials, which may range from 30 to 90 percent for
15 landfills and up to 100 percent for wastewater treatment.
16
17
6.
FURTHER WORK ON GREENHOUSE GAS EMISSION LIMITATION GOALS
18
19
There has been considerable international discussion of targets
20 for specific greenhouse gas emissions, in particular, CO2, which is the
21 most abundant of the greenhouse gases. The final declaration at the
22 November 1989 Noordwijk Conference on Atmospheric Pollution and Climate
23 Change encouraged the IPCC to include in its First Assessment Report
24 an analysis of quantitative targets to limit or reduce CO₂ emissions,
25 and urged all industrialized countries to investigate the feasibility
26 of achieving such targets, including, for example, a 20 percent
27 reduction of CO₂ emissions by the year 2005. The Conference also
28 called for assessing the feasibility of increasing net global forest
29 growth by 12 million hectares per year. During its Third Plenary, the
30 IPCC accepted the mandate.
31
32
Although the feasibility of quantitative targets on greenhouse
33 gas emissions fell within the RSWG's original mandate through its
34 Energy and Industry Subgroup (EIS), it was agreed that these new,
35 specific tasks would require more time, data and analyses in order to
36 be dealt with properly. It was decided, therefore, that the results
37 of the deliberations of the EIS on these remits. could not be fully
38 included in its report, but only treated in an incomplete and
39 preliminary way. A progress report is to be presented to the Fourth
40 IPCC Plenary following an international workshop to be hosted by the
41 United Kingdom in June 1990. As for the Noordwijk remit on global
42 forest growth, the RSWG through its Agriculture, Forestry and Other
43 Human Activities Subgroup (AFOS) noted that a framework and methodology
44 for analyzing its feasibility should be developed.
45
46
While the technical potential of a number of options has been
47 demonstrated, there is very little information available on the actual
48 economic and social feasibility associated with implementation of such
49 options. An adequate understanding of the benefits, in terms of
50 changes in climate variables that are avoided, is also seriously
51 lacking. It is imperative that further work on the cost and benefit
52 implications of response strategies be undertaken. These issues have
53 been identified as one of the most important areas for future research
54 by the RSWG, concerned international organizations, and individual
55 countries.
56
27
1
The material available to the EIS demonstrates the important
2
role emissions of industrialized countries play in total global
3
emissions in the near term. The material also indicates that the
4 technical potential for reduction is large, and differs greatly
5 between regions and countries. Therefore, in the near term, no
6
significant progress in limiting global emissions will occur without
7 actions by the industrialized countries. Some countries have already
8
decided to stabilize or reduce their emissions.
9
10
7.
MEASURES FOR ADAPTING TO GLOBAL CLIMATE CHANGE
11
12
In addition to the limitation options discussed above, the RSWG
13 reviewed measures for adapting to potential climate change. The
14 consideration of adaptation options is critical for a number of
15 reasons. First, because it is believed that there is likely to be a
16 lag time between emissions and subsequent climate change, the climate
17 may already be committed to a certain degree of change. Implementation
18 of adaptation measures may thus be necessary regardless of any
19 limitation actions which may be taken. Secondly, natural climatic
20 variability itself necessitates adaptation.
21
22
Furthermore, should significant adverse climate change occur,
23
it would be necessary to consider limitation and adaptation strategies
24 as part of an integrated package in which policies adopted in the two
25 areas complement each other so as to minimize costs. Limitation and
26 adaptation options should be developed and analyzed recognizing the
27 relationship between the timing and costs of limitation and adaptation.
28 For example, the more net emissions are reduced and the rate of climate
29 change potentially slowed, the easier it would be to adapt. A truly
30 comprehensive approach should recognize that controlling the different
31 gases might have different effects on the adaptive capacity of natural
32 resources.
33
34
The RSWG explored two broad categories of adaptation options:
35
36
O
Coastal zone management, or options which maximize the ability
37
of coastal regions to adapt to the projected sea level rise and
38
to reduce vulnerability to storms; and
39
40
o
Resource use and management, or options which address the
41
potential impacts of global climate change on food security,
42
water availability, natural and managed ecosystems, land, and
43
biodiversity.
44
45
7.1
Coastal zone management
46
47
Under the 2030 high emissions scenario, global climate change
48 is predicted to raise global mean sea level 65 cm (with an uncertainty
49 range of 30 to 100 cm) by the year 2100. If sea level rises by 1
50 metre, hundreds of thousands of square kilometres of coastal wetlands
51 and other lowlands could be inundated, while ocean beaches could erode
52 as much as a few hundred metres over the next century. Flooding would
53 threaten lives, agriculture, livestock, and structures, while saltwater
54 would advance inland into aquifers, estuaries, and soils, thus
55 threatening water supplies and agriculture in some areas. Loss of
56 coastal ecosystems would threaten fishery resources.
28
1
2
Some nations would be particularly vulnerable to such changes.
3 Eight to ten million people live within one metre of high tide in each
4 of the unprotected river deltas of Bangladesh, Egypt, and Vietnam.
5 Half a million people live in coral atoll nations that lie almost
6 entirely within three metres of sea level, such as the Maldives, the
7 Marshall Islands, Tuvalu, Kiribati, and Tokelau. Other states with
8 coastal areas, archipelagos and island nations in the Pacific and
9 Indian Oceans and the Caribbean could lose much of their beaches and
10 arable lands, which would cause severe economic and social disruption.
11
12
Available responses to sea level rise fall broadly into three
13 categories:
14
15
O
Retreat: Under this option no actions would be taken to protect
16
the land from the sea - the focus would instead be on providing
17
for people and ecosystems to shift landward in an optimal
18
fashion. This choice could be motivated by either excessive
19
costs of protection or by a desire to maintain ecosystems.
20
21
0
Accommodation: Under this strategy, while no attempt would be
22
made to protect the land at risk, measures would be taken to
23
allow for continued habitation of the area. Specific responses
24
under this options would include erecting flood shelters,
25
elevating buildings on pilings, converting agriculture to fish
26
farming, or growing flood- or salt-tolerant species.
27
28
o
Protection: A protection strategy uses site-specific features
29
such as sea walls, dikes, dunes, and vegetation to protect the
30
land from the sea so that existing land uses can be retained.
