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Global Climate Change Policy - Kyoto Protocol Analysis] [Binder] [1]
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Global Climate Change Policy - Kyoto Protocol Analysis] [Binder] [1]
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FOIA Number: 2017-1095-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 of Economic Advisers
Series/Staff Member:
Subject Files
Subseries:
OA/ID Number:
21599
FolderID:
Folder Title:
[Global Climate Change Policy - Kyoto Protocol Analysis] [Binder] [1]
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21
5
2
1
GCC Policy - Kyoto Protocol Analysis
2
21599
Enclosures filed in
Oversize Attachments #
NAMA 18783
July 9, 1998
TO:
Joe Aldy
FROM:
Zachary Candelario
SUBJECT:
Technical Support Document Data and Chart Files
The data for the TSD are located on H:GCCWHITE/Appendx, Main, Misc, Risk.
Appendx: appintl, car_gdp, co2globe, ec_grat, fsu, gdp_rat, joe427, nation~1.
Main: co2_pop, gccwhite.
Misc: korea
Risk: gat, icecore, mauna, oldtemp
The charts for the TSD are located on H:GCCWHITE/GCCchart
GCCchart: appendx3, gccappen, gccmast3
Attached is a list of the charts in the TSD by figure number, chart title, and data file name.
FIGURE #
TITLE
SOURCE
(File/Publication)
1
U.S. Greenhouse Gas Emissions, Actual and Projected without New Abatement Policies
ERP
2
Major Annex I Nations' Carbon Dioxide Emissions, 1950-1992
JOE427
3
World Carbon Dioxide Emissions from Fossil Fuel Combustion, 1996
EC_GRAT
4
Projected Carbon Dioxide Emissions of Major Annex I Countries without New Abatement Policies
GCCWHITE, Sheet B
5
Projected Growth in Carbon Dioxide Emissions Among Annex I Countries without New Abatement Policies
GCCWHITE, Sheet B
6
Projected Emissions Among Annex I and Non-Annex I Countries without New Abatement Policies
GCCWHITE, Sheet D
7
Projected Emissions Among the U.S. and China without New Abatement Policies
GCCWHITE, Sheet B
8
Projected Growth in Carbon Dioxide Emissions Among the U.S. and Several Developing Countries without
GCCWHITE, Sheet B
New Abatement Policies
9
The Greenhouse Effect
OSTP
10
Carbon Dioxide Concentrations
GCCWHITE, Sheet I
11
Global Average Temperature
GAT
12
Atmospheric Carbon Dioxide Concentration and Temperature Change
ICECORE, OLDTEMP
13
U.S. Coastal Lands at Risk from a 20-inch Sea Level Rise in 2100
TITUS, 1997
14
1995 Energy/GDP Ratios for the U.S. and Several Other Annex I Countries
EC_GRAT, Sheet B
15
1995 Energy/GDP Ratios for the U.S. and Several Developing Countries
EC_GRAT, Sheet B
16
1995 Carbon/GDP Ratios for the U.S. and Seveal Other Annex I Countries
EC_GRAT, Sheet B
17
1995 Carbon/GDP Ratios for the U.S. and Several Developing Countries
EC_GRAT, Sheet B
18
Cumulative Projected Electric Power Investments, 1995-2010
1998, IEO, Page 116
19
Percentage Reductions in Resource Costs Relative to "Domestic Only" Abatement under Various Trading
Scenarios
20
Average U.S. Electricity Prices Under $14/ton to $23/ton Permit Prices, Excluding the Cost-Savings
BAU: 1998 AEO, Page 112
Associated with Electricity Restructuring
21
Average U.S. Gasoline Prices Under $14/ton to $23/ton Permit Prices
BAU: 1998 AEO, Page 117
22
Average U.S. Fuel Oil Prices Under $14/ton to $23/ton Permit Prices
BAU: 1998 AEO, Page 117
23
Average U.S. Natural Gas Prices Under $14/ton to $23/ton Permit Prices
BAU: 1998 AEO,Page 119
24
U.S. GDP Under $14/ton and $23/ton Permit Prices
25
U.S. Investment Under $14/ton to $23/ton Permit Prices
26
U.S. Consumption Under $14/ton to $23/ton Permit Prices
Appendix D
Real Oil Prices
GCCWHITE, Sheet E
Appendix D
Real Coal Prices
GCCWHITE, Sheet E
Appendix D
Real Motor Gasoline Prices
GCCWHITE, Sheet E
Appendix D
Real Natural Gas Prices
GCCWHITE, Sheet E
Appendix E
United States E/GDP
APPINTL
Appendix E
United States CO2/GDP
APPINTL
Appendix E
Carbon Emissions: United States
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: United States
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: United States
GCCWHITE, Sheet D
Appendix E
Australia Energy/GDP
APPINTL
Appendix E
Australia CO2/GDP
APPINTL
Appendix E
Carbon Emissions: Australia
CO2GLOBE
Appendix E
1995 Total Primary Energy Supply Shares: Australia
GCCWHITE, Sheet D
Appendix E
Canada E/GDP
APPINTL
Appendix E
Canada CO2/GDP
APPINTL
Appendix E
Carbon Emissions: Canada
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: Canada
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: Canada
GCCWHITE, Sheet D
Appendix E
China Energy/GDP
APPINTL
Appendix E
China CO2/GDP
APPINTL
Appendix E
Carbon Emissions: China
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: China
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: China
GCCWHITE, Sheet D
Appendix E
European Union Energy/GDP
APPINTL
Appendix E
European Union CO2/GDP
APPINTL
Appendix E
Carbon Emissions: European Union
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: European Union
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: European Union
GCCWHITE, Sheet D
Appendix E
India Energy/GDP
APPINTL
Appendix E
India CO2/GDP
APPINTL
Appendix E
Carbon Emissions: India
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: India
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: India
GCCWHITE, Sheet D
Appendix E
Japan Energy/GDP
APPINTL
Appendix E
Japan CO2/GDP
APPINTL
Appendix E
Carbon Emissions: Japan
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: Japan
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: Japan
GCCWHITE, Sheet D
Appendix E
Mexico Energy/GDP
APPINTL
Appendix E
Mexico CO2/GDP
APPINTL
Appendix E
Carbon Emissions: Mexico
CO2GLOBE
Appendix E
Projected Carbon Emissions Without New Abatement Measures: Mexico
1998 IEO, PAGE 142
Appendix E
1995 Total Primary Energy Supply Shares: Mexico
GCCWHITE, Sheet D
Clearance Draft, Do Not Cite, 7/10/98
Economic Analysis
of the
Kyoto Protocol and the Administration's
Policies to Address Climate Change:
Technical Support Document
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EXECUTIVE SUMMARY
The primary purpose of this analysis is to examine the costs and benefits of taking action to
mitigate the threat of global warming. In particular, we examine the costs and benefits of complying
with the emissions reduction target for the United States set forth in the Kyoto Protocol on Climate
Change, negotiated in December 1997. For reasons discussed at length in this paper, it is our
conclusion that, with the flexibility mechanisms included in the treaty, the United States can reach
its Kyoto target at a relatively modest cost. And the benefits of mitigating climate change are likely
to be substantial.
Before considering the economics of taking action, however, we ought to step back and ask
the threshold question -- whether taking action to mitigate global climate change is necessary in the
first place.
The Rationale for Taking Action
The great weight of scientific authority suggests that climate change is a serious problem and
that prudent steps to mitigate it are in order. In essence, we need to take out an insurance policy with
reasonably priced premiums. As long ago as 1991, the National Academy of Sciences, in a study
P68
entitled Policy Implication of Greenhouse Warming, concluded that even given the considerable
uncertainties in our knowledge of the relevant phenomena, greenhouse warming poses a potential
threat sufficient to merit prompt responses. Investment in mitigation measures acts as insurance
protection against the great uncertainties and the possibility of dramatic surprises."
What the science tells us is that greenhouse gases are rapidly building up in the atmosphere
as a result of the burning of fossil fuels and deforestation; that the concentration of these gases is 30
percent higher than it was at the beginning of the industrial revolution; and that this concentration
is expected to reach twice current levels by 2100 -- a level not seen in 50 million years. Theory and
computer models suggest that this increased concentration of greenhouse gases could warm the earth
by about 2-6.5° F by 2100. By way of comparison, the last ice age was only about 9° F colder than
today. Moreover, much evidence suggests that warming is already underway. For example, we
know from ice cores and other data that we are living in the hottest century since at least 1400, that
the 1990s are the hottest decade on record, that 1997 is the hottest year, and that the nine hottest
years have all occurred since 1987.
Scientists predict a range of likely effects from global warming. For example, the rate of
evaporation is expected to increase as the climate warms, leading to increasingly frequent and intense
floods and droughts. Sea level is projected to rise 6-38 inches by 2100. A 20-inch rise could
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submerge around 7000 square miles of U.S. territory. Warmer temperatures would be expected to
increase the risk of mortality from heat stress, aggravate respiratory disease, and increase the range
and rates of transmission of some infectious diseases.
Scientific opinion is not unanimous on these points, but most independent climate scientists
believe that global climate change poses real risks. A few scientists contest the notion that
increasing concentrations of greenhouse gases will warm the planet, while a few others argue that
the earth is indeed getting warmer, but that this is a good thing -- "a wonderful gift from the
industrial revolution," in the words of one. But these are distinctly minority views. The prevailing
view is that the risks of climate change warrant prudent and prompt action. Prompt because to wait
for greater scientific certainty could have very large costs. Greenhouse gases are long-lived and the
decisions being taken by governments and firms in the next decade, with respect, for example, to the
kinds of power plants to build or the kinds of energy sources to develop, are likely to have significant
consequences for our ability to limit the buildup of greenhouse gases.
Consequently, there is a substantial rationale for acting now. Our task is to act in a manner
that responds appropriately to the scope of the risk while at the same time being economically
sensible.
The Kyoto Protocol
The Kyoto Protocol, which requires the industrialized nations to take on binding targets for
greenhouse gas emissions, includes three basic kinds of flexibility provisions that were proposed by
the United States. These provisions -- commonly referred to as "when", "what", and "where"
flexibility -- have great potential to significantly lower the costs of meeting the Kyoto targets.
"When" flexibility appears in the form of a multi-year commitment period (2008-2012), and
allowance for "banking" of emissions reductions. The freedom for countries or companies to delay
or accelerate reductions within an agreed upon time frame can help lower costs. "What flexibility"
is provided by the inclusion of all six greenhouse gases -- so that reductions in emissions of one gas
can be used to substitute for increases in emissions of another -- and the coverage of certain "sink"
activities, such as afforestation or reforestation, that absorb carbon. Most important, the Protocol
incorporates "where" flexibility in the form of international emissions trading and joint
implementation among countries that take on binding targets, coupled with a "clean development
mechanism" allowing industrial countries or firms to earn emissions reduction credit for investments
in clean energy projects in the developing world. These mechanisms can provide opportunities for
industrial countries and firms to secure low-cost reductions and for developing countries to achieve
sustainable growth.
Developing countries did not take on binding emissions targets at Kyoto. The President has
said that he will not submit the Protocol to the Senate without meaningful participation from key
developing countries. The Clean Development Mechanism provides a down payment on such
ii
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participation, and the Administration is actively engaged in seeking greater participation from key
developing countries. Robust developing country participation would likely lead to new
opportunities for low cost reductions, benefitting developing and developed countries alike.
Costs and Benefits of Mitigation
Analyzing the costs and benefits of mitigating climate change is a difficult undertaking for
three reasons. First, uncertainties remain about significant details of certain provisions in the
Protocol. Second, available models have inherent limitations in their abilities to analyze even short-
term costs and benefits. Third, it is extremely difficult to quantify the long-term economic benefits
of climate change mitigation, so we have made no effort to quantify these benefits in our analysis.
Recognizing these difficulties, our conclusion is that the net costs for the United States to
meet its Kyoto emissions target are likely to be modest if those reductions are undertaken in an
efficient manner employing the flexibility measures of international trading, joint implementation,
and the Clean Development Mechanism. This would be so even without considering the benefits
of mitigating climate change itself or the impact certain additional factors such as the President's
domestic climate change proposals, the ancillary benefits of improved air quality, or the inclusion
of sinks -- could have on lowering the costs of mitigation.
The conclusion about the costs of complying with the Kyoto Protocol is not entirely
dependent on, but is fully consistent with, formal model results. For example, given the flexibility
measures just noted, with key developing countries participating in trading, and excluding the
benefits of both mitigating climate change and restructuring the electricity sector, estimates derived
using Battelle's Second Generation Model suggest that the resource costs of attaining the Kyoto
targets for emission reductions might amount to $7-12 billion per year in 2008 to 2012 or just 0.1
percent of projected GDP. The same model predicts that emission permits in 2010 would cost
between $14 and $23 per ton of carbon equivalent which would translate into an increase of about
4 to 6¢ per gallon of gasoline. The increase in energy prices would raise the average household's
energy bill in 2010 by between $70 and $110 per year -- a relatively small amount compared to
typical energy price changes. Moreover, this increase would be substantially offset by the decline
in electricity prices resulting from the Administration's electricity restructuring proposal.
Further, even if international trading occurred only among developed countries, with
developing countries limiting their use of flexibility measures to the Clean Development Mechanism,
the costs of complying with Kyoto, and the price of emissions permits, would still be just a fraction
of what they would be if we had to reach our target entirely through domestic action.
Several factors not included in the estimate using the Battelle model could reduce cost further
and/or increase the amount of reductions accomplished through domestic action. These factors
include the benefits of reducing net emissions through carbon sinks; the Administration's electricity
iii
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restructuring proposal; the Administration's $6.3 billion budget proposal to improve energy
efficiency and spur the development of renewable energy, a proposal that could help increase the rate
of technology diffusion above the conservative estimate used in this analysis; the Administration's
consultations to encourage and support voluntary efforts by U.S. industry to undertake emissions
reductions; and the ancillary benefits of reducing greenhouse gas emissions.
All of the cost calculations above exclude the substantial long-term benefits of mitigating
global climate change. Monetary estimates of damages from the environmental, health, and
economic impacts of global warming during the next century range in the tens of billions of dollars
per year. One noted economist, William Cline, has estimated that a doubling of pre-industrial
concentrations of greenhouse gases would cost the U.S. economy about 1.1% of GDP annually --
some $89 billion a year in today's terms. Moreover, these estimates do not reflect the potential costs
of so-called "non-linearities" -- the risk that global warming will lead not to gradual and predictable
problems, but to relatively abrupt, unforeseen, and potentially catastrophic consequences. Although
we do not think the benefits of mitigating climate change are, at this stage, quantifiable with
adequate precision, they are nonetheless likely to be very real and very large in the long run.
Conclusion
The current state of the science provides a powerful rationale to take prompt, prudent action
to mitigate climate change; the agreement negotiated in Kyoto includes flexibility mechanisms that
will allow the United States to meet its Kyoto target at a modest cost. Additional factors not
included in the Battelle model we reference -- such as the President's domestic climate change
policies, the inclusion of sinks and the ancillary benefit of improving air quality could lower costs
even further and increase the percentage of reductions made through domestic action. The benefits
of avoiding long-term impacts of global climate change, while not precise enough to quantify at this
stage, are likely to be very important. In short, this is an insurance policy we should buy and it is one
we can buy for reasonably priced premiums.
iv
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TABLE OF CONTENTS
Page
Introduction
1
Trends in Greenhouse Gas Emissions
4
Historical Emissions
4
Projected Emissions
6
The Risks of Climate Change
9
Overview of U.S. Strategy in Kyoto Negotiations and Beyond
13
Realistic Targets and Timetables
14
Flexibility and Market Mechanisms
15
Developing Countries
28
Assessing the Costs and Benefits of Reducing Greenhouse Gas Emissions
30
Preliminary Assessment
30
Difficulties of an Economic Analysis of Climate Change
31
Illustrative Calculations: Methodology
34
Summary of Assumptions of Illustrative Analysis
41
Economic Cost of the Administration's Policies to Reduce Greenhouse
Gas Emissions in the Illustrative Analysis
42
Additional Cost Mitigating Factors
50
International Impacts Associated with Reducing Greenhouse
Gas Emissions
56
References
58
Appendices
A: Annex I and Non-Annex I Countries
B: Construction of Non-Carbon Dioxide Emissions Baselines
C: Potential Electricity Restructuring Cost-Savings
D: Historical Trends in U.S. Energy Prices
E: Country Specific Energy and Emissions Data
V
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FIGURES
Figure 1. U.S. Greenhouse Gas Emissions, Actual and Projected without New Abatement Policies
Figure 2. Major Annex I Countries' Carbon Dioxide Emissions from Fossil Fuel Combustion, 1950-
1995
Figure 3. World Carbon Dioxide Emissions from Fossil Fuel Combustion, 1996
Figure 4. Projected Carbon Dioxide Emissions of Major Annex I Countries without New Abatement
Policies
Figure 5. Projected Growth in Carbon Dioxide Emissions of Annex I Countries without New
Abatement Policies
Figure 6. Projected Emissions of Annex I and Non-Annex I Countries without New Abatement
Policies
Figure 7. Projected Emissions of the U.S. and China without New Abatement Policies
Figure 8. Projected Growth in Carbon Dioxide Emissions of Several Developing Countries without
New Abatement Policies
Figure 9. The Greenhouse Effect
Figure 10. Atmospheric Carbon Dioxide Concentration
Figure 11. Global Average Temperature
Figure 12. Atmospheric Carbon Dioxide Concentration and Temperature over the Past 160,000
Years
Figure 13. U.S. Coastal Lands at Risk from a 20-inch Sea Level Rise in 2100
Figure 14. 1995 Energy/GDP Ratios for the U.S. and Several Other Annex I Countries
Figure 15. 1995 Energy/GDP Ratios for the U.S. and Several Developing Countries
Figure 16. 1995 Carbon/GDP Ratios for the U.S. and Several Other Annex I Countries
Figure 17. 1995 Carbon/GDP Ratios for the U.S. and Several Developing Countries
Figure 18. Cumulative Projected Electric Power Investments, 1995-2010
Figure 19. Percentage Reductions in Resource Costs Relative to "Domestic Only" Abatement Under
Various Trading Scenarios
Figure 20. Average U.S. Electricity Prices Under $14/ton to $23/ton Permit Prices, Excluding the
Cost-Savings Associated with Electricity Restructuring
Figure 21. Average U.S. Electricity Prices Under $14/ton to $23/ton Permit Prices, Including the
Cost-Savings Associated with Electricity Restructuring
Figure 22. Average U.S. Gasoline Prices Under $14/ton to $23/ton Permit Prices
Figure 23. Average U.S. Fuel Oil Prices Under $14/ton to $23/ton Permit Prices
Figure 24. Average U.S. Natural Gas Prices Under $14/ton to $23/ton Permit Prices
Figure 25. U.S. GDP Under $14/ton to $23/ton Permit Prices
Figure 26. U.S. Investment Under $14/ton to $23/ton Permit Prices
Figure 27. U.S. Consumption Under $14/ton to $23/ton Permit Prices
vi
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TABLES
Table 1. Selected Annex I Countries' Emissions Targets
Table 2. Global Warming Potentials of Greenhouse Gases Included in the Kyoto Protocol
Table 3. Countries/Regions in Second Generation Model
Table 4. Permit Prices and Resource Costs Relative to "Domestic Only" Abatement of Various
Trading Scenarios
Table 5. U.S. Permit Prices and Resource Costs Under the Administration's Policies
Table 6. U.S. Energy Prices Under Permit Prices of $14/ton to $23/ton
Table 7. Unquantified Ancillary Emissions Benefits
vii
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INTRODUCTION
The earth's surface appears to be warming as a result of the accumulation of greenhouse
1
gases from myriad sources worldwide. None of the emitters of these gases presently pays the cost
to others of the adverse effects of warming. No individual firm, nor any single country, has an
incentive to reduce emissions sufficiently to protect the global environment against climate change.
Each has an economic incentive to "free ride" on the efforts of others. Without an international
agreement limiting emissions abroad, even if one country sharply reduces its emissions unilaterally,
greenhouse gas emissions from all other countries would continue to grow, and the risks posed by
climate change would not be significantly reduced. The complex nature of the climate change
problem requires global cooperation and a long-term solution.
In June of 1992, the Framework Convention on Climate Change, the first international
2
agreement to address the risks of climate change, was signed during the Earth Summit in Rio de
3
Janeiro. This treaty, ratified by the United States with the advice and consent of the Senate in
4
October 1992, established the following ultimate objective:
"[To achieve] stabilization of greenhouse gas concentrations in the atmosphere at a
level that would prevent the dangerous anthropogenic interference with the climate
system. Such a level should be achieved within a time-frame sufficient to allow
5
ecosystems to adapt naturally to climate change, to ensure that food production is not
threatened and to enable economic development to proceed in a sustainable manner"
(Framework Convention on Climate Change, Article 2).
The Framework Convention laid the foundation for international cooperation to reduce emissions
of greenhouse gases to achieve this objective. The treaty encouraged industrial countries to return
their greenhouse gas emissions to their 1990 levels by 2000.
6
7
Since the Framework Convention entered into force, the world's scientists have continued
to warn of the potential negative environmental and economic effects of climate change. In 1995,
the Intergovernmental Panel on Climate Change (IPCC), jointly established by the World
Meteorological Organization and the United Nations Environment Programme, and representing the
work of more than 2,000 scientists, concluded that "the balance of evidence suggests that there is
a discernible human influence on global climate" (Houghton et al. 1996, p. 5). Without measures
to abate the expected increase in greenhouse gas emissions over the next century, the IPCC projected,
10
that average global temperatures would increase by 1.8 to 6.3° F (1 to 3.5° C), resulting in coastal
damage from rising sea levels, greater frequency of severe weather events, shifts in agricultural
growing conditions from changing weather patterns, threats to human health from increased range
and incidence of diseases, changes in availability of freshwater supplies, and damage to ecosystems
and biodiversity.
1
Economic
Report
of the
President
Transmitted to the Congress
February 1998
sions trading could undercut the effectiveness of pollution controls if
it resulted in shifting emission reductions farther upwind. Trading
ratios that weight the reductions made at different sources according
to their distance from the downwind nonattainment area might be
considered to address this problem. In reality, however, there are a
large number of nonattainment areas spread out over the region, and
several different weather patterns and wind conditions characterize
the ozone pollution episodes that the program is trying to remedy.
Sources affect multiple nonattainment areas in a variety of directions
from them, and it affects any single nonattainment area differently
under different weather conditions. The polycentric nature of this
problem complicates the identification of a unique and stable set of
trading ratios that would work for all relevant cases. Thus, striking
the proper balance between achieving the cost savings from larger geo-
graphic scope and limiting the potentially significant adverse
environmental effects of trading is an ongoing challenge.
Like most air pollution control programs, NOₓ trading programs
would require an estimate of emissions from each regulated source in
order to ensure compliance. The estimation method can have signifi-
cant implications for cost-effectiveness, both directly, through the cost
f performing the estimate, and indirectly. One indirect implication is
that more costly requirements may limit the number of sources that
could meet the estimation requirements and participate in trading,
and thereby raise costs. On the other hand, a more reliable estimation
method may offer regulators and sources greater confidence in the
permits, and thereby increase the willingness of sources to buy them
or offer them for sale. For example, the SO₂ program requires contin-
uous emissions monitoring to provide precise information on
emissions. Such monitoring is expensive and impractical for many
smaller sources and thus may effectively exclude such sources from
participating. But such precise monitoring may not always be neces-
sary. Methods for estimating emissions that provide unbiased,
although less precise, estimates of emissions may be accurate enough
to ensure accountability.
CLIMATE CHANGE
Climate change is a global environmental externality: warming of
the earth's surface results from the accumulation of greenhouse gases
from myriad sources worldwide, none of which presently pay the cost
to others of warming's ill effects. The Intergovernmental Panel on
Climate Change, jointly established by the World Meteorological
8
Organization and the United Nations Environment Programme, con-
cluded in 1995 that "the balance of evidence suggests that there is a
discernible human influence on global climate." Current concentra-
tions of carbon dioxide (SO₂), methane, nitrous oxide (N₂O), and other
so-called greenhouse gases have reached levels well above those of
165
preindustrial times. Of these, CO₂ is the most important: net cumu-
lative CO₂ emissions resulting from the burning of fossil fuels and
deforestation account for about two-thirds of potential warming from
changes in greenhouse gas concentrations related to human activity.
If growth in global emissions continues unabated, the atmospheric
concentration of CO₂ will likely double, relative to its preindustrial
level, midway through the next century.
The accumulation of greenhouse gases poses significant risks to the
world's climate and to human well-being. Potential impacts include a
rise in sea levels, greater frequency of severe weather events, shifts
in agricultural growing conditions from changing weather patterns
threats to human health from increased range and incidence of dis-
=
eases, changes in availability of freshwater supplies, and damage to
ecosystems and biodiversity.
Climate change is a complex, long-term problem requiring global
cooperation and a long-term solution. No single country has an incen-
tive to reduce emissions sufficiently to protect the global environment
against climate change. Even if the United States sharply reduced its
emissions unilaterally, greenhouse gas emissions from all other coun-
tries would continue to grow, and the risks posed by climate change
would not be significantly abated. Since many of these gases remain
in the atmosphere for a century or more, the climatic effects of actions
taken today will primarily benefit future generations. But delaying
action to reduce greenhouse gas emissions until the disruptive effects
of climate change become widespread will considerably reduce the
options for remedial or preventive measures.
The Framework Convention on Climate Change
The threat of disruptive climate change has led to coordinated
international efforts to reduce the risks of global warming by reduc-
ing emissions of greenhouse gases. The first international agreement
to address global warming was the Framework Convention on
4
Climate Change signed during the Earth Summit in Rio de Janeiro in
1992. This convention established a long-term objective of limiting
greenhouse gas concentrations and encouraged the established indus-
trial countries to return their emissions to 1990 levels by 2000. Since
6
then it has become clear that the United States and many other par-
ticipating countries will not meet this goal.
To address the lack of progress among many industrial countries
toward meeting this first target, the United States and approximate-
ly 159 other nations, in negotiations held in Kyoto, Japan, last
December, agreed to take substantial steps to stabilize atmospheric
concentrations of greenhouse gases. The Kyoto agreement, which
requires the advice and consent of the Senate, would place binding
limits on industrial countries' emissions of the six principal categories
of greenhouse gases: CO₂, methane, N₂O, sulfur hexafluoride, perflu-
orocarbons, and hydrofluorocarbons. Each industrial country's "1990
166
Status of Ratification
http://www.unfcc.de/fec/conv/fel_toc.htm
Status of Ratification
in alphabetical order
The text of the Convention was adopted at the United nations Headquarters, New
York on the 9 May 1992; it was open for signature at the Rio de Janeiro from 4 to
14 June 1992, and thereafter at the United Nations Headquarters, New York, from
2
20 June 1992 to 19 June 1993. By that date the Convention had received 166
signatures. The Convention entered into force on 21 March 1994. Those States
7
that have not signed the Convention may accede to it at any time.
For those States that ratify, accept or approve the Convention or accede thereto
after the date of entry into force, the Convention shall enter into force on the
ninetieth day after the date of the deposit by such State of its instrument of
ratification, acceptance, approval or accession.
These pages contains information concerning dates of signature and ratification
received from the Secretary-General of the United nations, as at 29 May 1997. The
dates in the column entitled "date of ratification" are those of the receipt of the
instrument of ratification (R), acceptance (At), approval (Ap) or accession (Ac).
(For an explanation of these legal terms, please follow this link
as at 28-January-98 the Convention received 174 instuments of ratification
AB CDEFGH-IJ-KLMNO-P-QRSTUVW-Z
[The Convention] The Secretariat][Wha is Climate Change][CC:INFO Products]
[Official Documents] Country Information][ Emissions and other Data]
[Meetings / Workshops] Other Sites][About this site][Handbook][Home][Email us]
7/10/98 3:16 PM
1 of 1
State of Ratification
http://www.unfccc.de/fcc/conv/fe1_018.htm
Status of Ratification
Back to T
Up to
Ahead to V
Table of
Contents
Date of
Date of
Enter into
Country Name
Signature
Ratification
Type
Force
Uganda
13-Jun-92
08-Sep-93
R
21-Mar-94
Ukraine
11-Jun-92
13-May-97
R
11-Aug-97
United Arab Emirates
29-Dec-95
Ac
28-Mar-96
United Kingdom of
Great Britain and
Northern Ireland
12-Jun-92
08-Dec-93
R
21-Mar-94
United Republic of
Tanzania
12-Jun-92
17-Apr-96
R
16-Jul-96
United States of
2
3
America
12-Jun-92
15-Oct-92
R
21-Mar-94
Uruguay
04-Jun-92
18-Aug-94
R
16-Nov-94
Uzbekistan
20-Jun-93
Ac
21-Mar-94
[The Convention]| The Secretariat][What is Climate Change][CC:INFO Products]
[Official Documents] (Country Information][Emissions and other Data]
[Meetings / Workshops][Other Sites][About this site][Handbook][Home)][Email us)
7/10/98 3:16 PM
] of I
vention
http://www.unfccc.de/fccc/conv/conv.htm
"Sink" means any process, activity or mechanism which removes a
eenhouse gas, an aerosol or a precursor of a greenhouse gas from the
atmosphere.
9 "Source" means any process or activity which releases a greenhouse gas,
an aerosol or a precursor of a greenhouse gas into the atmosphere.
* Titles of articles are included solely to assist the reader.
ARTICLE 2
OBJECTIVE
The ultimate objective of this Convention and any related legal instruments
that the Conference of the Parties may adopt is to achieve, in accordance with
the relevant provisions of the Convention, stabilization of greenhouse gas
concentrations in the atmosphere at a level that would prevent dangerous
5
anthropogenic interference with the climate system. Such a level should be
achieved within a time-frame sufficient to allow ecosystems to adapt
naturally to climate change, to ensure that food production is not threatened
and to enable economic development to proceed in a sustainable manner.
ARTICLE 3
PRINCIPLES
In their actions to achieve the objective of the Convention and to implement
its provisions, the Parties shall be guided, INTER ALIA, by the following:
1 The Parties should protect the climate system for the benefit of present
and future generations of humankind, on the basis of equity and in
accordance with their common but differentiated responsibilities and
respective capabilities. Accordingly, the developed country Parties should
take the lead in combating climate change and the adverse effects thereof.
2 The specific needs and special circumstances of developing country
Parties, especially those that are particularly vulnerable to the adverse effects
of climate change, and of those Parties, especially developing country
Parties, that would have to bear a disproportionate or abnormal burden under
the Convention, should be given full consideration.
3 The Parties should take precautionary measures to anticipate, prevent or
minimize the causes of climate change and mitigate its adverse effects.
Where there are threats of serious or irreversible damage, lack of full
scientific certainty should not be used as a reason for postponing such
measures, taking into account that policies and measures to deal with climate
change should be cost-effective so as to ensure global benefits at the lowest
possible cost. To achieve this, such policies and measures should take into
account different socio-economic contexts, be comprehensive, cover all
relevant sources, sinks and reservoirs of greenhouse gases and adaptation,
and comprise all economic sectors. Efforts to address climate change may be
carried out cooperatively by interested Parties.
1/5/98 3:33
4 of 23
Global Warming: Intergovernmental Panel on Climate Change (IPCC)
http://www.epa.gov/oppeoel/globalwarming/actions/global/international/ipc.ht
EPA
United States
Environmental Protection
Agency
climate system
impacts
actions
State and Local
Intergovernmental Panel on Climate Change (IPCC)
National
The Intergovernmental Panel on Climate Change (IPCC) was established by
Global
the United Nations Environment Programme and the World Meteorological
Organization in 1988. The purpose of the IPCC is to assess information in
the scientific and technical literature related to all significant components of
the issue of global climate change. The IPCC provides the scientific
underpinnings for understanding global climate change and its
consequences for society and the environment. It relies upon preparation
and review of documents by 2,500 of the world's leading experts on climate
change and its consequences from some 60 nations With its capacity for
reporting on climate change, the IPCC also functions as the official advisory
body to the world's governments on the state of science of the issue.
Over the past two years the IPCC prepared its Second Assessment Report
(SAR), which considers results from approximately 20,000 peer-reviewed
articles pertaining to the science of climate change and its consequences.
This exhaustive review represents the consensus of scientific understanding
of global climate change.
The SAR confirms earlier findings that anthropogenic (i.e., human-induced)
greenhouse gas emissions are altering the chemical composition of the
atmosphere. An important new conclusion in this report is that "the balance
of evidence suggests that there is a discernible human influence on global
climate."
The IPCC further concludes that unless the world takes steps to reduce
emissions of these greenhouse gases, global temperatures could rise another
1.4 to 6.3 degrees Fahrenheit by the year 2100. This would be the fastest
rate of warming since the end of the last ice age more than 10,000 years
ago.
You can find additional information about the IPCC and its work by
clicking on the two documents listed below. Also, you can click on "IPCC"
below to access the web site of the Intergovernmental Panel on Climate
Change.
Key Findings of the Second Assessment Report of the
Intergovernmental Panel on Climate Change
IPCC Fact Sheet
Slide Presentation on IPCC Conclusions and Observations from the
1995 Second Assessment Report
1 of 2
7/17/98 12:21 PM
MAT HAN
The Science of Climate
Contribution of Working Gii
WMO
to the Second Assessment Regi
If Lear governmental Panel on There
Summary for Policymakers
5
change in climate is highly unusual in a statistical sense, but
correspondences could occur by chance as a result of
does not provide a reason for the change. "Attribution" is the
natural internal variability only. The vertical patterns
process of establishing cause and effect relations, including
of change are also inconsistent with those expected
he testing of competing hypotheses.
for solar and volcanic forcing.
Since the 1990 IPCC Report, considerable progress has
been made in attempts to distinguish between natural and
Our ability to quantify the human influence on global
anthropogenic influences on climate. This progress has been
climate is currently limited because the expected
achieved by including effects of sulphate aerosols in addition
signal is still emerging from the noise of natural
to greenhouse gases, thus leading to more realistic estimates
variability, and because there are uncertainties in key
of human-induced radiative forcing. These have then been
factors. These include the magnitude and patterns of
used in climate models to provide more complete simulations
long term natural variability and the time-evolving
of the human-induced climate-change "signal". In addition,
pattern of forcing by, and response to, changes in
new simulations with coupled atmosphere-ocean models
concentrations of greenhouse gases and aerosols, and
have provided important information about decade to century
land-surface changes. Nevertheless, the balance of
time-scale natural internal climate variability. A further major
evidence suggests that there is a discernible human
9
area of progress is the shift of focus from studies of global-
influence on global climate.
mean changes to comparisons of modelled and observed
spatial and temporal patterns of climate change.
The most important results related to the issues of
Climate is expected to continue to change in the future
detection and attribution are:
The IPCC has developed a range of scenarios, IS92a-f, of
future greenhouse gas and aerosol precursor emissions
The limited available evidence from proxy climate
based on assumptions concerning population and economic
indicators suggests that the 20th century global mean
growth, land-use, technological changes, energy
temperature is at least as warm as any other century
availability and fuel mix during the period 1990 to 2100.
since at least 1400 AD. Data prior to 1400 are too
Through understanding of the global carbon cycle and of
sparse to allow the reliable estimation of global mean
atmospheric chemistry, these emissions can be used to
temperature.
project atmospheric concentrations of greenhouse gases
and aerosols and the perturbation of natural radiative
Assessments of the statistical significance of the
forcing. Climate models can then be used to develop
observed global mean surface air temperature trend
projections of future climate.
over the last century have used a variety of new
estimates of natural internal and externally forced
The increasing realism of simulations of current and
variability. These are derived from instrumental data,
past climate by coupled atmosphere-ocean climate
palaeodata, simple and complex climate models, and
models has increased our confidence in their use for
statistical models fitted to observations. Most of
projection of future climate change. Important
these studies have detected a significant change and
uncertainties remain, but these have been taken into
show that the observed warming trend is unlikely to
account in the full range of projections of global
be entirely natural in origin.
mean temperature and sea level change.
More convincing recent evidence for the attribution
For the mid-range IPCC emission 'scenario, IS92a,
of a human effect on climate is emerging from
assuming the "best estimate" value of climate
pattern-based studies, in which the modelled climate
sensitivity¹ and including the effects of future
response to combined forcing by greenhouse gases
increases in aerosol, models project an increase in
and anthropogenic sulphate aerosols is compared
with observed geographical, seasonal and vertical
patterns of atmospheric temperature change. These
I
In IPCC reports, climate sensitivity usually refers to the long
studies show that such pattern correspondences
term (equilibrium) change in global mean surface temperature
increase with time, as one would expect as an
following a doubling of atmospheric equivalent CO₂ concentration.
anthropogenic signal increases in strength.
More generally, it refers to the equilibrium change in surface air
Furthermore, the probability is very low that these
temperature following a unit change in radiative forcing (°C/Wm²).
6
Summary for Policymakers
global mean surface air temperature relative to 1990
stabilisation of global mean temperature. Regional
of about 2°C by 2100. This estimate is approximately
sea level changes may differ from the global mean
one third lower than the "best estimate" in 1990. This
value owing to land movement and ocean current
is due primarily to lower emission scenarios
changes.
