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Clinton Presidential Records
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Council on Environmental Quality
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61
5
7
1
GLOBAL ENVIRONMENTAL CHANGE REPORT
money for the federal government
life cycle costs and are cost-effec-
Copies of the OTA report, Energy
immediately, and be more than paid
tive." All new federal buildings
Efficiency in the Federal Govern-
back in a few years or sooner."
must meet energy performance
ment: Government By Good
standards, and agencies must reduce
Example? are available for US $5
On 17 April, President Bush ordered
their motor vehicle fuel consump-
from the Superintendent of Docu-
each federal agency to develop and
tions by at least 10% in 1995 from
ments, USGPO, Washington, DC
implement a plan to reduce its over-
1991 levels. A "maximum number
20402-9325. Tel: +1-202-783-3238.
all energy use in buildings by 20%
practicable" of alternative fueled
Reference GPO Stock Number 052-
from 1985 energy use levels "to the
vehicles must be purchased by agen-
003-01242-1.
extent that these measures minimize
cies each year.
Science Update
Researchers Protest Their
in GECR. Andrew Lacis of NASA
the plants and animals that require
Inclusion in Skeptics'
Goddard, who was listed in the
them. Of course, coastal areas and
Agenda
same proposal as co-investigator,
regions of upwelling are more pro-
On page 1 of Global Climatic
hadn't heard of the meeting or the re-
ductive, but they account for only
search agenda until GECR tele-
10.1% of the ocean's surface. The
Change: A New Vision for the
1990s, the US greenhouse skeptics'
phoned him on 13 May. Both Kukla
rest, as Colinvaux says, is "a blue
and Robinson strongly objected to
desert more useless to life than most
alternative research agenda (see
GECR, 1 March, pp. 1-3), one finds
the "consensus" wording in the
of Arabia." The Antarctic ocean,
the following statement: "The con-
prospectus; Robinson has written
however, is the most enigmatic ex-
sensus of the scientists in this re-
to Patrick Michaels and Robert Ball-
ception to that sweeping statement.
ing (the organizers of the meeting
Nutrients are abundant there, and
search prospectus is that there is con-
siderable evidence that the impact of
and the authors of the prospectus' in-
yet phytoplankton are comparatively
troduction) to ask that the language
scarce. Because of the Antarctic's
future climatic change may be
neutral or even beneficial.'
be revised.
great unrealized potential for biotic
activity, scientists have looked to it
But to at least three of the scientists
Balling told GECR that he and
as a potential modifier of CO2 con-
whose proposals were included in the
Michaels are polling all of the scien-
centrations under different climate
agenda, that claim is misleading. Ac-
tists named in the prospectus and
regimes hence the proposals for
cording to one of them, there was no
will prepare a statement on the ac-
iron fertilization and the widely ac
tual level of consensus within the
formal consensus reached or even
cepted theory that a phytoplankton
called for at the meeting which pro-
group. Balling says that he and
bloom in the Antarctic ocean caused
duced the agenda, nor was the intro-
Michaels did circulate the agenda's
global CO₂ concentrations to drop
introduction to the conference atten-
duction to the research agenda circu-
during the last ice age.
lated among the participants for their
dees prior to publication, but Kukla
approval. Finally, at least four of
denies having seen it. As for the re-
These ideas, however, are set spin-
searchers who weren't invited to the
the researchers listed were not even
ning by a new study reported in the
invited to the meeting, did not know
meeting, Balling points out that all
16 May issue of Nature (vol. 351,
their proposals were being included,
of them were co-investigators. He
pp. 220-222). R.A. Mortlock and
and were unaware that their names
says it was the responsibility of the
colleagues from Lamont-Doherty
would appear in the prospectus.
principal investigators who attended
and Columbia University (Palisades,
the meeting to notify their co-inves-
New York) use three lines of
On 6 May, GECR received a letter
tigators that their names would be in-
evidence to show that phytoplankton
from David Robinson of Rutgers
cluded in the prospectus.
productivity was in fact low, not
University, urging us to print a
high, during the last ice age, and the
clarification. Robinson, who was
Ice Ages and Plankton
plants were less efficient at taking
listed on a project proposal as a co-
Don't Mix
up nutrients. Mortlock et al.
investigator with George Kukla of
analyzed records of the accumula-
the Lamont-Doherty Geophysical
As Paul Colinvaux pointed out in
tion rates of diatom shells, the ratio
Observatory, was not invited to the
his classic 1978 primer on ecology,
of germanium to silicon in opal
meeting and didn't hear about the re-
Why Big Fierce Animals Are Rare,
(also related to diatom production),
most of the world's ocean is a
search agenda until he read about it
and the carbon isotope ratio in the
desert. Nutrients are scarce, as are
shells of foraminifera to reach their
VOL. III, NO. 10
1991
5
GLOBAL ENVIRONMENTAL CHANGE REPORT
conclusions. As W.H. Berger of
keep declining. (Readers should
Sedjo told GECR that his analysis
Scripps Institution of Oceanography
keep in mind GECR's 15 March
"flies in the face of the conventional
points out in an accompanying ar-
Focus Report on the potential vul-
wisdom" that Northern temperate for-
ticle on pp. 191-192, this analysis
nerability of nonfossil energy sys-
ests are in balance with regard to CO2.
should "severely damage conven-
tems to climate, however. One
tional belief in Antarctic modulation
should also note that Ausubel's
of atmospheric carbon dioxide."