31
32
There are various environmental, economic, social, cultural,
33 legal, institutional and technological implications for each of these
34 options. Retreat could lead to a loss of property, potentially costly
35 resettlement of populations, and, in some notable cases, refugee
36 problems. Accommodation could result in declining property values, and
37 costs for modifying infrastructure. Protecting existing development
38 from a one metre sea level rise would require about 360,000 kilometres
39 of coastal defences at a total cost of US$ 500 billion, over the next
40 100 years. The annual cost of protection represents, on average, 0.04
41 percent of total gross national product (GNP), and ranges from zero to
42 20 percent for individual countries. The estimate is not discounted and
43 does not reflect present coastal defence needs or impacts of salt water
44 intrusion or flooding of unprotected lands. Further, the protection
45 could have negative impacts on fisheries, wildlife and recreation. The
46 loss of traditional environments could potentially disrupt family life
47 and create social instability.
48
49 Actions to prepare for possible sea level rise
50
51
A number of response options are available which not only
52 enhance the ability of coastal nations to adapt to sea level rise, but
53 are also beneficial in their own right. Implementation of such options
54 would be most effective if undertaken in the short-term, not because
55 there is an impending catastrophe, but because there are opportunities
29
1 to avoid adverse impacts by acting now - opportunities which may not
2
be as effective if the process is delayed. These options include:
3
4
National coastal planning:
5
6
O
Development and implementation in the short term of
7
comprehensive national coastal zone management plans which (a)
8
deal with both sea level rise and other impacts of global
9
climate change and (b) ensure that risks to populations are
10
minimized while recognizing the need to protect and maintain
11
important coastal ecosystems.
12
13
O
Identification of coastal areas at risk. National efforts are
14
needed to (a) identify functions and resources at risk from a
15
one metre rise in sea level and (b) assess the implications of
16
adaptive response measures on them.
17
18
O
Provisions to ensure that coastal development does not increase
19
vulnerability to sea level rise. Actions in particular need of
20
review include river levees and dams, conversions of mangroves
21
and other wetlands for agriculture and human habitation,
22
harvesting of coral and increased settlement in low-lying areas.
23
In addition, while structural measures to prepare for sea level
24
rise are not yet warranted, the design and location of coastal
25
infrastructure and coastal defenses should include consideration
26
of sea level rise and other coastal impacts of climate change.
27
It is sometimes less expensive to design a structure today,
28
incorporating these factors, than to rebuild it later.
29
30
O
Review and strengthening of emergency preparedness and coastal
31
zone response mechanisms. Efforts are needed to develop
32
emergency preparedness plans for reducing vulnerability to
33
coastal storms through better evacuation planning and the
34
development of coastal defense mechanisms that recognize the
35
impact of sea level rise.
36
37
International cooperation:
38
39
O
Maintenance of a continuing international focus on the impacts
40
of sea level rise. Existing international organizations should
41
be -augmented with new mechanisms to focus attention and
42
awareness on sea level change and to encourage the nations of
43
the world to develop appropriate responses.
44
45
O
Provision of technical assistance and co-operation to developing
46
nations. Institutions offering financial support should take
47
into account the need for technical assistance and co-operation
48
in developing coastal management plans, assessing coastal
49
resources at risk, and increasing a nation's ability - through
50
education, training, and technology transfer - to address sea
51
level rise.
52
53
O
Support by international organizations for national efforts to
54
limit population growth in coastal areas. In the final
55
analysis, rapid population growth is the underlying problem with
30
1
the greatest impact on both the efficacy of coastal zone
2
management and the success of adaptive response options.
3
4 Research, data, and information:
5
6
O
Strengthening of research on the impacts of global climate
7
change on sea level rise. International and national climate
8
research programmes need to be directed at understanding and
9
predicting changes in sea level, extreme events, precipitation,
10
and other impacts of global climate change on coastal areas.
11
12
O
Development and implementation of a global ocean observing
13
network, for example through the efforts of the IOC, WMO, and
14
UNEP to establish a coordinated international ocean observing
15
network that will allow for accurate assessment and continuous
16
monitoring of changes in the world's oceans and coastal areas,
17
particularly sea level change and coastal erosion.
18
19
O
Dissemination of data and information on sea level change and
20
adaptive options. An international mechanism could be
21
identified with the participation of the parties concerned for
22
collecting and exchanging data and information on climate change
23
and its impact on sea level and the coastal zone and on various
24
adaptive options. Sharing this information with developing
25
countries is critically important for preparation of coastal
26
management plans.
27
28
A programme could begin now to enable developing countries to
29 implement coastal zone management plans by the year 2000. The programme
30 would provide for training of country experts, data collection and
31 technical assistance and co-operation. Estimated funding to provide
32 the necessary support over the next 5 years is US$ 10,000,000. It is
33 suggested that international organizations such as UNEP and WMO
34 consider co-ordinating this programme in consultation with interested
35 nations.
36
37
38
7.2
Resource use and management
39
40
The reports of Working Groups I and II indicate significant and
41 unavoidable impacts, both positive and negative, upon the very
42 resources that humans and other species rely on to live. These
43 resources include water, agriculture, livestock, fisheries, land,
44 forests, and wildlife. The RSWG addressed these resource issues in the
45 context of considering options for ensuring food security; conserving
46 biological diversity; maintaining water supplies; and using land
47 rationally for managed and unmanaged ecosystems.
48
49
The potential impacts of climate change on natural resources and
50 human activities are poorly understood. First, credible regional
51 estimates of changes in critical climatic factors, such as temperature,
52 soil moisture, annual and seasonal variability, and frequencies of
53 droughts, floods and storms, are simply not available. For many of
54 these critical climatic factors even the direction of change is
55 uncertain. Secondly, methods for translating these changes into
56 effects on the quantity and quality of resources are generally lacking.
31
1 While it is clear that some of the impacts of climate change on
2
resources could be negative and others positive, a more specific
3
quantification of those impacts is not possible at this time.
4 Nevertheless, these uncertainties do not preclude taking appropriate
5 actions, especially if they are worthwhile for other non-climate
6 related reasons. However, it can be said that: (a) those resources
7 which are managed by humans (e.g. agriculture, forestry) are more
8 suited to successful adaptation than unmanaged ecosystems; and (b) the
9 faster the rate of change, the greater the impact. In that regard, it
10 is very important to realize that some species will not be able to
11 survive rapid climate changes.
12
13
Through the ages societies and living things have developed the
14 capability to adapt to the climate's natural variability and to extreme
15 events. Several climatic zones span the globe, and resource use and
16 management is an ongoing challenge in each of these zones. Therefore,
17 society could borrow from this existing large reservoir of experience
18 and knowledge" in developing policies to adapt to possible climate
19 change. In addition, expected future economic and technological
20 progress would provide the financial and technical resources required
21 to better adapt to a changing climate. Nevertheless, significant
22 costs, and legal, institutional and cultural adjustments may be
23 necessary to implement adaptation measures.