(particularly for CO₂ and the CFCs), the inclusion of
the cooling effect of sulphate aerosols, and
Confidence is higher in the hemispheric-to-
improvements in the treatment of the carbon cycle.
continental scale projections of coupled atmosphere-
Combining the lowest IPCC emission scenario
ocean climate models than in the regional
(IS92c) with a "low" value of climate sensitivity and
projections, where confidence remains low. There is
including the effects of future changes in aerosol
more confidence in temperature projections than
concentrations leads to a projected increase of about
hydrological changes.
1°C by 2100. The corresponding projection for the
highest IPCC scenario (IS92e) combined with a
All model simulations, whether they were forced
"high" value of climate sensitivity gives a warming
with increased concentrations of greenhouse gases
of about 3.5°C. In all cases the average rate of
and aerosols or with increased concentrations of
warming would probably be greater than any seen in
greenhouse gases alone, show the following features:
the last 10,000 years, but the actual annual to decadal
greater surface warming of the land than of the sea in
changes would include considerable natural
winter; a maximum surface warming in high northern
variability. Regional temperature changes could
latitudes in winter, little surface warming over the
differ substantially from the global mean value.
Arctic in summer; an enhanced global mean
Because of the thermal inertia of the oceans, only 50-
hydrological cycle, and increased precipitation and
90% of the eventual equilibrium temperature change
soil moisture in high latitudes in winter. All these
would have been realised by 2100 and temperature
changes are associated with identifiable physical
would continue to increase beyond 2100, even if
mechanisms.
concentrations of greenhouse gases were stabilised
by that time.
In addition, most simulations show a reduction in the
strength of the north Atlantic thermohaline
Average sea level is expected to rise as a result of
circulation and a widespread reduction in diurnal
thermal expansion of the oceans and melting of
range of temperature. These features too can be
glaciers and ice-sheets. For the IS92a scenario,
explained in terms of identifiable physical
assuming the "best estimate" values of climate
mechanisms.
sensitivity and of ice melt sensitivity to warming, and
including the effects of future changes in aerosol,
The direct and indirect effects of anthropogenic
models project an increase in sea level of about 50
aerosols have an important effect on the projections.
cm from the present to 2100. This estimate is
Generally, the magnitudes of the temperature and
approximately 25% lower than the "best estimate" in
precipitation changes are smaller when aerosol
1990 due to the lower temperature projection, but
effects are represented, especially in northern mid-
also reflecting improvements in the climate and ice
latitudes. Note that the cooling effect of aerosols is
melt models. Combining the lowest emission
not a simple offset to the warming effect of
scenario (IS92c) with the "low" climate and ice melt
greenhouse gases, but significantly affects some of
sensitivities and including aerosol effects gives a
the continental scale patterns of climate change, most
projected sea level rise of about 15 cm from the
noticeably in the summer hemisphere. For example,
present to 2100. The corresponding projection for the
models that consider only the effects of greenhouse
highest emission scenario (IS92e) combined with
gases generally project an increase in precipitation
"high" climate and ice-melt sensitivities gives a sea
and soil moisture in the Asian summer monsoon
level rise of about 95 cm from the present to 2100.
region, whereas models that include, in addition,
Sea level would continue to rise at a similar rate in
some of the effects of aerosols suggest that monsoon
future centuries beyond 2100, even if concentrations
precipitation may decrease. The spatial and temporal
of greenhouse gases were stabilised by that time, and
distribution of aerosols greatly influence regional
would continue to do so even beyond the time of
projections, which are therefore more uncertain.
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
4
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
To address these climate change risks better and to build on the existing treaty, approximately
160 countries met in Kyoto, Japan in December of 1997 and agreed to take substantial steps toward
meeting the Convention's ultimate objective. The Kyoto Protocol, which requires the advice and
consent of the Senate, would place binding limits on industrial countries' emissions of the six
principal types of greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O),
12
sulfur hexafluoride (SF₆), perfluorocarbons (PFCs), and hydrofluorocarbons (HFCs). The Protocol
embraces several flexible, market-based approaches to allow for the emissions targets to be achieved
at least cost. While the Protocol includes some participation by developing countries -- for example,
through the Clean Development Mechanism -- it does not currently include adequate participation
13
by key developing countries, and the Administration is working to promote such participation.
The Administration will continue its efforts to promote meaningful participation by key
developing countries and will work for effective implementation rules for international trading, the
Clean Development Mechanism, and joint implementation. The risks of climate change are global
and thus they require a global effort. The Administration will not submit the Kyoto Protocol to the
14
Senate for advice and consent until key developing countries agree to participate meaningfully.
Independent of the agreement reached in Japan, the Administration has proposed a suite of
measures to reduce emissions domestically.
Corresponding to the first stage of the three stage domestic strategy that the President
announced in October 1997, the Administration has proposed a five-year $6.3 billion
package of tax incentives and R&D investments to improve energy efficiency and spur the
6
development of renewable energy; commenced a set of consultations with our energy-
intensive sectors aimed at achieving voluntary agreements on how, with government support
where needed, including the provision of credit for early action they can most effectively
17
reduce greenhouse gas emissions; submitted a proposal for electricity restructuring that will
reduce greenhouse gas emissions; and commenced an intensive review of how to improve
the Federal government's own energy use and procurement.
Complementing these measures are the second and third stages of the Administration's plan
that would be implemented subsequent to ratification of the Kyoto Protocol.
The second stage will include a review of our program and an evaluation of next steps as we
18
prepare for a market-based trading system for greenhouse gas emissions. The details of the
domestic trading system would be refined and possibly tested.
1
For a discussion of the Clean Development Mechanism, see p. 25.
2
Economic
Report
of the
President
Transmitted to the Congress
February 1998
preindustrial times. Of these, CO₂ is the most important: net cumu-
lative CO₂ emissions resulting from the burning of fossil fuels and
deforestation account for about two-thirds of potential warming from
changes in greenhouse gas concentrations related to human activity.
If growth in global emissions continues unabated, the atmospheric
concentration of CO₂ will likely double, relative to its preindustrial
level, midway through the next century.
The accumulation of greenhouse gases poses significant risks to the
world's climate and to human well-being. Potential impacts include a
rise in sea levels, greater frequency of severe weather events, shifts
in agricultural growing conditions from changing weather patterns,
threats to human health from increased range and incidence of dis-
eases, changes in availability of freshwater supplies, and damage to
ecosystems and biodiversity.
Climate change is a complex, long-term problem requiring global
cooperation and a long-term solution. No single country has an incen-
tive to reduce emissions sufficiently to protect the global environment
against climate change. Even if the United States sharply reduced its
emissions unilaterally, greenhouse gas emissions from all other coun-
tries would continue to grow, and the risks posed by climate change
would not be significantly abated. Since many of these gases remain
in the atmosphere for a century or more, the climatic effects of actions
taken today will primarily benefit future generations. But delaying
action to reduce greenhouse gas emissions until the disruptive effects
of climate change become widespread will considerably reduce the
options for remedial or preventive measures.
The Framework Convention on Climate Change
The threat of disruptive climate change has led to coordinated
international efforts to reduce the risks of global warming by reduc-
ing emissions of greenhouse gases. The first international agreement
to address global warming was the Framework Convention on
Climate Change signed during the Earth Summit in Rio de Janeiro in
1992. This convention established a long-term objective of limiting
greenhouse gas concentrations and encouraged the established indus-
trial countries to return their emissions to 1990 levels by 2000. Since
then it has become clear that the United States and many other par-
ticipating countries will not meet this goal.
To address the lack of progress among many industrial countries
toward meeting this first target, the United States and approximate-
ly 159 other nations, in negotiations held in Kyoto, Japan, last
December, agreed to take substantial steps to stabilize atmospheric
concentrations of greenhouse gases. The Kyoto agreement, which
requires the advice and consent of the Senate, would place binding
limits on industrial countries' emissions of the six principal categories
12
of greenhouse gases: CO2, methane, N₂O, sulfur hexafluoride, perflu-
orocarbons, and hydrofluorocarbons. Each industrial country's "1990
166
stabilize the amount of greenhouse gases in the atmosphere.
go
Moreover, some of the least cost opportunities for reducing green-
fi
house gas emissions are in developing countries, because those
al
countries now use energy relatively inefficiently. Moreover, those that
CO
are industrializing rapidly have greater scope to build their industry
around cleaner and more efficient energy technologies and fuels than
ac
do mature economies whose capital stock is already in place.
W(
Failure to involve developing countries in an international agree-
th
ment limiting greenhouse gas emissions could lead to a more rapid
pr
rate of increase in emissions in those countries than would occur
ga
without any agreement at all. This "leakage" effect of emissions
are
reductions could come about in any of several ways. As industrial
jec
countries reduce their use of fossil fuels in response to emissions con-
cer
trols, future world oil and coal prices are likely to be lower than they
would be otherwise. This is likely to increase energy consumption in
Pr
countries not bound to limit their emissions. U.S. industries are also
T
concerned about their international competitiveness if some countries
res
remain outside an international agreement, since factories in those
of c
countries will face lower costs for producing goods that take relative-
The
ly large amounts of energy to manufacture. Some may be concerned
like
that energy-intensive industries might choose to relocate to countries
nies
not subject to emissions constraints, although there is little evidence
G
to suggest that this would pose a significant problem in most indus-
es a
tries. For example, energy costs for manufacturing industries average
to a
just 2.2 percent of total costs.
high
Given the projected growth of developing countries' emissions, the
inve
Administration's position is to seek meaningful participation by key
show
developing countries in the reduction of greenhouse gas emissions as
13
able
a condition for the United States taking on binding emissions reduc-
their
tions. The President has indicated he will not submit the Kyoto
14
be p.
agreement for Senate ratification until there is meaningful participa-
gy te
tion by key developing countries.
ener
regu
Joint Implementation and the Clean Development Mechanism
Th
To encourage participation by developing countries in the climate
frequ
change initiative even before they formally sign on for binding emis-
resea
sions limits, the President has proposed a program known as joint
es, b
implementation. This program would provide incentives to develop-
devel
ing countries to reduce their emissions of CO₂ and other greenhouse
gy in
gases. The Kyoto agreement embraces the President's proposal in its
exam
designation of a "clean development mechanism" (CDM): U.S. compa-
cializ,
nies that undertake projects that reduce greenhouse gas emissions in
High-
developing countries could count those reductions to meet their com-
rience
mitments. Institutionalizing key elements of joint implementation
for in
through this mechanism would encourage firms in the United States
lower
to transfer a larger volume of cleaner and more energy-efficient tech-
The
nology to developing countries, especially in the electric power
energy
172
003
02/13/98 FRI 18:41 FAX 2025867085
1
002
Climate Change Technology Initiative
INCENTIVE Frinds 2/98
1999 Budget Briefing Materials
February 2, 1998
Breakout
So while we recognize that the challenge we take on today is larger
than any environmental mission we have accepted in the past, climate change can
bring us together around what America does best - we innovate, we compete, we
find solutions to problems, and we do it in a way that promotes entrepreneurship
and strengthens the American economy.
If we do it right, protecting the climate will yield not costs, but profits; not
5.30)
burdens. but benefits; not sacrifice, but a higher standard of living.
President Clinton, October 22, 1997
@003
Climate Change Technology Initiative
Introduction
Last October the President outlined the three-stage approach the US will take in
addressing climate change. The first stage consists of immediate actions to stimulate
development and use of technologies that can minimize the cost of meeting US goals in reducing
greenhouse gas emissions. Stage two will review options created through ongoing technology
development and lead to detailed plans for a market-based permit trading system for carbon
emissions. Stage three will begin to implement a market-based emissions-trading system.
The President's 1999 budget includes $2.7 billion over five years for increased R&D and
deployment of energy efficiency. renewable energy, and carbon-reduction technologies, and an
additional $3.6 billion over five years in tax incentives. These provide a total initiative of
17
$6.3 billion in new funding and tax expenditures over five years to stimulate adoption of more
efficient technologies in buildings, industrial processes. vehicles, and power generation.
During the coming year, federal agencies will supplement these activities with three other
actions outlined in the President's plan:
Active support for industry-by-industry consultations with all major business sectors.
Changes in federal procurement policy to ensure that Federal agencies make all COSI-
effective energy investments and take advantage of energy savings performance
contracts and other services available from private investors.
Introduction of utility restructuring proposals that will reduce carbon emissions while
saving customers billions of dollars in electric bills.
Section 1 below shows several summary tables that provide a variety of views or
perspectives on the Climate Change Technology Initiative (CCTI) - by agency, by type of
activity, direct spending, and tax incentives. Following that, in Section 2. are programmatic
details organized by the sector or technical topic on which they are focused.
PRESIDENT CLINTON ANNOUNCES THE UNITED STATES
CLIMATE CHANGE POLICY
-
NATIONAL GEOGRAPHIC SOCIETY
GILBERT H. GROSVENOR AUDITORIUM
Washington, D.C.
October 22, 1997
SOLID PRINCIPLES: The President's five climate change principles include: that the policies
ould be guided by science, rely on market-based, common-sense tools, that we should seek win-win
solutions, that global participation is essential to addressing the global problem of climate change, and
that we must have regular common-sense reviews of the economics and science of climate change.
SOUND AND SENSIBLE THREE-STAGE APPROACH: Reflecting his five key principles, the
President's plan includes three stages: Stage 1 includes priming the pump through programs such as
R&D, tax incentives, incentives for early action, and Federal leadership, and industry consultations.
Stage 2 builds upon the first stage by including a review and evaluation in preparation for the permit
trading system. Stage 3 -- which does not occur for a decade -- involves meeting binding targets
through a domestic and international emissions trading program. The President is committed to
working with labor and Congress to insure that we give proper assistance to any workers dislocated by
the changes in energy usage inherent in any climate change plan.
INITIAL ACTION PLAN: The President's immediate action plan includes 9 elements:
1. $5 Billion in Tax Cuts and Federal R&D: To spur energy efficiency and encourage the development
and deployment of lower-carbon energy sources, the Administration supports a major new package of
tax cuts and R&D spending amounting to $5 billion over five years.
2. Credit for Early Action: To provide an immediate incentive for near-term actions, the President is
committed to ensuring that firms acting early are rewarded appropriately.
Industry-by-Industry Consultations: The Administration challenges key industry sectors to prepare
plans over the next 9 months on how they can best reduce emissions.
4. Encouraging the Use of Energy-Efficient Products: The President will complement his tax
incentives, commitment to early action credit, and industry consultations by engaging in a broad-based
effort to expand the use of existing energy-efficient technologies.
5. Federal Procurement and Energy Use: The Department of Energy will spearhead a comprehensive
effort to reduce greenhouse gas emissions from Federal sources.
16
6. Electricity Restructuring: To deliver a significant downpayment on emission reductions, while
saving consumers billions, we will pursue a bold plan for electricity restructuring.
7. Setting a Concentration Goal: The United States supports developing a specific, long-term
concentration goal with the assistance of the National Academy of Sciences and other bodies.
8. Bilateral Dialogues: In addition to pursuing agreement in Kyoto, the Administration will pursue
bilateral dialogues with key developing countries to promote clean energy.
.Economics and Science Reviews: The President proposes regular scientific and economic reviews.
These reviews will ensure that policy-makers have the best possible information on climate change.
WIN-WIN: There are numerous win-win solutions to reducing carbon emissions. For example, a
breakthrough in fuel cell technology announced yesterday will clear the way toward developing cars
that are three times as efficient as today's models -- cutting pollution while also cutting driving costs.
THE PRESIDENT'S THREE-STAGE PLAN ON CLIMATE CHANGE
October 22, 1997
Reflecting his five key principles, the President's plan will proceed in three stages:
Stage 1: Priming the Pump Through R&D, Tax Incentives, Incentives for Early Action,
Federal Leadership, and Industry Consultations. The first stage of the President's package
includes a 9-point action plan -- including $5 billion in tax incentives and spending for R&D
and energy efficiency, incentives for early action, a set of Federal government energy
15
initiatives, and industry-by-industry consultations to explore their best ideas on how to reduce
emissions in a cost-effective manner (including market-oriented standards for energy
efficiency). The first economic review would occur near the end of Stage 1.
Stage 2: Review and Evaluation. The second stage, which would begin around 2004, will
build upon the programs adopted in Stage 1, by including a review of our progress and an
evaluation of next steps as we move toward a market-based permit trading system for carbon
emissions. During this second stage, the details of the permit system would be refined and
perhaps tested. Such a permit system is similar in concept to the one that dramatically cut acid
rain emissions -- although the scale would be significantly larger than the current acid rain
program. The second economic review would occur near the end of Stage 2.
Stage 3: Meeting Binding Targets Through Domestic and International Emissions
Trading Program. In the third stage, we would reduce emissions to 1990 levels by 2008-
2012, and below 1990 levels in the 5-year period after that, through a market-based domestic
and international emissions trading system. Before beginning this third stage, the second
19
economic update and review would allow Congress and the President to evaluate how the
economy had responded to a decade's worth of experience in the first two stages of the
President's plan. The President is committed to working with labor and Congress to insure that
we give proper assistance to any workers dislocated by the changes in energy usage inherent in
any climate change plan.
This three-stage program recognizes the long-term nature of the effort to address climate change in
three ways:
By adopting a graduated approach to emissions reductions, it allows us to exploit the
tremendous opportunities for win-win reductions first.
By adopting a system of regular scientific and economic updates and reviews, it allows
us to monitor our progress and re-assess our success in reducing emissions, the state of
scientific knowledge, and how the economy is responding to our efforts. Only after we
have accumulated ten years of experience with the first two stages of the program would
we enter the internationally binding period.
By insisting that the United States will not adopt binding obligations without
developing country participation and by emphasizing the importance of an international
trading system and joint implementation, we take advantage of low-cost reduction
possibilities wherever they occur -- either here or abroad.
Clinton Presidential Records
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marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
5
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
In the final stage, emissions reductions would occur through the domestic trading program,
integrated with international flexibility mechanisms, including international trading of
19
emissions allowances, the Clean Development Mechanism, and joint implementation.
The international agreement that was reached in Kyoto this past December is a crucial step
forward in addressing global climate change. But it is only one step in a journey. Since the
international effort to reduce greenhouse gas emissions is still in some respects a work-in-progress,
it is not yet possible to provide a full authoritative analysis of it. However, key elements of the
Kyoto Protocol and the Administration's policy, such as international emissions trading, meaningful
developing country participation, inclusion of carbon sinks and six categories of gases, as well as
domestic initiatives, can ensure that reductions in global greenhouse gas emissions are consistent
with continued strong economic growth.
This report provides the reasoning underlying the Administration's conclusion that, with the
flexibility represented by key provisions of the Kyoto agreement, the economic impacts of complying
with the Kyoto Protocol are likely to be modest. First, the report provides a discussion of trends in
greenhouse gas emissions, both in the United States and internationally. Second, it presents a brief
survey of the scientific literature on the risks of climate change. Third, it provides an overview of
the Kyoto Protocol, with emphasis on its flexibility mechanisms, and the evidence in the economic
literature for cost-savings through these mechanisms. Fourth, it describes the methodology used to
provide illustrative cost estimates of the Administration's policy to address climate change and
presents the results of this illustrative cost analysis.
3
PRESIDENT CLINTON ANNOUNCES THE UNITED STATES
CLIMATE CHANGE POLICY
NATIONAL GEOGRAPHIC SOCIETY
GILBERT H. GROSVENOR AUDITORIUM
Washington, D.C.
October 22, 1997
THE PRESIDENT'S THREE-STAGE PLAN ON CLIMATE CHANGE
October 22, 1997
Reflecting his five key principles, the President's plan will proceed in three stages:
Stage 1: Priming the Pump Through R&D, Tax Incentives, Incentives for Early Action,
Federal Leadership, and Industry Consultations. The first stage of the President's package
includes a 9-point action plan -- including $5 billion in tax incentives and spending for R&D
and energy efficiency, incentives for early action, a set of Federal government energy
15
initiatives, and industry-by-industry consultations to explore their best ideas on how to reduce
emissions in a cost-effective manner (including market-oriented standards for energy
efficiency). The first economic review would occur near the end of Stage 1.
Stage 2: Review and Evaluation. The second stage, which would begin around 2004, will
build upon the programs adopted in Stage 1, by including a review of our progress and an
evaluation of next steps as we move toward a market-based permit trading system for carbon
18
emissions. During this second stage, the details of the permit system would be refined and
perhaps tested. Such a permit system is similar in concept to the one that dramatically cut acid
rain emissions -- although the scale would be significantly larger than the current acid rain
program. The second economic review would occur near the end of Stage 2.
Stage 3: Meeting Binding Targets Through Domestic and International Emissions
Trading Program. In the third stage, we would reduce emissions to 1990 levels by 2008-
2012, and below 1990 levels in the 5-year period after that, through a market-based domestic
and international emissions trading system. Before beginning this third stage, the second
19
economic update and review would allow Congress and the President to evaluate how the
economy had responded to a decade's worth of experience in the first two stages of the
President's plan. The President is committed to working with labor and Congress to insure that
we give proper assistance to any workers dislocated by the changes in energy usage inherent in
any climate change plan.
This three-stage program recognizes the long-term nature of the effort to address climate change in
three ways:
By adopting a graduated approach to emissions reductions, it allows us to exploit the
tremendous opportunities for win-win reductions first.
By adopting a system of regular scientific and economic updates and reviews, it allows
us to monitor our progress and re-assess our success in reducing emissions, the state of
scientific knowledge, and how the economy is responding to our efforts. Only after we
have accumulated ten years of experience with the first two stages of the program would
we enter the internationally binding period.
By insisting that the United States will not adopt binding obligations without
developing country participation and by emphasizing the importance of an international
trading system and joint implementation, we take advantage of low-cost reduction
possibilities wherever they occur -- either here or abroad.
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
8
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
TRENDS IN GREENHOUSE GAS EMISSIONS
Historical Emissions
The increase in atmospheric concentrations of greenhouse gases reflects in part the growth
in anthropogenic emissions of these gases. In the United States, emissions of carbon dioxide have
increased more than 2 ½ times since 1950, and are projected to continue to increase over the next
twenty years absent any new emissions abatement policies and efforts (see Figure 1). Most of the
projected increase in domestic greenhouse gas emissions results from anticipated growth in carbon
dioxide emissions; emissions of
methane and nitrous oxide are
Figure 1. U.S. Greenhouse Gas Emissions,
likely to remain roughly flat over
Actual and Projected without New Abatement Policies
2,500
the next decade (Energy
Historical emissions
Information
Administration
Projected emissions without new abatement policies
1997a; Climate Action Report
20
1997). 2 More than 98% of all
2,000
Greenhouse gas emissions
carbon dioxide emissions in the
United States result from the
combustion of fossil fuels
MMTCE
1,500
(Energy
Information
Administration
1997b).
3
Carbon dioxide emissions
Although emissions of the
1,000
synthetic gases, HFCs, PFCs, and
SF₆, are projected to increase,
they will still comprise only a
500
small share of total U.S.
1950
1960
1970
1980
1990
2000
2010
2020
Source: Energy Information Administration 1997a, 1998b; Climate Action Report 1997.
greenhouse gas emissions in 2010
21
Climate Action Report 1997). 4
2
A recent draft report by the Environmental Protection Agency (1998) indicates that N2O
22
emissions may have been higher in the past than previously reported, based on a new emissions
accounting methodology. This analysis implies that future N₂O emissions may grow.
3
Measures of carbon dioxide emissions from the Energy Information Administration and
23
the Carbon Dioxide Information Analysis Center do not include the effects of land use change
(such as reforestation, afforestation, and deforestation) on total net emissions of carbon dioxide.
4
Emissions of greenhouse gases are presented in terms of million metric tons of carbon
equivalent (MMTCE). Carbon equivalence is based on the 100 year global warming potentials
for greenhouse gases (see Table 2 for a review of global warming potentials).
4
figurel
4
Projected Greenhouse Gas
MMTCE between 2000 and 2010, and 117
Emissions: 1990-2020
MMTCE between 2010 and 2020. The
largest percentage increase in net carbon
Emissions of greenhouse gases are pro-
emissions, 16 percent, occurs between 1990
jected to rise at a decreasing rate between
and 2000. (Net carbon emission is equal to
now and the year 2020 (Table 4-2 and Figure
gross domestic energy-related carbon emis-
4-3). Between 1990 and 2000, emissions
sions, minus international bunker fuel, plus
increase by 12. percent; between 2000 and
Adjustments to U.S. Energy, plus emissions
2010, they increase by an additional 11 per-
from Other Sources, minus sequestered car-
cent; and between 2010 and 2020, they
bon.)
increase by another 9 percent. The growth of
Although the projected absolute increase
overall greenhouse gas emissions is due to the
in carbon-equivalent emissions for halo-
continued but slowing growth in projected
genated gases is relatively small compared to
baseline emissions.
net carbon emissions, halogenated gases
Among all gases, net carbon emissions
increase by 73 percent between 1990 and
increase the most in absolute terms, while
2000, by 115 percent between 2000 and
emissions from halogenated gases increase
2010, and by 46 percent between 2010 and
the most in percentage terms. Net carbon
2020. The largest absolute increase for these
emissions are projected to increase by 195
gases was 49 MMTCE, which is projected to
MMTCE between 1990 and 2000, by 137
occur between 2000 and 2010.
Table 4-2
Historical and Projected 1997 CAR Greenhouse Gas Emissions
(MMTCE)
Greenhouse Gas
Historical Emissions
Projected Emissions
1990
1995
2000
2010
2020
Net CO2
1,228
1,305
1,423
1,560
1,677
Energy
1,327
1,391
1,504
1,634
1,737
Adjustments and Other Sources
26
31
31
35
34
21
:
Carbon Sequestration
-125
-117
-112
-109
-95
Methane
170
177
150
152
154
N20
36
40
31
34
34
HFCs, PFCs and SF₆
24
37
42
91
133
Total
1,458
1,559
1,646
1,837
1,998
Difference from 1990
101
188
378
540
Note: Projections assume timely receipt of legislative authority for parking cash-out. Program funding is based on funding proportional to
current funding with respect to 1993 CCAP funding levels. Columns may not sum due to independent rounding.
Mitigating Climate Change
111
figurel
&
U.S. Department of Energy
TELEFAX TRANSMISSION
FROM
ENERGY INFORMATION ADMINISTRATION
Office of Integrated Analysis and Forecasting (EI-80)
1000 Independence Avenue, S.W.
Washington, D.C. 20585
DATE: 12/29/97
TO:
JUE ALOT- CEA
FAX NUMBER: 202 395 6870
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MESSAGE:
OTHER CASES 1980- 96
6PP
Table ES-1. Summary of Estimated U.S. Emissions of Greenhouse Gases, 1988-1996
(Million Metric Tons of Gas)
Greenhouse Gas
Units
1980
1981
1982
1983
1984
1985
1988
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
Carbon Dioxide
MMT
4,853.7
4,728.4
4,459.3
4,430.6
4,669.0
4.667.2
4,665.9
4,819.5
5,044.1
5,091.8
5,037.1
4,987.3
5,059.8
5,175.9
5,256.1
5,296.9
5,484.9
Methane
MMT
28.6
29.2
29.8
29.6
30.4
30.6
29.9
30.7
31.3
31.3
31.6
31.6
31.7
30.8
31.4
30.9
30.9
Nitrous Oxide
MMT
0.3
0.3
03
0.3
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.5
0.5
0.5
0.5
0.5
0.4
Halocarbons and Minor Gases
CFC-11, CFC-12, CFC-113
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.2
0.2
0.2
0.1
01
0.1
01
HCFC-22
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
01
0.1
0.1
0.1
0.1
0.1
HFCs, PFCs and SF6
MMT
.
R
.
.
.
.
.
*
.
.
.
.
Methyl Chioroform
MMT
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.2
0.1
0.1
Criteria Pollutants
Carbon Monoxide
MMT
104.9
103.5
99.7
104.6
103.7
104.0
99.0
97.9
105.0
93.5
91.3
88.3
85.3
85.4
896
83.5
NA
Nitrogen Oxides
MMT
21.1
20.9
20.4
20.2
21.0
20.7
20.3
20.3
21.4
21.1
20.9
20.6
20.7
21.1
21.5
19.7
NA
Nonmethane VOCS
MMT
23.5
22.3
21.3
22.3
23.2
234
22.7
22.5
23.3
21.7
21.4
20.8
20.3
20.5
21.1
20.7
NA
Sources: This report
Carbon Dioxide
MMTC
1323.7
1289.6
1216.2
1203.3
1273.4
1272.9
1272.5
1314.4
1375.7
1388.7
1373.8
1360.2
1379.9
1411.6
1433.5
1444.6
1495.9
memo HFCs. PFCs, & SF6
0.0068
0.007
0.00513
0.00609
0 0069
0.0053
0.008511
0.00881
0.008081
0 0083
0.0085
0.00915
0.0128
0.0145
0.0206
0.0229
0.03412
DRAFT 12/29/97 03:33 PM -
Page 1
Table ES-2. U.S. Emissions of Greenhouse Gases, Based on Global Warming Potential, 1988-1995
(Million Melric Tons of Carbon Equivalent)
Greenhouse Gas
GWP
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
Carbon Dioxide
1
1,324
1,290
1,216
1,208
1,273
1,273
1,273
1,314
1,376
1,389
1,374
Methene
1,360
1,380
1,412
5.7
1,433
164
167
1,445
1.498
170
170
174
175
171
176
179
179
181
181
Nitrous Oxide
182
177
180
85
177
177
29
29
27
27
31
32
32
33
36
38
38
38
HFCs, PFCs, and SF6
38
39
40
38
(a)
20
21
38
16
19
21
20
21
22
26
26
25
26
28
Total
27
31
35
1,537
42
1,507
1,429
1,424
1,500
1,500
1,497
1,546
1,616
1,632
1,618
1,806
1,628
1,654
1,684
1,696
1,753
Sources: Emissions Estimates: ELA, Greenhouse Gas Report, 1995
GWP: United Nations, Intergovemmental Panel on Climate Change (IPCC),
DRAFT 12/29/97 03:33 PM -
Page 2
Table
3.1.
U.S.
ne Emissions from Anthropogenic Sources, 1980-1996
(Million Metric Tons of Methane)
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
P1996
Source
Energy Sources
3.02
3.60
388
3.73
4.01
4.24
4.31
4.63
4.38
4.28
3.50
3.90
3.98
3.93
Coal Mining
3.05
2.80
3.23
5.31
5.93
6.09
6.21
6.30
6.26
6.22
6.37
6.47
6.48
6.59
6.73
6.78
6.78
6.73
6.32
6.80
Oil and Gas
0.83
0.89
0.88
0.88
0.84
0.82
0.81
0.84
0.87
0.57
0.60
0.63
0.55
0.54
0.59
0.59
Stationary Combustion
0.83
0.38
0.38
0.37
0.36
0.35
0.33
0.32
0.31
0.30
0.29
0.27
0.26
0.26
0.25
0.24
0.25
0.25
Transportation
9.57
9.93
10.57
10.46
11.13
11.31
11.09
11.50
11.85
11.95
12.07
11.97
11.96
11.08
11.42
11.15
11.57
Total Energy Sources
Waste Management
9.85
10.02
10.18
10.34
10.48
10.58
10.61
10.81
10.89
10.89
10.96
10.85
10.74
10.68
10.57
10.45
10.28
Landfills
0.1369
0.1382
0.1395
0.1408
0.1421
0.1433
0.1446
0.1459
0.1473
0.1487
0.1502
0.1519
0.1536
0.1553
0.1568
0.1583
0.1598
Waste Water Treatment
10.44
Total Waste Management
9.99
10.16
10.32
10.49
10.62
10.72
10.76
10.96
11.04
11.04
11.11
11.00
10.89
10.83
10.73
10.60
Agricultural Sources
5.47
5.56
5.50
5.46
5.33
5.27
5.13
5.08
5.10
5.08
5.13
5.31
5.39
5.46
5.62
5.61
5.46
Ruminat Animals
2.88
2.76
2.88
2.75
2.66
2.71
2.64
2.64
2.39
2.63
2.64
2.60
2.63
2.73
2.81
2.81
2.88
Animal Waste
Rice Paddies
0.48
0.54
0.47
0.31
0.40
036
0.34
0.33
0.41
0.38
0.40
0.39
0.44
0.40
0.46
0.43
0.40
0.11
0.15
0.12
0.14
Agricultural Residue
0.12
0.14
0.14
0.10
0.13
0.14
0.13
0.12
0.10
0.12
0.13
0.12
0.14
Total Agriculture Sources
8.95
8.99
8.77
859
8.51
8.41
7.99
8.16
8.24
8.18
8.29
8.55
8.77
8.79
9.11
9.05
8.75
0.11
0.12
0.12
0.13
0.13
0.13
Industrial Processes
0.13
0.14
0.10
0.11
0.11
0.11
0.10
0.11
0.12
0.12
0.12
Total
28.64
29.23
29.75
29.64
30.37
30.55
29.94
30.73
31.26
31.29
31.59
31.63
31.74
30.82
31.38
30.93
30.90
12/29/97 03:03 PM - DBCH4IND.WK4
Table 4.1. Estimateu U.S. Nitrous Oxide Emissions, 1980-1996
(Thousand Metric Tons of Nitrous Oxide)
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
P1996
1980
Agriculture
Fertilizer
163
143
144
161
156
147
148
150
154
159
162
163
171
174
154
141
166
5
5
5
5
4
6
5
5
4
5
5
4
5
5
5
5
4
Crop Residue Burning
171
168
149
148
166
162
152
152
154
159
164
167
168
176
179
159
146
Total
Energy Use
50
52
54
64
79
91
101
116
134
147
150
148
150
147
147
148
148
Transport
32
33
35
35
35
36
38
38
38
37
37
38
39
39
41
Stationary Combustion
35
34
Total
84
86
86
96
113
126
136
152
172
184
188
185
188
186
186
187
189
95
100
97
100
96
101
107
108
111
90
87
82
81
89
90
85
90
Industrial Sources
345
341
317
325
368
378
374
394
420
444
449
452
452
463
472
454
446
Total
0.3
0.3
0.3
0.3
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.5
0.5
0.5
0.5
0.5
0.4
Total (10^6 Metric Tons)
12/29/97 03:01 PM -- DBN2OSUM.WK4
Table 5-2. Estimated U.S. Emissions of Halocarbons and Other Greenhouse Gases, 1980-1996
(Thousand Metric Tons)
Item
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
P199
CFCs
CFC-11
52.299
60.189
54.195
71.752
78.237
77.035
84.511
84.999
84.999
80.004
60.004
53.996
48.043
39.359
37.000
36.000
10.292
59.002
52.002
47.473
CFC-12
76.940
81.272
87.218
92.630
98.862
111.294
109.280
110.210
110.378
114.177
112.999
107.626
96.606
90.291
CFC-113
40.520
42.408
44.170
51.888
66.641
72.362
.
77.596
83.259
82.843
77.720
49.998
38.540
27.826
19.702
17.000
17.000
16.143
NA
9.000
8.750
8.500
8.250
8.000
5.000
4.000
Other CFCs
NA
NA
NA
NA
NA
NA
NA
NA
NA
Halons
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
3.000
3.000
3.000
3.000
3.000
3.000
2.000
HCFCs
73.617
70.350
70.325
68.113
73.951
76.369
71.997
82.332
91.799
100.064
104.996
91.996
92.634
HCFC-22
58.646
64.374
67.762
73.176
HCFC-141b
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
*
0.500
3.000
8.000
16.000
22.047
32.796
HCFC-142b
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
2.500
3.000
6.000
10.000
8.204
10.966
9.000
Other HCFCs
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
2.000
2.500
3.000
3.500
4.000
7.000
HFCs
HFC-23
3.097
3.425
2.371
3.206
3.458
3.203
3.687
3.741
4.525
4.661
4.165
4.279
4.486
3.965
4.160
4.200
4.200
0.900
3.470
5.920
10.410
12.031
21.660
HFC-134a
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.500
HFC-152a
0.000
0.000
0.000
0.000
0.000
0.000
0.00D
0.000
0.000
0.000
1.030
1.040
1.530
0.910
1.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
2.020
4.680
6.500
Other HFCs
0.000
0.000
0.000
PFCs/PFPEs
3.071
2.962
2.160
2.212
2.705
2.310
2.004
2.206
2.603
2.660
2.672
2.720
2.668
2.439
2.177
3.258
3.472
Other Chemicals
Carbon Tetrachloride
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
30.000
NA
25.600
21.600
16.000
5.000
4.745
25.840
Methyl Chloroform
294.801
283.790
252.460
252.598
276.438
261.120
296.089
261.137
323.429
295.616
316.004
224.365
215.012
121.886
77.997
46.000
Sulfur Hexaflouride
0.629
0.644
0.603
0.666
0.771
0.794
0.819
0.861
0.932
0.989
1.000
1.071
1.132
1.170
1.213
1.290
1.404
Source: 1990 emissions estimates: Unpublished information, EPA Office of Air and Radiation
Other estimates, E1A estimates described in this chapter.