24
25
In recognition of the uncertainties regarding the impacts of
26 climate change on resource use and management, the following sections
27 provide general, rather than specific, options in three categories.
28 The appropriateness of these options for individual countries may vary
29 depending on the specific social, environmental and economic context.
30
31 Short-term research related options
32
33
There are a number of actions which would augment our knowledge
34 base for making reasoned judgments about response strategies. These
35
include:
36
37
Developing inventories, data bases, monitoring systems, and
38
catalogues of the current state of resources and resource use
39
and management practices.
40
41
Improving our scientific understanding of and predictive tools
42
for critical climatic factors, their impacts on natural
43
resources, and their socio-economic consequences.
44
45
Undertaking studies and assessments to gauge the resilience and
46
adaptability of resources and their vulnerability to climate
47
change.
48
49
Encouraging research and development by both public and private
50
enterprises directed toward more efficient resource use and
51
biotechnological innovation (with adequate safeguards for
52
health, safety, and the environment), including allowing
53
innovators to benefit from their work.
54
55
O
Continuing existing research and development of methods to cope
56
with the potentially worst consequences of climate change, such
32
1
as developing more drought- or salinity-resistant cultivars or
2
using classical and modern breeding techniques to help keep
3
farming and forestry options open, and research on
4
agrometeorology or agroclimatology.
5
6
O
Increasing research on the preservation of biological resources
7
in situ and ex situ, including investigations into the size and
8
location of protected natural areas and conservation corridors.
9
10 Short-term policy options
11
12
Some response strategies are available which are probably
13 economically justified under present-day conditions and which could be
14 undertaken for sound resource management reasons, even in the absence
15 of climate change. In general, these relate to improving the
16 efficiency of natural resource use, fuller utilization of the
17 "harvested" component of resources, and waste reduction. Measures that
18 could be implemented in the short-term include:
19
20
O
Increased emphasis on the development and adoption of
21
technologies which may increase the productivity or efficiency
22
(per unit of land or water) of crops, forests, livestock,
23
fisheries, and human settlements, consistent with the principles
24
of sustainable development. Such efficiencies reduce the demand
25
for land for human activities and could also help reduce
26
emissions of greenhouse gases. Examples of specific options
27
include more efficient milk and meat production; improved food
28
storage and distribution; and better water management practices.
29
30
O
Increased promotion and strengthening of resource conservation
31
and sustainable resource use - especially in highly vulnerable
32
areas. Various initiatives could be explored for conserving the
33
most sensitive and valuable resources, including strengthening
34
conservation measures, managing development of highly vulnerable
35
resources, and promoting reforestation and afforestation.
36
37
O
Acceleration of economic development efforts in developing
38
countries. Because these countries often have largely
39
resource-based economies, efforts at improving agriculture and
40
natural resource use would be particularly beneficial. Such
41
efforts would also promote capital formation, which would
42
generally make adaptation to climate change and sustainable
43
development more feasible.
44
45
O
Developing methods whereby local populations and resource users
46
gain a stake in conservation and sustainable resource use, for
47
example by investing resource users with clear property rights
48
and long-term tenure, and allowing voluntary water transfer or
49
other market mechanisms.
50
51
o
Decentralizing, as practicable, decision-making on resource use
52
and management.
53
54
Longer-term options
55
33
1
There are also a number of other possible responses which are
2 costly or otherwise appear to be more appropriate for consideration in
3 the longer term, once uncertainties regarding climate change impacts
4 are reduced. Options in this category include:
5
6
O
Building large capital structures (such as dams) to provide for
7
enhanced availability of water and other resources.
8
9
O
Strengthening and enlarging protected natural areas and
10
examining the feasibility of establishing conservation corridors
11
to enhance the adaptation prospects for unmanaged ecosystems.
12
13
O
As appropriate, reviewing and eliminating direct and indirect
14
subsidies and incentives for inefficient resource use, and other
15
institutional barriers to efficient resource use.
16
17
18
8.
MECHANISMS FOR IMPLEMENTING RESPONSE STRATEGIES
19
20
The RSWG also considered several priority areas which must be
21 addressed in order to adequately implement limitation or adaptation
22 responses. These "implementation mechanisms" represent the primary
23 vehicles through which national, regional and international responses
24 to climate can be brought into force. The specific implementation
25 mechanisms considered were:
26
27
o
Public information and education;
28
29
O
Technology development and transfer;
30
31
o
Economic (market) mechanisms;
32
33
o
Financial mechanisms;
34
35
O
Legal and institutional mechanisms, including possible elements
36
of a framework convention on climate change.
37
38
The results of the RSWG's deliberations on these issues are
39 provided below.
40
41
8.1
Public information and education
42
43
A well informed global population is essential for addressing
44 and coping with an issue as complex as climate change. Because climate
45 change would affect, either directly or indirectly, almost every sector
46 of society, broad global understanding of the issue will facilitate the
47 adoption and implementation of such response options as deemed
48 necessary and appropriate. The dissemination of information also
49 represents a powerful economic instrument for ensuring that markets
50 accurately take into account potential consequences and/or
51 opportunities of climate change.
52
53
The core aims of public education and information programmes are
54
to:
55
56
o
Promote awareness and knowledge of climate change issues;
34
1
2
o
Provide guidance for positive practices to limit and/or adapt
3
to climate change;
4
5
o
Encourage wide participation of all sectors of the population
6
of all countries, both developed and developing, in addressing
7
climate change issues and developing appropriate responses; and
8
9
O
Especially emphasize key target groups, such as children and
10
youth, as well as individuals at household levels, policymakers
11
and leaders, media, educational institutions, scientists,
12
business and agricultural sectors.
13
14
Given the importance of a well-informed population, the RSWG
15 developed. suggestions and approaches for improving international
16 awareness of the potential causes and impacts of climate change. In
17 this process it was recognized that, while broad-based understanding
18 is essential, no single mechanism can work for every group or in every
19 culture or country. The social, economic, and cultural diversity of
20 nations will likely require educational approaches and information
21 tailored to the specific requirements and resources of particular
22 locales, countries, or regions. The importance of education and
23 information for developing countries cannot be overemphasized.
24
25
A number of national and international actions should be taken
26 to disseminate broadly information on climate change. These include
27
the:
28
29
O
Establishment of national committees or clearing houses to
30
collect, develop, and disseminate objective materials on climate
31
change issues. This could help provide focal points for
32
information on issues such as energy efficiency, energy savings,
33
forestry, agriculture, etc.
34
35
o
Use by international organizations (UNESCO, UNEP, WMO, etc.) and
36
non-governmental organizations of IPCC and other relevant
37
reports in developing and providing to all countries an adequate
38
understanding for future actions.
39
40
O
Use of an existing international institution, or development of
41
a new institution, if necessary, to serve as a clearinghouse for
42
informational and educational materials.
43
44
O
Upon completion of the IPCC reports, or earlier, arrange a
45
series of short seminars targeted to inform high priority
46
decision makers, world leaders and others of causes and effects
47
of climate change.
48
49
8.2
Technology development and transfer
50
51
The development and transfer of technologies is vital to any
52 effort to address global climate change. The development of new
53 technologies may provide the means by which societies can meet their
54 energy, food, and other needs in the face of changes in global climate,
55 while at the same time minimizing emissions of greenhouse gases.
56 Prompt transfer of technologies, especially to developing countries,
35
1 is likewise an important aspect of any effort to limit or adapt to
2 climate change.
3
4 Technology research and development
5
6
Technological development, including improvement and
7 reassessment: of existing technologies, is needed to limit or reduce
8 anthropogenic greenhouse gas emissions; absorb such gases by protecting
9 and increasing sinks; adapt human activities and resource use and
10 management to the impacts of climate change; and detect, monitor and
11 predict climate change and its impacts. Technological development
12 could be pursued in a wide range of activities such as energy,
13 industry, agriculture, transport, water supply, coastal protection,
14 management of natural resources, and housing and building construction.
15
16
Adequate and trained human resources are a prerequisite for
17 development and transfer of technologies, and technological actions,
18 founded on a sound scientific basis, must be consistent with the
19 concept of sustainable development.
20
21
Criteria for selecting technologies include such factors as the
22 existence of economic and social benefits in addition to environmental
23 benefits, economic efficiency taking into account all the external
24 costs, suitability to local needs, ease of administration, information
25 needs, acceptability to the public.
26
27
Appropriate pricing policies where applicable, information
28 exchange on the state of development of technologies, and the support
29 of governments are important measures that can promote technology
30 development. Also of importance are international collaborative
31 efforts, especially between the industrialized and the developing
32 countries in the bilateral and multilateral context.
33
34 Technology Transfer
35
36
There is a need for the rapid transfer to the developing
37 countries, on a preferential basis, of technologies for addressing
38 climate change. Developing countries are of the view that transfer of
39 technologies on a non-commercial basis is necessary and that specific
40 bilateral and multilateral arrangements should be established to
41 promote this. Some other countries where technologies are not owned
42 by the government believe that transfer of technologies would be a
43 function of commercial negotiations. The issue of intellectual
44 property rights also presents a case where international opinion is
45 mixed.
46
47
A number of impediments also exist which hinder the effective
48 transfer of technologies to developing countries. These include lack
49 of financial resources, necessary institutions, and trained human
50 resources. Existing institutions could be strengthened, or new
51 mechanisms established, where appropriate, to finance technology
52 transfers, train human resources, and evaluate, introduce and operate
53 existing or new technologies. Legal barriers and restrictive trade
54 practices are also impeding factors.
55
36
1
It has not been possible to bridge the difference on views on
2 some of the questions mentioned above. It is extremely important to
3 reach early international agreement on these issues in order to promote
4 effective flow of technologies to monitor, limit or adapt to climate
5 change. One area where international agreement may be possible is the
6 promotion of CFC substitutes and provision of assistance and
7 cooperation to the developing countries in the acquisition and
8 manufacture of such substitutes.
9
10
Several countries have suggested that the issue of technology
11 transfer to Eastern European countries be addressed.
12
13
8.3
Economic mechanisms
14
15
It is important that any potential measures to limit or adapt
16 to global climate change be as economically efficient and
17 cost-effective as possible, while taking into account important social
18 implications. In general, environmental objectives can be achieved
19 either through regulations requiring the use of a specific technology
20 or attainment of specified goals, or economic instruments such as
21 emissions fees, subsidies, tradeable permits, or sanctions.
22
23
Economic instruments, through their encouragement of flexible
24 selection of abatement measures, frequently offer the possibility of
25 achieving environmental improvements at lower cost than regulatory
26 mechanisms. Unlike many regulations, they tend to encourage innovation
27 and the development of improved technologies and practices for reducing
28 emissions. Economic mechanisms also have the potential to provide the
29 signals necessary for more environmentally sensitive operation of
30 markets. It is unlikely, however, that economic instruments will be
31 applicable to all circumstances.
32
33
Three factors are considered as potential barriers to the
34 operation of markets and/or the achievement of environmental objectives
35 through market mechanisms. These are: information problems, which can
36 often cause markets to produce less effective or unfavorable
37 environmental outcomes; existing measures and institutions, which can
38 encourage individuals to behave in environmentally damaging ways; and
39 balancing competing objectives (social, environmental, and economic).
40 An initial response strategy may therefore be to address information
41 problems directly and to review existing measures which may be
42 barriers. For example, prior to possible adoption of a system of
43 emission charges, countries should examine existing subsidies and tax
44 incentives on energy and other relevant greenhouse gas producing
45 sectors.
46
47
A general advantage of market based economic instruments is that
48 they encourage limitations or reductions in emissions by those who can
49 achieve them at least cost. They also provide an ongoing incentive for
50 industry and individual consumers to apply the most efficient
51 limitation/reduction measures through, for example, more efficient and
52 cleaner technologies. Such incentives may be lacking in the case of
53 regulations.
54
55
Regulations, are the customary means of controlling pollution
56 in both market and centrally planned economies. An advantage of
37
1 regulations is that, in certain circumstances, they create more
2 certainty as to desired outcomes, whereas major disadvantages are that
3 they may discourage innovation, introduce inflexibilities in meeting
4 objectives, can discourage resource use efficiency, and offer few or
5 no incentives to reduce emissions below specified levels.
6
7
It is evident that the question of adoption of any form of
8 economic instrument, whether domestically or internationally, raises
9 many complex and difficult issues. Careful and substantive analysis
10 of all implications of such instruments is needed. Possible specific
11 economic instruments which have been identified for consideration
12
include:
13
14
O
A system of tradeable emissions permits: An emission permit
15
system is based on the concept that the economic costs of
16
attaining a given environmental goal can be minimized by
17
allowing for the trading of emissions rights. Once an overall
18
limit on emissions has been set, emissions entitlements
19
amounting to that limit could be provided to emitting sources
20
and free trading of such entitlements allowed. This would
21
reduce the costs of meeting a given emission target because:
22
(a) as in trade, comparative advantages between trading entities
23
would be maximized; and (b) economic incentives would be created
24
for the development of improved greenhouse gas limitation
25
technologies, sink enhancement, and resource use efficiency
26
(energy conservation). Concerns with this approach include the
27
limited experience with this instrument, the potential scope and
28
size of trading markets and the need for the development of an
29
administrative structure not currently in place.