12/29/97 02:59 PM - CFC.WK4
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7039310655 P.02
TOTAL P.02
Detailed In (DI)
Summary
Emissions of Carbon Dioxide by Sector, 1949-1996
Sector
Units
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
Residential
10^6 MTC
83.8
91.1
96.0
98.0
98.0
101.5
109.0
114.8
114.9
120.8
126.8
136.0
Commercial
10^6 MTC
75.3
79.2
78.8
77.9
75.4
74.9
79.2
81.3
78.0
80.6
82.6
88.0
Industrial
10^6 MTC
268.4
295.7
321.2
309.0
328.1
300.3
347.0
357.7
356.8
331.8
346.0
353.8
Transportation
10^6 MTC
164.5
172.0
180.8
175.6
174.8
168.5
179.6
182.1
182.5
181.4
185.7
203.2
Total
1006 MTC
591.9
637.9
676.7
660.5
676.4
645.2
714.7
735.9
732.1
714.6
741.0
781.0
Electric Utility
10^6 MTC
67.6
75.1
83.5
87.3
96.7
98.3
114.8
124.0
128.3
125.1
138.1
144.5
Emissions of Carbon Dioxide By Fuel, 1949-1996
Sector
Units
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
Petroleum
10^6 MTC
218.2
244.5
264.1
271.1
281.0
283.9
307.5
316.2
317.2
324.0
335.8
358.5
Coal
10^6 MTC
297.6
306.5
310.9
280.4
281.7
240.9
276.9
281.3
268.1
236.5
236.5
244.2
Natural Gas
1006 MTC
76.1
86.9
101.8
109.0
113.7
120.3
130.3
138.4
146.9
154.1
168.8
178.3
Geothermal
10^8 MTC
Total
10^6 MTC
591.9
637.9
676.7
660.5
676.4
645.2
714.7
735.9
732.1
714.6
741.0
781.0
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Executive Summary
20
Carbon Dioxide
tion of water to accommodate salmon, 1996 hydre-
electric generation was the second highest CG
Some 98.5 percent of U.S. anthropogenic carbon dioxide
record.
emissions come from the combustion of fossil fuels.
Changes in carbon dioxide emissions can be traced to
Currently, however, the growth in nuclear power gen-
eration has leveled off, and it is unlikely that (uture
energy consumption trends and changes in the compo-
sition of fossil fuels burned to provide energy services.
hydroelectric generation will often match 1996 levels
During the 1980s and early 1990s, the energy intensity
World oil prices remain relatively low, and the US
of the U.S. economy and the carbon intensity of U.S.
economy is growing rapidly.
energy consumption steadily declined (Figure ES2).
Severe weather conditions in 1996 produced a series R.
anomalous results: residential and commercial natural
Figure ES2. Emissions Intensity of U.S. Gross
gas consumers used 7.8 percent more natural gas and
Domestic Product, Population, Energy
3.5 percent more electricity than in 1995, and natural
Use, and Electricity Production,
8as prices increased sharply. In response to the price
1980-1996
signals, electric utilities reduced their gas consumption
by 15 percent and substituted coal The result was =
130
Greenhouse Gas Emissions
sharp increase in both total carbon emissions and
per Unit of Gross Domestic Product
emissions per kilowatthous for the electric utility sector,
co, Emissions
120
accompanied by rapid increases in both direct (from
per Unit of End-Use Energy
natural gas and heating oil) and indirect (from elec-
Greenhouse Gas Emissions
tricity) emissions from the residential and commercial
Index (1990=100)
110
per Capita
sectors. Emissions from the industrial and transporta-
tion sectors increased by a "more normal" 26 percent
and 23 percent, respectively, in 1996 (Figure ES3).
100
Figure ES3. U.S. Carbon Dioxide Emissions
Electric Utility CO, Emissions
90
per Unit of Electricity Produced
by Sector, 1980-1996
115
o
1980
1985
1990
1996
110
Industrial
Sources: EIA estimates documented in this report.
105
The deregulation of the natural gas industry bore
Index (1990.= 100)
Residential
Several unrelated factors caused the decline:
100
95
fruit in the form of greatly increasing gas supplies
at low prices. Natural gas use expanded rapidly in
90
the residential, commercial, and industrial sectors,
Transportation
accounting for much of the growth of energy
85
Electric Utility
consumption.
Commercial
0
Many events of the period-including the Gulf War,
1585
1990
1996
1980
the oil price spike of 1990, the recession of 1991,
and the vogue for utility demand-side management
Source: EIA estimates siscumented in Chapter N of this
programs-tended to restrain the growth of energy
report.
consumption.
Utility operators began to solve nuclear power plant
ethane
operating problems and, by 1995, were able to pro-
duce 17 percent more electricity from nuclear plants
Methane emissions extimates are more uncertain than
than in 1990.
those for carbon diortice U.S. anthropogenic methane
With more snowfall in the Pacific Northwest,
emissions have three peincipal sources: production and
hydroelectric power generation has returned to the
transportation of coal natural gas, and oil; anaerobic
levels of the early 1980s. Despite widespread alloca-
decomposition of mossicipal waste in landfills; and
Energy Information Administration/ Emissions of Greenhouse Gases in the vasted States 1996
xi
DRAFT
Including missing emission sources. Quantitative estimates of some of the sources and sinks of greenhouse gas
emissions are not available at this time. In particular, emissions from some land-use activities and industrial
processes are not included in the inventory either because data are incomplete or because methodologies do not
exist for estimating emissions from these source categories.
Improving the accuracy of emission factors. Further research is needed in some cases to improve the accuracy of
emission factors used to calculate emissions from a variety of sources. For example, the accuracy of current
emission factors applied to methane and nitrous oxide emissions from stationary and mobile source fossil fuel
combustion are highly uncertain.
Collecting detailed activity data. Although methodologies exist for estimating emissions for some sources,
problems arise in obtaining activity data at a level of detail in which aggregate emission factors can be applied.
For example, the ability to estimate emissions of methane and nitrous oxide from jet aircraft is limited due to a lack
of activity data by aircraft type and number of landing and take-off cycles.
Applying Global Warming Potentials. GWP values have several limitations including that they are not applicable
to unevenly distributed gases and aerosols such as tropospheric ozone and its precursors. They are also intended to
reflect global averages and, therefore, do not account for regional effects (IPCC 1996).
Emissions calculated for the U.S. inventory reflect current best estimates; in some cases, however, estimates are
based on approximate methodologies, assumptions, and incomplete data. As new information becomes available in
the future, the U.S. will continue to improve and revise its emission estimates.
Changes in U.S. Greenhouse Gas Inventory Report
This year's inventory of greenhouse gas emissions and sinks includes several significant additions and
methodological changes that, depending on the source, improve the accuracy, precision, or comprehensiveness of
the estimates presented relative to previous U.S. inventories. A summary of these additions and changes is
provided below:
An improved methodology for estimating methane and nitrous oxide emissions from mobile sources was
employed that accounts for changes in emission control technologies over time and vehicle miles traveled by
22
model year. Improved CH₄ and N2O emission factors were also used, which had the primary result of revising
N₂O emission estimates from highway vehicles upward significantly.
An additional analysis of carbon dioxide emission from fossil fuel combustion in the transportation end-use
sector is provided showing emissions by fuel and vehicle type.
Carbon sequestration from non-fuel uses of fossil fuels in U.S. territories was included for the first time in
emission estimates of CO₂ from fossil fuel combustion.
Due to inconsistencies in natural gas production and consumption data available from the Energy Information
Agency, CO₂ emissions from unmetered natural gas consumption were not included. This exclusion had a
insignificant effect on reported emissions.
Carbon dioxide emissions from geothermal steam extraction for electric power generation are included for the
first time, although its contribution to total emissions is less than 0.1 MMTCE.
Improved emission factors and a more detailed analysis of activities contributing to methane emissions from
natural gas systems have been employed.
Several new industrial processes were included for the first time. Methane emissions from the production of
select petrochemicals and silicon carbide production were added, although their contribution is minor. Carbon
dioxide emissions from ammonia, iron and steel, and ferroalloy production were estimated, even though their
emissions are accounted for under the fossil fuel combustion of industrial coking coal and natural gas.
The discussion of HFC, PFC, and SF₆ emissions has been expanded to include multiple sources and improved
estimating methodologies.
U.S. Greenhouse Gas Emissions and Sinks: 1990-1996
Page 13
DOE/EIA-0383(9)
December 1997
Annual
Energy Ouflook
1998
With Projections Through 2020
Energy Information Administration
Carbon Emissions and Energy Use
AEO98 Projects Higher Carbon
U.S. Carbon Emissions per Capita
Emissions Than AEO97
Level Off Late in the Projections
Figure 106. Carbon emissions by sector, 1990-2020
Figure 107. Carbon emissions per capita, 1990-2020
(million metric tons per year)
(metric tons per person)
2,000
1,956
6.2
History
Projections
1,803
1,577*
6.0
Transportation
1,500
1,463
5.8
1,000
Industrial
5.6
5.4
500
Commercial
5.2
Residential
0
1990
1996
2000
2020
1990
1995
2000
2005
2010
2015
2020
Carbon emissions from energy use are projected to
U.S. carbon emissions from energy use are projected
increase by an average of 1.2 percent a year from
to grow at an average annual rate of 1.2 percent;
1996 to 2020, reaching 1,956 million metric tons
however, per capita emissions grow by only 0.4 per-
(Figure 106). The 2015 projection of 1,888 million
cent a year (Figure 107). To achieve stabilization of
metric tons is higher than the AEO97 projection of
total emissions, population growth would need to be
1,799 million metric tons, due to higher energy con-
offset by reductions in per capita emissions.
sumption and a reduced share of renewable fuels.
Emissions in the residential sector, including emis-
Increasing concentrations of greenhouse gases-
sions from the generation of electricity used in the
carbon dioxide, methane, nitrous oxide, and others-
sector, are projected to increase by 1.2 percent a
may increase the Earth's temperature and, in turn,
year, reflecting the ongoing trends of electrification
affect the climate. The AEO98 projections include
and penetration of new appliances and services. Sig-
analysis of the Climate Change Action Plan (CCAP),
nificant growth in office equipment and other uses is
developed by the Clinton Administration in 1993 to
also projected in the commercial sector, but growth
stabilize U.S. greenhouse gas emissions by 2000 at
in consumption-and in emissions, which increase
1990 levels. Carbon emissions from fuel combustion,
by 1.1 percent a year-is likely to be moderated by
the primary source of carbon emissions, were about
slowing growth in floorspace, coupled with efficiency
1,346 million metric tons in 1990. The analysis does
standards, voluntary efficiency programs, and tech-
not account for carbon-absorbing sinks, the 13 CCAP
nology improvements. Transportation emissions
actions that are related to non-energy programs or
grow at an average annual rate of 1.6 percent as a re-
gases other than carbon dioxide, nor any future miti-
sult of increases in vehicle-miles traveled and freight
gation actions that may be proposed.
and air travel, combined with slow growth in the av-
erage light-duty fleet efficiency. Industrial emissions
Emissions in the 1990s have grown more rapidly
are projected to grow by only 0.9 percent a year, as
than projected at the time the plan was formulated,
shifts to less energy-intensive industries and effi-
partly due to moderate energy price increases and
ciency gains moderate growth in energy use.
higher economic growth, which have led to higher
energy demand. In addition, some CCAP programs
Further reductions in emissions could result from
have been curtailed. Additional carbon mitigation
Climate Wise and Climate Challenge, voluntary pro-
programs, technology improvements, or more rapid
grams for emissions reductions by industry and elec-
adoption of voluntary programs could result in lower
tricity generators, which are cosponsored by the U.S.
emissions levels than projected here.
Environmental Protection Agency (EPA) and the
U.S. Department of Energy.
74
Energy Information Administration/ Annual Energy Outlook 1998
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
9
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
The pattern of emissions growth in the United States is similar to that of most other Annex
I nations (see Figure 2) (Marland and Boden 1998). 5 In many cases, the emissions increases have
2L
tracked the output of these
nations' economies.
For
Figure 2. Major Annex I Countries' Carbon Dioxide Emissions
example, the rapid development
from Fossil Fuel Combustion, 1950-1995
1,600
of Japan since World War II
United States
resulted in a large increase in
1,400
carbon dioxide emissions in spite
1,200
of that economy's high energy
Former Soviet Union
efficiency. Further, the nations of
1,000
the former Soviet Union have
MMTCE
800
experienced a decline in their
European Union
carbon dioxide emissions since
600
the beginning of this decade
Japan
because of the significant fall in
400
economic output during their
200
Australia
transitions to market economies.
Canada
0
1950
1960
1970
1980
1990
In 1996, the industrial
Source: Marland and Boden 1998.
countries emitted a majority of
the world's energy-related carbon
dioxide emissions. The United
Figure 3. World Carbon Dioxide Emissions from
States emitted approximately 1/4
Fossil Fuel Combustion, 1996
of the world's carbon dioxide
Other Developed
United States
emissions from fossil fuel
Countries
24%
combustion (see Figure 3).
26%
China, the world's second largest
emitter, had emissions almost
equal to those of all of Eastern
25
Europe and the former Soviet
Union. The industrial world's
share of global emissions has
Eastern Europe and
declined over time as developing
Former Soviet Union
Other Developing
14%
Countries
countries' economies have grown
22%
(Energy
Information
Administration 1998).
China
13%
Source: Energy Information Administration 1998a.
5
Annex I includes most of the world's industrial countries (see Appendix A for a
description of Annex I and a list of these countries).
5
Boden T A <tab @ tab.esd.ornl.gov>
06/09/98 01:23:17 PM
Please respond to Boden TA <[email protected]>
Record Type:
Record
To:
Zachary M. Candelario/CEA/EOP
CC:
tab @ ornl.gov
Subject: Re: Vostok temperature record
Dear Zachary,
You are welcome for the data. I truly enjoy providing data to people.
I've attached an ASCII file (global.dat) that contains the Jones et al. global
monthly and annual temperature anomalies for 1856-1997. If you need to
convert the anomalies to actual temperatures use 16 degrees C as the
reference period mean. For example, an annual anomaly of -0.20 equals
15.8 degrees C. An anomaly of +0.08 equals 16.08 degrees C.
The CO2 emissions file you have is old and out-of-date. Based on the
header on your file I'm guessing you got this from the World Resources
Institute or some similar organization. I suggest you use a more current
version of our database. I've attached the latest version of the file
containing the national estimates (nation95.ems) and recommend the following
citation.
Marland, G., and T.A. Boden. 1998. Global, Regional, and National CO2 Emissions.
In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information
24
Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tenn., U.S.A.
Please contact me if you have further questions or need additional information.
Sincerely,
Tom Boden
> Delivered-To: [email protected]
> X-Lotus-Fromdomain: EOP
> From: [email protected]
> To: Boden T A <[email protected]>
> Date: Mon, 8 Jun 1998 15:43:52 -0400
> Subject: Re: Vostok temperature record
> Mime-Version: 1.0
>
> Thank you for the data.
> I have two more questions for you.
DOE/EIA-0383(9)
December 1997
Annual
Energy Ouflook
1998
With Projections Through 2020
Energy Information Administration
25
Table A9. World Total Carbon Emissions by Region, Reference Case, 1990-2020
(Million Metric Tons)
History
Projections
Average Annual
Percent Change,
Region/Country
1990
1995
1996
2000
2005
2010
2015
2020
1995-2020
Industrialized
North America
1,550
1,629
1,687
1,829
1,967
2,105
2,217
2,313
1.4
United States
1,346
1,411
1,463
1,577
1,689
1,803
1,888
1,956
1.3
Canada
126
135
140
152
161
170
183
198
1.5
Mexico
78
82
84
99
117
132
145
159
2.7
Western Europe
971
925
947
978
1,037
1,101
1,169
1,239
1.2
Industrialized Asia
364
379
389
409
434
461
485
514
1.2
Japan
274
281
291
303
320
342
361
385
1.3
Australasia
90
99
99
107
113
119
124
129
1.1
Total Industrialized
2,885
2,933
3,023
3,216
3,437
3,667
3,870
4,066
1.3
EE/FSU
Former Soviet Union
991
636
613
653
720
792
850
913
1.5
Eastern Europe
299
230
228
249
266
280
293
310
1.2
Total EE/FSU
1,290
866
842
903
986
1,072
1,144
1,223
1.4
Developing Countries
Developing Asia
1,065
1,427
1,474
1,758
2,161
2,603
3,158
3,835
4.0
China
620
792
805
978
1,202
1,481
1,866
2,340
4.4
India
153
222
230
281
340
399
456
523
3.5
Other Asia
293
413
439
499
620
723
836
971
3.5
Middle East
194
229
241
253
285
322
363
409
2.3
Africa
178
192
198
219
247
276
306
341
2.3
Central and South America
174
194
206
250
318
391
475
574
4.4
Brazil
57
64
71
85
111
139
170
208
4.9
Other Central/South America
117
130
135
165
206
252
305
366
4.2
Total Developing
1,611
2,043
2,118
2,480
3,011
3,591
4,302
5,158
3.8
Total World
5,786
5,841
5,983
6,598
7,434
8,330
9,315
10,447
2.4
Includes the 50 States and the District of Columbia. U.S. Territories are included in Australasia.
Notes: EE/FSU = Eastern Europe/Former Soviet Union. The U.S. numbers include carbon emissions attributable to renewable
energy sources.
Sources: History: Energy Information Administration (EIA), International Energy Annual 1996, DOE/EIA-0219(96) (Washington,
DC, February 1998). Projections: EIA, Annual Energy Outlook 1998, DOE/EIA-0383(98) (Washington, DC, December 1997), Table
A19; and World Energy Projection System (1998)
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Projected Emissions
Figure 4. Projected Carbon Dioxide Emissions of Major Annex I
Countries without New Abatement Policies
Absent new measures to
2,500
26
abate emissions in industrial
countries, emissions of carbon
United States
2,000
dioxide will grow in all Annex I
nations (see Figure 4).⁶ The
1,500
Energy
Information
Administration (1998) projects
MMTCE
Western Europe
that the United States will
1,000
Former
experience the largest absolute
Soviet Union
Australasia
Japan
increase in emissions, while
Eastern Europe
500
Canada
nations of the former Soviet
Union are not expected to achieve
0
their 1990 carbon emissions level
1990
1995
2000
2005
2010
2015
2020
before 2020.
Note: Data represent carbon dioxide emissions from fossil fuel combustion.
Source: Energy Information Administration 1998a.
The United States is
Figure 5. Projected Growth in Carbon Dioxide Emissions
projected to experience the
Among Annex I Countries without New Abatement Policies
second fastest rate of emissions
1.8
growth among the major Annex I
Canada
1.6
nations (see Figure 5). Canada is
United States
projected to experience the fastest
growth rate. After declines in
emissions during most of this
Index (1990 carbon emissions = 1.0)
Australasia
1.4
27
1.2
Japan
decade, nations of the former
Soviet Union and eastern Europe
1.0
Western Europe
will also have comparable growth
rates.
0.8
Eastern Europe
Former Soviet
0.6
Union
0.4
1990
1995
2000
2005
2010
2015
2020
Source: Energy Information Administration 1998a.
6
The Energy Information Administration defines Australasia to include Australia, New
Zealand, and U.S. Territories. Western Europe includes all of OECD Europe except for the
28
Czech Republic, Hungary, and Poland.
6
DOE/EIA-0484(98)
Distribution Category UC-950
International
Energy Outlook
1998
April 1998
Energy Information Administration
Office of Integrated Analysis and Forecasting
U.S. Department of Energy
Washington, DC 20585
This report was prepared by the Energy Information Administration, the independent statistical and
analytical agency within the Department of Energy. The information contained herein should be
attributed to the Energy Information Administration and should not be construed as advocating or
reflecting any policy position of the Department of Energy or of any other organization.
Preface
The Energy Information Administration's outlook for world energy trends
is presented in this report. Model projections now extending to the
year 2020 are reported, and regional trends are discussed.
The International Energy Outlook 1998 (IEO98) presents
international energy projections in general are dis-
an assessment by the Energy Information Admin-
cussed in the first chapter of the report. The status of
istration (EIA) of the outlook for international energy
environmental issues, including global carbon emis-
markets through 2020. The report is an extension of the
sions, is reviewed. Comparisons of the IEO98 pro-
EIA's Annual Energy Outlook 1998 (AEO98), which was
jections with other available international energy
prepared using the National Energy Modeling System
forecasts are also included in the first chapter, along
(NEMS). U.S. projections appearing in IEO98 are consis-
with a review of the performance of EIA's international
tent with those published in AEO98. IEO98 is provided
energy projections from previous editions of the IEO.
as a statistical service to energy managers and analysts,
both in government and in the private sector. The pro-
The next part of the report is organized by energy
jections are used by international agencies, Federal and
source. Regional consumption projections for oil, natu-
State governments, trade associations, and other
ral gas, coal, nuclear power, and renewable energy
planners and decisionmakers. They are published
(hydroelectricity, geothermal, wind, solar, and other
pursuant to the Department of Energy Organization Act
renewables) are presented in five fuel chapters, with a
of 1977 (Public Law 95-91), Section 205(c). The IEO98
review of the current status of each fuel on a worldwide
projections are based on U.S. and foreign government
basis. This IEO98 includes expanded coverage of the
policies in effect on October 1, 1997.
transportation sector. A discussion of energy use in the
transportation sector-where EIA expects robust
Projections in IEO98 are displayed according to six basic
growth over the next 25 years-has been added to the
country groupings (Figure 1). The industrialized region
chapter on world oil markets. The last chapter of the
includes projections for four individual countries-the
report contains a discussion of energy use for electricity
United States, Canada, Mexico, and Japan-along with
production.
the subgroups Western Europe and Australasia (defined
28
as Australia, New Zealand, and the U.S. Territories). The
Summary tables of the IEO98 projections for world
developing countries are represented by four separate
energy consumption, carbon emissions, oil production,
regional subgroups: developing Asia, Africa, Middle
and nuclear power generating capacity are provided in
East, and Central and South America. China and India
Appendix A. The reference case projections for total
are represented in developing Asia. New to this year's
foreign energy consumption and for natural gas, coal,
report, country-level projections are provided for
and renewable energy were prepared using EIA's World
Brazil-which is represented in Central and South
Energy Projection System (WEPS) model, as were
America. Eastern Europe and the former Soviet Union
projections of carbon emissions, net electricity con-
(EE/FSU) are considered as a separate country
sumption, and energy use for electricity generation.
grouping.
Reference case projections of foreign oil production and
consumption were prepared using the International
The report begins with a review of world trends in
Energy Module of the National Energy Modeling
energy demand. The historical time frame starts with
System (NEMS). The NEMS Coal Export Submodule
data from 1970 and extends to 1996, providing readers
(CES) was used to derive flows in international coal
with a 26-year historical view of energy demand. For the
trade. Nuclear consumption projections were derived
first time, IEO98 projections are extended to 2020, so that
from the International Nuclear Model, PC Version (PC-
the forecasts cover a 24-year period.
INM). Alternatively, nuclear capacity projections were
developed by two methods: the nuclear reference case
High economic growth and low economic growth cases,
and low growth case projections were based on analysts'
based on different rates of growth in regional gross
knowledge of the nuclear programs in different coun-
domestic product (GDP), are used to depict a set of alter-
tries; the high growth case was generated by the World
native growth paths for the energy forecast. The projec-
Integrated Nuclear Evaluation System (WINES), a
tions and the uncertainty associated with making
demand-driven model.
Figure 1. Map of the Six Basic Country Groupings
Key
Industrialized Countries
EE/FSU
Developing Asia
Middle East
Africa
Central and South America
Source: Energy Information Administration, Office of Integrated Analysis and Forecasting.
The six basic country groupings used in this report
Kyrgyzstan, Moldova, Russia, Tajikistan, Turk-
(Figure 1) are defined as follows:
menistan, Ukraine, and Uzbekistan.
Industrialized Countries (the industrialized
Developing Asia (54 percent of the 1997 world
countries contain 18 percent of the 1997 world
population): Afghanistan, Bangladesh, Bhutan,
population): Australia, Austria, Belgium, Canada,
Brunei, Cambodia (Kampuchea), China, Fiji,
Denmark, Finland, France, Germany, Greece,
French Polynesia, Hong Kong, India, Indonesia,
Iceland, Ireland, Italy, Japan, Luxembourg,
Kiribatia, Laos, Malaysia, Macau, Maldives,
Mexico, the Netherlands, New Zealand, Norway,
Mongolia, Myanmar (Burma), Nauru, Nepal, New
Portugal, Spain, Sweden, Switzerland, Turkey, the
Caledonia, Niue, North Korea, Pakistan, Papua
United Kingdom, and the United States. The
New Guinea, Philippines, Samoa, Singapore,
industrialized countries actually represent all the
Solomon Islands, South Korea, Sri Lanka, Taiwan,
countries that are members of the Organization
Thailand, Tonga, Vanuatu, and Vietnam.
for Economic Cooperation and Development
(OECD), with the exceptions of the most recent
Middle East (2 percent of the 1997 world popula-
additions-the Czech Republic, Hungary, Poland,
tion): Bahrain, Cyprus, Iran, Iraq, Israel, Jordan,
and South Korea.
Kuwait, Lebanon, Oman, Qatar, Saudi Arabia,
Syria, the United Arab Emirates, and Yemen.
Eastern Europe and the former Soviet Union
(EE/FSU) (7 percent of the 1997 world population):
Africa (12 percent of the 1997 world population):
Algeria, Angola, Benin, Botswana, Burkina Faso,
- Eastern Europe: Albania, Bosnia and Herze-
Burundi, Cameroon, Cape Verde, Central African
govina, Bulgaria, Croatia, Czech Republic,
Republic, Chad, Comoros, Congo (Brazzaville),
Hungary, Macedonia, Poland, Romania, Serbia
Congo (Kinshasa), Djibouti, Egypt, Equatorial
and Montenegro, Slovakia, and Slovenia.
Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana,
Guinea, Guinea-Bissau, Ivory Coast, Kenya,
- Former Soviet Union (FSU): The Baltic States of
Lesotho, Liberia, Libya, Madagascar, Malawi,
Estonia, Latvia, and Lithuania, as well as Arme-
Mali, Mauritania, Mauritius, Morocco, Mozam-
nia, Azerbaijan, Belarus, Georgia, Kazakhstan,
bique, Namibia, Niger, Nigeria, Reunion,
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The Energy Information
Figure 6. Projected Emissions of Annex I and Non-Annex I
Countries without New Abatement Policies
Administration (1998) projects
6,000
29
that Non-Annex I countries'
emissions will surpass the
5,000
Annex I
emissions of Annex I countries
between 2015 and 2020 (see
Figure 6).⁷
4,000
MMTCE
Non-Annex I
3,000
2,000
1,000
1990
1995
2000
2005
2010
2015
2020
Note: Data represent carbon dioxide emissions from fossil fuel combustion.
Source: Energy Information Administration 1998a.
Figure 7. Projected Emissions of the U.S. and China without
According to projections,
New Abatement Policies
China will surpass the United
2,500
States as the world's largest
annual emitter of carbon dioxide
around 2015 (Energy Information
2,000
United States
Administration 1998). China's
emissions will surpass 2 billion
31
metric tons between 2015 and
MMTCE
1,500
China
2020 because of its expected
rapid economic growth and its
reliance on its vast coal reserves
1,000
(see Figure 7).
500
1990
1995
2000
2005
2010
2015
2020
Note: Data represent carbon dioxide emissions from fossil fuel combustion.
Source: Energy Information Administration 1998a.
7 See Appendix A for a discussion of Annex I and Non-Annex I countries.
7
DOE/EIA-0383(
December 1997
Annual
Energy Ouflook
1998
With Projections Through 2020
Energy Information Administration
29
31
Table A9. World Total Carbon Emissions by Region, Reference Case, 1990-2020
(Million Metric Tons)
History
Projections
Average Annual
Percent Change,
Region/Country
1990
1995
1996
2000
2005
2010
2015
2020
1995-2020
Industrialized
North America
1,550
1,629
1,687
1,829
1,967
2,105
2,217
2,313
1.4
United States
1,346
1,411
1,463
1,577
1,689
1,803
1,888
1,956
1.3
Canada
126
135
140
152
161
170
183
198
1.5
Mexico
78
82
84
99
117
132
145
159
2.7
Western Europe
971
925
947
978
1,037
1,101
1,169
1,239
1.2
Industrialized Asia
364
379
389
409
434
461
485
514
1.2
Japan
274
281
291
303
320
342
361
385
1.3
Australasia
90
99
99
107
113
119
124
129
1.1
Total Industrialized
2,885
2,933
3,023
3,216
3,437
3,667
3,870
4,066
1.3
EE/FSU
Former Soviet Union
991
636
613
653
720
792
850
913
1.5
Eastern Europe
299
230
228
249
266
280
293
310
1.2
Total EE/FSU
1,290
866
842
903
986
1,072
1,144
1,223
1.4
Developing Countries
Developing Asia
1,065
1,427
1,474
1,758
2,161
2,603
3,158
3,835
4.0
China
620
792
805
978
1,202
1,481
1,866
2,340
4.4
India
153
222
230
281
340
399
456
523
3.5
Other Asia
293
413
439
499
620
723
836
971
3.5
Middle East
194
229
241
253
285
322
363
409
2.3
Africa
178
192
198
219
247
276
306
341
2.3
Central and South America
174
194
206
250
318
391
475
574
4.4
Brazil
57
64
71
85
111
139
170
208
4.9
Other Central/South America
117
130
135
165
206
252
305
366
4.2
Total Developing
1,611
2,043
2,118
2,480
3,011
3,591
4,302
5,158
3.8
Total World
5,786
5,841
5,983
6,598
7,434
8,330
9,315
10,447
2.4
Includes the 50 States and the District of Columbia. U.S. Territories are included in Australasia.
Notes: EE/FSU = Eastern Europe/Former Sovlet Union. The U.S. numbers include carbon emissions attributable to renewable
energy sources.
Sources: History: Energy Information Administration (EIA), International Energy Annual 1996, DOE/EIA-0219(96) (Washington,
DC, February 1998). Projections: EIA, Annual Energy Outlook 1998, DOE/EIA-0383(98) (Washington, DC, December 1997), Table
A19; and World Energy Projection System (1998)
DOE/EIA-0484(98)
Distribution Category UC-950
International
Energy Outlook
1998
April 1998
Energy Information Administration
Office of Integrated Analysis and Forecasting
U.S. Department of Energy
Washington, DC 20585
This report was prepared by the Energy Information Administration, the independent statistical and
analytical agency within the Department of Energy. The information contained herein should be
attributed to the Energy Information Administration and should not be construed as advocating or
reflecting any policy position of the Department of Energy or of any other organization.
igure 22. World Carbon Emissions by Region,
Figure 23. Carbon Emissions per Capita by
1970-2020
Region, 1990, 2010, and 2020
Billion Metric Tons
Metric Tons per Person
6
5
Industrialized
EE/FSU
Developing
World
Annex $
Non-Annex I
5
4
4
3
3
2
2
1
1
0
0
1970
1980
1990
2000
2010
2020
1990
2010
2020
Sources: History: Energy Information Administration (EIA),
Sources: 1990: Energy Information Administration (EIA),
Office of Energy Markets and End Use, International Statistics
Office of Energy Markets and End Use, International Energy
Database and International Energy Annual 1996, DOE/EIA-
Annual 1996, DOE/EIA-0219(96) (Washington, DC, February
0219(96) (Washington, DC, February 1998). Projections
1998). Projections: EIA, World Energy Projection System
EIA, World Energy Projection System (1998).
(1998).
carbon emissions between 1990 and 2020 and three
throughout the forecast, reaching 6.1 and 5.6 metric tons
fourths of the increment for all the developing countries.
per person in 2020, respectively (Figure 24). However,
The increase reflects the region's continuing heavy reli-
the growth rate of per capita emissions in both countries
ance on coal, the most carbon-intensive of the fossil
is projected to be fairly flat after 2000. In contrast, out-
fuels. Increased coal use accounts for 1.7 billion metric
side the Annex I countries, per capita emissions are pro-
tons of developing Asia's 2.8 billion metric ton incre-
jected to increase more rapidly. In China, for instance,
ment in carbon emissions. At the end of the forecast peri-
per capita carbon emissions in 2020 are projected to be
od, emissions in China alone surpass those of the United
more than triple their 1990 level, reflecting fast-paced
States.
industrialization based largely on fossil fuel consump-
tion over the forecast period.
Worldwide, carbon emissions per person grow from 1.1
metric tons in 1990 to 1.2 metric tons in 2010 and to 1.4
Figure 24. Carbon Emissions per Capita for
metric tons in 2020 (Figure 23). Per capita carbon emis-
Selected Regions and Countries,
sions for the Annex I countries remain markedly higher
1990-2020
than those for other countries throughout the forecast
Metric Tons per Person
period, increasing from a 1990 level of 3.2 metric tons of
6
United States
carbon per person in 1990 to 3.7 metric tons per person in
2020. In comparison, the 1990 level for non-Annex I
5
countries was 0.4 metric tons per person, and the pro-
Canada
jected 2020 level of 0.8 metric tons is one-fourth the 1990
4
level of per capita emissions for the Annex I countries.
Industrial Pacific
EE/FSU
On the other hand, the increments for the Annex I and
3
non-Annex 1 countries over the forecast period are actu-
ally equivalent. The non-Annex I countries accounted
2
Western Europe
for 75 percent of the world's population in 1990; in 2020
China
they will account for almost 82 percent of the world's
1
population; therefore, the effects of relatively small
India
increases in per capita emissions for non-Annex I
0
countries on overall emissions levels will be far greater
1990
1995
2000
2005
2010
2015
2020
than the effects of equivalent per capita increases for the
Sources: History: Energy Information Administration (EIA),
Annex I countries.
Office of Energy Markets and End Use, International Energy
Annual 1996, DOE/EIA-0219(96) (Washington, DC, February
Within the Annex I countries, the United States and
1998). Projections: EIA, World Energy Projection System
Canada have the highest per capita emissions levels
(1998).
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The rapid increase in
Figure 8. Projected Growth in Carbon Dioxide Emissions of Several
Non-Annex I emissions is not
Developing Countries without New Abatement Policies
4.0
solely the result of rapid
China
emissions growth in China. The
3.5
emissions of several other large
developing economies are also
projected to grow at nearly the
same rate (Energy Information
Index (1990 carbon emissions = 1.0)
3.0
Brazil
32
2.5
India
Administration 1998; see Figure
8).⁸
2.0
1.5
1.0
0.5
1990
1995
2000
2005
2010
2015
2020
Source: Energy Information Administration 1998a.
The projected growth in emissions of carbon dioxide and other greenhouse gases can increase
atmospheric concentrations of these gases, and further accelerate climate change. The next section
details the risks associated with continuing along the business as usual emissions path.
8
For additional country specific energy and emissions data, refer to Appendix E.
8
DOE/EIA-0383(9)
December 1997
Annual
Energy Ouflook
1998
With Projections Through 2020
Energy Information Administration
32
Table A9. World Total Carbon Emissions by Region, Reference Case, 1990-2020
(Million Metric Tons)
History
Projections
Average Annual
Percent Change,
Region/Country
1990
1995
1996
2000
2005
2010
2015
2020
1995-2020
Industrialized
North America
1,550
1,629
1,687
1,829
1,967
2,105
2,217
2,313
1.4
United States
1,346
1,411
1,463
1,577
1,689
1,803
1,888
1,956
1.3
Canada
126
135
140
152
161
170
183
198
1.5
Mexico
78
82
84
99
117
132
145
159
2.7
Western Europe
971
925
947
978
1,037
1,101
1,169
1,239
1.2
Industrialized Asia
364
379
389
409
434
461
485
514
1.2
Japan
274
281
291
303
320
342
361
385
1.3
Australasia
90
99
99
107
113
119
124
129
1.1
Total Industrialized
2,885
2,933
3,023
3,216
3,437
3,667
3,870
4,066
1.3
EE/FSU
Former Soviet Union
991
636
613
653
720
792
850
913
1.5
Eastern Europe
299
230
228
249
266
280
293
310
1.2
Total EE/FSU
1,290
866
842
903
986
1,072
1,144
1,223
1.4
Developing Countries
Developing Asia
1,065
1,427
1,474
1,758
2,161
2,603
3,158
3,835
4.0
China
620
792
805
978
1,202
1,481
1,866
2,340
4.4
India
153
222
230
281
340
399
456
523
3.5
Other Asia
293
413
439
499
620
723
836
971
3.5
Middle East
194
229
241
253
285
322
363
409
2.3
Africa
178
192
198
219
247
276
306
341
2.3
Central and South America
174
194
206
250
318
391
475
574
4.4
Brazil
57
64
71
85
111
139
170
208
4.9
Other Central/South America
117
130
135
165
206
252
305
366
4.2
Total Developing
1,611
2,043
2,118
2,480
3,011
3,591
4,302
5,158
3.8
Total World
5,786
5,841
5,983
6,598
7,434
8,330
9,315
10,447
2.4
"Includes the 50 States and the District of Columbia. U.S. Territories are included in Australasia.
Notes: EE/FSU = Eastern Europe/Former Soviet Union. The U.S. numbers include carbon emissions attributable to renewable
energy sources.
Sources: History: Energy Information Administration (EIA), International Energy Annual 1996, DOE/EIA-0219(96) (Washington,
DC, February 1998). Projections: EIA, Annual Energy Outlook 1998, DOE/EIA-0383(98) (Washington, DC, December 1997), Table
A19; and World Energy Projection System (1998).
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THE RISKS OF CLIMATE CHANGE
The greenhouse effect
Figure 9: The Greenhouse Effect
naturally warms the Earth's
surface (see Figure 9). Without
it, the Earth would be 60° F
cooler than it is today --
Some solar radiation
uninhabitable for life as we know
Some of the intrared
is reflected by the
SUN
Earth and the
radiation passes through
the atmosphere,
it. Water vapor, carbon dioxide,
atmosphere.
and some is absorbed and
33
re-emitted in all directions
and other trace gases such as
by greenhouse gas
molecules. The effect of
methane and nitrous oxide, trap
this is to warm the Earth's
surface and the lower
solar heat by slowing the loss of
atmosphere.