30
31
O
A system of emission charges: Emission charges are levied on
32
specified emissions depending on their level of contribution to
33
climate change. Such charges may provide a means of encouraging
34
emitters to limit or reduce emissions and provide an incentive
35
for diverse parties to implement efficient means of limiting or
36
reducing emissions. Another advantage of charges is that they
37
generate revenue which could provide a funding base for further
38
pollution abatement, research, and administration, or allow
39
other taxes to be lowered. Concerns with this approach include
40
the difficulty of deciding on the basis and size of the tax, and
41
the lack of certainty that the tax will achieve the agreed
42
emission reduction target.
43
44
O
Subsidies: Subsidies are aimed at encouraging environmentally
45
sound actions by lowering their costs. Subsidies could be used,
46
inter alia, to encourage the use of energy-efficient equipment
47
and non-fossil energy sources, and the development and greater
48
use of environmentally sound technologies. Concerns with
49
subsidies include the possible size of the required financial
50
commitment of governments, the need for careful design, the need
51
for review, and the international trade aspects of such
52
measures.
53
54
O
Sanctions: A final type of economic instrument is the use of
55
economic sanctions for the enforcement of international
56
agreements. This would require an international convention to
38
1
establish a system of agreed trade or financial sanctions to be
2
imposed on countries not adhering to agreed regimes. Many
3
contributors expressed considerable reservations about applying
4
this approach to greenhouse gas emissions because of the
5
complexity of the situation. The concerns include a belief that
6
sanctions could appear to be arbitrary, could create confusion
7
and resentment and could be used as a pretext to impose new non-
8
tariff trade barriers.
9
10
It has also been suggested that the environmental protection
11 could be advanced and economic costs of meeting greenhouse gas
12 limitation targets , if any, minimized by addressing, to the extent
13 feasible, all greenhouse gas sources and sinks comprehensively. This
14 approach could employ an "index" relating net emissions of various
15 greenhouse gases by further development of the index formulated by
16 Working Group I.
17
18
Each of the approaches outlined above, however, poses
19 potentially significant challenges in terms of implementation and
20 acceptability. There is an incomplete understanding of the economic
21 and social consequences of these various approaches. It is evident
22 that further work is required in all countries, and in ongoing IPCC
23 work, to fully evaluate the practicality of such measures and costs and
24 benefits associated with different mechanisms, especially with their
25 use internationally. It has, however, been pointed out that an
26 international system of tradeable permits, or, alternatively, an
27 international sytem of emissions charges, could offer the potential of
28 serving as a cost-efficient main instrument for achieving a defined
29 target for the reduction of greenhouse gas emisssions.
30
31
Finally, it was stressed that in order to share equitably the
32 economic burdens, implementation of any of the international economic
33 instruments discussed above should take into account the circumstances
34 that most emissions affecting the atmosphere at present originated in
35 the industrialised countries where the scope for change is the
36 greatest, and that, under present conditions, emissions from developing
37 countries are growing and may need to grow in order to meet their
38 development requirements and thus, over time, are likely to represent
39 an increasingly significant percentage of global emisssions. It is
40 appreciated that each instrument assessed has a role in meeting
41 greenhouse gas emission objectives, but the suitability of particular
42 instruments is dependent on the particular circumstances and at this
43 stage no measure can be considered universally superior to any other
44 available mechanisms.
45
46
8.4
Financial mechanisms
47
48
Industrialized and developing countries consider it important
49 that assurances of financial mechanisms are needed for undertaking
50 adequate measures to limit and/or adapt to climate change.
51
52 GUIDING PRINCIPLES
53
54
The following principles should guide the financial approach:
55
39
1
a)
Industrialized countries and developing countries have a
2
common responsibility in dealing with problems arising from
3
climate change, and effective responses require a global
4
effort.
5
6
b)
Industrialized countries should take the lead and have
7
specific responsibilities on two levels:
8
9
i)
Major part of emissions affecting the atmosphere at present
10
originates in industrialized countries where the scope for
11
change is greatest. Industrialized countries should adopt
12
domestic measures to limit climate change by adapting their
13
own economies in line with future agreements to limit
14
emissions;
15
16
ii)
To cooperate with developing countries in international
17
action, without standing in the way of the latter's
18
development, by contributing additional financial
19
resources, by appropriate transfer of technology, by
20
engaging in close cooperation concerning scientific
21
observation, by analysis and research, and finally by means
22
of technical co-operation geared to forestalling and
23
managing environmental problems;
24
25
c)
Emissions from developing countries are growing and may need
26
to grow in order to meet their development requirements and
27
thus, over time, are likely to represent an increasingly
28
significant percentage of global emissions. Developing
29
countries should, within the limits feasible, take measures
30
to suitably adapt their economies.
31
32
Financial resources channelled to developing countries would be
33
most effective if focused on those activities which contribute both to
34
limiting greenhouse gas emissions and promoting economic development.
35
Areas for cooperation and assistance could include:
36
37
O
Efficient use of energy resources and the increased use of
38
fossil fuels with lower greenhouse gas emission rate or non-
39
fossil sources;
40
41
Rational forest management practices and agricultural techniques
42
which reduce greenhouse gas emissions;
43
44
Facilitating technology transfer and technology development;
45
46
O
Measures which enhance the capacity of developing countries to
47
develop programmes to address climate change, including research
48
and development activities and public awareness and education;
49
50
Participation by developing countries in international fora on
51
global climate change, such as the IPCC.
52
53
It was also recognized that cooperation and assistance for
54
adaptive measures would be required, noting that for some regions and
55
countries, adaptation rather than limitation activities are potentially
56
most important.
40
1
2
A number of possible sources for generating financial resources
3 were considered. These include general taxation, specific taxation on
4 greenhouse gas emissions, and emissions trading. For the significant
5
compl xities and implications of such taxes, reference is made to the
6 economic measures paper (section 8.3). Creative suggestions include
7 using undisbursed official resources, which might result from savings
8 on government energy bills and lower levels of military expenditures,
9 a fixed percentage tax on travel tickets, and levies on countries that
10 have been unable to meet their obligations. The question has also been
11 raised of whether such financial cooperation and assistance should
12 only be given to those countries which abstain from activities
13 producing greenhouse gases. A positive international economic
14 environment, including further reduction of trade barriers, and
15 implementation of more equitable trade practices would help to generate
16 resources which can be applied towards pressing needs.
17
18
With respect to institutional mechanisms for providing financial
19 cooperation and assistance to developing countries, a two track
20 approach was considered:
21
22
i)
one track built on work underway or planned in existing
23
institutions. In this regard, the World Bank, a number of
24
regional banks, other multilateral organizations, and bilateral
25
agencies have initiated efforts to incorporate global climate
26
change issues into their programmes. Bilateral donors could
27
further integrate and reinforce the environmental components of
28
their assistance programmes and develop cofinancing arrangements
29
with multilateral institutions while ensuring that this does not
30
impose inappropriate environmental conditions.
31
32
ii)
parallel to this track the possibility of new mechanisms and
33
facilities was considered. Some developing and industrialized
34
countries suggested that new. mechanism directly related to a
35
future climate convention and protocols, such as a new
36
international fund, were required. It was added that such new
37
instruments could be located within the World Bank (with new
38
rules) or elsewhere. It was also noted that the Global
39
Environmental Facility proposed by the World Bank in
40
collaboration with UNEP and UNDP was welcomed by industrialized
41
and developing countries at the World Bank Development Committee
42
meeting in May 1990.
43
44
It was noted that the issue of generating financial resources
45 was distinct from that of allocating those resources.
46
47
Areas identified for future work include studies, with donor
48 assistance, for developing countries on their current and projected
49 net emissions levels and assistance and cooperation needs for limiting
50 such emissions. Further consideration is also needed of the important
51 role which the private sector might play, through technology transfer,
52 foreign direct investment and other means to assist and cooperate with
53 developing countries to respond to climate change.
54
55
41
1.,8.5
Legal and institutional mechanisms
2
3
A number of institutions and international legal mechanisms
4
exist which have a bearing on the climate change issue, in particular
5 those dealing with the environment, science and technology, energy,
6 natural resources, and financial assistance. One of these existing
7 international legal mechanisms, the Vienna Convention on the Protection
8 of the Ozone Layer and its associated Montreal Protocol on Substances
9 that Deplete the Ozone Layer, deals specifically with reducing
10 emissions of important greenhouse gases which also deplete the ozone
11 layer. However, there is a general view that, while existing legal
12 instruments and institutions related to climate change should be fully
13 utilized and further strengthened, they are insufficient alone to meet
14 the challenge.
15
16
A consensus emerged at the 44th session of the UN General
17 Assembly on the need to prepare as a matter of urgency a framework
18 convention on climate change, laying down, as a minimum, general
19 principles and obligations. It should, in the view of RSWG, be framed
20 in such a way as to gain the adherence of the largest possible number
21 and most suitably balanced range of countries while permitting timely
22 action to be taken. It may contain provision for separate
23 annexes/protocol (s) to deal with specific obligations. As part of the
24 commitment of the parties to action on greenhouse gas emissions and
25 adverse effects of climate change, the convention should also address
26 the particular financial and other needs of the developing countries
27 (notably those most vulnerable to climate change agriculturally or
28 otherwise), the question of access to and transfer of technology, the
29 need for research and monitoring, and institutional requirements.
30
31
Decisions will have to be taken on a number of key issues.
32 These include:
33
34
o
the political imperative of striking the correct balances (a)
35
between the arguments for a far-reaching, action-oriented
36
convention and the need for urgent adoption of a convention so
37
as to begin tackling the problem of climate change; and (b)
38
among the risks of inaction, the costs of action and current
39
levels of scientific uncertainty;
40
41
O
the extent to which specific obligations, particularly on the
42
control of emissions of greenhouse gases, should be included in
43
the convention itself, possibly as annexes, or be the subject
44
of a separate protocol (s) ;
45
46
o
the timing of negotiation of protocol (s) in relation to the
47
negotiations on the convention;
48
49
O
the introduction as appropriate of sound scientific bases for
50
establishing emission targets (such as total emission levels,
51
per capita emissions, emissions per GNP, emissions per energy
52
use, climatic conditions, past performance, geographic
53
characteristics, fossil fuel resource base, carbon intensity per
54
unit of energy, energy intensity per GNP, socio-economic costs
55
and benefits or other equitable considerations) ;
56
42
1
o
the extent to which specific goals with respect to global levels
2
of emissions or atmospheric concentrations of greenhouse gases
3
should be addressed;
4
5
o
whether obligations should be equitably differentiated
6
according to countries' respective responsibilities for causing
7
and combatting climate change and their level of development;
8
9
O
the need for additional resources for developing countries and
10
the manner in which this should be addressed, particularly in
11
terms of the nature, size and conditions of the funding, even
12
if detailed arrangements form the subject of a separate
13
protocol;
14
15
O
the basis on which the promotion of the development and transfer
16
of technology and provision of technical assistance and co-
17
operation to developing countries should take place, taking into
18
account considerations such as terms of transfer (preferential
19
or non-preferential, commercial or non-commercial), assured
20
access, intellectual property rights, the environmental
21
soundness of such technology, and the financial implications;
22
23
o
the nature of any new institutions to be created by the
24
convention (such as a Conference of the Parties, an Executive
25
Organ, as well as other bodies), together with their functions,
26
composition and decision-making powers, e.g. whether or not they
27
should exercise supervision and control over the obligations
28
undertaken.
29
30
The international negotiation on a framework convention should
31 start as quickly as possible after the completion of the IPCC interim
32 report. The full and effective participation of developing countries
33 in this process is essential. Many, essentially developing, countries
34 stressed that the negotiation must be conducted in the forum, manner
35 and with the timing to be decided by the UN General Assembly. This
36 understanding also applies to any associated protocols. In the view
37 of many countries and international and non-governmental organizations,
38 the process should be conducted with a view of concluding it not later
39 than the 1992 UN Conference on Environment and Development.
40
41
The foregoing does not necessarily constitute an exclusive list
42 of issues which will arise in the negotiations. However, a readiness
43 to address these fundamental problems will be a prerequisite for
44 ensuring the success of the negotiations and the support of a
45 sufficiently wide and representative spread of nations.
46
47
9.
THE SPECIAL CIRCUMSTANCES OF THE DEVELOPING COUNTRIES
48
49
RSWG has taken note of the report of the IPCC Special Committee
50 on the Participation of Developing Countries, presented by its
51 Chairman, Mr. J. Ripert (see Annex I). According to the report, the
52 difficulties encountered by the developing countries in participating
53 in IPCC include:
54
55
43
1
*insufficient information
2
*insufficient communication
3
*limited human resources
4
*institutional difficulties
5
*limited financial resources.