Solar radiation
heat by radiative cooling to space,
passes through
ATMOSPHERE
the clear
atmosphere
thereby keeping the Earth's
surface warmer than it otherwise
would be.
Moste
absorb
the
surface
Infrared radiation
emitted from the
rface
Since the beginning of the Industrial Era in the middle of the 19th century, the concentration
of CO₂ in the atmosphere has been steadily increasing (Neftel et al. 1985, 1994; Keeling and Whorf
1997; see Figure 10). Beginning
in 1957, continual measurements
Figure 10. Atmospheric Carbon Dioxide Concentration
of
380
atmospheric
CO₂
concentrations have been made
34
by scientists at an observatory on
360
Mauna Loa
Mauna Loa, Hawaii (Keeling and
(Hawaii)
Whorf 1997). The seasonal
cycle of vegetation in Northern
latitudes is evident in this record;
each spring the vegetation
Parts per million
340
320
"inhales" and absorbs CO2, and
Ice core data
each autumn most of that CO₂ is
released back to the atmosphere.
300
Overall, atmospheric CO₂ has
increased over 30% from 280
280
parts per million (ppm) to over
1860
1880
1900
1920
1940
1960
1980
360 ppm since 1860 (Schimel et
Sources: Neftel et al. 1985; Keeling and Whorf 1997.
al. 1996).
9
CLIMATE CHANGE
State of Knowledge
October 1997
The Greenhouse Effect and Historical Emissions
Life as we know it is possible on Earth because
industrialization and population growth, green-
of a natural greenhouse effect that keeps our
house gas emissions from human activities have
planet about 60° F warmer than it otherwise
consistently increased. These steady additions
would be (Figure 1). Water vapor, carbon diox-
have begun to tip a delicate balance, signifi-
ide (CO2) ), and other trace gases, such as
cantly increasing the amount of greenhouse
methane and nitrous oxide, trap solar heat and
gases in the atmosphere, and enhancing their
slow its loss by re-radiation back to space. With
insulating effect.
The Greenhouse Effect
Some solar radiation
Some of the infrared
is reflected by the
SUN
Earth and the
radiation passes through
atmosphere.
the atmosphere, and some
is absorbed and re-emitted
in all directions by
greenhouse gas
molecules. The effect of
this is to warm the Earth's
surface and the lower
33
atmosphere.
Solar radiation
passes through
ATMOSPHERE
the clear
atmosphere
Most
absorbed
SU
Infrared radiation.in
emitted from the
rth's rfad
Figure 1. The greenhouse effect naturally warms the Earth's surface. Without it, Earth would be 60° F cooler than it is today
- uninhabitable for life as we know it.
2
The result is that the atmospheric level of CO2,
The overall emissions of greenhouse gases are
the most important human-derived greenhouse
growing at about 1 percent per year. For millen-
gas, has increased 30 percent, from 280 to 360
nia, there has been a clear correlation between
parts per million (ppm) since 1860 (Figure 4).
CO2 levels and the global temperature record.
Over the same time period, agricultural and
Fluctuations of CO2 and temperature have
industrial practices have also substantially
roughly mirrored each other over the last
increased the levels of other potent greenhouse
160,000 years (Figure 5). The current level of
gases -- methane concentrations have doubled
CO2 is already far higher than it has been at
and nitrous oxide levels have risen by about 15
any point during this period. If current emis-
percent. These gases have atmospheric lifetimes
sions trends continue over the next century,
ranging from decades to centuries; today's emis-
concentrations will rise to levels not seen on
sions will be affecting the climate well into the
the planet for 50 million years.
21st century.
Carbon Dioxide Concentrations
Ice Core Data
Mauna Loa
370
(Hawaii)
360
350
340
parts per million
330
320
310
300
290
1860
1880
1900
1920
1940
1960
1980
2000
Figure 4. Since the beginning of the Industrial Revolution in the middle of the 19th century, the concentration of carbon diox-
ide (CO2) in the atmosphere has steadily increased. Beginning in 1957, continual measurements of atmospheric CO2 concen-
trations have been made by scientists at an observatory in Mauna Loa, Hawaii. The seasonal cycle of vegetation in Northern
latitudes can be seen in this record: each spring the vegetation "inhales" and absorbs CO2, and each autumn most of that
CO2 is released back to the atmosphere.
34
4
2
Radiative Forcing of Climate Change
D. SCHIMEL, D. ALVES, I. ENTING, M. HEIMANN,
F. JOOS, D. RAYNAUD, T. WIGLEY (2.1)
M. PRATHER, R. DERWENT, D. EHHALT, P. FRASER,
E. SANHUEZA, X. ZHOU (2.2)
P. JONAS, R. CHARLSON, H. RODHE, S. SADASIVAN (2.3)
K.P. SHINE, Y. FOUQUART, V. RAMASWAMY,
S. SOLOMON, J. SRINIVASAN (2.4)
D. ALBRITTON, R. DERWENT, I. ISAKSEN, M. LAL, D. WUEBBLES (2.5)
Contributors:
F. Alyea, T.L. Anderson, M. Andreae, D. Blake, O. Boucher, C. Brühl, J. Butler,
D. Cunnold, J. Dignon, E. Dlugokencky, J. Elkins, I. Fung, M. Geller, D. Hauglustaine,
J. Haywood, J. Heintzenberg, D. Jacob, A. Jain, C.D. Keeling, S. Khmelevtsov,
H. Le Treut, J. Lelieveld, I. Levin, M. Maiss, G. Marland, S.F. Marshall, P. Midgley,
B. Miller, J.F.B. Mitchell, S Montzka, H. Nakane, P. Novelli, B. O 'Neill, D. Oram,
S. Penkett, J.E. Penner, S. Pinnock, R. Prinn, P. Quay, A. Robock, S.E. Schwartz,
Simmonds, A. Slingo, F. Stordal, E. Sulzman, P. Tans, A. Wahner, R. Weiss, T. Whorf
SUMMARY
Climate change can be driven by changes in the
As well as the issue of natural fluctuations discussed
atmospheric concentrations of a number of radiatively
above, other issues raised since IPCC (1994) have been
active gases and aerosols. We have clear evidence that
addressed. There are some unresolved concerns about the
human activities have affected concentrations, distributions
¹⁴C budget which may imply that previous estimates of the
and life cycles of these gases. These matters, discussed in
atmosphere-to-ocean flux were slightly too high. However,
this chapter, were assessed at greater length in IPCC WGI
the carbon budget remains within our previously quoted
report "Radiative Forcing of Climate Change" (IPCC
uncertainties and the implications for future projections are
1994). The following summary contains some material
minimal. Suggestions that the observed decay of bomb-¹⁴C
more fully discussed in IPCC (1994): bullets containing
implies a very short atmospheric lifetime for CO₂ result
significant new information are marked "***"; those
from a mis-understanding of reservoir lifetimes. Current
containing information which has been updated since IPCC
carbon cycle modelling is based on principles that have
(1994) are marked and those which contain
been well-understood since the 1950s and correctly
information which is essentially unchanged since IPCC
accounts for the wide range of reservoir time-scales that
(1994) are marked
affect atmospheric concentration changes.
Carbon dioxide (CO₂)
The major components of the anthropogenic
* Carbon dioxide concentrations have increased by almost
perturbation to the atmospheric carbon budget, with
30% from about 280 ppmv in the late 18th century to 358
estimates of their magnitudes over the 1980s, are: (a)
ppmv in 1994. This increase is primarily due to combustion
emissions from fossil fuel combustion and cement
of fossil fuel and cement production, and to land-use
production (5.5 + 0.5 GtC/yr); (b) atmospheric increase (3.3
change. During the last millennium, a period of relatively
± 0.2 GtC/yr); (c) ocean uptake (2.0 +1 0.8 GtC/yr); (d)
stable climate, concentrations varied by about ±10 ppmv
tropical land-use changes (1.6 ± 1.0 GtC/yr); and (e)
around the pre-industrial value of 280 ppmv. On the
Northern Hemisphere forest regrowth (0.5 + 0.5 GtC/yr).
century time-scale these fluctuations were far less rapid
Other potential terrestrial sinks include enhanced terrestrial
than the change observed over the 20th century.
carbon storage due to CO₂ fertilisation (0.5-2.0 GtC/yr) and
nitrogen deposition (0.2-1.0 GtC/yr), and possibly response
The growth rate of atmospheric CO₂ concentrations
to climatic anomalies. The latter is estimated to be a sink of
over the last few years is comparable to, or slightly above,
0-1.0 GtC/yr over the 1980s, but this term could be either a
the average of the 1980s (~1.5 ppmv/yr). On shorter
sink or a source over other periods. This budget is changed
(interannual) time-scales, after a period of slow growth (0.6
from IPCC (1994) by a small adjustment (from 3.2 to 3.3
ppmv/yr) spanning 1991 to 1992, the growth rate in 1994
GtC/yr) to the atmospheric rate of increase and a
was higher (~2 ppmv/yr). This change in growth rate is
corresponding decrease in "other terrestrial sinks" from 1.4
similar to earlier short time-scale fluctuations, which
to 1.3 GtC/yr.
reflect large but transitory perturbations of the carbon
system. Isotope data suggest that the 1991 to 1994
*
In IPCC (1994) calculations of future CO₂ concentrations
fluctuations resulted from natural variations in the
and emissions from 18 different carbon cycle models were
exchange fluxes between the atmosphere and both the land
presented based on the IPCC (1992) carbon budget.
biota and the ocean, possibly partly induced by interannual
Concentrations were derived for the IS92 emission
variations in climate.
scenarios. Future CO₂ emissions were derived leading to
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
14
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
Over the past century, the
Figure 11. Global Average Temperature
global average temperature has
62.0
risen by approximately 1° F
(Nicholls et al. 1996; Jones et al.
61.5
1998; see Figure 11).9 Further,
recent analyses have indicated
that 1997 was the warmest year
on record (Quayle et al. 1998,
Degrees fahrenheit
61.0
37
Karl 1998), and that the decade of
60.5
the 1990's will be the warmest
38
decade for at least the past 600
years (Mann-et al. 1998).
60.0
38
+ Rosina's Email
59.5
1860
1880
1900
1920
1940
1960
1980
Note: Data are expressed as 3-year centered averages.
Source: Jones et al. 1998.
Temperature changes in
Figure 12. Atmospheric Carbon Dioxide Concentration and
recent decades bear out the close
Temperature over the Past 160,000 Years
40
correlation between carbon
800
dioxide concentration and
temperature found in ice core
30
Temperature (degrees celsius)
600
data going back 160,000 years
(Barnola et al. 1987, 1994).
20
Temperature
Since the beginning of the
Carbon dioxide
level relative
Current level
(right scale)
to current
400
Industrial Era, the CO₂ level has
temperature
10
increased steadily and is already
(left scale)
Carbon dioxide (ppmv)
outside the bounds of variability
200
seen in the 160,000 year record
0
(see Figure 12). Continuation of
current levels of emissions is
-10
0
-150
-100
-50
0
projected to raise concentrations
Thousands of years ago
to over 700 ppm by the year
40
Sources: Barnola et al. 1994; Energy Information Administration 1998;
2100, a level not experienced on
Chapellaz and Jouzel 1992.
Earth since about 50 million
9
The approximate 1° F temperature rise over the past century is derived from a
regression analysis of the temporal data. Because the annual global average temperature is
variable from year to year, it is inappropriate to simply select two years to quantify the increment.
The trend or regression is a more appropriate means to calculate the century's temperature rise.
10
CLIMATE CHANGE
State of Knowledge
October 1997
Climate Change Over the Last 100 Years
Global surface temperature has been measured
parts of the Earth system (the surface, and vari-
since 1880 at a network of ground-based and
ous layers of the atmosphere). In addition to
ocean-based sites. Over the last century, the
this, a variety of factors, such as the presence of
P
average surface temperature of the Earth has
airborne materials from the 1991 eruption of
increased by about 1.0° F. The eleven warmest
the volcano Mt. Pinatubo, affect each record in
years this century have all occurred since 1980,
a different way. Satellite observations were ini-
with 1995 the warmest on record (Figure 7).
tially interpreted as showing a slight cooling,
The higher latitudes have warmed more than
but more recent analyses accounting for natur-
Cr
the equatorial regions.
al, short-term fluctuations imply warming, just
as the ground-based measurements have indi-
Beginning in 1979, satellites have been used to
cated over a longer time period. As more data
measure the temperature of the atmosphere up
from the satellite record become available, and
to a height of 30,000 feet. The long-term sur-
as the quality of measurements is improved,
face record and the recent satellite observations
comparison of these two records should yield
differ, but that fact is not surprising: the two
additional insights.
techniques measure the temperature of different
Global Average Temperature
°C
°F
14.4
57.92
14.3
57.74
14.2
57.56
57.38
14.1
14.0
57.20
13.9
57.02
13.8
56.84
13.7
56.66
56.48
13.6
5 year average
13.5
56.30
1860
1880
1900
1920
1940
1960
1980
2000
Figure 7. The global average temperature has risen by approximately 1° F over the last century.
7
Observed Climate Variability and Change
NICHOLLS, G.V. GRUZA, J. JOUZEL, T.R. KARL, L.A. OGALLO,
D.E. PARKER
Key Contributors:
J.R. Christy, J. Eischeid, P.Ya. Groisman, M. Hulme, P.D. Jones, R.W. Knight
Contributors:
J.K. Angell, S. Anjian, P.A. Arkin, R.C. Balling, M.Yu. Bardin, R.G. Barry, W. BoMin, R.S. Bradley, K.R. Briffa,
A.M. Carleton, D.R. Cayan, F.H.S. Chiew, J.A. Church, E.R. Cook, T.J. Crowley, R.E. Davis, N.M. Datsenko,
B. Dey, H.F. Diaz, Y. Ding, W. Drosdowsky, M.L. Duarte, J.C. Duplessy, D.R. Easterling, W.P. Elliott,
B. Findlay, H. Flohn, C.K. Folland, R. Franke, P. Frich, D.J. Gaffen, V.Ya. Georgievsky, B.M. Ginsburg,
V.S. Golubev, J. Gould, N.E. Graham, D. Gullet, S. Hastenrath, A. Henderson-Sellers, M. Hoelzle, W.D. Hogg,
G.J. Holland, L.C. Hopkins, N.N. Ivachtchenko, D. Karoly, R.W. Katz, W. Kininmonth, N.K. Kononova,
L.V. Korovkina, G. Kukla, C.W. Landsea, S. Levitus, T.J. Lewis, H.F. Lins, J.M. Lough, T.A. McMahon,
L Malone, J.A. Marengo, E. Mekis, A. Meshcherskya, P.J. Michaels, E. Mosley-Thompson, S.E. Nicholson,
J. Oerlemans, G. Ohring, G.B. Pant, T.C. Peterson, N. Plummer, F.H. Quinn, E.Ya. Ran 'kova, V.N. Razuvaev,
E.V. Rocheva, C.F. Ropelewski, K. Rupa Kumar, M.J. Salinger, B. Santer, H. Schmidt, E. Semenyuk,
I.A. Shiklomanov, M. Shinoda, I.I. Soldatova, D.M. Sonechkin, R.W. Spencer, N. Speranskaya, A. Sun,
K.E. Trenberth, C. Tsay, J.E. Walsh, B. Wang, K. Wang, M.N. Ward, S.G. Warren, Q. Xu, T. Yasunari
SUMMARY
Has the climate warmed?
Cooling of the lower stratosphere since 1979 is
shown by both Microwave Sounding Unit and
The estimate of warming since the late 19th century
radiosonde data (as noted in IPCC, 1992), but is
has not significantly changed since the estimates in
larger (and probably exaggerated because of changes
IPCC (1990) and IPCC (1992), although the data
in instrumentation) in the radiosonde data. The
have been reanalysed, and more data are now
current (1994) global stratospheric temperatures are
available. Global surface temperatures have
the coolest since the start of the instrumental record
increased by about 0.3 to 0.6°C since the late-19th
(in both the satellite and radiosonde data).
century, and by about 0.2 to 0.3°C over the last 40
years (the period with most credible data). The
As predicted in IPCC (1992), relatively cool surface
warming has not been globally uniform. Some areas
and tropospheric temperatures, and a relatively
have cooled. The recent warming has been greatest
warmer lower stratosphere, were observed in 1992
over the continents between 40° and 70°N.
and 1993, following the 1991 eruption of Mt.
Pinatubo. Warmer surface and tropospheric
The general, but not global, tendency to reduced
temperatures reappeared in 1994. Surface
diurnal temperature range over land, at least since the
temperatures for 1994, averaged globally, were in the
middle of the 20th century, noted in IPCC (1992), has
warmest 5% of all years since 1860.
been confirmed with more data (representing more
than 40% of the global land mass). The range has
Further work on indirect indicators of warming such
decreased in many areas because nights have warmed
as borehole temperatures, snow cover, and glacier
more than days. Cloud cover has increased in many of
recession data, confirm the IPCC (1990) and (1992)
the areas with reduced diurnal temperature range.
findings that they are in substantial agreement with
Minimum temperature increases have been about
the direct indicators of recent warmth. Variations in
twice those in maximum temperatures.
sub-surface ocean temperatures have been consistent
with the geographical pattern of surface temperature
Radiosonde and Microwave Sounding Unit
variations and trends.
observations of tropospheric temperature show slight
overall cooling since 1979, whereas global surface
As noted in IPCC (1992) no consistent changes can
temperature has warmed slightly over this period.
be identified in global or hemispheric sea ice cover
There are statistical and physical reasons (e.g., short
since 1973 when satellite measurements began.
record lengths; the different transient effects of
Northern Hemisphere sea ice extent has, however,
volcanic activity and El Niño-Southern Oscillation)
been generally below average in the early 1990s.
for expecting different recent trends in surface and
tropospheric temperatures. After adjustment for these
transient effects, which can strongly influence trends
Has the climate become wetter?
calculated from short periods of record, both
tropospheric and surface data show slight warming
There has been a small positive (1%) global trend in
since 1979. Longer term trends in the radiosonde
precipitation over land during the 20th century,
data. since the 1950s, have been similar to those in
although precipitation has been relatively low since
the surface record.
about 1980. Precipitation has increased over land in
(Februa 1998)
Source: P. D. Jones
D. E. Parker
T. J. Osborn
Hadley Centre for Climate
K. R. Briffa
Prediction and Researc
Climatic Research Unit
Meteorological Office
School of Environmental Sciences
Bracknell, Berkshire,
University of East Anglia
United Kingdom
Norwich NR4 7TJ, United Kingdom
GAT Level
YEAR
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
ANNUAL Celsius
Far
3-YEAR CE
1856
-0.22
-0.38
-0.53
-0.39
-0.37
-0.16
-0.33
-0.3
-0.37
-0.4
-0.6
-0.32 -0.36
15.64
60.152
60.044
1857
-0.3
-0.33
-0.51
-0.53
-0.63
-0.42
-0.43
-0.4
-0.53
-0.63
-0.73
-0.35-0.48
15.52
59.936
60.038
1858
-0.62
-0.83
-0.65
-0.38
-0.36
-0.31
-0.32
-0.28
-0.23
-0.22
-0.65
-0.28-0.43
15.57
60.026
60.104
1859
-0.29
-0.24
-0.15
-0.14
-0.11
-0.32
-0.3
-0.18
-0.47
-0.18
-0.34
-0.27 -0.25
15.75
60.35
60.158
1860
-0.14
-0.49
-0.57
-0.46
-0.36
-0.14
-0.28
-0.28
-0.22
-0.39
-0.63
-0.72 -0.39
15.61
60.098
60.158
1861
-0.85
-0.53
-0.46
-0.45
-0.71
-0.25
-0.25
-0.11
-0.35
-0.4
-0.48
-0.32-0.43
15.57
60.026
60.002
1862
-0.74
-0.79
-0.38
-0.22
-0.19
-0.25
-0.49
-0.66
-0.39
-0.38
-0.87
-0.78-0.51
15.49
59.882
60.062
1863
0.02
-0.08
-0.33
-0.17
-0.39
-0.38
-0.53
-0.36
-0.3
-0.34
-0.37
-0.29-0.29
15.71
60.278
60.038
1864
-0.8
-0.59
-0.46
-0.45
-0.43
-0.21
-0.25
-0.42
-0.44
-0.6
-0.48
-0.53-0.47
15.53
59.954
60.182
1865
-0.06
-0.52
-0.57
-0.15
-0.16
-0.28
-0.2
-0.28
-0.11
-0.33
-0.25
-0,29-0.27
15.73
60.314
60.23
1866
0.1
-0.09
-0.34
-0.16
-0.49
0.07
-0.11
-0.25
-0.19
-0.36
-0.31
-0.38-0.21
15.79
60.422
60.326
1867
-0.27
0.01
-0.44
-0.24
-0.41
-0.35
-0.28
-0.29
-0.2
-0.24
-0.37
-0.64-0.31
15.69
60.242
60.344
1868
-0.56
-0.35
-0.11
-0.29
-0.09
-0.26
-0.1
-0.15
-0.16
-0.24
-0.4
-0.13-0.24
15.76
60.368
60.29
1869
-0.29
0.2
-0.53
-0.21
-0.2
-0.38
-0.34
-0.3
-0.25
-0.43
-0.45
-0.48-0.3
15.7
60.26
60.272
1870
-0.16
-0.47
-0.41
-0.25
-0.35
-0.31
-0.15
-0.33
-0.33
-0.4
-0.25
-0.67-0.34
15.66
60.188
60.2
1871
-0.46
-0.6
-0.06
-0.22
-0.39
-0.34
-0.12
-0.29
-0.44
-0.54
-0.38
-0.47-0.36
15.64
60.152
60.242
1872
-0.3
-0.34
-0.36
-0.17
-0.13
-0.24
-0.14
-0.08
-0.19
-0.3
-0.21
-0.34-0.23
15.77
60.386
60.272
1873
0.03
-0.29
-0.27
-0.45
-0.36
-0.31
-0.22
-0.2
-0.32
-0.33
-0.44
-0.3 -0.29
15.71
60.278
60.242
1874
-0.05
-0.36
-0.6
-0.57
-0.56
-0.44
-0.17
-0.4
-0.22
-0.49
-0.57
-0.49-0.41
15.59
60.062
60.128
1875
-0.58
-0.58
-0.61
-0.47
-0.14
-0.24
-0.39
-0.29
-0.37
-0.43
-0.56
-0.41-0.42
15.58
60.044
60.062
1876
-0.34
-0.33
-0.37
-0.36
-0.52
-0.34
-0.24
-0.22
-0.37
-0.45
-0.66
-0.65-0.4
15.6
60.08
60.23
1877
-0.25
-0.05
-0.3
-0.37
-0.49
-0.14
-0.03
-0.05
-0.02
-0.05
-0.04
0.17 -0.13
15.87
60.566
60.482
1878
0.04
0.32
0.42
0.26
-0.12
-0.02
-0.1
-0.06
-0.07
-0.14
-0.21
-0.3
0
16
60.8
60.542
1879
-0.22
-0.19
-0.23
-0.3
7-0.24
-0.28
-0.29
-0.24
-0.26
-0.25
-0.49
-0.57 -0.3
15.7
60.26
60.452
1880
-0.14
-0.28
-0.19
-0.18
-0.31
-0.36
-0.32
-0.15
-0.3
-0.41
-0.46
-0.25-0.28
15.72
60.296
60.302
1881
-0.43
-0.28
-0.25
-0.19
-0.03
-0.23
-0.15
-0.12
-0.29
-0.37
-0.45
-0.17-0.25
15.75
60.35
60.344
1882
0.05
-0.04
0.01
-0.28
-0.3
-0.35
-0.22
-0.2
-0.15
-0.37
-0.39
-0.48-0.23
15.77
60.386
60.326
1883
-0.42
-0.36
-0.33
-0.39
-0.3
-0.11
-0.22
-0.24
-0.3
-0.43
-0.31
-0.28-0.31
15.69
60.242
60.26
1884
-0.32
-0.28
-0.33
-0.44
-0.38
-0.33
-0.38
-0.33
-0.27
-0.3
-0.59
-0.39-0.36
15.64
60.152
60.194
1885
-0.51
-0.49
-0.38
-0.4
-0.45
-0.48
-0.25
-0.33
-0.22
-0.27
-0.19
-0.07-0.34
15.66
60.188
60.218
1886
-0.31
-0.44
-0.39
-0.19
-0.11
-0.26
-0.19
-0.15
-0.21
-0.31
-0.35
-0.26-0.27
15.73
60.314
60.212
1887
45
-0.52
-0.33
-0.43
-0.28
-0.38
-0.18
-0.36
27
-0.47
-0.33
-0.4-0.37
15.63
60.134
60.23
1888
-0.66
-0.53
-0.53
-0.27
-0.28
-0.24
-0.28
-0.26
6.17
-0.09
-0.2
-0.19-0.31
15.69
60.242
60.29
1889
-0.12
-0.08
-0.01
-0.02
-0.05
-0.16
-0.18
-0.22
-0.34
-0.25
-0.38
-0.2-0.17
15.83
60.494
60.278
1890
-0.29
-0.31
-0.32
-0.3
-0.42
-0.34
-0.34
-0.44
-0.47
-0.48
-0.58
-0.37-0.39
15.61
60.098
60.272
1891
-0.52
-0.49
-0.41
-0.39
-0.2
-0.32
-0.26
-0.23
-0.17
-0.3
-0.54
-0.06-0.32
15.68
60.224
60.122
1892
-0.42
-0.1
-0.44
-0.43
-0.4
-0.38
-0.48
-0.37
-0.22
-0.38
-0.64
-0.78-0.42
15.58
60.044
60.08
1893
-1.08
-0.79
-0.37
-0.53
-0.55
-0.34
-0.23
-0.33
-0.35
-0.25
-0.38
-0.31-0.46
15.54
59.972
60.044
1894
-0.43
-0.33
-0.33
-0.4
-0.37
-0.43
-0.34
-0.33
-0.43
-0.38
-0.44
-0.38 -0.38
15.62
60.116
60.08
1895
-0.48
-0.71
-0.51
-0.34
-0.38
-0.36
-0.35
-0.26
-0.18
-0.27
-0.2
-0.32-0.36
15.64
60.152
60.26
1896
-0.23
-0.19
-0.35
-0.35
-0.14
-0.08
-0.11
-0.08
-0.04
-0.06
-0.24
-0.06-0.16
15.84
60.512
60.398
1897
-0.2
-0.12
-0.18
-0.03
-0.01
-0.09
-0.07
-0.13
-0.05
-0.16
-0.44
-0.38-0.15
15.85
60.53
60.416
1898
-0.05
-0.35
-0.74
-0.49
-0.36
-0.2
-0.25
-0.23
-0.24
-0.44
-0.36
-0.27-0.33
15.67
60.206
60.38
1899
-0.14
-0.46
-0.47
-0.22
-0.24
-0.34
-0.19
-0.11
-0.08
-0.08
0.1
-0.39-0.22
15.78
60.404
60.392
1900
-0.2
-0.2
-0.2
-0.15
-0.14
-0.06
-0.11
-0.1
-0.15
0.03
-0.28
-0.02-0.13
15.87
60.566
60.458
1901
-0.16
-0.23
-0.15
-0.13
-0.14
-0.11
-0.11
-0.13
-0.36
-0.27
-0.45
-0.39-0.22
15.78
60.404
60.368
1902
-0.19
-0.22
-0.37
-0.43
-0.39
-0.36
-0.36
-0.34
-0.35
-0.42
-0.48
-0.49-0.37
15.63
60.134
60.182
1903
-0.17
-0.09
-0.3
-0.47
-0.45
-0.52
-0.46
-0.55
-0.54
-0.58
-0.56
-0.63-0.44
15.56
60.008
60.02
1904
-0.65
-0.52
-0.59
-0.59
-0.51
-0.5
-0.5
-0.49
-0.5
-0.4
-0.31
-0.31-0.49
15.51
59.918
60.02
1905
-0.47
-0.71
-0.44
-0.53
-0.33
-0.31
-0.3
-0.3
-0.28
-0.37
-0.25
-0.18-0.37
15.63
60.134
60.104
1906
-0.14
-0.35
-0.29
-0.12
-0.27
-0.26
-0.32
-0.31
-0.34
-0.39
-0.53
-0.29-0.3
15.7
60.26
60.098
1907
-0.49
-0.55
-0.38
-0.55
-0.61
-0.55
-0.45
-0.49
-0.45
-0.37
-0.6
-0.48-0.5
15.5
59.9
60.008
1908
-0.44
-0.39
-0.6
-0.54
-0.51
-0.44
-0.49
-0.53
-0.43
-0.6
-0.65
-0.57-0.52
15.48
59.864
59.894
1909
-0.56
-0.54
-0.67
-0.61
-0.58
-0.5
-0.54
-0.34
-0.29
-0.36
-0.35
-0.61-0.49
15.51
59.918
59.918
1910
-0.33
-0.49
-0.38
-0.4
-0.49
-0.49
-0.4
-0.44
-0.38
-0.48
-0.61
-0.59-0.46
15.54
59.972
59.942
1911
-0.52
-0.66
-0.63
-0.64
-0.54
-0.49
-0.44
-0.44
-0.43
-0.4
-0.35
-0.24-0.48
15.52
59.936
59.99
1912
-0.33
-0.24
-0.39
-0.3
-0.35
-0.27
-0.46
-0.57
-0.54
-0.61
-0.49
-0.39-0.41
15.59
60.062
60.014
-0.47
-0.52
-0.49
-0.58
-0.52
-0.48
-0.37
-0.42
-0.48
-0.24
-0.07-0.42
15.58
60.044
60.158
1913
-0.4
1914
-0.04
-0.19
-0.26
-0.34
-0.22
-0.26
-0.32
-0.24
-0.32
-0.1
-0.32
-0.29-0.24
15.76
60.368
60.326
1915
-0.13
0.05
-0.36
0.03
-0.14
-0.07
-0.07
-0.13
-0.11
-0.26
-0.1
-0.29-0.13
15.87
60.566
60.362
1916
-0.19
-0.24
-0.41
-0.29
-0.41
-0.48
-0.3
-0.28
-0.34
-0.27
-0.47
-0.68-0.36
15.64
60.152
60.2
1917
-0.51
-0.84
-0.89
-0.52
-0.75
-0.33
-0.17
-0.24
-0.16
-0.41
-0.33
-0.92-0.51
15.49
59.882
60.044
1918
-0.4
-0.46
-0.38
-0.56
-0.63
-0.38
-0.4
-0.4
-0.33
-0.03
-0.32
-0.39-0.39
15.61
60.098
60.08
1919
-0.21
-0.17
-0.42
-0.01
-0.35
-0.25
-0.28
-0.26
-0.18
-0.31
-0.67
-0.47-0.3
15.7
60.26
60.248
1920
-0.16
-0.45
-0.07
-0.17
-0.09
-0.17
-0.21
-0.1
-0.18
-0.24
-0.47
-0.48-0.23
15.77
60.386
60.368
-0.09
-0.22
-0.2
-0.13
-0.16
-0.07
-0.14
-0.27
-0.22
-0.18
-0.43
-0.17-0.19
15.81
60.458
60.368
1921
1922
-0.36
-0.31
-0.31
-0.32
-0.31
-0.28
-0.27
-0.29
-0.29
-0.33
-0.32
-0.26-0.3
15.7
60.26
60.344
1923
-0.15
-0.45
-0.34
-0.42
-0.29
-0.19
-0.39
-0.39
-0.34
-0.28
0.01
-0.01-0.27
15.73
60.314
60.26
1924
-0.33
-0.24
-0.31
-0.36
-0.29
-0.24
-0.27
-0.25
-0.31
-0.3
-0.45
-0.58-0.33
15.67
60.206
60.308
1925
-0.42
-0.31
-0.23
-0.19
-0.29
-0.26
-0.23
-0.12
-0.18
-0.32
-0.12
0.01-0.22
15.78
60.404
60.422
1926
0.12
0.08
0.04
-0.2
-0.15
-0.14
-0.2
-0.01
-0.13
-0.07
-0.1
-0.14-0.08
15.92
60.656
60.506
1927
-0.21
-0.14
-0.27
-0.23
-0.24
-0.16
-0.11
-0.1
-0.06
-0.04
-0.2
-0.47-0.19
15.81
60.458
60.506
1928
-0.1
-0.19
-0.41
-0.32
-0.26
-0.29
-0.16
-0.2
-0.21
-0.18
-0.13
-0.2-0.22
15.78
60.404
60.332
1929
-0.48
-0.81
-0.41
-0.43
-0.38
-0.34
-0.32
-0.21
-0.28
-0.11
-0.11
-0.6-0.37
15.63
60.134
60.368
1972
1971
1970
1969
1968
1967
1966
1965
1964
1963
1962
1961
1960
1959
1958
1957
1956
1955
1954
1953
1952
1951
1950
1949
1948
1947
1946
1945
1944
1943
1942
1941
1940
1939
1938
1937
1936
1935
1934
1933
1932
1931
1930
-0.42
-0.1
0.07
-0.25
-0.27
-0.19
-0.08
-0.15
-0.01
-0.02
0.04
0.04
0
0.13
0.34
-0.16
-0.22
0.11
-0.28
0.09
0.16
-0.36
-0.38
0.15
0.12
-0.22
0.26
0.05
0.47
-0.19
0.25
0.03
-0.34
0.03
0.08
-0.16
-0.22
-0.25
-0.24
-0.27
0.21
0.04
84
-0.3
-0.35
0.21
-0.17
-0.2
-0.24
-0.08
-0.29
-0.19
0.22
0.15
0.17
0.22
0.06
0.23
-0.11
-0.36
-0.14
-0.08
0.19
0.1
-0.5
-0.3
-0.16
-0.18
-0.2
0.2
-0.07
0.29
0.12
-0.03
0.14
-0.12
0
0.08
0.05
-0.38
0.21
-0.11
-0.31
-0.27
-0.26
-0.19
-0.13
-0.3
-0.05
0.02
0.09
-0.09
-0.05
-0.23
-0.28
-0.1
0.03
0.1
-0.29
0.14
0.08
-0.11
-0.32
-0.41
-0.17
0.12
-0.11
-0.27
-0.16
-0.23
-0.26
-0.04
-0.14
-0.02
0.2
-0.21
0.04
-0.09
-0.14
-0.19
0.18
-0.24
-0.22
-0.21
-0.36
-0.32
-0.3
-0.07
-0.15
-0.04
-0.25
0.09
0.12
-0.15
-0.04
-0.11
-0.27
-0.23
-0.03
0.04
0.1
-0.12
0.09
0.12
-0.03
-0.3
-0.27
-0.22
0.22
0.07
-0.07
-0.18
-0.02
-0.09
0.03
0.13
0.16
0.11
0.04
0.05
0.11
0.07
-0.04
0.19
-0.11
-0.22
-0.29
-0.23
-0.19
-0.05
-0.14
-0.17
-0.05
-0.2
-0.01
0.11
-0.17
0.07
-0.12
-0.15
-0.16
-0.02
0
0.1
-0.11
0.02
0.11
0.08
-0.29
-0.17
-0.24
0.13
0.04
0.02
-0.1
-0.05
0.05
-0.13
-0.18
-0.08
0.19
0.11
0.06
-0.03
-0.07
0.07
-0.03
-0.11
-0.31
-0.06
-0.19
-0.15
0
-0.12
-0.21
0.02
-0.25
-0.01
0.03
-0.06
-0.07
0.05
-0.11
-0.12
-0.02
-0.04
0.12
0.06
0.11
0.06
0.15
-0.21
-0.09
-0.12
0.14
0.07
0.07
-0.1
-0.14
0.06
-0.06
-0.23
0.05
0.24
-0.07
0.14
0.08
-0.02
0.11
0.06
0.07
-0.05
-0.16
-0.14
0
-0.1
0.07
-0.17
-0.02
-0.16
-0.05
0.06
-0.06
-0.06
0.05
-0.18
-0.16
0.11
0.04
0.01
-0.21
0
0.05
0.08
0.07
-0.16
-0.19
0.07
0.06
0.04
-0.1
-0.14
-0.13
-0.07
-0.1
0
0.24
0.08
-0.02
0.06
0.13
0.09
0.11
0.1
0.11
-0.1
-0.05
-0.12
-0.08
0.07
-0.09
0.05
-0.13
-0.09
0.02
-0.04
-0.02
-0.14
-0.25
0
0.12
0.03
0.03
0.07
0.05
0.07
0.14
-0.22
-0.02
-0.1
0.09
0.1
0.13
-0.15
-0.01
-0.03
-0.11
-0.19
0.31
0.27
0.07
0
0.07
-0.02
0.11
0.12
0.13
0.04
-0.05
-0.01
-0.1
-0.06
0.04
-0.05
-0.04
-0.14
-0.06
0.04
-0.06
-0.05
0.02
-0.1
-0.29
0.14
0.03
-0.05
0.08
0.11
0.11
-0.28
-0.09
-0.07
0.09
0.11
0.11
0
-0.07
-0.1
-0.08
-0.09
-0.02
0.2
0.35
0.07
0.06
-0.07
0.08
-0.01
0.16
0.21
-0.05
-0.1
-0.11
-0.19
0.03
-0.01
2
0.05
-0.13
-0.12
0.04
0.01
0.14
-0.06
-0.03
-0.3
0.25
0.1
-0.07
0.03
-0.02
0.08
0.06
-0.18
-0.09
-0.04
0.09
0.12
-0.1
-0.01
-0.04
0
0.08
-0.07
0.28
0.32
0.35
0.12
0.31
-0.04
-0.17
0.25
0.15
-0.02
0.03
-0.01
-0.13
-0.01
-0.07
0
0.01
-0.08
-0.06
0.11
-0.03
-0.08
-0.08
-0.15
-0.28
0.17
0.01
-0.02
-0.1
-0.15
0.07
0.13
-0.27
-0.23
0.03
-0.09
-0.27
-0.03
-0.43
-0.08
-0.12
-0.03
-0.14
0.07
0.02
0.1
0.03
0.04
-0.11
-0.06
0.12
-0.06
-0.33
-0.02
-0.29
-0.21
0
-0.17
0.1
0.15-0.06 0.15
-0.18 -0.18-0.19
-0.24 -0.24-0.03 -0.03
0.18
-0.1 -0.1-0.09
-0.09-0.06
-0.24-0.06 -0.24 -0.06
-0.08 -0.08-0.16 -0.16
-0.39 -0.22
-0.01
0.03
-0.11
0.19
-0.08
0.14
0.25
-0.2 -0.26
-0.31 -0.16
-0.28 -0.15
0.06
-0.06
0.19 -0.05
-0.23-0.19 -0.23 -0.19
-0.25 -0.09
-0.22 -0.08
-0.19 -0.08
-0.43 -0.08
-0.21
-0.06
0.29
-0.04
0.08
-0.16
0.07
0.04
0.12
0.05
0.13 -0.04
0.37
-0.26
0.03
0-0.1
0.03
-0.22 -0.22-0.15 -0.15
-0.1 -0.11
-0.55 -0.55 -0.23 -0.23
-0.18 -0.1
-0.07 -0.05
-0.07 -0.13
0
0.04
0.1
0.02
0.06
0.22
0.06
0.06
0.06
0.02
0.1
0
15.94
15.81
15.97
16.03
15.91
15.94
15.94
15.84
15.78
16.07
16.04
16.03
16
16.04
16.12
16.05
15.74
15.84
15.85
16.1
16.02
15.95
15.81
15.91
15.92
15.92
15.92
16.06
16.22
16.06
16.06
16.06
15.96
16.02
16.1
16
15.9
15.85
15.89
15.77
15.9
15.95
15.87
60.692
60.458
60.746
60.854
60.638
60.692
60.692
60.512
60.404
60.926
60.872
60.854
60.8
60.872
61.016
60.89
60.332
60.512
60.53
60.98
60.836
60.71
60.458
60.638
60.656
60.656
60.656
60.908
61.196
60.908
60.908
60.908
60.728
60.836
60.98
60.8
60.62
60.53
60.602
60.386
60.62
60.71
60.566
60.698
60.632
60.686
60.746
60.728
60.674
60.632
60.536
60.614
60.734
60.884
60.842
60.842
60.896
60.926
60.746
60.578
60.458
60.674
60.782
60.842
60.668
60.602
60.584
60.65
60.656
60.74
60.92
61.004
61.004
60.908
60.848
60.824
60.848
60.872
60.8
60.65
60.584
60.506
60.536
60.572
60.632
60.47
1973
0.28
0.2
0.15
0.12
0.15
0.07
0.04
0
-0.09
-0.05
0.08
16.08
60.944
60.704
1974
-0.36
-0.2
-0.15
-0.13
-0.11
-0.09
-0.07
-0.12
-0.18
-0.27-0.18
15.82
60.476
668
1975
-0.03
-0.07
-0.02
-0.06
-0.03
-0.08
-0.11
-0.16
-0.2
-0.27
-0.3 -0.12
15.88
60.584
.488
1976
-0.17
-0.31
-0.39
-0.16
-0.28
-0.18
-0.18
-0.18
-0.16
-0.33
-0.19
-0.14-0.22
15.78
60.404
60.632
1977
-0.15
0.08
0.14
0.14
0.1
0.13
0.05
0
0.08
0.01
0.16
-0.05
0.06
16.06
60.908
60.686
1978
0.05
0.01
0.06
-0.01
-0.07
-0.13
-0.05
-0.16
-0.05
-0.08
0.07
-0.06-0.03
15.97
60.746
60.854
1979
-0.05
-0.1
0.04
-0.09
-0.02
0.07
0.01
0.07
0.12
0.16
0.16
0.39
0.06
16.06
60.908
60.878
1980
0.16
0.16
0.05
0.13
0.19
0.13
0.08
0.05
0
0.02
0.19
0.08
0.1
16.1
60.98
60.98
1981
0.34
0.2
0.23
0.18
0.05
0.1
0.02
0.1
0.06
0.03
0.05
0.28
0.14
16.14
61.052
60.974
1982
0
0.05
-0.06
0.09
0.07
-0.02
0.01
0
0.11
0.09
0.02
0.3
0.05
16.05
60.89
61.058
1983
0.47
0.4
0.28
0.18
0.16
0.16
0.18
0.25
0.23
0.15
0.28
0.14
0.24
16.24
61.232
60.986
1984
0.17
0.04
0.09
-0.01
0.15
0.01
0.01
0.09
0.02
-0.01
-0.11
-0.27
0.02
16.02
60.836
60.956
1985
0.02
-0.13
0.01
0.02
0.05
-0.04
-0.05
0.05
0
0.05
-0.02
0.02
0
16
60.8
60.866
1986
0.17
0.14
0.11
0.11
0.1
0.13
0.04
0.05
0.07
0.12
0.02
0.06
0.09
16.09
60.962
60.992
1987
0.17
0.35
0.06
0.15
0.19
0.17
0.3
0.28
0.33
0.22
0.2
0.38
0.23
16.23
61.214
61.142
1988
0.42
0.24
0.31
0.32
0.27
0.28
0.2
0.21
0.24
0.2
0.09
0.22
0.25
16.25
61.25
61.196
1989
0.12
0.2
0.2
0.13
0.12
0.12
0.22
0.21
0.18
0.23
0.15
0.26
0.18
16.18
61.124
61.268
1990
0.28
0.37
0.58
0.38
0.27
0.33
0.27
0.3
0.24
0.41
0.42
0.3
0.35
16.35
61.43
61.292
1991
0.35
0.4
0.24
0.42
0.31
0.39
0.36
0.27
0.25
0.24
0.15
0.15
0.29
16.29
61.322
61.274
1992
0.39
0.37
0.31
0.15
0.19
0.17
-0.02
0.04
0.01
0.02
-0.02
0.15
0.15
16.15
61.07
61.178
1993
0.35
0.36
0.3
0.23
0.25
0.16
0.15
0.11
0.05
0.15
-0.01
0.15
0.19
16.19
61.142
61.16
1994
0.23
-0.01
0.26
0.28
0.29
0.27
0.23
0.25
0.26
0.35
0.44
0.31
0.26
16.26
61.268
61.304
1995
0.5
0.64
0.4
0.3
0.29
0.37
0.4
0.44
0.33
0.4
0.38
0.25
0.39
16.39
61.502
61.322
1996
0.18
0.36
0.23
0.16
0.28
0.25
0.28
0.22
0.17
0.13
0.16
0.28
0.22
16.22
61.196
61.424
1997
0.28
0.36
0.36
0.32
0.31
0.43
0.45
0.48
0.52
0.59
0.49
0.53
0.43
16.43
61.574
61.385
Anomalies are expressed in degrees Celsius and are relative to the 1961-1990 mean.
36
http://www.ncdc.noaa.gov/ol/climate/research/1997/climate97.htm
Climate of 1997 - 1997 Warmest Year of Century
NCDC / Climate Resources / Climate Research / Climate of 1997 / Search / Help
National Oceanic and Atmospheric Administration
DEPARTMENT DE COMMENTS
The Climate of 1997
THE
пояя
-
CHATE STATES OF AMOUNT
Global Temperature Index:
$
1997 Warmest Year of Century
or
Rob Quayle, Tom Peterson, Catherine Godfrey, Alan Basist
National Climatic Data Center, Asheville, NC
January 12, 1998
Global Temperature Index
National Climatic Data Center ! NESDIS / NOAA
0.50
1997: +0.42 C / +0.76 F
0.25
Degrees C
0.00
-0.25
-0.50
1900
1920
1940
1960
1980
2000
Year
37
1997 was the warmest year of this century, based on land and ocean surface temperature data,
reports a team of scientists from the National Oceanic and Atmospheric Administration's National
Climatic Data Center in Asheville, NC.
7/13/98 11:07
1 of 3
UNITED STATES DEPARTMENT OF
NATIONAL
COMMERCE
OCEANIC AND
ATMOSPHERIC
ADMINISTRATION
WASHINGTON, D.C. 20230
Kerl
NOAA 98-1
CONTACT: Patricia Viets, NOAA
FOR IMMEDIATE RELEASE
(301) 457-5005
1/8/98
Dane Konop, NOAA
(301) 713-2483
1997 WARMEST YEAR OF CENTURY, NOAA REPORTS
1997 was the warmest year of this century, based on land and ocean surface
temperature data, reports a team of scientists from the National Oceanic and Atmospheric
Administration's National Climatic Data Center in Asheville, N. C.
Led by the center's Senior Scientist Tom Karl, the team analyzed temperatures from
around the globe during the years 1900 to 1997 and back to 1880 for land areas. For 1997,
land and ocean temperatures averaged three-quarters of a degree Fahrenheit above normal.
(Normal is defined by the mean temperature, 61.7 degrees F, for the 30-years 1961-90.)
37
The 1997 figure exceeds the previous record warm year, 1990, by 0.15 degrees Fahrenheit.
The record-breaking warm conditions of 1997 continues the pattern of very warm
global temperatures. Nine of the past eleven years have been the warmest on record.
"Land temperatures did not break the previous record set in 1990, but 1997 was one
of the five warmest years since 1880," said Karl. Including 1997, the top ten warmest years
over the land have all occurred since 1981, and the warmest five years all since 1990. Land
temperatures for 1997 averaged three-quarters of a degree above normal, falling short of the
1990 record by one-quarter of a degree.
Ocean temperatures during 1997 also averaged three-quarters of a degree above
normal, which makes it the warmest year on record, exceeding the previous record warm
years of 1987 and 1995 by 0.3 of a degree Fahrenheit.
With the new data factored in, global temperature warming trends now exceed 1.0
degree Fahrenheit per 100 years, with land temperatures warming at a somewhat faster rate.
"It is likely that the sustained trend toward increasingly warmer global temperatures is
related to anthropogenic increases in greenhouse gases," Karl said.
###
Joseph E. Aldy
07/19/98 10:43:35 PM
Record Type:
Record
To:
Matthew C. Weinzierl/CEA/EOP
CC:
Subject: annotated input on aldy questions
Below you will find Rosina's comments on some of the outstanding issues in the report. I would
appreciate it if you could follow up on a couple of these:
On #2, could you copy pp. 28, 37 of the Working Group I report (science) -- this should have the quotes
Rosina references.
On #3, could you check figure 12 and see if it has CO2 ppm of 710 in 2100.
On #4, could you read Gibbons testimony (see my Admin Testimonies binder on the right wall of my office;
Gibbons testified at the 2/12 hearing) and find/copy the part of his testimony that says this.
Could you also print out Rosina's email and include that in our fact-check binder.
Thanks,
Joe
Forwarded by Joseph E. Aldy/CEA/EOP on 07/19/98 10:33 PM
Rosina M. Bierbaum
07/17/98 07:33:19
Record Type:
Record
To:
Joseph E. Aldy/CEA/EOP
CC:
Peter W. Backlund/OSTP/EOP
Subject: annotated input on aldy questions
More on Monday
1. p. 9, continual measurements of atmospheric CO2 at Mauna Loa began in 1957. The data set we
received from the CDIAC web page for Keeling and Whorf's work indicates that the period of the record is
1958-1996. One of our interns spoke with Keeling today who told us the measurement at Mauna Loa
began in 1958 (while measurement at the South Pole began in 1957). Is your understanding that 1957 or
1958 is the right year? March '58
2. p. 10, the 1990's will be the warmest decade for at least the past 600 years. I read the Mann et al
paper last night, and they do not make this point. The paragraph in our report refers to global average
annual temperature, while the Mann et al results that are related to this statement are based on analyses
of northern hemisphere climate/temperature proxies since 1400. Further, the authors note simply that 3
years in this decade are "hotter" than any others with a statistical significance at the 99.7% level (pp.
783-784 of Nature article). I did not see any statistical tests by decade to determine if the 1990's (or the
past ten years) are "hotter" than any decade in the constructed temperature record. I think we have two
options: 1) cite this paper, and use a line like "A recent study indicates that the Northern Hemisphere
appears to have experienced its three warmest years since 1400 during the present decade"; or 2) make a
reference to the historical temperature record, where I believe we can say something like "The 1990's will
likely be the warmest decade on record." If we go with the second option, we will need a paper to back it
up. Note that this appears to be related to the reference to this century being the hottest since 1400 on p. i
of the Executive Summary. ipcc wg1 spm (p. 32) says" As an average over the Northern
Hemisphere for summer, recent decades appear to be the warmest since at least 1400 from the
limited available evidience." It also says "Ice core data from several sites suggest that the 20th
century is at least as warm as any century in the past 600 years, although the recent warming is
not exceptional everywhere." So these are two separate points that can be cited, and then Mann
et al could be used to speak about the 1990's. See also memo developed for POTUS by
NOAA/USGCRP in next e-mail
3. p. 10, Figure 12, CO2 Concentration in 2100 under IS92a scenario. As I understand from our RA
who used to work on the charts (he left CEA last week as a part of the annual CEA summer turnover), we
do not have the exact value for the 2100 CO2 concentration. Do you have any paper that indicates
explicitly the CO2 concentration in 2100 in the IS92a scenario? i forwarded wigley's and Mike M's
answer on this to you, which is that ipcc did not publish a number. But, 710 was the number the
IPCC and the GCRP leadership agreed we should cite.
4. pp. 10-11, Earth has not experienced CO2 concentrations at 700 ppm for 50 million years. We
could not find the reference to this in the Berner 1994. If someone on your staff who is familiar with this
paper or this reference could point it out for us, I would appreciate it Hope Peter sent you the file we
have on this. You can cite Jack Gibbon's testimony
5. p. 11, thermal lag and sea level rise from a doubling of CO2. In reading the Manabe and Stouffer
papers, it appears that the 1% concentration increase per annum to 2xCO2 refers to a doubling of
pre-industrial, not current CO2 concentration. While the authors appear to not explicitly state the
concentration that serves as their starting point, they do call it the "normal value" (Manabe and Stouffer
1993, p. 215) and the "initial condition, which is in a quasi-equilibrium state" (Manabe and Stouffer 1994, p.
6). I have interpreted these to mean pre-industrial. If I have missed the reference to the exact
concentration they use as their starting point, or have misinterpreted this, please let me know. If not, then
we will change the reference to approximately twice pre-industrial (about 560 ppm) from approximately
700. Further, their analysis tends to indicate that a 1% concentration increase per annum to 2xCO2 would
reach this concentration in 70 years, stabilize through 500 years, and in total result in a 1 meter sea level
rise, not an additional 1m rise after 2100 (Manabe and Stouffer 1993, p. 216; Manabe and Stouffer 1994,
p. 9 and Figure 3). Below is how I propose to rewrite the second half of this paragraph:
"Even if greenhouse gas concentrations were stabilized at about 560 ppm (double pre-industrial
concentration) within the next century, the sea level would continue to rise for several centuries because of
the large inertia in the coupled ocean-atmosphere-climate system (Warrick et al. 1996). If the carbon
dioxide concentration were to increase 1% per year until it reached approximately 560 ppm, and then were
to stabilize, the sea level would continue to rise from thermal expansion alone (Manabe and Stouffer 1993,
1994)."
This is ok,
Climate Change 1995
The Science of Climate Change
Edited by J.T. Houghton,
L.G. Meira Filho, B.A. Callander, N. Harris,
A. Kattenberg and K. Maskell
Production Editor: J.A. Lakeman
Contribution of WGI to the Second Assessment Report
of the Intergovernmental Panel on Climate Change
Published for the Intergovernmental Panel on Climate Change
CAMBRIDGE
UNIVERSITY PRESS
28
Technical Summary
term events such as volcanic eruptions and El Niño are
interglacial (the last 10,000 years, known as the
taken into account. After adjustment for these transient
Holocene). Changes in annual mean temperature of about
effects, both tropospheric and surface data show slight
5°C occurred over a few decades, at least in Greenland and
warming (about 0.1°C per decade for the troposphere and
the North Atlantic, and were probably linked to changes in
nearly 0.2°C per decade at the surface) since 1979.
oceanic circulation. These rapid changes suggest that
Cooling of the lower stratosphere has been observed
climate may be quite sensitive to internal or external
since 1979 both by satellites and weather balloons, as noted
climate forcings and feedbacks. The possible relevance of
in IPCC (1992) and IPCC (1994). Current global mean
these rapid climate changes to future climate is discussed
stratospheric temperatures are the coldest observed in the
in Section F.5.
relatively short period of the record. Reduced stratospheric
Temperatures have been less variable during the last
temperature has been projected to accompany both ozone
10,000 years. Based on the incomplete evidence available,
losses in the lower stratosphere and atmospheric increases
it is unlikely that global mean temperatures have varied by
of carbon dioxide.
more than 1°C in a century during this period.
C.2 Is the 20th century warming unusual?
C.3 Has the climate become wetter?
In order to establish whether the 20th century warming is
As noted in IPCC (1992), precipitation has increased over
part of the natural variability of the climate system or a
land in high latitudes of the Northern Hemisphere,
response to anthropogenic forcing, information is needed
especially during the cold season. A step-like decrease of
on climate variability on relevant time-scales. As an
precipitation occurred after the 1960s over the subtropics
average over the Northern Hemisphere for summer, recent
and tropics from Africa to Indonesia. These changes are
decades appear to be the warmest since at least 1400 from
consistent with changes in streamflow, lake levels and soil
the limited available evidence (Figure 10). The warming
moisture (where data analyses are available). Precipitation,
over the past century began during one of the colder
averaged over global land areas, increased from the start of
periods of the last 600 years. Prior to 1400 data are
the century up to about 1960. Since about 1980
insufficient to provide hemispheric temperature estimates.
precipitation over land has decreased (Figure 11).
Ice core data from several sites suggest that the 20th
There is evidence to suggest increased precipitation over
century is at least as warm as any century in the past 600
the central equatorial Pacific Ocean in recent decades, with
38
years, although the recent warming is not exceptional
decreases to the north and south. Lack of data prevents us
everywhere.
from reaching firm conclusions about other precipitation
Large and rapid climatic changes occurred during the
changes over the ocean.
last glacial period (around 20,000 to 100,000 years ago)
Estimates suggest that evaporation may have increased
and during the transition period towards the present
over the tropical oceans (although not everywhere) but
decreased over large portions of Asia and North America.
There has also been an observed increase in atmospheric
1.0
0.8
Northern Hemisphere Summer (JJA)
water vapour in the tropics, at least since 1973.
for decades from 1400-09 to 1970-79,
0.6
relative to 1961-90
Temperature anomoly (°C)
0.4
60
0.2
0
-0.4
Precipitation anomaly (mm)
30
-0.2
0
-0.6
-0.8
-30
-1.0
1500
1600
1700
1800
1900
-60
Year
1900
1920
1940
1960
1980
Year
Figure 10: Decadal summer (June to August) temperature index
for the Northern Hemisphere (to 1970-1979) based on 16 proxy
Figure 11: Changes in land-surface precipitation averaged over
records (tree-rings, ice cores, documentary records) from North
regions between 55°S and 85°N. Annual precipitation departures
America, Europe and East Asia. The thin line is a smoothing of
from the 1961-90 period are depicted by the hollow bars. The
the same data. Anomalies are relative to 1961 to 1990.
continuous curve is a smoothing of the same data.
37
Technical Summary
qualitative agreement between observations and those
0.75
model predictions that either include aerosol effects or do
(a)
OBS
AT2x=1.5°C
not depend critically on their inclusion. As in the
0.50
Temperature anomaly (°C)
T2x=2.5°C
T2x=4.5°C
quantitative studies, one must be cautious in assessing
0.25
consistency because the expected climate change signal
due to human activities is still uncertain, and has changed
0.00
as our ability to model the climate system has improved. In
-0.25
addition to the surface warming, the model and observed
commonalities in which we have most confidence include
-0.50
1850
1880
1910
1940
1970
2000
stratospheric cooling, reduction in diurnal temperature
Time (years)
range, sea level rise, high latitude precipitation increases
and water vapour and evaporation increase over tropical
oceans.
0.75
(b)
OBS
AT2x=1.5°C
Temperature anomaly (°C)
0.50
T2x=2.5°C
E.6 Overall assessment of the detection and attribution
T2x=4.5°C
issues
0.25
In summary, the most important results related to the issues
0.00
of detection and attribution are:
-0.25
The limited available evidence from proxy climate
indicators suggests that the 20th century global mean
-0.50
1850
1880
1910
1940
1970
2000
temperature is at least as warm as any other century
Time (years)
since at least 1400 AD. Data prior to 1400 are too
Figure 16: Observed changes in global mean temperature over
sparse to allow the reliable estimation of global mean
1861 to 1994 compared with those simulated using an upwelling
temperature (see Section C.2).
diffusion-energy balance climate model. The model was run first
with forcing due to greenhouse gases alone (a) and then with
Assessments of the statistical significance of the
greenhouse gases and aerosols (b).
observed global mean temperature trend over the last
century have used a variety of new estimates of
the model-observed correspondence in these experiments
natural internal and externally forced variability.
occurs at the largest spatial scales - for example,
These are derived from instrumental data, palaeodata,
temperature differences between hemispheres, land and
simple and complex climate models, and statistical
ocean, or the troposphere and stratosphere. Model
models fitted to observations. Most of these studies
predictions are more reliable at these spatial scales than at
have detected a significant change and show that the
the regional scale. Increasing confidence in the
observed warming trend is unlikely to be entirely
identification of a human-induced effect on climate comes
natural in origin.
primarily from such pattern-based work. For those seasons
during which aerosol effects should be most pronounced
More convincing recent evidence for the attribution
the pattern correspondence is generally higher than that
of a human effect on climate is emerging from
achieved if model predictions are based on changes in
pattern-based studies, in which the modelled climate
greenhouse gases alone (Figure 17).
response to combined forcing by greenhouse gases
As in the global mean studies, pattern-oriented detection
and anthropogenic sulphate aerosols is compared
work relies on model estimates of internal natural
with observed geographical, seasonal and vertical
variability as the primary yardstick for evaluating whether
patterns of atmospheric temperature change. These
observed changes in temperature patterns could be due to
studies show that such pattern correspondences
natural causes. Concerns remain regarding the reliability of
increase with time, as one would expect as an
this yardstick.
anthropogenic signal increases in strength.
Furthermore, the probability is very low that these
E.5 Qualitative consistency
correspondences could occur by chance as a result of
In addition to quantitative studies, there are broad areas of
natural internal variability only. The vertical patterns
Global-scale temperature patterns
and climate forcing over the past
six centuries
Michaet E. Mann, Raymond S. Bradley* & Malcolm K. Hughest
Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003-5820, USA
Laboratory of Tree Ring Research, University of Arizona, Tucson, Arizona 85721, USA
Spatially resolved global reconstructions of annual surface temperature patterns over the past six centuries are based
on the multivariate calibration of widely distributed high-resolution proxy climate Indicators. Time-dependent
correlations of the reconstructions with time-series records representing changes In greenhouse-gas concentrations,
solar Irradiance, and volcanic aerosols suggest that each of these factors has contributed to the climate variability of
the past 400 years, with greenhouse gases emerging as the dominant forcing during the twentieth century. Northern
Hemisphere mean annual temperatures for three of the past eight years are warmer than any other year since (at least)
AD 1400.
Knowing both the spatial and temporal patterns of climate change
instrumental records have been formed into annual mean anoma-
over the past several centuries remains a key to assessing a possible
lies relative to the 1902-80 reference period, and gridded onto a
anthropogenic impact on post-industrial climate¹. In addition to
5° X5° grid (yielding 11 temperature grid-point series and 12
the possibility of warming due to increased concentrations of
precipitation grid-point series dating back to 1820 or earlier) similar
greenhouse gases during the past century, there is evidence that
to that shown in Fig. 1b. Certain densely sampled regional den-
both solar irradiance and explosive volcanism have played an
droclimatic data sets have been represented in the network by a
important part in forcing climate variations over the past several
smaller number of leading principal components (typically 3-11
centuries". The unforced 'natural variability' of the climate system
depending on the spatial extent and size of the data set). This form
y also be quite important on multidecadal and century
of representation ensures a reasonably homogeneous spatial sam-
escales If a faithful empirical description of climate variability
pling in the multiproxy network (112 indicators back to 1820).
could be obtained for the past several centuries, a more confident
Potential limitations specific to each type of proxy data series
estimation could be made of the roles of different external forcings
must be carefully taken into account in building an appropriate
and internal sources of variability on past and recent climate.
network. Dating errors in a given record (for example, incorrectly
Because widespread instrumental climate data are available for
assigned annual layers or rings) are particularly detrimental if
only about one century, we must use proxy climate indicators
mutual information is sought to describe climate patterns on a
combined with any very long instrumental records that are available
year-by-year basis. Standardization of certain biological proxy
to obtain such an empirical description of large-scale climate
records relative to estimated growth trends, and the limits of
variability during past centuries. A variety of studies have sought
constituent chronology segment lengths (for example, in dendro-
to use a 'multiproxy' approach to understand long-term climate
climatic reconstructions), can restrict the maximum timescale of
variations, by analysing a widely distributed set of proxy and
climate variability that is recorded, and only a limited subset of the
instrumental climate indicators's to yield insights into long-
indicators in the multiproxy network may thus 'anchor in' the
term global climate variations. Building on such past studies, we
longest-term trends (for example, variations on timescales greater
take a new statistical approach to reconstructing global patterns of
than 500 years). However, the dendroclimatic data used were
annual temperature back to the beginning of the fifteenth century,
carefully screened for conservative standardization and sizeable
based on the calibration of multiproxy data networks by the
segment lengths. Moreover, the mutual information contained in
dominant patterns of temperature variability in the instrumental
a diverse and widely distributed set of independent climate indica-
record.
tors can more faithfully capture the consistent climate signal that is
Using these statistically verifiable yearly global temperature
present, reducing the compromising effects of biases and weak-
reconstructions, we analyse the spatiotemporal patterns of climate
nesses in the individual indicators.
change over the past 500 years, and then take an empirical approach
Monthly instrumental land air and sea surface temperature¹⁰
to estimating the relationship between global temperature changes,
grid-point data (Fig. 1b) from the period 1902-95 are used to
variations in volcanic aerosols, solar irradiance and greenhouse-gas
calibrate the proxy data set. Although there are notable spatial
concentrations during the same period.
gaps, this network covers significant enough portions of the globe to
form reliable estimates of Northern Hemisphere mean temperature,
Data
and certain regional indices of particular importance such as the
We use a multiproxy network consisting of widely distributed high-
'NINO3' eastern tropical Pacific surface temperature index often
quality annual-resolution proxy climate indicators, individually
used to describe the El Niño phenomenon. The NINO3 index is
llected and formerly analysed by many palaeoclimate researchers
constructed from the eight grid-points available within the con-
ails and references are available: see Supplementary Informa-
ventional NINO3 box (5° S to 5° N, 90-150° W).
1). The network includes (Fig. la) the collection of annual-
resolution dendroclimatic, ice core, ice melt, and long historical
Multiproxy calibration
records used by Bradley and Jones6 combined with other coral, ice
Although studies have shown that well chosen regional paleoclimate
core, dendroclimatic, and long instrumental records. The long
reconstructions can act as surprisingly representative surrogates for
NATUREIVOL 392123 APRIL 1998
779
JUN. 19. 1998
2:28PM
EPA HQ LIBRARY
Barnda
NO.703
P.2/12
405
ARTICLES
12 Jenkins. G. M. & Walls. p. G. Special Analysis and in Application (Holden-Day. San
40. Fairbanks, R. G. & Matthews, R. K. QUEL Res. 10, 181-197 (1978).
Francisco, 19831.
41. Chappell, J. Bull god Sec, Am 85, 553-570 (1974).
33. Barrodale, I. & Ericksson. R. E. Geophysics 45, 420-432 (1980).
42. Chappell, 1. Search H 99-101 (19832.
r Rind, D., Percet, D. Brocker, W., Mcintyre, A. A Ruddiman, W. ("Emate Dynam. 1. 1-31
43. Aharon. P. Name 30, 720-723 (1983).
(1956).
44. Climap project members Qual. Rrs. 21, 123-224 (1984).
33. Jourel, 1- Lorius. c. Meriivat, L & Petk, 1. R. Symp. on Abrupt Climatic Changes (In the
43. Dorige, R. E. Fairbanks, R. O., Benninger. L K. & Maurasse, L Science 219, 1423-1425
presel.
(1983).
36. Johnson, R. O. & Andrews, 1. T. Paleage., Paleoctiment 53. 107-138 (1986).
46. Edwards, R. L Chen, J. H. & Waseerburg. Q. J. Earth planet, Srl. LETL 81, 175-192 (1986).
37. Genther, C. " al Nature 329, 414-412 (1987).
47. Rech, N. Name 317, 797-799 (1985).
38. Broccker. W. S. in Milankoctich and Climate Vol. 2 leds Berger, A. L of all 687-698
48. Pimients, P. Dural, P. & Lipenkov, V. Ya. Ann. Glarid (submitted).
(Reidel, Dordrecht, 1984).
49. Kukla, G. in Climatic Change (ed. Cribbin, 1.1 114-129 (Cambridge University Press, 1978).
39. Mesolella. K. 1. Matthews, R. K., Broecker, W. S. & Thurber. D. L & Ord 77. 250-274
30. Bernard, E. A. Daker Symposium, Union Internationale power Ende du Quaternaire
119691.
(1986).
Vostok ice core provides 160,000-year record of
atmospheric CO2
J. M. Barnola, D. Raynaud', Y.S. Korotkevich' & C. Lorius'
Laboratoire de Glaciologie et de Ocophysique de l'Environnement, BP 96, 38402 Saint Martin d'Hères Cedex, France
1 Arctic and Antarctic Research Institute, Beringa Street 38, Leningrad 199226, USSR
Direct evidence of past atmospheric CO2 changes has been extended to the past 160,000 years from the Vostok Ice core.
These changes are most notably an inherent phenomenon of change between glacial and Interglacial periods. Besides this
major 100,000-year cycle, the CO2 record seems to exhibit a cyclic change with a period of some 21,000 years.
ALTHOUGH the first direct CO2 measurements in the atmos-
320
phere were made in the second half of the nineteenth century,
atmospheric CO₂ variations have been monitored in a systematic
and reliable manner only since 1958. Fortunately, nature has
been taking continuous samples of the atmosphere at the surface
280
of the ice sheets throughout the ages. This natural sampling
process takes place when snow is transformed into ice by sinter-
ing at the surface of the melt-free zones of the Ice sheets, with
pores of the newly formed ice. After pore closure the gas remains
CO2 (p.p.m.v.)
240
air becoming isolated from the surrounding atmosphere in the
stored in the ice moving within the Ice sheet. During this natural
air sampling and storage process, different mechanisms could
alter the original atmospheric composition¹² But by choosing
200
appropriate sampling sites, ice cores (for example see ref. 1)
and experimental methods', past CO2 changes in the atmosphere
can be determined with high confidence by analysing the air
160
enclosed in the pores of the ice.
0
400
800
1200
1600
2000
Previous results from ice-core analysis have already provided
Depth (m)
important reliable information on the "pre-Industrial" CO2 level
Fig. 1 CO2 concentrations (p.p.m.v.) plotted against depth in the
and the recent CO2 increase induced by anthropogenic
Vostok Ice core. The best estimates' of the CO₂ concentrations
activities⁴. Striking CO2 changes have also been detected in
are indicated by dots and the envelope shown has been plotted
this way in the Ice record covering the last 30-40 kyr7-10, includ-
taking Into account the different uncertainty sources.
ing the large CO2 increase associated with the climatic shift
from the Last Glacial Maximum (-18 kyr BP) to the Holocene.
Because of the extremely low temperatures at Vostok (present-
method is based on crushing the Ice under vacuum without
day mean annual temperature is -55.5°C) and the good core
melting, expanding the gas released during the crushing In a
quality, the 2,083-m-long ice core recovered by the Soviet
pre-evacuated sampling loop, and analysing the CO₂ concentra-
Antarctic Expeditions at Vostok (East Antarctica) provides a
tions by gas chromatography.
unique opportunity to extend the Ice record of atmospheric CO₂
The analytical system, except for the stainless steel container
over the last glacial-interglacial cycle back to the penultimate
in which the ice is crushed, is calibrated for each ice sample
Ice age about 160 kyr ago". Over this timescale a high correlation
measurement with a standard mixture of CO2 in nitrogen and
is found between CO2 concentrations and Antarctic climate,
oxygen. The corresponding accuracy (2o) is evaluated from the
with significant oscillatory behaviour of CO2 between high levels
standard deviation of the residuals corresponding to the calibra-
during Interglacial and low levels during glacial periods. The
tion regression and ranges from 3 to 12 parts per million by
CO2 record also seems to exhibit R cyclic change with & period
volume (p.p.m.v.) for the measurements presented in this article.
of ~21 kyr, that is, around the orbital period corresponding to
We recently discovered an additional error due to our experi-
the precession.
mental system when a significant amount of water vapour is
detected by the gas chromatograph. In such a case, selective
Experimental procedure
CO₂ transport by water vapour (similar to that observed by
Gas extraction and measurements were performed with the
Neftel el al.4) back to the ice crushing container is suspected of
'Grenoble analytical setup' described by Barnola el al.". The
depleting the CO₂ from the air extracted from the ice and Injected
CLIMATE CHANGE
State of Knowledge
October 1997
Climate Change Over the Next 100 Years
Atmospheric Carbon Dioxide Concentration
Where is the climate headed? If the
and Temperature Change
world proceeds on a "business as
750
usual" path, atmospheric CO2 concen-
trations will likely be more than 700
ppm by 2100, and they will still be
rising. This is nearly double the cur-
700
rent level and much more than dou-
ble the preindustrial level of 280 ppm
(Figure 10). State-of-the-art climate
models suggest that this will result in
an increase of about 3.5° F in global
temperatures over the next century.
600
This would be a rate of climate
change not seen on the planet for at
least the last 10,000 years. It is the
combined threat of elevated concen-
trations of greenhouse gases and this
unprecedented rate of increase that
500
causes great concern.
What are the projected extent and
pattern of warming over the globe?
The higher latitude regions will warm
relatively more than areas nearer to
the equator. The land surface will
400
warm more than the oceans, and
there will be less variation in tempera-
ture from night to day.
Current
Level
300
Carbon dioxide (ppmv)
4
250
2
200
Temperature change (°C)
0
Current
-2
Level
-4
Figure 10. The CO2 level has increased sharply
since the beginning of the Industrial Era and is
-6
already outside the bounds of natural variabili-
ty seen in the climate record of the last
150
100
50
0
160,000 years. Continuation of current levels
Thousands of years ago
of emissions will raise concentrations to over
CO₂ concentration in the
Temperature changes through time
700 ppm by 2100, a level not experienced
atmosphere (Antarctic Ice Core)
compared to the present temperature
since about 50 million years ago.
9
and fresh and wastewater treatment and distribution. This infrastructure is extremely vulnerable
to extreme weather events. I want to emphasize that one can't point to any single extreme
weather event today and say for sure that global warming caused it. But we can say that such
events are examples of the kinds of impacts we expect to occur with greater frequency in a
warmer world. There are likely to be more "storms of the century," "100-year floods," and severe
droughts in the future than there were in the past.
The temperature increases, intensification of the water cycle, and sea-level rise already
observed over the past century are all consistent with theoretical predictions of the consequences
of an enhanced greenhouse effect. They are also consistent with the projections from simulations
of global climate by general circulation models.
The IPCC "business as usual" scenario indicates that even with continued technological
improvement (such as energy efficiency increases of about 1 percent per year), unless policies to
control emissions of greenhouse gases are implemented, the atmospheric concentrations of these
gases will be much higher by 2100. Assuming "business as usual" CO₂ concentrations will reach
about 710 parts per million by volume (ppm), a level higher than any seen on this planet in the
last 50 million years (Figure 2). For context, the pre-industrial level of CO₂ was about 280 ppm,
and has increased to the current level of about 360 ppm. If realized, this increase is expected to
result in significant future climate changes:
Global surface temperature would increase an average of another 2-6 °F by 2100, with a
best estimate of 3.5 °F. Higher Northern latitudes are projected to warm by more.
Temperature change of this magnitude would be faster than any observed changes in the
last 10,000 years.
Global mean sea level would rise another 6 to 38 inches by the end of the 21st century.
The rate of evaporation would increase as the climate warms, leading to an increase in
average global precipitation as well as frequency of intense rainfall and floods in some
regions. In some regions, the soil moisture will decrease, leading to increased frequency
and intensity of droughts.