6
7
The RSWG calls the attention on the need of the IPCC to consider
8 fully the report of the Special Committee during its Fourth Plenary
9
(Sundsvall, Sweden, 27 - 30 August 1990).
10
44
1
ANNEX I
2
3
4
SUMMARY OF THE REMARKS OF THE CHAIRMAN, MR. J. RIPERT,
5
OF THE IPCC SPECIAL COMMITTEE ON THE PARTICIPATION
6
OF DEVELOPING COUNTRIES TO THIS SESSION OF THE RSWG
7
8
9
In its third plenary in Washington, IPCC requested the Special
10 Committee to prepare a report and policymakers summary for inclusion
11 in the IPCC first assessment report. Such a report and policymakers
12 summary were drafted in a meeting in Paris in April 1990 with inputs
13 from several governments. The drafts were circulated to all governments
14 and finalized during an open-ended plenary of the Special Committee
15 from 31 May - 1 June 1990.
16
17
The initial emphasis in the work of the Committee was on how to
18 further facilitate the physical participation of representatives from
19 the developing countries at the meetings of IPCC, its Working Groups
20 and their subgroups. It was very much on facilitating travel,
21 identification of experts, better information flow, and internal and
22 external co-ordination. There was realization from the outset in the
23 Special Committee that it should not interfere with the work of the
24 IPCC Working Groups or their subgroups which had been asked to look
25 at issues like transfer of technology or financial aid. In addition,
26 the work of the Special Committee was done in parallel with that in the
27 Working Groups, a necessity since not all the completed reports of the
28 Working Groups were available at the time of the plenary session of the
29 Special Committee.
30
31
It may be recalled that in Washington several countries
32 expressed the view that the mandate of the Special Committee could not
33 be perceived in so narrow a way, but one role of the Committee should
34 be to consider what is preventing the full participation of developing
35 countries in the scientific and other assessments and the elaboration
36 of response options. Developing countries have to be active partners
37 in all ongoing and envisaged climate change-related international
38 process and not only in discussions within IPCC.
39
40
The analysis of the Committee has identified the following
41 inhibiting factors with respect to the full participation of the
42 developing countries in climate change activities: insufficient
43 information, insufficient communication, limited human resources,
44 specific institutional difficulties, and limited financial resources.
45 While the full discussion on these matters is to be found in the report
46 of the Special Committee, the Committee was very anxious to convey in
47 addition the following message.
48
49
1)
Most of the developing countries are on the horns of the dilemma
50
of deciding the priorities between environmental issues and
51
economic development. While global environment today has
52
acquired greater significance for industrialized countries,
53
priority for alleviation of poverty continues to be the
54
overriding concern of the developing countries;
55
45
1
2)
This situation poses a serious obstacle to enhancing th.
2
participation of developing countries;
3
4
The Committee noted also that for developing countries, the lack
5 of sufficient assurance, so far, on the provision and requisite,
6 adequate, additional funding particularly for the identification,
7 transfer, adaptation and implementation of alternative safe
8 technologies added substantially to the inhibition of the developing
9 countries to take active part. Many delegates strongly felt that this
10 has to be recognized as a real obstacle to the development of a global
11 strategy and therefore this should be taken into account in any
12 meaningful attempt to elaborate response strategies. The Committee
13 further considered that the formulation of funding mechanisms for
14 transfer, adaptation and implementation of clean technology as against
15 economic and legal measures would create healthier conditions for the
16 participation of developing countries. This is a very difficult issue,
17 clearly a controversial one, nevertheless of great importance to the
18 developing countries.
19
20
The Special Committee has made a number of specific
21 recommendations regarding strenghtening the participation which
22 requires action in some areas which might look trivial, as for example,
23 not only travel facilities but organization of communication between
24 governments and the IPCC Secretariat, as well as more substantive areas
25 where the IPCC Working Groups are active. In all these areas, the
26 Committee has pointed out the need to develop action or to undertake
27 action without waiting for the outcome of the negotiations of a
28 convention or protocols, particularly in those areas where there is no
29 doubt that there is a need to help the developing countries.
30
31
The Special Committee expressed the view that it is necessary
32 to prepare specific programmes of action for the furtherance of the
33 participation by developing countries. Such programmes should include
34 specific action items, time schedules, identification of requisite
35 resources, and institutions for implementation.
36
37
Also, serious consideration should be given to providing
38 simultaneous interpretation and translation in all UN languages during
39 the meetings of the IPCC. This aspect is of particular importance for
40 many developing countries.
41
42
To reiterate, financial support should be ensured in the coming
43 months for the IPCC Trust Fund to facilitate the uninterrupted
44 participation of as many experts from developing countries as possible
45 in the work to be conducted after the IPCC Fourth Plenary.
46
47
46
List of acronyms and chemical symbols
AFOS
Agriculture, Forestry and Other Human Activities Subgroup
of IPCC Working Group III
Bt
Billion tonnes
Btc
Billion (or 1000 millions) tonnes Carbon
CFCs
Chlorofluorocarbons
CH₄
Methane
CI
Carbon Intensity in kilogram carbon per gigajoule
CO
Carbon monoxide
CO₂
Carbon dioxide
EIS
Energy and Industry Subgroup of IPCC Working Group III
Gg
Gigagram (10 grams)
GHG
Greenhouse Gas
GNP
Gross National Product
HCFC
Hydrochlorofluorocarbon
HFCs
Hydrofluorocarbon
IOC
Intergovernmental Oceanographic Commission of UNESCO
IPCC
Intergovernmental Panel on Climate Change
ITTO
International Tropical Timber Organization
N₂O
Nitrous oxide
NGOs
Non-Governmental Organizations
NOx
Nitrogen oxides
O₃
Ozone
OECD
Organization for Economic Cooperation and Development
PC
Per Capita carbon emissions in tonne carbon
ppm
part per million
RSWG
Response Strategies Working Group of IPCC Working Group 3
SOx
Sulphur oxides
TC
Tonne Carbon
TC-GJ
Tonne Carbon per GigaJoule
TFAP
Tropical Forestry Action Plan
Tg
Teragram (10 12 grams)
TgC
Teragram Carbon
TgCH4
Teragram Methane
TgN
Teragram Nitrogen
UN
United Nations
UNDP
United Nations Development Programme
UNEP
United Nations Environment Programme
UNESCO
United Nations Educational, Scientific and Cultural
Organization
VOCs
Volatile Organic Compounds
WMO
World Meteorological Organization
FROM CLIMATE CHANGE DIV
11.19.1992 15:11
P. 2
UNITED STATES.
file IPCC
NEW
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
PROTECTION
WASHINGTON, D.C. 20460
November 19, 1992
OFFICE OF
POLICY, PLANNING AND EVALUATION
Subject:
IPCC Plenary Meeting - Harare, Zimbabwe, November 10-13, 1992
To:
See Distribution
From:
Dennis A. Tirpak, Director
Tak
Climate Change Division
Dunie
Joel D. Scheraga, Chief
Adaptation Branch
Summary:
The Eighth IPCC Plenary meeting in Zimbabwe restructured the IPCC into three
workgroups, i.e., WG-1 (Science), WG-II (Impacts, Mitigation and Adaption), and WG-III
(Cross-cutting Economic and Other Issues). (See Draft Report Doc 14). A new slate of
officers was elected with the U.S. and Zimbabwe serving as co-chairmen of WG-II. (See Bureau
Membership Attachment). The next Plenary will be in late June or early July. WG-II will hold
a meeting in early February. EPA was represented at the meeting by Dennis Tirpak, Joel
Scheraga, and Lowell Smith.
Discussion:
John Houghton (UK) presented the workplan for WG-I (Attached). The workplan was
approved with the understanding that modifications would be made to reflect the concerns of
various countries. A preliminary Workplan for WG-II was presented by Bob Reinstein
islimn?
(Attached). Because the plan was stitched together at the meeting, most countries viewed the
plan as preliminary. Countries were requested to provide the U.S. with comments by early
January. The U.S. offered to prepare a revised version in sufficient time for a WG-II meeting
in early February. Topics which need considerable thought are: how to provide a global
synthesis, how to address desertification, how to integrate climate scenarios and impacts, how
to provide the INC scientific advice on the objective of the convention (Article 2). and how to
take advantage of the network of prior participants in old WG-II on impacts.
Printed on Recycled Paper
FROM CLIMATE CHANGE DIV
11.19.1992 1992 15:12
P. 3
The plenary also approved the formation of WG-III and supported the development of a
workplan covering scenarios and economic analysis. (See page 7 of Doc 14). Language for the
The Terms of Reference was initially drafted with the aid of delegates from the U.S.,
Netherlands, U.K., Canada, France, and Norway. (Tirpak, Scheraga, Sally Kane [NOAA], and
Rick Bradley [DOE] participated in these discussions.) The Terms of Reference call for WG-III
to consider such topics as top-down and bottom-up economic modeling, the evolution of
can
technological change, methods for risk assessment, and methods for assessing response
consider
artuals
instruments. Don Pearlman, Kuwait, and Saudi Arabia resisted including the terms "response
instruments" (taxes, permits, etc.) in the Terms of Reference, but subsequently agreed to the final
language. Canada will co-chair WG-III with South Korea. A workshop will be held in March
requirent mexre pist dealy disclip
care
or April to develop the workplan.
In addition to the plenary - several other meetings took place on the sidelines.
The Dutch held a meeting on an international coastal zone conference to be held
next fall. It is anticipated that at least two regional workshops will be held prior
to the conference. These workshops will produce information that will contribute
to the conference. The U.S. is considering hosting an Atlantic Region Workshop
to feed into the conference. (Contact Scheraga for details.)
The U.K. hosted two meetings on emission inventories to discuss the current work
program and finances needed to complete the methodology document by next
summer. A number of countries offered to consider additional financial
contributions. (Contact Tirpak)
Preliminary discussions were held with a number of countries on plans for several
WG-III Workshops. Several possible workshop topics were considered, including
macroeconomic modeling, impacts analysis, adaptation, decision making under
uncertainty, and response instruments. (Contact Scheraga)
The Netherlands, Germany, UK, Canada, and Australia expressed considerable
interest in the OECD project to design/analyze future action plans. (Contact
Tirpak)
Finally, the U.S. provided a flyer to all participants on the President's $25 million Country
Study Initiative. A number of countries (Mexico, Zimbabwe, China, Indonesia, Latvia, Malta)
sought additional information from the U.S. delegation.
NOTE: Clinton/Gore-buttons and stickers were heavily sought after by the participants
at the IPCCH
FROM CLIMATE CHANGE DIV
11.19.1992 15:13
P. 4
World Meteorological Organization
United Nations
Organisation météorologique mondiale
Environment Programme
Programme des Nations Unles
Case postale N° 2300
pour l'Environnement
1211 . GENEVA 2
SWITZERLAND
P.O.Box 30552 B Nairobi, Kenya
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
CHAIRMAN'S PROPOSAL ON THE IPCC BUREAU MEMBERSHIP
(where names have been formally received from governments,
they are included)
IPCC
Vice-Chairs
Saudi Arabia
Dr. A. Al-Gain
Russian Federation
Prof. Yu. A. Izrael
WG I
Co-Chairs
United Kingdom
sir John Houghton
Brazil
Dr. L.G. Meira Filho
Vice-Chairs
China
Prof. Ding Yihvi (firstrame)
Germany
Dr. H. Grassl
Senegal
Mr. M. Seck
weth
WG II
Co-Chairs
United States
Mr. Robert A. Reinstein
-free
Zimbabwe
Dr. M.C. zinyowera/
alternate Mrs. Karimanzira
Vice-Chairs (who are also the Co-Chairs of)
Subgroup A
India
Dr. M. Parabrahmam
Japan
Dr. K. Yokobori
1
1PCC Secretariat. WMO. Phone: +41 22 7308 215/254/284 Fax: +41 22 7331270 Telex: 414199 OMM CH
FROM CLIMATE CHANGE DIV
11.19.1992 15:13
P.5
Subgroup B
The Netherlands
Dr. P. Vellinga
Venezuela
Ing. Martha Perdomo
Subgroup C
Argentina
Dr. O. Canziani
Switzerland
Dr. M. Beniston
Subgroup D
France
Dr. M. Petit
Tunisia
WG III
Co-Chairs
Canada
Ms. E. Dowdeswell
Republic of Korea
Dr. H. Lee
Vice-Chairs
Kenya
Prof. R.S. odingo
Norway
Mr. T. Hanisch
Regional Representation
Region 1
Nigeria
Africa
Dr. Adejokun
Region II
Kuwait
Asia
De Nasavall Hassama
Region III
Colombia
S. America
Region IV
Cuba
North and Central
America
Region V
Australia
SW Pacific
Dr. McG. Tegart
Region VI
Spain
Europe
Dr. M. Bautista Perez
IPCC-VIII/Harare/13 November 1992
2
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