Most of the climate impacts have been evaluated for a world at equilibrium after
greenhouse gases have reached either 550 or 700 ppm. But stabilizing at double the pre-
industrial concentration of greenhouse gases, or 550 ppm, would require massive intervention.
On the other hand, a continuation of "business as usual" implies a world with far higher
concentrations and far greater effects. The Geophysical Fluid Dynamics Laboratory at Princeton
has recently modeled the effects of doubling and quadrupling the level of greenhouse gases:
A quadrupling of such concentrations (to about 1100 ppm) is likely to increase
temperatures in North America by 15 - 20° F, as opposed to the 5-10° F expected from
doubling.
In the growing season, soil moisture deficits would approach 30 - 50 percent for
quadrupling, as opposed to 10 - 30 percent for doubling.
6
TESTIMONY OF
JOHN H. GIBBONS
ASSISTANT TO THE PRESIDENT FOR SCIENCE AND TECHNOLOGY
BEFORE THE
COMMITTEE ON SCIENCE
UNITED STATES HOUSE OF REPRESENTATIVES
HEARING ON GLOBAL CLIMATE CHANGE
FEBRUARY 12, 1998
Introduction
Thank you for providing the opportunity to talk to you today about the U.S. Global
Change Research Program's (USGCRP) current and planned activities. The best way to describe
how these activities relate to the Kyoto Protocol is to describe the current state of scientific
knowledge of climate change, a significant portion of which is the product of our Nation's strong
support for the USGCRP since its inception.
The USGCRP began as a Presidential Initiative in 1989, and was codified by the Global
Change Research Act of 1990. The program has been strongly backed by every Administration
and Congress since its inception. The FY 1999 Budget Request demonstrates President
Clinton's ongoing commitment to the program, with an overall request of approximately $1.86
billion dollars. The President and the Vice President believe that global change research is one
of the foundations of a sustainable future. The Administration looks forward to working with the
Congress to carry on this bipartisan tradition of support for sound science.
I want to emphasize that the planning of the USGCRP budget and research programs for
this year, or any year, were not directly impacted by the Kyoto negotiations. The USGCRP is
not a policy-driven program, but rather is driven by critical science questions and the need to
develop a long term understanding of the scientific information that is of most relevance to U.S.
policy makers. The results obtained through the sustained USGCRP research effort over the past
decade have been very helpful in U.S. government climate change policy deliberations. As we
look ahead to the next decade of global change research, it is apparent that much of the USGCRP
research effort is addressing questions of ecological impacts and rates of change, both of which
are relevant to the decisions the world must make about long term emissions trajectories beyond
2010.
The USGCRP, along with the global change research efforts supported by other countries
such as Japan and the European nations, has provided the knowledge base for national and
international decision making on climate change issues, both by providing research results
directly to national governments and to the international process of the Intergovernmental Panel
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
15
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
years ago (Berner 1994). It is anticipated that if the CO₂ levels increase to this level, then the global
42
10
average temperature will rise by between 1.8 and 6.3° F by the year 2100 (Kattenberg et al. 1996)
This range of temperature impacts was developed by the Intergovernmental Panel on Climate
Change using a set of alternative plausible assumptions about climatic response to higher greenhouse,
gas concentrations, the effects of aerosols (such as sulfate particles) that can offset warming, and
43
several economic parameters. In general, the temperature change experienced would be greater at
higher latitudes than at lower latitudes, and greater over land than over the oceans (Kattenberg et al
44
1996).
Global warming of the magnitude projected by the IPCC will have many effects due to
changes in local temperature and precipitation patterns, an induced rise in sea level, and altered
distribution of freshwater supplies. By 2100, sea level is expected to rise by 6 to 37 inches (Warrick
et al. 1996). An average 20-inch sea level rise would result in substantial loss of coastal land in the
45
46
United States especially along the southern Atlantic and Gulf Coasts, which are currently subsiding
47
and are particularly vulnerable (Titus et al. 1991; Smith and Tirpak 1989; see Figure 13). Even if
to
greenhouse gas concentrations were stabilized within the next century, the sea level would continue
to rise for several centuries because of the large inertia in the coupled ocean-atmosphere-climate.
50
system (Warrick et al. 1996). For example, if the carbon dioxide concentration were to increase 1%
per year until it reached
approximately 700 ppm, roughly
Figure 13. U.S. Coastal Lands at Risk from a
double the current level, and then
20-inch Sea Level Rise in 2100
5
were to stabilize, the sea level
4,000
would continue to rise from
Wetlands
thermal expansion alone. Several
Drylands
3,000
researchers estimate that after 500
years, the sea level would have
risen one meter in addition to the
rise experienced through 2100
Square miles
2,000
due to thermal expansion of the
ocean waters and would still be
1,000
rising, even though the
temperature changes had largely
been stabilized (Manabe and
0
Northeast
Mid-
South-
Stouffer 1993, 1994).
S & W
Louisiana
Rest of
West
Atlantic
Atlantic
Florida
Gulf
Coast
Note: Assumes currently developed areas are protected.
Source: Titus et al. 1991.
11
what about Berner?
6
Climate Models - Projections of Future Climate
A. KATTENBERG, F. GIORGI, H. GRASSL, G.A. MEEHL, J.F.B. MITCHELL,
R.J. STOUFFER, T. TOKIOKA, A.J. WEAVER, T.M.L. WIGLEY
Contributors:
P.A. Barros, M. Beniston, G. Boer, T.A. Buishand, R. Colman, J. Copeland, P.M. Cox,
A. Cress, J.H. Christensen, U. Cubasch, M. Deque, G. Flato, C. Fu, I. Fung, J. Garratt,
S. Ghan, H. Gordon, J.M. Gregory, P. Guttorp, A. Henderson-Sellers, K.J. Hennessy,
H. Hirakuchi, G.J. Holland, B. Horton, T. Johns, A. Jones, M. Kanamitsu, T. Karl,
D. Karoly, A. Keen, T. Kittel, T. Knutson, T. Koide, G. Können, M. Lal, R. Laprise,
R. Leung, A. Lupo, M. Lynch, C.-C. Ma, B. Machenhauer, E. Maier-Reimer,
M.R. Marinucci, B. McAvaney, J. McGregor, L.O. Mearns, N.L. Miller, J. Murphy,
A. Noda, M. Noguer, J. Oberhuber, S. Parey, H. Pleym, J. Raisanen, D. Randall,
S.C.B. Raper, P. Rayner, J. Roads, E. Roeckner, G. Russell, H. Sasaki, F. Semazzi,
C.A. Senior, S.V. Singh, C. Skelly, K. Sperber, K. Taylor, S. Tett, H. von Storch,
K. Walsh, P. Whetton, D. Wilks, F.I. Woodward, F. Zwiers
Modelling Contributors: see tables
SUMMARY
General circulation models (GCMs), and in particular
corresponding projections presented in IPCC (1990) partly
coupled atmosphere-ocean general circulation models
because of the inclusion of aerosols in the pre-1990
(AOGCMs), are the state-of-the-art tool for understanding
radiative forcing history and partly for other reasons,
the Earth's present climate, and for estimating the effects
including revised understanding of the carbon cycle (see
on past and future climate of various natural and human
Chapter 2). Incorporating possible effects of future changes
factors. This chapter focuses on the estimation of the
of anthropogenic aerosol concentrations implied by the
effects on future climate of changes in atmospheric
IS92 scenarios leads to lower projections of temperature
composition due to human activities. An important
change of between 1°C and 3.5°C by 2100. In all cases
development since IPCC(1990) is the improved
these projections would represent a substantial warming of
quantification of some radiative effects of aerosols, and
climate. Uncertainty in the projections is introduced by
climate projections presented here include, in addition to
uncertainty in the climate sensitivity and by uncertainty in
the effects of increasing greenhouse gas concentrations,
the radiative forcing scenarios.
some potential effects of anthropogenic aerosols.
Climate simulations using GCMs require substantial
Projections of continental scale climate change
computer resources and it is not generally feasible to carry
Spatial patterns of climate change in recent publications
separate simulations for a large number of forcing
tend to confirm and extend the 1990 results. With
cenarios. In order to interpolate and extrapolate global
increasing greenhouse gases, the warming of the land is
mean projections from GCMs to a wider range of
generally more than that of the oceans, similar to
greenhouse gas and aerosol scenarios, simple upwelling
equilibrium simulations. There is a minimum warming
diffusion-energy balance models are employed. These
around Antarctica and in the northern North Atlantic which
44
models are calibrated to give the same globally averaged
is associated with deep oceanic mixing in those areas. The
temperature response as the global coupled GCMs. Since
maximum annual mean warming occurs in high northern
the amount of anthropogenic aerosols has most probably
latitudes associated with reduced sea ice cover. The
grown alongside the growth in fossil fuel use since pre-
warming here is largest in late autumn and winter, but
industrial times, the estimated historical changes of
becomes negligible for a short period in summer. There is
radiative forcing up to 1990 used in this report for global
little seasonal variation of the warming in low latitudes or
mean temperature projections include a component due to
over the southern circumpolar ocean. The diurnal range of
aerosols.
land temperature is reduced in most seasons and most
regions.
Projections of global mean temperature
Including the effects of aerosols in simulations of future
Using the IS92 emission scenarios, projected global mean
climate leads to a somewhat reduced warming in middle
temperature changes were calculated up to 2100 assuming
latitudes of the Northern Hemisphere and the maximum
low (1.5°C), "best estimate" (2.5°C) and high (4.5°C)
winter warming in high northern latitudes is less extensive.
values of the climate sensitivity (similar to IPCC (1990)).
All models produce an increase in global mean
Taking account of increases of greenhouse gas
precipitation. If the direct effect of sulphate aerosol forcing
concentrations alone (i.e., assuming aerosol concentrations
is taken into account, the total increase in global
remain constant at 1990 levels) the models project an
precipitation is smaller, as would be expected with the
increase in global mean temperature relative to the present
smaller net warming. Precipitation increases in high
of between 1 and 4.5°C by 2100 for the full range of
latitudes in winter and in most cases the increases extend
PCC scenarios. These projections are lower than the
well into mid-latitudes. In the tropics, the patterns of
CLIMATE CHANGE
State of Knowledge
October 1997
transmission. This could result in 50 million to
ally exceed 40 inches. A CO2 level of 1100 ppm
80 million additional malaria cases per year
could produce a sea level rise of 80 inches or
worldwide by 2100.
even more, depending on the extent to which
the Greenland and Antarctic ice sheets melt.
Rising Sea Level - Rising sea level erodes
beaches and coastal wetlands, inundates low-
A 20-inch sea level rise would double the
lying areas, and increases the vulnerability of
global population at risk from storm surges,
coastal areas to flooding from storm surges and
from roughly 45 million at present to over 90
intense rainfall. By 2100, sea level is expected
million, and this figure does not account for
43
to rise by 6 to 37 inches. A 20-inch sea level
any increases in coastal populations. A 40-
rise will result in substantial loss of coastal land
inch rise would triple the number.
Y
in the United States, especially along the south-
ern Atlantic and Gulf coasts, which are subsid-
South Florida is highly vulnerable to sea level
ing and are particularly vulnerable. The oceans
rise (Figure 16). A third of the Everglades has
will continue to expand for several centuries
an elevation of less than 12 inches. Salt water
after temperatures stabilize. Because of this, the
intrusion would adversely affect delicate eco-
sea level rise associated with CO2 levels of 550
logical communities and degrade the habitat
ppm (double pre-industrial levels) could eventu-
for many species.
South Florida
Shoreline Change after a
1-Meter Rise in Sea Level
Orlando
Tampa
Fort Myers
Areas shown.in.red.are
subject to Inundation after
T-meter rise seallevel
Source: Elevations from USGS digital
Prepared by the U.S. Geological Survey,
Figure 16. Sea level rise could
inundate many low-lying coastal
areas in Florida, and will increase
the vulnerability of all such areas
to storm surges.
13
Changes in Sea Level
R.A. WARRICK, C. LE PROVOST, M.F. MEIER, J. OERLEMANS,
P.L. WOODWORTH
Contributors:
R.B. Alley, R.A. Bindschadler, C.R. Bentley, R.J. Braithwaite, J.R. de Wolde,
B.C. Douglas, M. Dyurgerov, N.C. Flemming, C. Genthon, V. Gornitz, J. Gregory,
W. Haeberli, P. Huybrechts, T. Jóhannesson, U. Mikolajewicz, S.C.B. Raper,
D.L. Sahagian, R.S.W. van de Wal, T.M.L. Wigley
Changes in Sea Level
364
which tend to raise sea level. However, the potential
because much of the rise has already been determined by
future effect on sea level from such sources is
past changes in radiative forcing, due to lags in the
probably relatively small, of the order of a few
response of the oceans and ice masses. For this same
centimetres during the next century.
reason, in model simulations sea level continues to rise
over many centuries even after concentrations of
An exact accounting of the past sea level rise is difficult,
greenhouse gases are stabilised. In contrast, the scientific
particularly in the light of the large uncertainties associated
uncertainties - as reflected partly in intra-model
with the mass balances of the ice sheets. However, the
uncertainties in the choice of individual model parameter
observed rise lies well within the combined ranges of
values, and partly in inter-model uncertainties in the choice
uncertainty of the above factors.
of methods for climate, glacier and ice sheet modelling -
Projections of future changes in sea level as a
make a very large difference in the estimate of future sea
consequence of greenhouse-gas-induced warming were
level rise.
made for each of the six IPCC IS92 emission scenarios,
A major source of uncertainty concerns the polar ice
with and without the effect of aerosol changes after 1990,
sheets. Not only is there a lack of understanding of the
for the period 1990 to 2100. In addition, high, middle and
current mass balance, but there is also considerable
low estimates, using a range of parameter values based on
uncertainty regarding the possible dynamic responses on
key model uncertainties, were made for IS92a (the
time-scales of centuries. Concern has been expressed that
emission scenario most comparable to the IPCC (1990)
the West Antarctic Ice Sheet might "surge", causing a rapid
Scenario A, the so-called "Business-as-usual" scenario).
rise in sea level. The current lack of knowledge regarding
The results showed that:
the specific circumstances under which this might occur,
either in total or in part, limits the ability to quantify the
for Scenario IS92a, sea level is projected to be about
risk. Nonetheless, the likelihood of a major sea level rise
50 cm higher than today by the year 2100, with a
by the year 2100 due to the collapse of the West Antarctic
range of uncertainty of 20-86 cm;
Ice Sheet is considered low.
The changes in future sea level will not occur uniformly
for the range of emission scenarios IS92a-f using
around the globe. Recent coupled atmosphere-ocean model
"best-estimate" model parameters, sea level is
experiments suggest that the regional responses could
projected to be 38-55 cm higher than today by the
differ significantly, due to regional differences in heating
year 2100;
and circulation changes. In addition, geological and
geophysical processes cause vertical land movements and
the extreme range of projections, taking into account
thus affect relative sea levels on local and regional scales.
both emission scenarios and model uncertainties, is
Finally, extreme sea level events - tides, waves and storm
13-94 cm;
surges - could be affected by regional climate changes but
are, at present, difficult to predict.
most of the projected rise in sea level is due to thermal
Overall, the basic understanding of climate-sea level
expansion, followed by increased melting of glaciers
relationships has not changed fundamentally since IPCC
and ice caps. On this time-scale, the contributions
(1990). The estimates of global sea level rise presented
made by the major ice sheets are relatively minor, but
here are lower than those presented in IPCC (1990), due
are a major source of uncertainty.
primarily to significantly lower estimates of global
temperature change which drive the projections of sea
It is evident that the choice of emission scenario makes
level rise. Thus, if global warming were to occur more
relatively little difference to the projected rise in sea level,
rapidly than expected, the rate of sea level rise would
especially for the first half of the next century. This is
consequently be higher.
CLIMATE CHANGE
State of Knowledge
October 1997
transmission. This could result in 50 million to
ally exceed 40 inches. A CO2 level of 1100 ppm
80 million additional malaria cases per year
could produce a sea level rise of 80 inches or
worldwide by 2100.
even more, depending on the extent to which
the Greenland and Antarctic ice sheets melt.
Rising Sea Level - Rising sea level erodes
beaches and coastal wetlands, inundates low-
A 20-inch sea level rise would double the
lying areas, and increases the vulnerability of
global population at risk from storm surges,
coastal areas to flooding from storm surges and
from roughly 45 million at present to over 90
intense rainfall. By 2100, sea level is expected
million, and this figure does not account for
to rise by 6 to 37 inches. A 20-inch sea level
any increases in coastal populations. A 40-
rise will result in substantial loss of coastal land
inch rise would triple the number.
Y
in the United States, especially along the south-
ern Atlantic and Gulf coasts, which are subsid-
South Florida is highly vulnerable to sea level
ing and are particularly vulnerable. The oceans
rise (Figure 16). A third of the Everglades has
will continue to expand for several centuries
an elevation of less than 12 inches. Salt water
after temperatures stabilize. Because of this, the
intrusion would adversely affect delicate eco-
sea level rise associated with CO2 levels of 550
logical communities and degrade the habitat
ppm (double pre-industrial levels) could eventu-
for many species.
South Florida
Shoreline Change after a
1-Meter Rise in Sea Level
Orlando
Tampa
Fort Myers
Areas relate
which after
ealevel
Figure 16. Sea level rise could
inundate many low-lying coastal
areas in Florida, and will increase
the vulnerability of all such areas
to storm surges.
13
level
Rise
http://www.erols.com/jtitus/Holding/NRJ.htm
By
James G. Titus, Richard A. Park, Stephen P. Leatherman,
J. Richard Weggel, Michael S. Greene, Paul W. Mausel,
Scott Brown, Cary Gaunt, Manjit Trehan, and Gary Yohe
ABSTRACT
Previous studies suggest that the expected global warming from the greenhouse effect could raise sea
level 50 to 200 centimeters (2 to 7 feet) in the next century or two. This article presents the first
nationwide assessment of the primary impacts of such a rise on the United States: (1) the cost of
protecting ocean resort communities by pumping sand onto beaches and gradually raising barrier
islands in place; (2) the cost of protecting developed areas along sheltered waters through the use of
levees (dikes) and bulkheads; and (3) the loss of coastal wetlands and undeveloped lowlands. The
total cost for a one meter rise would be $270-475 billion, ignoring future development.
48
We estimate that if no measures are taken to hold back the sea, a one meter rise in sea level would
inundate 14,000 square miles, with wet and dry land each accounting for about half the loss. The
1500 square kilometers (600-700 square miles) of densely developed coastal lowlands could be
protected for approximately one to two thousand dollars per year for a typical coastal lot. Given
high coastal property values, holding back the sea would probably be cost-effective.
The environmental consequences of doing so, however, may not be acceptable. Although the most
common engineering solution for protecting the ocean coast--pumping sand--would allow us to keep
our beaches, levees and bulkheads along sheltered waters would gradually eliminate most of the
nation's wetland shorelines. To ensure the long-term survival of coastal wetlands, federal and state
environmental agencies should begin to lay the groundwork for a gradual abandonment of coastal
lowlands as sea level rises.
INTRODUCTION
At the turn of the century, scientific opinion regarding the practical implications
of the greenhouse effect was sharply divided. Since the 1860s, people had known that
by absorbing outgoing infrared radiation, atmospheric CO₂ keeps the earth warmer than
it would otherwise be (Tyndall, 1863). Svante Arrhenius (1896), who coined the term
"greenhouse effect," pointed out that the combustion of fossil fuels might increase
the level of CO₂ in the atmosphere, and thereby warm the earth several degrees.
Because the 19th century had experienced a cooling trend, however, others speculated
that the oceans and plant life might gradually reduce CO₂ levels and cause an ice age
(Barrel et al., 1919).
Throughout the first half of the 20th century, scientists generally recognized the
significance of the greenhouse effect, but most thought that humanity was unlikely to
substantially alter its impact on climate. The oceans contain 50 times as much CO₂ as
the atmosphere, and physical laws governing the relationship between the
concentrations of CO₂ in the oceans and in the atmosphere seemed to suggest that this
ratio would remain fixed, implying that only 2 percent of the CO₂ released by human
activities would remain in the atmosphere. This complacency, however, was shattered
in 1957 when Revelle and Seuss (1957) demonstrated that the oceans could not absorb
CO₂ as rapidly as humanity was releasing it: "Human beings are now carrying out a
6/9/98
THE POTENTIAL EFFECTS OF
GLOBAL CLIMATE CHANGE
ON THE UNITED STATES
REPORT To CONGRESS
Editors: Joel B. Smith and Dennis Tirpak
United States Environmental Protection Agency
Office of Policy, Planning and Evaluation
Office of Research and Development
December 1989
Smith/Tirpele
Chapter 7
sand costs would increase by the same pattern
Cost of Raising Barrier Islands
nationwide as they would in Florida.
The data provided by Weggel focused only on
Results
elevating roads, buildings, and bulkheads. Thus,
Titus and Greene do not consider the cost of
Loss of Wetlands and Dryland
replacing sewers, water mains, or buried cables. On
the other hand, Weggel's cost factors assume that
Table 7-4 illustrates 95% confidence intervals
rebuilt roads would be up to engineering standards;
for the nationwide losses of wetlands and dryland.
it is possible that communities would tolerate
If all shorelines were protected, a 1-meter rise
substandard roads. In addition, the census data
would result in a loss of 50 to 82% of U.S. coastal
Titus and Greene used were only available for
wetlands, and a 2-meter rise would result in a loss
incorporated communities, many of which are part
of 66 to 90%. If only the densely developed areas
barrier island and part mainland; thus, the data
were protected, the losses would be 29 to 69% and
provide only a rough measure of typical road
61 to 80% for the 1- and 2-meter scenarios,
density.
respectively. Except for the Northeast, no
protection results in only slightly lower wetland loss
Sensitivity of Sand Costs to Increased Scarcity of
than protecting only densely developed areas.
Sand
Although the estimates for the Northeast, mid-
Atlantic, the gulf regions outside Louisiana, and the
Finally, Titus and Greene made no attempt to
Florida peninsula are not statistically significant (at
determine how realistic their assumption was that
the 95% confidence levels), results suggest that
wetlands loss would be least in the Northeast and
Northwest.
Table 7-4. Nationwide Loss of Wetlands and Drylandᵃ (95% confidence intervals)
49
Square milesᵇ
Baseline
50-cm rise
100-cm rise
200-cm rise
Wetlands
Total protection
N.C.
4944-8077
6503-10843
8653-11843
(38-61)
(50-82)
(66-90)
Standard
1168-3341
2591-5934
3813-9068
4350-10995
protection
(9-25)
(20-45)
(29-69)
(33-80)
No protection
N.C.
2216-5592
3388-8703
3758-10025
(17-43)
(26-66)
(29-76)
Dryland
Total protection
0
0
0
0
Standard
1906-3510
2180-6147
4136-9186
6438-13496
protection
No protection
N.C.
3315-7311
5123-10330
8791-15394
Wetlands loss refers to vegetative wetlands only.
b Numbers in parentheses are percentages.
NC = Not calculated.
Source: Titus and Greene (Volume B).
140
7
Changes in Sea Level
R.A. WARRICK, C. LE PROVOST, M.F. MEIER, J. OERLEMANS,
P.L. WOODWORTH
Contributors:
R.B. Alley, R.A. Bindschadler, C.R. Bentley, R.J. Braithwaite, J.R. de Wolde,
B.C. Douglas, M. Dyurgerov, N.C. Flemming, C. Genthon, V. Gornitz, J. Gregory,
W. Haeberli, P. Huybrechts, T. Jóhannesson, U. Mikolajewicz, S.C.B. Raper,
D.L. Sahagian, R.S.W. van de Wal, T.M.L. Wigley
364
Changes in Sea Level
which tend to raise sea level. However, the potential
because much of the rise has already been determined by
future effect on sea level from such sources is
past changes in radiative forcing, due to lags in the
probably relatively small, of the order of a few
response of the oceans and ice masses. For this same
centimetres during the next century.
reason; in model simulations sea level continues to rise
over many centuries even after concentrations of
An exact accounting of the past sea level rise is difficult,
greenhouse gases are stabilised. In contrast, the scientific
particularly in the light of the large uncertainties associated
uncertainties - as reflected partly in intra-model
with the mass balances of the ice sheets. However, the
uncertainties in the choice of individual model parameter
observed rise lies well within the combined ranges of
values, and partly in inter-model uncertainties in the choice
uncertainty of the above factors.
of methods for climate, glacier and ice sheet modelling -
Projections of future changes in sea level as a
make a very large difference in the estimate of future sea
consequence of greenhouse-gas-induced warming were
level rise.
made for each of the six IPCC IS92 emission scenarios,
A major source of uncertainty concerns the polar ice
with and without the effect of aerosol changes after 1990,
sheets. Not only is there a lack of understanding of the
for the period 1990 to 2100. In addition, high, middle and
current mass balance, but there is also considerable
low estimates, using a range of parameter values based on
uncertainty regarding the possible dynamic responses on
key model uncertainties, were made for IS92a (the
time-scales of centuries. Concern has been expressed that
emission scenario most comparable to the IPCC (1990)
the West Antarctic Ice Sheet might "surge", causing a rapid
Scenario A, the so-called "Business-as-usual" scenario).
rise in sea level. The current lack of knowledge regarding
The results showed that:
the specific circumstances under which this might occur,
either in total or in part, limits the ability to quantify the
for Scenario IS92a, sea level is projected to be about
risk. Nonetheless, the likelihood of a major sea level rise
50 cm higher than today by the year 2100, with a
by the year 2100 due to the collapse of the West Antarctic
range of uncertainty of 20-86 cm;
Ice Sheet is considered low.
The changes in future sea level will not occur uniformly
for the range of emission scenarios IS92a-f using
around the globe. Recent coupled atmosphere-ocean model
"best-estimate" model parameters, sea level is
experiments suggest that the regional responses could
projected to be 38-55 cm higher than today by the
differ significantly, due to regional differences in heating
year 2100;
and circulation changes. In addition, geological and
geophysical processes cause vertical land movements and
the extreme range of projections, taking into account
thus affect relative sea levels on local and regional scales.
both emission scenarios and model uncertainties, is
Finally, extreme sea level events - tides, waves and storm
13-94 cm;
surges - could be affected by regional climate changes but
are, at present, difficult to predict.
most of the projected rise in sea level is due to thermal
Overall, the basic understanding of climate-sea level
expansion, followed by increased melting of glaciers
relationships has not changed fundamentally since IPCC
and ice caps. On this time-scale, the contributions
(1990). The estimates of global sea level rise presented
made by the major ice sheets are relatively minor, but
here are lower than those presented in IPCC (1990), due
are a major source of uncertainty.
primarily to significantly lower estimates of global
temperature change which drive the projections of sea
It is evident that the choice of emission scenario makes
level rise. Thus, if global warming were to occur more
relatively little difference to the projected rise in sea level,
rapidly than expected, the rate of sea level rise would
especially for the first half of the next century. This is
consequently be higher.
LETTERS TO NATURE
scales of the disk correspond to those of the large-scale radio jets
and lobes. For example, the kinetic timescale in which the radio
On much larger scales, dust has been seen before in many
other elliptical galaxies9.13, as lanes, disks and filamentary
jet structures change is about 10⁶ yr. while the synchrotron
structures. These structures, often assumed to be the remnants
lifetimes of radio regions range from ~ 10h yr for the hot spots to
of a captured late-type galaxy, are generally 10 to 100 times
~ 108 yr for the more extended lobes. Similarly, the total
'equipartition' energy in the lobes, ~ 10⁵⁷ erg, corresponds to
larger than the disk shown here. Although their presence may be
correlated statistically with nuclear activity, their dynamic and
the mass energy available in the disk: for a dust/gas ratio similar
decay timescales are much longer than those associated with
to our Galaxy, the disk mass is about 10⁵ solar masses.
AGN phenomena.
Converted to energy at an efficiency of 1%, a value often
If the disk is in simple circular rotation, measurements of the
assumed, this mass would yield 10⁵⁷ erg.
rotation curve at HST resolution should lead to an estimate of
These facts, combined with the alignment of the radio axis and
the central mass that is free from the ambiguities of estimates
disk spin axis, lead us to describe the feature seen in NGC4261 as
derived from the orbits of stars. Measurements of the turbulent
the 'outer accretion disk' of the central active nucleus. The
velocities should help to constrain models of the nature of the
bright unresolved point at the centre of the disk probably
angular momentum and mass transport in the disk¹¹.
represents thermal optical emission from the hot inner accretion
disk. The outer disk supplies fuel by way of the inner disk to the
central engine, probably a massive black hole, in quantities that
Received January: accepted May 1993.
determine the luminosity, size and orientation of the extended
1. Rees. M. J. A. Rev. Astr. Astrophys. 22. 471-506 (1984).
radio emission.
2. Baade, D. & Lucy. L. B. Messenger 61, 24-27 (1990).
3. Petetier, R. F., Davies. R.L... Illingworth, G. D., Davis, L. E. & Cawson, M. Astr. J. 100.
Hints of such features have been obtained earlier: a previous
1091-1142(1989).
ground-based image of NGC4261 showed a small central dust
4. Davies, R.L. & Birkinshaw, M. Astrophys. J. 303. L45-49 (1986).
5. Jacoby. G. H., Ciardullo. R., Ford, H. C. Astrophys.J 356, 332-349 (1990).
region (~ 3" in diameter), but neither its size nor morphology
6. de Vaucouleurs. G. Astrophys J. suppl. Series 6. 213-234 (1961).
could be accurately determined. Molecular radio observations¹²
7. Binggeli. 8., Sandage. A. & Tammann, G. A. AstrJ. 90. 1681-1758 (1985).
of Centaurus A have indicated the presence of rotating cold
8. Mollenhoff, C., Bender, R. Astr. Astrophys. 174. 63-66 (1987).
9. Kormendy. J., Stauffer, J. in IAU Symp. No. 127. Structure and Dynamics of Elliptical
material in a rather larger region (~ 1 kpc). To our knowledge,
Galaxies (ed. de Zeeuw, P. T.) 405-406 (Reidel, Dordrecht. 1987).
however, the image presented here is the first of an accretion
10. Birkinshaw, M. & Davies, R. C. Astrophys.J. 291. 32-44 (1985).
11. Pringle, J. E. A. Rev. Astr. Astrophys. 19. 137-162 (1981).
disk where size and structure can be directly associated with the
12. Israel, F. P. et al. Astr. Astrophys. 227. 342-350 (1990).
results of nuclear activity.
13. Bertola. F. in IAU Symp. No. 127. Structure and Dynamics of Elliptical Galaxies' (ed. de
Zeeuw P. T.) 135-143 (Reidel. Dordrecht. 1987).
Century-scale effects of increased
global model with realistic geography. The atmospheric GCM
includes the seasonal variation of insolation, and predicted
atmospheric CO₂ on the
cloud over which depends only on the relative humidity. It has
nine vertical finite difference levels. The horizontal distribution
ocean-atmosphere system
of predicted variables is represented by spherical harmonics (15
associated Legendre functions for each of 15 Fourier compo-
Syukuro Manabe &Ronald J. Stouffer
nents) and by corresponding grid-point values. The oceanic
GCM uses a finite difference technique with a regular grid
Geophysical Fluid Dynamics Laboratory/NOAA Princeton University,
system which has horizontal spacing (4.5° latitude) by (3.75°
PO Box 308, Princeton, New Jersey 08542. USA
longitude) and 12 vertical levels. This model is similar to that of
Bryan and Lewis¹², except that it mimics the effect of mesoscale
SEVERAL studies have addressed the likely effects of CO2-induced
eddies by the diffusion of potential temperature and salinity on
climate change over the coming decades 1-10, but the longer-term
isopycnal surfaces. The atmospheric and oceanic GCMs interact
effects have received less attention. Yet these effects could be very
through the exchange of heat, water and momentum.
significant, as persistent Increases in global mean temperatures
Assuming the temporal variations of atmospheric CO₂ in
may ultimately influence the large-scale processes in the coupled
Fig. 1a, three 500-year integrations of the coupled model are
ocean-atmosphere system that are thought to play a central part
done. One is a standard integration (S) in which the atmospheric
in determining global climate. The thermohaline circulation is
CO2 remains unchanged. In a second integration (4XC), the
one such process - Broecker has argued¹¹ that it may have
CO₂ concentration increases by 1% yr⁻¹ (compound) (close to
undergone abrupt changes in response to rising temperatures
the 'business as usual' (BAU) radiative forcing rate obtained by
and Ice-sheet melting at the end of the last glacial period. Here we
the Intergovernmental Panel on Climate Change¹³; IPCC) until
use a coupled ocean-atmosphere climate model to study the
it reaches four times the normal value at about the 140th year
evolution of the world's climate over the next few centuries,
and remains unchanged thereafter. In a third integration (2xC),
driven by doubling and quadrupling of the concentration of
the CO2 concentration also increases at the rate of 1% yr⁻¹
atmospheric CO2. We find that the global mean surface air
(compound) until it doubles around the 70th year and remains
temperature increases by about 3.5 and 7 °C, respectively, over
unchanged thereafter. By comparing the three integrations, one
500 years, and that sea-level rise owing to thermal expansion
can evaluate the long-term impact of the doubling and
alone is about 1 and 2 m respectively (ice-sheet melting could
quadrupling of atmospheric CO₂ on the coupled system.
make these values much larger). The thermal and dynamical
The initial conditions for these integrations have realistic
structure of the oceans changes markedly in the quadrupled-CO₂
climate in particular, the ocean settles into a new stable state in
seasonal and geographical distributions of surface temperature,
which the thermohaline circulation has ceased entirely and the
surface salinity and sea ice; the atmospheric and oceanic
thermocline deepens substantially. These changes prevent
components of the model are nearly in equilibrium with these
the ventilation of the deep ocean and could have a profound
distributions. When the time integration of the model starts
from this initial condition, the model climate rapidly drifts
system. Impact on the carbon cycle and biogeochemistry of the coupled
towards its own equilibrium state. To minimize the drift, the
The model used here consists of a general circulation model
fluxes of heat and water at the ocean-atmosphere interface are
(GCM) of the atmosphere and oceans, and a simple model of
adjusted by amounts that vary seasonally and geographically8.
land surfaces that includes the budgets of heat and water. It is a
These adjustments, applied to all three integrations identified
above, are independent of the anomalies of temperature and
NATURE
VOL 364
15 JULY 1993
215
LETTERS TO NATURE
cales of the disk correspond to those of the large-scale radio jets
On much larger scales, dust has been seen before in many
and lobes. For example, the kinetic timescale in which the radio
other elliptical galaxies9.13, as lanes, disks and filamentary
structures change is about 10⁶ yr. while the synchrotron
structures. These structures, often assumed to be the remnants
etimes of radio regions range from ~ 10h yr for the hot spots to
of a captured late-type galaxy, are generally 10 to 100 times
108 yr for the more extended lobes. Similarly, the total
larger than the disk shown here. Although their presence may be
'equipartition energy in the lobes, ~ 10⁵⁷ erg, corresponds to
correlated statistically with nuclear activity, their dynamic and
the mass energy available in the disk: for a dust/gas ratio similar
decay timescales are much longer than those associated with
to our Galaxy, the disk mass is about 10⁵ solar masses.
AGN phenomena.
Converted to energy at an efficiency of 1%, a value often
If the disk is in simple circular rotation, measurements of the
assumed, this mass would yield 10⁵⁷ erg.
rotation curve at HST resolution should lead to an estimate of
These facts, combined with the alignment of the radio axis and
the central mass that is free from the ambiguities of estimates
disk spin axis, lead us to describe the feature seen in NGC4261 as
derived from the orbits of stars. Measurements of the turbulent
the 'outer accretion disk' of the central active nucleus. The
velocities should help to constrain models of the nature of the
bright unresolved point at the centre of the disk probably
angular momentum and mass transport in the disk¹¹.
represents thermal optical emission from the hot inner accretion
disk. The outer disk supplies fuel by way of the inner disk to the
central engine, probably a massive black hole, in quantities that
Received January: accepted May 1993.
determine the luminosity, size and orientation of the extended
1. Rees, M. 1. A. Rev. Astr. Astrophys. 22. 471-506 (1984).
2. Baade. D. & Lucy. L. B. Messenger 61. 24-27 (1990).
radio emission.
3. Peletier, R. F., Davies. R. L.. Illingworth, G. D., Davis, L. E. & Cawson, M. Astr. J. 100.
Hints of such features have been obtained earlier: a previous
1091-1142(1989).
ground-based image of NGC4261 showed a small central dust
4. Davies, R. L. & Birkinshaw, M. Astrophys. J. 303. L45-49 (1986).
5. Jacoby. G. H., Ciardullo, R., Ford. H. C. Astrophys. 356, 332-349 (1990).
region 3" in diameter), but neither its size nor morphology
6. de Vaucouleurs, G. Astrophys. suppl. Series 6. 213-234 (1961).
could be accurately determined. Molecular radio observations¹²
7. Binggeli. B., Sandage. A. & Tammann, G. A. Astr.J. 90, 1681-1758 (1985).
8. Mollenhoff, C., Bender, R. Astr. Astrophys. 174. 63-66 (1987).
of Centaurus A have indicated the presence of rotating cold
9. Kormendy, J.. Stauffer, J. in IAU Symp. No. 127, Structure and Dynamics of Elliptical
material in a rather larger region (~ 1 kpc). To our knowledge,
Galaxies (ed. de Zeeuw. P. T.) 405-406 (Reidel, Dordrecht. 1987).
10. Birkinshaw, M. & Davies. R. C. Astrophys 291. 32-44 (1985).
however, the image presented here is the first of an accretion
11. Pringle. J. E. A. Rev. Astr. Astrophys. 19. 137-162(1981).
disk where size and structure can be directly associated with the
12. Israel. F. P. et al. Astr. Astrophys. 227. 342-350 (1990).
results of nuclear activity.
13. Bertola. F. in LAU Symp. No. 127, "Structure and Dynamics of Elliptical Galaxies' (ed. de
Zeeuw P. T.) 135-143 (Reidel. Dordrecht, 1987).
Century-scale effects of Increased
global model with realistic geography. The atmospheric GCM
includes the seasonal variation of insolation, and predicted
mospheric CO₂ on the
cloud over which depends only on the relative humidity. It has
nine vertical finite difference levels. The horizontal distribution
ocean-atmosphere system
of predicted variables is represented by spherical harmonics (15
associated Legendre functions for each of 15 Fourier compo-
Syukuro Manabe &Ronald J. Stouffer
nents) and by corresponding grid-point values. The oceanic
GCM uses a finite difference technique with a regular grid
Geophysical Fluid Dynamics Laboratory/NOAA Princeton University,
system which has horizontal spacing (4.5° latitude) by (3.75°
PO Box 308, Princeton, New Jersey 08542, USA
longitude) and 12 vertical levels. This model is similar to that of
Bryan and Lewis¹², except that it mimics the effect of mesoscale
SEVERAL studies have addressed the likely effects of CO2-induced
eddies by the diffusion of potential temperature and salinity on
climate change over the coming decades 1-10, but the longer-term
isopycnal surfaces. The atmospheric and oceanic GCMs interact
effects have received less attention. Yet these effects could be very
through the exchange of heat, water and momentum.
significant, as persistent increases in global mean temperatures
Assuming the temporal variations of atmospheric CO₂ in
may ultimately influence the large-scale processes in the coupled
Fig. 1a, three 500-year integrations of the coupled model are
ocean-atmosphere system that are thought to play a central part
done. One is a standard integration (S) in which the atmospheric
in determining global climate. The thermohaline circulation is
CO₂ remains unchanged. In a second integration (4XC), the
one such process - Broecker has argued" that it may have
CO₂ concentration increases by 1% yr⁻¹ (compound) (close to
undergone abrupt changes in response to rising temperatures
the 'business as usual' (BAU) radiative forcing rate obtained by
and ice-sheet melting at the end of the last glacial period. Here we
the Intergovernmental Panel on Climate Change¹³; IPCC) until
use a coupled ocean-atmosphere climate model to study the
it reaches four times the normal value at about the 140th year
evolution of the world's climate over the next few centuries,
and remains unchanged thereafter. In a third integration (2xC),
driven by doubling and quadrupling of the concentration of
the CO₂ concentration also increases at the rate of 1% yr⁻¹
atmospheric CO2. We find that the global mean surface air
(compound) until it doubles around the 70th year and remains
temperature increases by about 3.5 and 7 °C, respectively, over
unchanged thereafter. By comparing the three integrations, one
500 years, and that sea-level rise owing to thermal expansion
can evaluate the long-term impact of the doubling and
alone is about 1 and 2 m respectively (ice-sheet melting could
quadrupling of atmospheric CO₂ on the coupled system.
make these values much larger). The thermal and dynamical
The initial conditions for these integrations have realistic
structure of the oceans changes markedly in the quadrupled-CO₂
seasonal and geographical distributions of surface temperature,
climate - in particular, the ocean settles into a new stable state in
surface salinity and sea ice; the atmospheric and oceanic
which the thermohaline circulation has ceased entirely and the
components of the model are nearly in equilibrium with these
thermocline deepens substantially. These changes prevent
distributions. When the time integration of the model starts
ventilation of the deep ocean and could have a profound
from this initial condition, the model climate rapidly drifts
act on the carbon cycle and biogeochemistry of the coupled
towards its own equilibrium state. To minimize the drift, the
system.
fluxes of heat and water at the ocean-atmosphere interface are
The model used here consists of a general circulation model
adjusted by amounts that vary seasonally and geographically8.
(GCM) of the atmosphere and oceans, and a simple model of
These adjustments, applied to all three integrations identified
land surfaces that includes the budgets of heat and water. It is a
above, are independent of the anomalies of temperature and
NATURE
VOL 364
15 JULY 1993
215
TERS IU NATURE
a
4XC
qualitatively similar feature is indicated in the curve of sea-level
4X
rise in the 2XC integration. The total sea-level rise over the
entire 500-year period of the 4XC amounts to about 1.8 m and is
substantially larger than the corresponding rise of about 1 m in
log CO2
2XC
the 2XC.
2X
Although the melt water from continental ice sheets is not
included in the computation of sea-level rise mentioned above,
the rate of melting at the surface of ice sheets has been estimated
S
1X
from the surface heat budget. If the effect of melt water were
(70)
100
(140)
200
300
taken into consideration, the resulting sea-level rise could be
292
400
500
much larger.
b
4XC
Figure 2 indicates that, in the 4XC, the thermohaline
circulation (THC) almost disappears in most of the model
290
oceans, leaving behind wide-driven cells. For example, the THC
nearly vanishes in the North Atlantic during the first 200-yr
Temperature (K)
integration (Fig. 3). In the immediate vicinity of the Antarctic
288
2XC
continent, the THC weakens and becomes shallower (Fig. 2),
markedly reducing the formation of Antarctic Bottom Water.
This in turn weakens the northward flow of bottom water in both
Pacific and Atlantic.
286
The near-extinction of the THC described above is attribut-
S
able mainly to the capping of oceans by relatively fresh water in
high latitudes, where the supply of water to the ocean surface
284
0
100
200
300
400
500
increases markedly. The excess of precipitation over evapora-
200
c
tion and runoff from continents increases in high-latitude oceans
180
because of the enhanced poleward transport of water vapour in
160
the warmer model troposphere.
:40
The evolution of the THC in 4XC described above can be
Sea level rise (cm)
120
100
4XC
80
60
2XC
40
12
V
20
0
0
1
0
100
200
300
400
500
16
Time from present (yr)
12
2
FIG. 1 Temporal variations of: a, logarithm of atmospheric CO₂
Depth (km)
8
0
concentration; b, global mean surface air temperature (K); and C,
3
0
global mean increase of sea level (cm) due to thermal expansion,
12
0
computed as the difference between 4xC and S, and 2xc and S.
12
4
salinity at oceanic surface, and so neither damp nor amplify the
anomalies.
INITIAL
5
Figure 1b contains the time series of global mean surface air
temperature from the 4XC, 2XC, and S integrations. During the
first 140 years of the 4XC integration, the global mean surface
air temperature increases by 5 °C, at the rate of ~3.5 °C per
1
0
century. After the 140th year, the global mean surface air
temperature increases slowly by an additional 1.5 °C despite the
absence of further CO₂ increase in the model atmosphere. The
2
large thermal inertia of the deep ocean is mainly responsible for
this residual warming.
Depth (km)
A qualitatively similar feature is evident in the time series of
3
the 2XC integration. During the first 70 years, the global mean
temperature increases by 2.2 °C, again at the rate of 3.5 °C per
century. After atmospheric CO2 stops increasing at the 70th
4
year, the global mean surface air temperature increases by an
additional 1 °C.
0
The temporal variations of global mean sea level due to
400-500
5
thermal expansion of sea water alone are estimated for both the
90° N
60:
30°
EQ
30°
60°
90° S
4XC and 2XC integrations (Fig. 1c), although sea level is not
Latitude
explicitly predicted in the present model¹². During the first few
decades of the 4XC experiment, the sea level rises by ~ 1 cm per
FIG. 2 Stream function of zonal mean meridional circulation in model
decade. The sea level continues to rise long after the 140th year
oceans. Top: initial distribution obtained from the S. Bottom: average
over the 400-500th year of the 4xC. Units on contours are in
when the atmospheric carbon dioxide stops increasing. A
Sverdrups (10⁶ s⁻¹).
216
NATURE
VOL 364
15 JULY 1993
15:27 FAX 301 7134598
NOAA CENTRAL LIBRARY
002
VOLUME 7
JOURNAL OF CLIMATE
JANUARY 1994
Multiple-Century Response of a Coupled Ocean-Atmosphere Model to an Increase
of Atmospheric Carbon Dioxide
SYUKURO MANABE AND RONALD J. STOUFFER
Geophysical Fluid Dynamics Laboratory/NOAA, Princeton University, Princeton, New Jersey
(Manuscript received 10 June 1993, in final form 7 July 1993)
ABSTRACT
To speculate on the future change of climate over several centuries, three 500-year integrations of a coupled
ocean-atmosphere model were performed. In addition to the standard integration in which the atmospheric
concentration of carbon dioxide remains unchanged, two integrations are conducted. In one integration, the
CO2 concentration increases by 1% yr⁻¹ (compounded) until it reaches four times the initial value at the 140th
year and remains unchanged thereafter. In another integration, the CO2 concentration also increases at the rate
of 1% yr⁻¹ until it reaches twice the initial value at the 70th year and remains unchanged thereafter.
One of the most notable features of the CO7quadrupling integration is the gradual disappearance of ther-
mohaline circulations in most of the model oceans during the first 250-year period, leaving behind wind-driven
cells. For example, thermohaline circulation nearly vanishes in the North Atlantic during the first 200 years of
the integration. In the Weddell and Ross scas, thermohaline circulation becomes weaker and shallower. thereby
reducing the rate of bottom water formation and weakening the northward flow of bottom water in the Pacific
and Atlantic oceans. The weakening or near disappearance of thermohaline circulation described above is
attributable mainly to the capping of the model oceans by relatively fresh water in high latitudes where the
excess of precipitation over evaporation increases markedly due to the enhanced poleward moisture transport
in the warmer model troposphere.
In the CO2-doubling integration, the thermohaline circulation weakens by a factor of more than 2 in the
North Atlantic during the first 150 years but almost recovers its original intensity by the 500th year. The increase
and downward penetration of positive heat and temperature anomaly in low and middle latitudes of the North
Atlantic helps to increase the density contrast between the sinking and rising regions, contributing to this slow
recovery. The recovery is aided by the gradual increase in surface salinity that accompanies the intensification
of the thermohaline circulation.
During the 500-year period of the doubling and quadrupling experiments, the global mean surface air tem-
perature increases by about 3.5°C and 7°C, respectively. The rise of sea level due to the thermal expansion of
sea water is about 1 and 1.8 m, respectively, and could be much larger if the contribution of meltwater from
continental ice sheets were included It is speculated that the two experiments described above provide a probable
range of future climate change.
1. Introduction
SM for the convenience of identification.) By exam-
ining the multiple-century responses of the coupled
The CO₂-induced change of climate has been the
model to the quadrupling and doubling of atmospheric
subject of many studies using general circulation mod-
CO2, the present study examines the robustness of the
els of the coupled ocean-atmosphere system (e.g.,
results from the earlier work. The study also speculates
Bryan et al. 1982; Spelman and Manabe 1984; Schle-
on the nature of a large change of climate that may
singer et al. 1985; Bryan and Spelman 1985; Bryan ct
occur in the more distant future.
al. 1988; Washington and Mechl 1989; Stouffer et al.
Stouffer and Manabe noted that the CO2-induced
1989; Manabe et al. 1991, 1992; Cubasch et al. 1992).
warming of sea surface temperature is delayed mark-
This study, recently summarized by Manabe and
edly in the northern North Atlantic and the Circum-
Stouffer (1993), is an extension of the earlier studies
polar Ocean of the Southern Hemisphere due partly
by Stouffer et al. and Manabe et al., which explored
to the deep mixing of heat trapped by the increasing
the response of a coupled ocean-atmosphere model to
greenhouse gas. This study investigates whether such
4 gradual increase of atmospheric carbon dioxide.
a delay continues when the time integration of the
(Hereafter, these earlier studies will be referred to as
coupled model is extended over several centuries.
Based upon the paleo-oceanographic evidence,
Broecker (1987) raised the possibility that the ther-
mohaline circulation in the Atlantic and the rest of the
Corresponding author address: Dr. Syukuro Manabe. Geophysical
Fluid Dynamics Laboratory/NOAA, Princeton University, Forrestal
world oceans may undergo an abrupt change in re-
Campus, US Route 1, P.O. Box 308, Princeton, NJ 08542.
sponse to the global warming of climate. Using a cou-
5
FRI 1.
NOAA CENTRAL LIBRARY
006
JANUARY 1994
MANABE AND STOUFFER
9
200
(For the temporal variation of the meltwater from
180
continental ice sheets, see Fig. 14 in section 4b.)
160
4. Thermohaline circulation
140
a Temporal variation
120
-4XC
on
One of the most remarkable aspects of the 4XC in-
100
tegration is the gradual disappearance of the thermo-
52
60
ZXC
haline circulations in the model oceans. For example,
the thermohaline circulation almost vanishes in the
60
North Atlantic Ocean before the end of the 4XC in-
40
tegration (Fig. 4). It weakens rapidly during the first
20
140 years of the CO2 increase, and continues to decrease
after the 140th year despite the absence of the CO₂
0
0
100
200
300
400
500
increase until its intensity is reduced to a few Sverdrups
YEARS
(1 Sv = 10⁶ m³ s⁻¹) around the 200th year. During
FiG. 3. Temporal variation of the global mean sea level from the
the second half of the integration, very weak overturn-
4XC and 2XC experiments. The 4XC and 2XC time series represent
ing is essentially confined equatorward of 45°N with
the difference between the 4XC and S, and 2XC and S integrations,
practically no sinking in the northern North Atlantic
respectively. Units are in centimeters.
(Fig. 5c). In the immediate vicinity of the Antarctic
continent, the thermohaline overturning not only
weakens markedly but also shifts toward the surface
year. Even after the 180th year, the rate of sea level
during the first 140 years of the 4XC integration (Figs.
rise is reduced only very gradually. As discussed in sec-
5g and 5h). Although the coastal cell of thermohaline
tion 5. the gradual, downward penetration of positive
circulation reintensifies slightly after the 140th year, it
temperature anomaly in the model oceans is mainly
is essentially confined to the top 1.5-km layer of ocean,
responsible for the continuous sea level rise after the
(Fig. 5i), resulting in a marked reduction of the for-
140th year when the atmospheric CO₂ stops increasing.
mation of Antarctic Bottom Water. Thus, the north-
In the 2XC experiment, the initial rate of sca level
ward flow of the bottom water stops and the deep cell
rise is nearly identical to the initial rate in the 4XC
of clockwise circulation disappears in the Pacific Ocean
experiment. By the 70th year when atmospheric carbon
(Fig. 5f). The reduction in the formation of the Ant-
dioxide stops increasing, the rate of sea level rise reaches
arctic Bottom Water (AABW) also affects deep cir-
3 cm decade⁻¹ and stays at this value until about the
culation in the Atlantic sector. Although the clockwise
10th year when it begins to decrease very gradually.
cell of AABW in the Atlantic intensifies during the first
A qualitatively similar feature is indicated in the curve
140 years as the upper thermohaline cell becomes shal-
of sea level rise obtained by Warrick and Oerlemans
lower, it eventually disappears and the northward flow
[Fig. 9.8 of IPCC (1990)]. Note, however, that their
of the bottom water also stops for all practical purposes
result includes the contribution of meltwater from ice
toward the end of the 4XC integration (Fig. 5c). In
sheets and mountain glaciers.
summary, most of the thermohaline circulations dis-
Because of the downward penetration of a larger
appear in the model oceans toward the end of the 4XC
temperature anomaly, the rate of sea level rise is larger
integration, leaving the wind-driven, shallow cells in
in the 4XC than the 2XC experiment even after the
atmospheric CO₂ stops increasing in both experiments.
Thus, the total sea level rise over the entire 500-year
25
period of the 4XC experiment amounts to about 1.8
m and is substantially larger than the corresponding
20
rise of about 1 m in the 2XC experiment.
15
Although the meltwater from continental ice sheets
di
is not included in the computation of sea level rise
10
mentioned above, the rate of melting at the surface of
4XC
ice sheets has been estimated as described in section
5
2b for the sake of bookkeeping. Assuming that the
0
a
100
200
300
400
500
meltwater does not refreeze at all in the ice sheet, sea
YEARS
Icvel would rise by as much as an additional 7 m during
the 500-year period of the 4XC integration, resulting
FIG. 4, Temporal variation of the intensity of the thermohaline
in a total sea level rise of about 9 m. Even if only half
circulation in the North Atlantic Ocean from the 4XC, 2XC. and S
integrations. Here the intensity is defined as the maximum value of
of the meltwater were to eventually run off into the
the streamfunction representing the meridional circulation in the
oceans, the total sea level rise would be about 5 m.
North Atlantic Ocean (e.g., Fig. 5a). Units are in Sverdrups.
Clinton Presidential Records
Digital Records Marker
This is not a presidential record. This is used as an administrative
marker by the William J. Clinton Presidential Library Staff.
This marker identifies the place of a tabbed divider. Given our
digitization capabilities, we are sometimes unable to adequately
scan such dividers. The title from the original document is
indicated below.
10
Divider Title:
Clearance Draft, Do Not Cite, 7/10/98
The effects of the global climate system described above do not include potential non-
linearities in the relationships between greenhouse gas concentrations and temperature, between
temperature and economic damages, or in the various other complicated relationships governing
interactions among greenhouse gas emissions, the climate, and the economy. Three possibilities
serve as illustrations. Warming of Northern tundra might release large amounts of methane from
53
the subarctic permafrost, thereby acting as a positive feedback on the climate, leading to potentially
devastating acceleration of an otherwise controllable global warming process (Gorham 1991, 1995;
54
Nisbet and Ingham 1995). Second, evidence from the historic record suggests that some types of
climate change might lead to abrupt changes in ocean currents, including displacement of the
55
currents that warm Western Europe. Evidence from ocean core samples suggests such changes of
ocean currents have occurred in previous ice ages (Broeker 1997). Third, warming might cause
accelerated melting of the Antarctic ice sheet causing even more substantial increases in sea levels
57
(Rott et al. 1996; Vaughan and Doake 1996). These potential nonlinearities strengthen the argument
for taking prompt, reasonable steps to mitigate climate change.
12
GM woodwell & F.T. Mackenzie, eds. Oxford Unit.
In Biotic Feedback clobal Climatic System.
10
Pruss, NY
Methane Output from Natural
and Quasinatural Sources:
A Review of the Potential for
Change and for Biotic and
Abiotic Feedbacks
E. G. NISBET AND B. INGHAM
Methane output from "natural" sources has changed rapidly in the recent geological
past, is changing at present under human influence, and may change further as the earth
warms. Unfortunately, the causes, feedback processes, and extent of geological changes
are still only poorly understood, the relative strengths of modern sources of CH₄ remain
controversial, and prediction is virtually impossible. One of the most difficult problems
is in linking accurate but very imprecise, qualitative, and often anecdotal field biogeo-
chemical observations with precise but not necessarily accurate quantitative synthetic
models.
This discussion is confined to an analysis of those major "natural" sources and sinks
5.09
that may have caused the postglacial fluctuations in atmospheric CH4. The net effect of
Figure 10.1. Plot of the CH4 mixing ratio at the marine boundary layer, Pacific and Arctic. Note the
seasonality in high latitudes, especially in the Northern Hemisphere. Southern seasonality in part
reflects OH seasonality in the tropical upper troposphere, and in part may derive from northern
seasonality, blown south over the equator in the midtroposphere by tropospheric circulation cells
(From U.S. NOAA data, courtesy of E. Dlugokencky and P. Tans. See also Steele et al. 1992.)
the latitudinal and seasonal distribution of sources, sinks, and atmospheric transport is
shown in Figure 10.1, from Steele et al. (1992). This plot reveals the most important
constraint on the global CH, budget; the other major constraint is the isotopic finding
N.O.
(e.g., Lowe et al. 1991) that roughly 20% of the a:mospheric CH₄ is outut from fossil
sources. The present budget is still not well understood (Watson et al. 1990; Tyler 1991),
I
and prediction of future concentrations is difficult.
1900
1800
1700
600
1500
(qdd) 'HC
THE MAJOR SOURCES
Arctic and Sub-Arctic Hydrates
Very large stores of CH4 exist in permafrost regions, held in soil and in sedimentary rock
as gas hydrates (clathrates) (Kvenvolden 1988). Gas hydrates, composed of rigid cages
of water molecules that trap molecules of gas (Cox 1983), are potentially stable where
BIOTIC PROCESSES AND POTENTIAL FEEDBACKS
METHANE
Table 10.1. Global CH4 Budget
Table 10.2. Model of the "Fossil" CH4 Content of the Atrnosphere: Natural Gas
and Coal Industry CH4 Production and Losses, and Contribution from the Oil
Estimated
Possible feedback (change
Source
flux (Tg)
Comment
after global warming)
Industry and Hydrates: A Simple Model to Calculate Atmospheric Burden of
"Fossil" Methane
"Quasi-natural"
CH4 hydrates
5
Significant danger
Natural gas
Coalb
Totalᶜ
Variable
Wetlands
Production
Loss
Production
Loss
Annual
Cumulative
Northern bogs, tundra
35
Too low ?
May increase or decrease
109
(Tg)
(109 metric ton)
(Tg)
(Tg)
(Tg)
Swamps/alluvial
80
Too high ?
May increase
1981
1503
49
3814
27
61
770
Biomass burning
55
Fluctuates
Substantial increase
28
63
776
1982
1484
49
3930
Termites
20
May decrease
1490
51
3951
28
66
783
1983
Oceans and freshwater
10
1984
1626
52
4122
29
66
790
205
1985
1686
55
4345
31
71
803
Animals
80
May increase
1986
1738
57
4518
32
74
817
Anthropogenic
285
1987
1830
60
4630
33
77
834
Rice
100
Will increase
34
80
1988
1906
63
4730
853
Landfi'ls
40
Too high
Decreasing?
1989
1975
61
4816
34
77
868
Natural gas vents
10
Controllable
1990
2028
57
4736
34
72
877
Natural gas leaks
30
Controllable
1991
2059
52
4566
33
66
881
Coal mining
35
Poorly
Controllable
1992
2066
47
4484
32
60
878
known
215
a The loss is calculated on the assumption that 95% of natural gas is CIL and that in the industry (excluding the
territory of the former Soviet Union) the average loss rate is 3%. For the former Soviet Union, a loss rate of 9%
is assumed until 1983, 8% from 1984 to 1988, % in 1989, 6% in 1990, and 5% from 1991 to 1992. These
Total
500
The loss for the global coal industry excluding China is calculated or. the basis of 10 m 3 gas per metric ton.
assumptions are arbitrary but within the range of anecdotal information.
Source: Estimates of flux from Fung et al. (1991): scenario 7.
using & conversion factor of 714 g/m from United Kingdom sources, Production figures include brown coal
with low losses of CH4. and hard coal with losses on the order of 15 /metric ton. The assumption of a global
loss rate of 10 m /metric ton falls between estimates of Smith and Sloss (1992) and Beck et al. (1993).
The total figure includes the loss of CH4 as a by-product of the oil industry, approximately Tg/year, scaled up
well-studied area, albeit a small one (in global terms) without permafrost, the North Sea
from United Kingdom industry data to a global figure. It also includes 5 Tg/year from hydrate release. This figure
is simply a "placeholder" (Cicerone and Oremland 1988): the true figure is unknown. The cumulative total
seepage losses to the atmosphere have been thought to be small, on the order of a few
assumes a pre-1981 content of 820 Tg of fossil-derived CH4 in the stmosphere and an annual exponential decay
kilotons (Judd in A. Williams 1993). Globally, however, the flux from shallow marine
of one-tenth of the previous year's value. The cumulative total should be coinpared with the total CH4 content
of the troposphere from all sources, which is roughly 4000 Tg. This model is very approximate, but it illustrates
sediment has been estimated as being as large as 8-65 Tg annually (Hovland et al 1993).
the scale of "fossil" emissions of CH4.
The isotopic data imply that between 80 and 125 Tg of fossil CH₄ are released
Sources: Encyclopedia Britannica Yearbooks, 1982-1992: BP Statistical Review of World Energy. 1993. and
annually (Table 10.1). Fung et al. (1991) took the lower figure and allocated 35 Tg to
previous years: and BP Review of World Gas 1993. British Petroleum Company. London.
loss from coal mining, 40 Tg to loss from the natural gas industry, and 5 Tg to loss from
CH₄ hydrates. However, the 5-Tg figure, which is ultimately derived from the estimate
of Cicerone and Oremland (1988), is essentially a "placeholder," to use Cicerone and
Vulnerability of Hydrate to Climatic Change
Oremland's term. The true figure may be rather different and is very poorly constrained.
The 40-Tg figure for gas industry losses may be a shapshot of a moving figure, roughly
Any changes that increase temperature or reduce pressure may liberate CH4 from
correct in the 1970s and too low for the 1980s, but perhaps an attainable target for the
hydrate (Figure 10.3A). Specific changes that can occur include heating from a rise in
1990s as losses from the huge Russian natural gas industry are reduced. Table 10.2 is a
atmospheric temperature, heating from a change in surface albedo, and heating because
rough estimate of the "fossil" CH4 burden of the atmosphere.
of marine transgression. Pressure release can occur as a result of sea-level drop, either as
Subtracting fossil fuel losses from the isotopically derived total of 80-125 Tg of
a global effect or (a more important cause at present) from local uplift as the lithosphere
fossil CH₄ emitted annually gives, by difference, the hydrate loss. Tables 10.1 and 10.2
recovers after glacial loading. Pressure release also occurs in slumping. Perhaps the
make the assumption that hydrate gas emission at present is roughly 5 Tg annually. This
major cause for concern is the risk of a sudden massive release of CH, either from a
3
estimate is highly approximate, and within the sotopic constraints it is possible that the
marine slump or from the rupturing of a major pool of Arctic gas. Such massive release
hydrate output is either virtually nil or perhaps as high as 10 Tg. The only way to
would not be directly attributable to modern warming in the past few decades; rather it
improve the estimate of the hydrate contribution is through steady isotopic monitoring;
would be a stochastically timed part of a longer-term process. The largest source would
even then, since the Russian gas is derived partly from hydrate, it may be impossible to
be a major marine slump (Figure 10.3B). Marine slumps are more likely at times of
quantify hydrate losses until detailed knowledge of Russian gas industry losses is
lowered sea-level (i.e., just before the end of the last major glaciation, around 13-
available. Nevertheless, the hope is that hydrate losses are at present fairly small.
15 kaBP), but can occur at any time and release enormous quantities of CH₄ (Paull et al.
ARTICLE
Thermohaline Circulation, the Achilles Heel of Our Climate
System: Will Man-Made CO₂ Upset the Current Balance?
Wallace S. Broecker
During the last glacial period, Earth's climate underwent frequent large and abrupt global
How Today's Ocean Functions
changes. This behavior appears to reflect the ability of the ocean's thermohaline cir-
culation to assume more than one mode of operation. The record in ancient sedimentary
A complex of currents collectively known as
rocks suggests that similar abrupt changes plagued the Earth at other times. The trigger
the Conveyor (7) dominates circulation in
mechanism for these reorganizations may have been the antiphasing of polar insolation
today's Atlantic Ocean (see Fig. 1). The
associated with orbital cycles. Were the ongoing increase in atmospheric CO₂ levels to
waters in the upper 1500 m of the Atlantic
trigger another such reorganization, it would be bad news for a world striving to feed 11
Ocean carry heat to its northern reaches.
to 16 billion people.
Much of this transport is by western bound-
ary currents. During the cold winter months,
this heat is transferred to the overlying at-
One of the major elements of today's ocean
mosphere, greatly supplementing that re
sition followed the sinusoidal insolation
ceived from the sun (8). The primary bene
system is a conveyor-like circulation that
cycles.
ficiary of this extra heat is northern Europe,
delivers an enormous amount of tropical
Might the ongoing buildup of greenhouse
where winters are far warmer than one would
heat to the northern Atlantic. During win-
gases in our atmosphere trigger yet another
otherwise expect.
ter, this heat is released to the overlying
reorganization of the climate system? Were
Cooling in the North Atlantic increases
eastward moving air masses, thereby greatly
this to happen a century from now, at a time
the density of this upper ocean water to the
ameliorating winter temperatures in north-
when we struggle to produce enough food to
point where it sinks to the bottom and flows
em Europe. The record contained in ice (1)
nourish the projected population of 11 to 16
southward, forming the lower limb of the
and sediment (2) indicates that this current
billion, the consequences could be devastat-
Conveyor. This limb extends all the way to
has not run steadily, but jumped from one
ing. Thus, it behooves us to get a better grasp
the southern tip of Africa where it joins the
mode of operation to another. The changes
than we now have of this phenomenon.
raceway, which transports water around the
in climate associated with these jumps have
now been shown to be large, abrupt, and
global (3-5). Although the exact linkages
Fig. 1. The present-day large-scale thermohaline circulation pattern of the ocean. (Top) Salty upper
that promote such climate changes have yet
Atlantic water moves northward into the vicinity of Iceland, where it is cooled through contact with cold
to be discovered, a case can be made that
winter wind. This thermally densified salty water sinks to the bottom and flows to the south, forming the
their roots must lie in the ocean's large-
Conveyor's (orange) lower limb. After passing the
scale thermohaline circulation [see (2)].
tip of Africa, it joins the Southern Ocean raceway,
The results of a wide variety of modeling
which carries water around the Antarctic conti-
nent. Here it is blended with brine-densified winter
PACIFIC AND INDIAN
exercises clearly demonstrate that because
ANTICONVEYOR
waters that pour off the shelves surrounding the
CIRCULATION
waters dense enough to sink to the deep sea
Antarctic continent into the abyss (blue). The mix-
can be generated at more than one place on
ture (purple) thus formed enters the Pacific and
the planet, several quasi-stable patterns of
Indian Oceans as bottom water forming the lower
circulation exist (6). Variations in the con-
limbs of large anti-Conveyor circulation cells. Pen-
ditions governing the density of high-lati-
etrating into all three oceans are tongues of inter-
ATLANTIC
tude surface waters can lead to abrupt reor-
mediate depth water formed along the northern
CONVEYOR
CIRCULATION
ganizations of the ocean's circulation. The
margins of the Southern Ocean (black). This water
SOUTHERN OCEAN
surprise revealed to us by the climatic
is mixed downward into the deep ocean, forming
RACEWAY
CIRCULATION
record is the extent, rapidity, and magni-
the third end member. As can be seen in the PO
tude of these atmospheric changes.
versus salinity diagram (below), its presence is
made known by a deviation toward lower salinity.
Although to date the documentation of
The PO* of these waters is about 1.4 µmol/kg,
abrupt global climate change is confined
3
their salinity about 34.4 g/liter, and their potential
to the last 110,000 years, the time interval
temperature about 3°C (right).
preserved in the Summit Greenland ice
2
SOUTHERN
cores (1), there is reason to suspect that
2
SOUTHERN
SOUTHERN DEEP
50:50
NORTHERN
POTENTIAL TEMPERATURE (C)
OCEAN
NORTHERN
INTERMEDIATE
DEEP
this phenomenon has operated off and on,
OCEAN
SOURCE WATER
WATER
SOURCE
INTERMEDIATE
WATER
throughout the history of the Earth. The
WATER
75:25
1
WORK
evidence comes from the well-document-
(µmol/kg)
1.5
ASING
ed cyclicity in sedimentary rock sequenc-
es. In many of these sedimentary cycles,
0
DEEP
ALISNAO
the boundaries between the individual
Geosecs data;
25:75
SOURCE
1
depth 1500m
SOUTHERN
units are sharp rather than gradational, as
WATER
DEEP
Pacific
might be expected if the sediment compo-
-1
SOURCE
WATER
Indian
Atlantic
FREEZING POINT SEAWATER
The author is at The Lamont-Doherty Earth Observatory
0.5
-2
34.3
34.4
34.5
34.6
34.7
34.8
34.9
35
35.1
34.5
35.0
of Columbia University, Palisades, NY 10964, USA.
35.5
SALINITY
SALT CONTENT (g/kg)
1582
SCIENCE
VOL. 278
28 NOVEMBER 1997
www.sciencemag.org
ARTICLE
Thermohaline Circulation, the Achilles Heel of Our Climat
System: Will Man-Made CO2 Upset the Current Balance?
Wallace S. Broecker
During the last glacial period, Earth's climate underwent frequent large and abrupt global
How Today's Ocean Function:
changes. This behavior appears to reflect the ability of the ocean's thermohaline cir-
culation to assume more than one mode of operation. The record in ancient sedimentary
A complex of currents collectively know
rocks suggests that similar abrupt changes plagued the Earth at other times. The trigger
the Conveyor (7) dominates circulation
mechanism for these reorganizations may have been the antiphasing of polar insolation
today's Atlantic Ocean (see Fig. 1).
associated with orbital cycles. Were the ongoing increase in atmospheric CO₂ levels to
waters in the upper 1500 m of the Atlai
trigger another such reorganization, it would be bad news for a world striving to feed 11
Ocean carry heat to its northern reacl
to 16 billion people.
Much of this transport is by western bou
ary currents. During the cold winter mon
this heat is transferred to the overlying
mosphere, greatly supplementing that
One of the major elements of today's ocean
sition followed the sinusoidal insolation
ceived from the sun (8). The primary be
system is a conveyor-like circulation that
cycles.
ficiary of this extra heat is northern Euro
delivers an enormous amount of tropical
Might the ongoing buildup of greenhouse
where winters are far warmer than one wc
heat to the northern Atlantic. During win-
gases in our atmosphere trigger yet another
otherwise expect.
ter, this heat is released to the overlying
reorganization of the climate system? Were
Cooling in the North Atlantic incre:
eastward moving air masses, thereby greatly
this to happen a century from now, at a time
the density of this upper ocean water to
ameliorating winter temperatures in north-
when we struggle to produce enough food to
point where it sinks to the bottom and fl.
ern Europe. The record contained in ice (1)
nourish the projected population of 11 to 16
southward, forming the lower limb of
and sediment (2) indicates that this current
billion, the consequences could be devastat-
Conveyor. This limb extends all the way
has not run steadily, but jumped from one
ing. Thus, it behooves us to get a better grasp
the southern tip of Africa where it joins
mode of operation to another. The changes
than we now have of this phenomenon.
raceway, which transports water around
in climate associated with these jumps have
now been shown to be large, abrupt, and
global (3-5). Although the exact linkages
Fig. 1. The present-day large-scale thermohaline circulation pattern of the ocean. (Top) Salty up
that promote such climate changes have yet
Atlantic water moves northward into the vicinity of Iceland, where it is cooled through contact with
to be discovered, a case can be made that
winter wind. This thermally densified salty water sinks to the bottom and flows to the south, forming
their roots must lie in the ocean's large-
Conveyor's (orange) lower limb. After passing the
scale thermohaline circulation [see (2)].
tip of Africa, it joins the Southern Ocean raceway,
which carries water around the Antarctic conti-
The results of a wide variety of modeling
nent. Here it is blended with brine-densified winter
PACIFIC AND INDIAN
ANTICONVEYOR
exercises clearly demonstrate that because
CIRCULATION
waters that pour off the shelves surrounding the
waters dense enough to sink to the deep sea
Antarctic continent into the abyss (blue). The mix-
can be generated at more than one place on
ture (purple) thus formed enters the Pacific and
the planet, several quasi-stable patterns of
Indian Oceans as bottom water forming the lower
circulation exist (6). Variations in the con-
limbs of large anti-Conveyor circulation cells. Pen-
ditions governing the density of high-lati-
etrating into all three oceans are tongues of inter-
ATLANTIC
mediate depth water formed along the northern
CONVEYOR
tude surface waters can lead to abrupt reor-
CIRCULATION
ganizations of the ocean's circulation. The
margins of the Southern Ocean (black). This water
SOUTHERN OCEAN
surprise revealed to us by the climatic
is mixed downward into the deep ocean, forming
RACEWAY
CIRCULATION
the third end member. As can be seen in the PO
record is the extent, rapidity, and magni-
versus salinity diagram (below), its presence is
tude of these atmospheric changes.
made known by a deviation toward lower salinity.
Although to date the documentation of
The PO* of these waters is about 1.4 µmol/kg,
3
abrupt global climate change is confined
their salinity about 34.4 g/liter, and their potential
to the last 110,000 years, the time interval
temperature about 3°C (right).
preserved in the Summit Greenland ice
SOUTHERN
cores (1), there is reason to suspect that
POTENTIAL TEMPERATURE (C)
2
2
OCEAN
NORTHERN
SOUTHERN
SOUTHERN DEEP
INTERMEDIATE
DEEP
OCEAN
SOURCE WATER
WATER
SOURCE
this phenomenon has operated off and on,
WATER
INTERMEDIATE
throughout the history of the Earth. The
WATER
75:25
1
evidence comes from the well-document-
ed cyclicity in sedimentary rock sequenc-
(µmol/kg)
1.5
50:50
NORTHERN
es. In many of these sedimentary cycles,
0
ALISNANT ENISY
DEEP
the boundaries between the individual
Geosecs data;
25:75
SOURCE
1
depth 1500m
SOUTHERN
WATER
units are sharp rather than gradational, as
DEEP
Pacific
-1
SOURCE
might be expected if the sediment compo-
WATER
Indian
Atlantic
FREEZING POINT SEAWATER
0.5
The author is at The Lamont-Doherty Earth Observatory
-2
34.3
34.4
34.5
34.6
34.7
34.8
34.9
35
35.1
34.5
35.0
of Columbia University, Palisades, NY 10964, USA.
SALINITY
SALT CONTENT (g/kg)
1582
SCIENCE
VOL. 278
28 NOVEMBER 1997
www.sciencemag.org
Broecher.
Summary
about 3°C. Thus, the heat release to the atmosphere
(1990); H. R. Kudrass et al., Nature 349, 406 (1991).
is 8 cal/cm3 X 15 X 10¹²cm³/s X 3:14 x 10⁷ s/year, or
35. R. J. Behl and J. P. Kennett, Nature 379, 243 (1996).
about 4 X 102¹ cal/year. This is equal to roughly 25%
36. J.P. Kennett, I. Hendy, K. Cannariato, in ODP Great-
Through the record kept in Greenland ice, a
of the energy supplied annually to the troposphere
est Hits brochure (Joint Oceanographic Institutions.
disturbing characteristic of the Earth's climate
over the Atlantic north of the Straits of Gibraltar.
Washington, DC, 1997). p. 13.
system has been revealed, that is, its capability
9. W. S. Broecker et al., J. Geophys. Res., in press.
37. T. Sowers and M. Bender, Science 269. 210 (1995).
10. E. C. Carmack, NATO ASIB 146, 641 (1986).
38. K. A. Hughen et al., Nature, in press.
to undergo abrupt switches to very different
11. T.D. Foster and J. H. Middleton, Deep-Sea Res. 27,
39. W. Broecker, Paleoceanography, in press: T. Blunier
states of operation. I say "disturbing" because
367 (1980); A. Foldvik, T. Gammelsr'bfd, T.
et al., Geophys. Res. Lett., in press.
there is surely a possibility that the ongoing
T'bfrrensen, in Oceanology of the Antarctic Conti-
40. J. L. Wilson, Geol. Soc. Am. Bull. 78, 805 (1967);
nental Shelf, Antarctic Research Series, S. S. Ja-
P. H. Heckel, Geology 14, 330 (1986); D. R. Board-
buildup of greenhouse gases might trigger yet
cobs, Ed. (American Geophysical Union, Washing-
man II and P. H. Heckel, ibid. 17, 802 (1989).
another of these ocean reorganizations and
ton, DC, 1985), pp. 5-20; E. Fahrbach et al., J. Mar.
41. T. D. Herbert and A. G. Fischer, Nature 321. 739
thereby the associated large atmospheric
Res. 53, 515 (1995).
(1986); L. Hardie and E. Shinn, Color. School Mines
12. A number of estimates of net flux of water vapor out
Quart. 81, 1 (1986); R. K. Goldhammer, P. A. Dunn,
changes. Should this occur when 11 to 16
of the Atlantic Ocean and its continental drainage
L A. Hardie, Am. J. Sci. 287, 853 (1987); D. Jacobs
billion people occupy our planet, it could lead
basin have been made. Baumgartner and Reichel's
and D. Sahagian, Nature 361, 710 (1993); B. Witkin-
to widespread starvation, for in order to feed
global water balance yielded 0.45 Sv. Using Oort's
son, N. W. Diedrich, C. N. Drummond, J. Sed. Res.
these masses, it will be necessary to produce
(A. H. Oort, NOAA Prof. Pap. 14, (1983)] humidity
66, 1065 (1996).
and wind data, Zaucker and Broecker F. Zaucker
42. D. V. Kent, P.E. Olsen, W. K. Witte, J. Geophys. Res.
two to three times as much food per acre of
and W. S. Broecker, J. Geophys. Res. 97, 2765
100, 14,965 (1995); P. E. Olsen and D. V. Kent,
arable land than we now do. More problem-
(1992)] obtained 0.32 Sv. Estimates obtained using
Palaeogeogr. Palaeoclimatol. Palaeoecol. 122, 1
atic perhaps than adapting to the new global
GCM models are generally lower, for example, the
(1996); P. Olsen, Annu. Rev. Earth Planet. Sci. 25,
Miller and Russell J. R. Miller and G. L. Russell,
337 (1997).
climate produced by such a reorganization will
Paleoceanography 5, 397 (1990)] GISS 8° X 10°
43. M. E. Raymo et al., Paleoceanography 4, 413 (1989).
be the flickers in climate that will likely punc-
model obtain 0.12 Sv. Based on this wide range of
44. C. G. Langereis and F. J. Hilgen, Earth Planet. Sci.
tuate the several-decade-long transition peri-
estimates, I conclude that the flux likely lies in the
Lett. 104, 211 (1991); F.J. Hilgen et al., EOS 78, 285
range 0.25 + 0.15 Sv. In order to balance this loss,
(1997).
od (Fig. 3, right panel).
the difference in salinity between the 15 Sv of North
45. R. Y. Anderson, J. Geophys. Res. 87, 7285 (1982).
So what do we do? Everyone would agree
Atlantic deep water carried around the southern tip
46. S. Manabe and R. J. Stouffer, Nature 364, 215
that the smaller the CO2 buildup the less the
of Africa by the Conveyor's lower limb and that of the
(1993).
aggregate return flow must be 0.57 + 0.34 g/liter.
47. T. F. Stocker and A. Schmittner, ibid. 388, 862
likelihood of dire impacts. But we are
13. The Sverdrup (Sv) is a unit of water transport. One
(1997).
hooked on cheap energy and the demand for
Sverdrup is equal to 1 X 106 m³/s. The transport by
48. T.D. Foster, A. Foldvik, J. H. Middleton, Deep-Sea Res.
it continues to grow. Furthermore, no viable
today's Conveyor is about 15 Sv compared to that of
34, 1771 (1987); A. Foldvik and T. Gammelsr'bfd,
all the world's rivers of about 1 Sv.
Palaeogeogr. Palaeoclimatol. Palaeoecol. 67, 3 (1988);
and acceptable option to fossil fuels has yet
14. W. S. Broecker, Oceanography 4, 79 (1991).
A. L Gordon, B. A. Huber, H. H. Hellmer, A. Ffield,
been devised. Although efforts to bring
15. T. Takahashi, W. S. Broecker, S. Langer, J. Geo-
Science 262, 95 (1993); E. Fahrback, J. Mar. Res. 53,
about more efficient use of energy must be
phys. Res. 90, 6907 (1985); L. A. Anderson and J.L.
515 (1995).
Sarmiento, Global Biogeochem. Cycles 8, 65 (1994).
49. J.F. McManus et al., Nature 371. 326 (1994).
redoubled, it is my feeling that this route is
16. J. Marotzke and J. Willebrand, J. Phys. Ocean. 21,
50. G. M. Woillard, Quat. Res. 9, 1 (1978).
not likely to succeed in bringing about an
1372 (1991). E. Tziperman, Nature 386, 593 (1997).
51. R. L Michel, J. Geophy. Res. 83, 6192 (1978); R. F.
adequate reduction in CO₂ emissions.
17. A. T. Roach et al., J. Geophys. Res. 100, 18,443
Weiss, H. G. Ostlund, H. Craig, Deep-Sea Res., 26,
Hence, as a backstop, we must strive to
(1995).
1093 (1979); R. Bayer and P. Schlosser, Mar. Chem.
18. A. Baumgartner and E. Reichel, in The World Water
35, 123 (1991); P. Schlosser, J. L. Bullister, R. Bayer,
develop an energy supply that does not load
Balance, R. Oldenbourg (Verlag, München, Germa-
ibid., p. 97.
the atmosphere with CO2 To this end I see
ny, 1975).
52. P. Schlosser, G. Bönisch, M. Rein, P. Bayer, Science
a ray of hope. The idea is to separate the
19. S. Manabe and R. J. Stouffer, J. Clim. 1, 841 (1988);
251, 1054 (1991); G. Bönisch et al., J. Geophys.
E. Maier-Reimer and U. Mikolajewicz, Proc. Joint
Res. 102, 18,553 (1997).
hydrogen atoms contained in fossil fuels by
Oceanogr. Assem. 87, (1989); T. F. Stocker and
53. W. K. de la Mare, Nature 389. 57 (1997).
reacting them with steam. The H₂ produced
D. G. Wright, Nature 351, 729 (1991); A. J. Weaver
54. H. J. Herzog, ed., "Carbon Dioxide Removal," Pro-
in this way would be used in fuel cells, and
et al., J. Phys. Oceanogr. 23, 1470 (1993); S. Rahm-
ceedings of the Third International Conference on
storf, Nature 372, 82 (1994): ibid. 378, 145 (1995); S.
Carbon Dioxide Removal," Cambridge, MA, 9 to 11
the CO2 would be captured at its source,
Manabe and R. J. Stouffer, Paleoceanography 12.
September 1996, Energy Conversion Management
liquified, and injected either into continen-
321 (1997).
38 (suppl. 689) (1997); B. Hileman, Chem. Eng. News
tal reservoirs or onto the sea floor (54).
20. R. B. Alley et al., Nature 362, 527 (1993).
34 (1997); A. K. N. Reddy, R. H. Williams, T. B. Jo-
While perhaps doubling the cost of energy,
21. G. C. Bond and R. Lotti, Science 267, 1005 (1995).
hansson, Energy After Rio (UNDP, New York, 1997),
22. P. E. Biscaye et al., in J. Geophys. Res., in press.
R.H. Williams, Princeton University, Center for Energy
this is something that could be accom-
23. J. Chappellaz et al., Nature 366, 443 (1993); J. P.
and Environmental Studies Report No. 295, January
plished. But as such a transition in energy-
Severinghaus et al., ibid., in press.
1996; in Eco-Restructuring, R. U. Ayres et al., Eds.
generation technology would require at least
24. G. H. Denton and C. H. Hendy, Science 264, 1434
(United Nations Univ. Press, Tokyo, in press).
(1994); T. V. Lowell et al., ibid. 269, 1541 (1995).
55. D. A. Meese et al., Science 266. 1680 (1994); R. B
50 years to implement, we must get off to a
25. R. B. Alley et al., Geology 25, 483 (1997).
Alley et al., Nature 362, 527 (1993); D. A. Meese ei
running start to put into place this insurance
26. D. Rind and D. Peteet, Quat. Res. 24, 1 (1985).
al., J. Geophys. Res., in press.
policy.
27. L. G. Thompson et al., Science 269, 46 (1995).
56. My recent ideas about sedimentary cycles in the distant
28. W. S. Broecker, Global Biogeochem. Cycles, in
past have been tempered by discussions with A
press.
Fischer, B. Berggren, N. Christie-Blick, D. Kent, P. OI-
REFERENCES AND NOTES
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Barkov, V. N. Petrov, Nature 325, 318 (1987); J. R.
case, it was ideas about multiple climate states ex-
3. W. Dansgaard, J. W. C. White, S. J. Johnsen, Nature
Petit et al., ibid. 343, 56 (1990); K. C. Taylor et al.,
pressed to me by H. Oeschger in 1984 that sparked my
339, 532 (1989).
ibid. 366, 549 (1993); M. Ram and R. I. Gayley,
thinking. My research on the oceans has benefited from
4. K. C. Taylor et al., ibid. 361, 432 (1993).
Geophys. Res. Lett. 21, 437 (1994).
the wisdom of T. Stocker, T. Takahashi, S. Rahmstori
5. W. Broecker, GSA Today 6, 1 (1996).
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33. L. D. Keigwin and G. A. Jones, Paleoceanography 5,
spired me to a new level of thinking and action (that is
and C. Wunsch, Nature 382, 436 (1996).
1009 (1990).
the GEOSECS program). S. Peacock has worked with
8. The aggregate temperature of waters carried into the
34. K. Chinzel et al., Mar. Micropaleontol. 11, 273 (1987);
me on the problem of deep water formation in the
northern Atlantic is about 11°C. That of the aggre-
N. Kallel et al., Oceanol. Acta 12, 369 (1988); B. K.
Southern Ocean. J. Totton and P. Catanzaro trans
gate deep water formed in the northern Atlantic is
Linsley and R. C. Thunell, Paleoceanography 5, 1025
formed my hand scribbles into readable manuscript.
1588
SCIENCE
VOL. 278
28 NOVEMBER 1997
www.sciencemag.org
LETTERS TO NATURE
Recent atmospheric warming
(ref. 2). We thus adopt mean annual air temperature as the best
available indicator of the amount of summer melt.
and retreat of ice shelves on
Meteorological records along the west coast of the Antarctic
Peninsula² show a spatially consistent warming trend. At Faraday
the Antarctic Peninsula
Station, a warming of 0.056 has been measured² since 1945,
a total of 2.5 °C. Consistency along the west coast is to be
D. G. Vaughan & C. S. M. Doake
expected, as sea-ice extent in the Bellingshausen Sea strongly
modulates the temperature of the entire area¹⁸. In 1988-91 sea-ice
extent in the Bellingshausen Sea reached a minimum, coinciding
British Antarctic Survey, Natural Environment Research Council,
Madingley Road, Cambridge CB3 OET, UK
with the warmest recorded temperatures on the west coast of the
Antarctic Peninsula¹⁹. In contrast, the climate of the east coast is
governed by conditions in the Weddell Sea" and there is little
IN 1978 Mercer' discussed the probable effects of climate warm-
meteorological evidence that warming has also occurred on the
ing on the Antarctic Ice Sheet, predicting that one sign of a
east coast. The temperature record from Marambio Station is
warming trend in this region would be the retreat of ice shelves on
short and incompletex, and Jones' comparison of a two-year
the Antarctic Peninsula. Analyses of 50-year meteorological
record from Snow Hill Island with spatially smoothed mean
records have since revealed atmospheric warming on the Antarctic
temperatures 1957-75 (ref. 21) is untrustworthy, because the
Peninsula², and a number of ice shelves have retreated⁴⁴. Here
area has extremely high spatial gradients of mean annual air
we present time-series of observations of the areal extent of nine
temperature.
ice shelves on the Antarctic Peninsula, showing that five northerly
Figure 2 presents a catalogue of changes in ice-shelf areas on
ones have retreated dramatically in the past fifty years, while
the Antarctic Peninsula since direct observations began, compiled
those further south show no clear trend. Comparison with air-
from published sources 4-8,22-27 and recent satellite imagery. How
temperature data shows that the pattern and magnitude of ice-
do we distinguish climate-induced retreat from normal calving?
shelf retreat is consistent with the existence of an abrupt thermal
We suggest that an ice shelf which is no longer viable will suffer a
limit on ice-shelf viability, the isotherm associated with this limit
progressive retreat, via a series of small calming events occurring
having been driven south by the atmospheric warming. Ice
each year over a period of many years, without substantial
shelves therefore appear to be sensitive indicators of climate
readvance. Such behaviour was clearly seen during the disintegra-
change.
tion of Wordie Ice Shelf (Fig. 3), and Fig. 2 suggests similar
Ice shelves fringe most of the Antarctic continent where there
behaviour in three other ice shelves close to the -5°C isotherm;
are bays or islands to constrain them. Robin and Adie, however,
namely, the ice shelf that occupied Prince Gustav Channel, Larsen
noted that a portion of the Antarctic Peninsula was free of ice
Inlet, and the northernmost section of Larsen Ice Shelf (Sobral
shelves, despite many glacier-fed bays and offshore islands. The
Peninsula to Robertson Island, hereafter Larsen-A). An order of
limit of ice shelves apparently corresponded with the 0°C January
magnitude smaller and potentially quite different, Müller Ice
isotherm, and they concluded this marked a "limit of viability".
Shelf has shown a progressive retreat since the 1950s, but without
Other constraints on ice-shelf viability based on ocean tempera-
complete disintegration. In summary, each retreat was pro-
ture¹⁰ and tidal amplitude¹¹ have been proposed, but have not
been shown to fit the known distribution.
Where there is little summer melting, the yearly surface tem-
perature cycle is attenuated to ~5% at a depth below the ice
surface of 10 m (ref. 12). The 10-m temperature thus provides an
estimate of the mean annual air temperature. Mercer¹ suggested
60°S
that the downward percolation and subsequent refreezing of
surface melt could eliminate the cold thermal wave from the
previous winter and raise the ice shelf to the pressure melting
3
point throughout. The so-called temperate ice shelf thus created
was at that time thought to be inviable. However, it is unlikely that
this process would be sufficient to form a temperate ice shelf if
percolation is restricted to the near surface layers (~10m).
65°S
Furthermore, there is strong evidence that portions of stable ice
-10
shelves can approach the temperate state¹. Nevertheless, we
-11
believe that increased melt could play an important role in
providing the reason for a climate-imposed limit.
-12
The duration and extent of the summer melt season has
13
been determined from satellite passive microwave data¹⁴. The
threshold for melting in the Antarctic Peninsula region is about
14
-2.5°C (monthly average) and the area of melt increases rapidly
70°S
15
with temperature¹⁴. Trends are not well established, being masked
by the inter-annual variability from 1978 to 1987¹⁴, but the number
16
of days per year with summer melting seems to have increased
(one day per year) over the period 1978-91 on four ice shelves on
-17
the Antarctic Peninsula¹⁵.
The only climate parameter that is well mapped on the
-10
Antarctic Peninsula is the mean annual air temperature¹⁶
75°S
(Fig. 1). The distribution of ice shelves indicates that the -5°C
50°W
60°W
mean annual isotherm in Reynolds' compilation¹⁶ could be taken
70°W
as proxy for the limit of viability of ice shelves. Although the 0°C
January isotherm is not well mapped, the sparse data available
80°W
suggest that it coincides with the mean annual -5°C isotherm¹.
For example. mean January temperatures at Faraday Station are
FIG. 1 Map of pre-1981 mean annual air temperatures in °C. Derived from
temperatures 10m below the ice surface, normalized to sea-level by
around 0.5 C. whereas the mean annual temperature is -4.4 C
Reynolds Ice shelves (shaded) are indicated at their mid-1970s extent.
328
NATURE VOL 379 . 25 JANUARY 1996
6. M. 1. L'Vovich et al., in The Earth as Transformed by
Action, B. L. Turner et al., Eds. (Cambridge Univ.
dams are currently being completed at an average
Human Action, B. L. Tumer et al., Eds. (Cambridge
Press, Cambridge, 1990), pp. 253-269.
rate of 500 per year, or 56% of the rate of the period
Univ. Press, Cambridge, 1990), pp. 235-252.
20. Even in the countries of the Organization for Eco-
from 1950 to 1986.
7. P. M. Vitousek, P. R. Ehrlich, A. H. Ehrlich, P. A.
nomic Cooperation and Development, domestic
28. Because -85% of existing large dams were built
Matson, Bioscience 36, 368 (1986).
wastewater treatment is estimated to cover only
since mid-century (25), this calculation assumes that
8. G. L. Ajtay, P. Ketner, P. Duvigneaud, in The Global
-60% of the population [A. K. Biswas, Water Int. 17.
85% of total existing storage capacity was con-
Carbon Cycle, B. Bolin, E. T. Degens, S. Kempe, P.
68 (February 1992)]. Information for developing
structed since then, or 4675 km³ (5500 km³ X 0.85)
Ketner, Eds. (Wiley, New York, 1979), pp. 129-182.
countries is sparse, but treatment coverage is cer-
With the assumption that 40% as many dams would
tainly far lower. Moreover, few regions control for
be constructed between 1990 and 2025 as between
9. Our global estimate conforms well to values derived
from small-scale field studies with crops [B. A. Stew-
farm runoff and other dispersed pollution sources
1950 and 1985, and that capacity per dam remains
art, J. T. Musick, D. A. Dusek, Agron. J. 75, 629
that add substantial quantities of sediment, pesti-
constant, 1870 km³ (4675 km3 X 0.40) of capacity
(1983); Yield Response to Water (U.N. Food and
cides, and fertilizers to water bodies.
would be added by ca. 2025, of which 1190 km
Agriculture Organization, Rome, 1979); Z. Zoci, B. A.
21. Even if wastewater treatment coverage should be-
would be live storage for water supply.
Stewart, F. Xiangjun, Field Crops Res. 36, 175
come nearly universal, substantial instream flows
29. Even as dam construction is adding to the total stable
(1994)].
would still be required to maintain fisheries, support
runoff, other human activities are reducing it. Defores
10. 1990 Production Yearbook (U.N. Food and Agricul-
recreational demands, and satisfy other instream
tation and the paving over of aquifer recharge areas
needs. For example, California's instream environ-
often reduce rainwater infiltration, thereby reducing
ture Organization, Rome, 1991), with adjustments
for United States and Taiwan based on data from
mental water requirements (after omission of the
base flow and increasing surface flood runoff. More
U.S. Department of Agriculture.
north coast hydrologic region, which contains sever-
important globally, many reservoirs are losing active
11. E. Czaya, Rivers of the World (Van Nostrand Rein-
al wild and scenic rivers and thus may not be indic-
storage capacity faster than originally estimated be
hold, New York, 1981).
ative of instream needs more narrowly defined) equal
cause of rapid siltation from deforestation, soil ero
22% of average annual runoff [California Water Plan
sion, and generally poor watershed management
12. Population estimates from C. Haub and M.
Update (California Department of Water Resources,
The Nizamsagar reservoir in India, for instance, los
Yanagishita, Population Reference Bureau (personal
communication, Washington, DC, January 1995).
Sacramento, CA, 1994).
more than 60% of its capacity over 40 years [M. New
13. M. Dynesius and C. Nilsson, Science 266, 753
22. We did not consider it feasible to estimate accessible
son, Land, Water and Development: River Basin Sys
ET in a manner comparable to our estimate of AR. To
tems and Their Sustainable Management (Routledge
(1994).
be conservative, we therefore assumed all terrestrial
London, 1992]. Lacking global estimates, we mak
14. We do not include in our estimate of remote northern
ET to be accessible.
no subtraction for these losses.
river flows a large number of rivers that have one or
two dams (typically for hydropower) on their main
23. Wangnick Consulting, 1990 IDA Worldwide Desalt-
30. P.E. Waggoner, Ed., Climate Change and U.S. Wa
channels but have flows vastly in excess of water
ing Plants Inventory (International Desalination Asso-
ter Resources (Wiley, New York, 1990).
supply needs in the region, including, for example,
ciation, Englewood, NJ, 1990).
31. National Research Council, Restoration of Aquati
the Ob and Lena rivers of Siberian Russia, with a
24. P. H. Gleick, Annu. Rev. Energy Environ. 19, 267
Ecosystems (National Academy Press, Washingtor
combined flow of 935 km³. The ambitious Soviet
(1994).
DC, 1992).
25. J. A. Veltrop, in Water for Sustainable Development
32. 1994 World Population Data Sheet (Population Re
scheme to divert water from the Ob to the Aral Sea
in the Twenty-first Century, A. K. Biswas, M. Jellali,
erence Bureau, Washington, DC, 1994).
basin would initially have involved 25 km³/year, just
G. E. Stout, Eds. (Oxford Univ. Press, Oxford, 1992),
33. We gratefully acknowledge comments from W. Fa
6% of the Ob's annual average flow. Likewise, a
proposal to ship water via undersea pipeline from
pp. 102-115.
con, P. Gleick, R. Naylor, A. Vickers, P. Vitouse
26. Status of Dam Construction, 1991 (International
and two anonymous reviewers. Supported by
southeast Alaska to California involved 5 km³ annu-
Commission on Large Dams, Paris, 1992), suggests
grant from Charles and Nancy Munger, the Winslo
ally, just under 5% of the combined average annual
that ~300 dams are now commissioned each year,
and Heinz foundations, and an anonymous donor
flow of the Copper and Stikine rivers, leaving 95% of
their flow still remote [Alaskan Water for California?
but these data include only 64 countries.
The Subsea Pipeline Option-Background Paper
27. A. P. Covich [in (5), pp. 40-55] indicates that large
28 September 1995; accepted 21 December 199
(U.S. Office of Technology Assessment, Washing-
ton, DC, 1992)].
15. Uncaptured flood runoff provides a variety of human
benefits, including support of flood-recession farming,
Rapid Collapse of Northern
fisheries, and generation of hydroelectricity; however,
in these capacities, its use is either insignificant glo-
Larsen Ice Shelf, Antarctica
bally or does not involve actual appropriation.
16. Theoretically, a reservoir could be filled and emptied
Helmut Rott, Pedro Skvarca, Thomas Nagler
more than once a year, creating a greater effective
capacity to regulate runoff than the storage capacity
alone would indicate. We know of no estimates of
In January 1995, 4200 square kilometers of the northern Larsen Ice Shelf, Antarc
this effective storage capacity other than the state-
Peninsula, broke away. Radar images from the ERS-1 satellite, complemented by fie
ment by K. Mahmood [Reservoir Sedimentation: Im-
pact, Extent, and Mitigation (The World Bank, Wash-
observations, showed that the two northernmost sections of the ice shelf fractured a:
ington, DC, 1987)] that the usable reservoir storage
disintegrated almost completely within a few days. This breakup followed a period
capacity "is nearly used once every year." We there-
steady retreat that coincided with a regional trend of atmospheric warming. The obs
fore make no adjustments to the estimated 3500
km³ of capacity usable for runoff storage on an av-
vations imply that after an ice shelf retreats beyond a critical limit, it may collapse rapi
erage annual basis.
as a result of perturbated mass balance.
17. This is a somewhat higher rate than is implied by
Shiklomanov's estimates (4), which suggest rates of
10,700 to 11,000 m³/ha. We arrived at our figure
after examining data for California that suggest an
average water application rate on that state's imgat-
Ice shelves cover 11% of the total area of
of either (3). The 0°C summer isotherm I
ed area of ~10,300 m³ ha [California Water Plan
Update (California Department of Water Resources,
Antarctica (1) and play an important role
been taken as the climatic limit for
Sacramento, CA, 1994), vol. 1]. Because the aver-
in the mass budget and dynamics of the
existence of ice shelves along the west CC
age irrigation efficiency in California is reported to be
Antarctic Ice Sheet. Most of the ice that
of the Antarctic Peninsula (4). Betwe
70%, which is substantially higher than the world-
has accumulated over the grounded parts of
1966 and 1989, the Wordie Ice Shelf (1
wide average [S. Postel, in (5), pp. 56-66], we be-
lieve that 12,000 m³/ha is closer to the actual global
Antarctica is discharged to ice shelves,
1) decreased from 2000 to 700 km², pr
average application rate. Moreover, the California
where it is lost as icebergs along the seaward
ably as a result of regional atmosph
figures account only for on-farm water applications
and do not include the portion of diversions lost to
edges as well as by basal melting (2). Be-
warming (5). Here, we report on the rec
seepage or evaporation between reservoirs and
cause ice shelves are exposed to both atmo-
disintegration of the northern Larsen
farmers' fields.
sphere and ocean, they are sensitive to
Shelf (LIS).
18. Evaporative losses from Lake Nassar, for example,
changes in the temperature and circulation
The LIS extends along the eastern
have averaged 10 km³/year, which is equal to 12%
of the Antarctic Peninsula from latit
of the Nile's average annual flow [J. A. Allan, in The
Nile: Shanng A Scarce Resource, P.P. Howell and J.
H. Rott and T. Nagler, Institut für Meteorologie und Geo-
64° to 74°S (Fig. 1). The part of the
A. Allan, Eds. (Cambridge Univ. Press, Cambridge,
physik der Universität Innsbruck, Innrain 52, A-6020
north of Robertson Island has retre:
1994), pp. 313-320].
Innsbruck, Austria.
slowly but constantly since the 1940s (6
19. H. E. Schwarz, J. Emel, W. J. Dickens, P. Rogers, J.
P. Skvarca, Instituto Antártico Argentino, Cerrito 1248,
1010 Buenos Aires, Argentina.
The retreat accelerated after 1975 (8),
Thompson, in The Earth as Transformed by Human
788
SCIENCE
VOL. 271
9 FEBRUARY 1996
Rott et.
Our observations suggest that ice shelves
noamericana sobre Gerofisica, Geodesia e Investiga-
A. Scambos, Ann. Glaciol. 20, 319 (1994).
ción Espacial Antárticas. Buenos Aires, 30 July to 3
25. A wind velocity of 49 knots results in a surface stres
close to the climatic limit for existence may
August 1990, p. 160 (1:991).
due to wind shear of ~1 N m⁻². For an undisturbe
disintegrate rapidly. During the next years,
22. P. Skvarca. H. Rott, T. "Vagler, Ann. Glaciol. 21, 291
ice shelf of the size of the LIS. this force would b
increased attention should be paid to the
(1995).
~0.1 to 0.2% of the stress due to shear at the side
section of the LIS south of Seal Nunataks,
23. The following conditions for stability [J. Oerlemans
walls. For the breakup of a heavily disturbed ice shel
and C. J. van der Versn, Ice Sheets and Climate
even these small forces due to wind may play a role
which may be subject to major changes if
(Reidel, Dordrecht, Netherlands, 1984), pp. 41-64]
as may the effects of wind on ocean circulation. A
the warming continues. In November 1994,
were no longer valid after the retreat of the LIS along
increased probability of calving events during per
we observed a transverse rift ~50 km in
Sobral Peninsula: (i) The gradient thickness H along a
ods of persistent offshore winds and air tempera
flow line in direction X for a stable ice shelf in an
tures above 0°C has been reported for Arctic ic
length in section 1, ~30 km inland from
embayment with two parallel sides is given by
shelves (M. O. Jeffries, Rev. Geophys. 30, 24.
the ice front.
aH
(1992)).
Ts
=
26. H. Rott, K. Sturm, H. Miller, Ann. Glaciol. 17, 33
ax pg[1 (p/pw)]W
REFERENCES AND NOTES
(1993); H. Rott and C. Mätzler, ibid. 9, 195 (1987).
where T₈ is the shear stress at the sidewalls, g is the
27. The ERS-1 SAR data (from ERS-1 Experimen
1. C. Swithinbank, U.S. Geol. Surv. Prof. Pap. 1386-B
acceleration of gravity, A and Pw are the density of ice
A01.A2 and ERS-1/ERS-2 Experiment AO2.A101
(1988).
and water, respectively. and Wis the width of the ice
were provided by the European Space Agency. The
shelf. When the ice front retreated into the bay west
2. S. S. Jacobs, H. H. Helmer, C. S. M. Doake, A.
temperature data from Marambio station were pro
Jenkins, R. M. Frolich, J. Glaciol. 38, 375 (1992).
of Sobral Peninsula, W became enlarged suddenly,
vided by Servicio Meteorológico Nacional, Fuerz
3. A. Jenkins and C. M. Doake, J. Geophys. Res. 96,
violating the stability criterion. (ii) The shear strain
Aérea Argentina. This work is a contribution to Aus
791 (1991).
(au/ay + av/ax) at a stable ice front is zero, where is
trian Science Fund (FWF) Project 10709-GEO, to the
4. J. H. Mercer, Nature 271, 321 (1978).
the velocity in direction X of the flow line and V is the
National Space Research Program of the Austriar
5. C. S. M. Doake and D. G. Vaughan, ibid. 350, 328
velocity in direction y. This essentially means that the
Academy of Sciences, and to the Larsen Ice Shel
(1991).
front is perpendicular to the flow lines. After 1986,
Project of Instituto Antártico Argentino, Dirección
6. P. Skvarca, Ann. Glaciol. 20, 6 (1994).
the ice front north of Lindenberg Island differed in-
Nacional del Antártico.
7. C.S. M. Doake, ibid. 3, 77 (1982).
creasingly from this stable geometry.
8. P. Skvarca, ibid. 17, 317 (1993).
24. R. A. Bindschadler, M. A. Fahnestock, P. Skvarca, T.
5 September 1995; accepted 14 November 1995
9. The ERS-1 SAR images were acquired at the Ger-
man receiving station near the Chilean Antarctic
Base O'Higgins, operating on a campaign basis. The
northern LIS was imaged by ERS-1 SAR in July
DNA: An Extensible Molecule
1992, between December 1992 and February 1993,
in August 1993, and between mid-January and mid-
February 1995. For comparison with conditions pre-
Philippe Cluzel, Anne Lebrun, Christoph Heller,*
vious to the accelerated retreat, we analyzed Land-
sat Multispectral Scanner (MSS) images from 1
Richard Lavery, Jean-Louis Viovy, Didier Chatenay,+
March 1986.
10. We obtained the ERS-1 SAR data in Universal Trans-
François Caron
verse Mercator projection based on the WGS-84
ellipsoid with nominal spatial resolution of 25 m by 25
The force-displacement response of a single duplex DNA molecule was measured. The
m and location accuracy of better than 100 m in
areas of low relief. We used geodetic field data to
force saturates at a plateau around 70 piconewtons, which ends when the DNA has beer
control and improve the absolute location accuracy.
stretched about 1.7 times its contour length. This behavior reveals a highly cooperative
Geometric accuracy was high only close to sea level,
transition to a state here termed S-DNA. Addition of an intercalator suppresses this
because terrain-induced distortions resulting from
radar imaging geometry could not be corrected be-
transition. Molecular modeling of the process also yields a force plateau and suggests a
cause of a lack of high-resolution elevation data.
structure for the extended form. These results may shed light on biological processes
11. Data on ice motion, surface mass balance, and ice
involving DNA extension and open the route for mechanical studies on individual mol-
thickness were obtained for sections 1, 2, and 3
during field observations beginning in the early
ecules in a previously unexplored range.
1980s. Mean annual velocities from 1984 to 1994 in
the center of the profiles (Fig. 2) were 385 m/year in
section 1 and 248 m/year in section 3. Ice thickness-
es at the same points were 250 m (section 1) and
220 m (section-3).
Many biologically important processes in-
cules. The extension of a duplex DNA mol-
12. D. A. Peel, in The Contribution of the Antarctic Pen-
volving DNA are accompanied by deforma-
ecule under the action of an external force
insula to Sea Level Rise, E. M. Morris, Ed. (British
Antarctic Survey, Cambridge, 1992), pp. 11-15.
tions of the double helix, and the ability of
was measured by Smith et al. (4) and com-
13. W.M. Sackinger, M. O. Jeffries, H. Tippens, F. Li, M.
DNA to stretch "like a spiral spring in ten-
pared to predictions of the wormlike chair
Lu, Ann. Glaciol. 12, 152 (1989).
sion" (1, p. 739) was recognized long ago
model (5). In good agreement with this the
14. N. Contreras, unpublished data.
(1-3). The mechanics of DNA has regained
ory, these researchers observed that a force o
15. The value of 320 km² was derived from an image of
the Advanced Very High Resolution Radiometer
interest in recent years as a result of the
2 to 3 pN is able to stretch the DNA to 90%
(AVHRR) of the NOAA satellite with 1-km spatial res-
possibility of working with individual mole-
of its contour length at rest in the B-form, 10
olution, acquired on 22 March 1995. An ERS-1 im-
and that the force then rises sharply wher
age from 11 February 1995, covering the area
around Seal Nunataks, shows the southern ice
P. Cluzel, C. Heller, J.-L. Viovy, Institut Curie (URA Centre
the extension approaches Lo. This experi-
boundary close to the position of 22 March.
National de la Recherche Scientifique (CNRS) 448 and
ment was restricted to forces smaller than 2C
16. Because of a lack of images, the exact date of the
1379], 11-13 Rue Pierre et Marie Curie, Paris 75005,
France.
to 30 pN, whereas it has been suggested that
final opening of Prince Gustav Channel is not known.
17. T. Hughes, J. Glaciol. 29, 98 (1983).
A. Lebrun and R. Lavery, Laboratoire de Biochimie Théo-
DNA is able to withstand about 500 pN
18. Surface mass balance was determined from mea-
rique (URA77 CNRS), Institut de Biologie Physico-
before breaking (6). We present here a study
surements at stakes and snow pits. The specific
Chimique, 13 Rue Pierre et Marie Curie, Paris 75005,
France.
of the force-extension response of a single
mass balance is the change of mass per unit area
within a given time period (the algebraic sum of ac-
D. Chatenay, LUDFC, Institut de Physique, 3 Rue de
duplex DNA molecule submitted to force:
cumulation and ablation). Mass balance for an entire
l'Université, Strasbourg 67084, France.
ranging from 10 to 160 pN, using an appa-
glacier or ice shelf represents the overall change in
F. Caron, Ecole Normale Superieure, Laboratoire de Gé-
nétique Moléculaire (URA CNRS 1302), 46 Rue d'Ulm,
ratus (Fig. 1) that improves on that devel
mass.
19. The specific mass balance averaged over sites 15,
Paris 75230, France.
oped by Kishino and Yanagida to study the
25, and 35 km south of Seal Nunataks revealed the
*Permanent address: Max-Planck-Institut für Moleku-
actin-myosin interaction (7).
following temporal changes: 1980 to 1988, 220 mm/
lare Genetik, Ihnestraße 73, D-14195 Berlin-Dahlem,
We repeated our experiment many time:
year; 1988 to 1991, 130 mm/year; and 1991 to
Germany.
1994, 70 mm/year.
using different fibers and stretching velocitie:
tPresent address: Rockefeller University, Box 265, 1230
20. J.C. King, Int. J. Climatol. 14, 357 (1994).
York Avenue, New York, NY 10021, USA.
(a few seconds was typically required for
21. J.A. J. Hofmann, in Actas, Primera Conferencia Lati-
#To whom correspondence should be addressed.
stretching). Two types of curves were ob
792
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9 FEBRUARY 1996