Upgrade on NIST
analysis is based on industrialized
However, Berger says the question
Refrigerant Mixtures
countries.) Ausubel notes that
Database Available
is still not totally resolved, since
ecosystem vulnerability is another
there could be alternative explana-
question entirely, and does not sug-
The US National Institute of Stand-
tions for some of Mortlock's find-
gest overtly that climate change is
ards and Technology (NIST) has
ings.
nothing to worry about, but he im-
released an update to its Thermo-
plies that "business as usual" may
dynamic Properties of Refrigerants
Technologies Reduce
yield a more favorable future for
and Refrigerant Mixtures Database.
Societies' Vulnerability to
humanity than many have suggested.
The database, which will run on any
Climate
AT- or XT-class personal computer
Reforestation in the
(and requires 512 K of memory) al-
In the 25 April issue of Nature (vol.
lows researchers to produce tables
350, pp. 649-652), Jesse Ausubel of
Northern Hemisphere:
of thermodynamic properties of 18
The Rockefeller University in New
The Missing Sink?
pure refrigerants, including ethane-
York discusses evidence that tech-
According to an article in the 4 May
based compounds, and 24 mixtures.
nology has allowed human societies
issue of New Scientist, the spread of
Mixtures of up to five components
to become increasingly shielded from
forests in the Northern Hemisphere
can be analyzed.
the effects of climate and weather.
could account for much of the miss-
Ausubel argues convincingly that
ing sink for carbon. Roger Sedjo of
The upgrade contains new data on
there is a trend toward systems that
the Washington-based Resources for
mixing parameters for four blends
are less vulnerable to climate, citing
the Future used forestation data
(including HCFC-22 and HFC-
examples ranging from food preserv-
from the UN Food and Agriculture
152a), and has revised Carnahan-
atives to weather satellites. "In
Organization to conclude that 700
Starling-DeSantis coefficients for all
many respects we seem to be
million metric tons of carbon are
18 refrigerants.
'climate-proofing' society, Ausubel
being captured in Northern Hemi-
Version 2.0 of the REFPROP
says. Even agriculture may be more
sphere trees and soils each year.
database is available for US $340
robust than many people think:
Sedjo presented his paper at this
from the Standards Reference Data
transportation systems allow people
to rely on food sources outside their
year's annual meeting of the
Program, A320 Physics Building,
area and thus "spread production
American Association for the
NIST, Gaithersburg, MD 20899,
risks across more climatic zones,"
Advancement of Science. A second
USA. Tel: +1-301-975-2208; Fax:
and existing crop cultivars in the US
unpublished paper by Sedjo, which
+1-301-926-0416.: Upgrading to ver-
considers the effect of tropical
sion 2.0 from 1.0 costs $90.
are generally replaced by new ones
within just eight to nine years.
deforestation, concludes that while
the destruction of tropical forests
New Climate Journal Calls
Ausubel points out that the adapta-
adds 2 billion tons of carbon into the
for Papers
tions for long-term climatic change
atmosphere, much of that will be
Climate Research, subtitled Interac-
will probably resemble those for
reabsorbed while the forests grow.
tions of Climate with Organisms, Eco-
other climate variations - those
Sedjo says the net emission of car-
systems, and Human Societies, has
that "mollify the difference between
bon from tropical deforestation is
issued a call for papers. The new
daytime and nighttime temperatures,
700 million tons, coincidentally the
journal is published by Inter-Research
protect against normal variability be-
same amount that's being absorbed
in Germany, and appears to be in the
tween days, shield from storms and
by Northern Hemisphere forests.
same league as Climatic Change and
hail, adjust to the seasons, and adapt
Last year, Taro Takahashi and Pieter
Global Environmental Change:
to the wide range of climates where
Tans reported in Science that oceans
Human and Policy Dimensions.
people already live."
absorb only at most one billion tons
of carbon, and there must be a large
Climate Research invites papers on
Ausubel points to the steady im-
terrestrial sink (GECR, 9 March
interactions of climate with or-
provements in technological perfor-
1990, p. 5). Sedjo's findings could
ganisms, populations, ecosystems,
mance and efficiency, suggesting
explain "a large amount" of the miss-
and human societies; short- and
that this trend will continue and that
ing sink.
long-term changes in climatic ele-
human vulnerability to climate will
ments; methodological aspects of
6
17 MAY 1991
VOL. III, NO. 10
ALBERT GORE, JR.
393 RUSSELL SENATE OFFICE BUILDING
TENNESSEE
PHONE: 202-224-4944
United States Senate
WASHINGTON, DC 20510-4202
May 7, 1991
Discover Magazine
3 Park Avenue
New York, N.Y. 10016
To the Editor:
John Martin proposes iron fertilization of the Southern
Ocean as at least a partial solution to the threat of global warming.
("Earth On Ice", April 1991). In my opinion, he's got it exactly
wrong. Our manhandling of the global environment created the problems
we face; it is not part of the solution.
It would be easy to attack Martin's suggestion on technical
grounds: there is evidence that iron is not the limiting nutrient in
the oceans; very recent research shows that, even if adding iron would
increase plankton populations, the net amount of carbon sequestered
would be modest; massive amounts of money and other resources would
have to be mustered if the program were to be even marginally
successful in achieving its objectives.
But my opposition to Martin's suggestion runs much deeper. The
proposal is dangerous because it plays to wishful thinking that there
is no need for fundamental change in the design of our civilization;
and that, with a little creative engineering, we can out-smart nature
once again. The truth, however, is that we cannot, without serious
repercussions, continue our hubristic campaign of re-creating the
environment.
You would think we would have learned that lesson by now. This
is certainly not the first time we have undertaken such technological
"fixes". Our determination to produce crops in areas not suited to
produce them, for example, has poisoned the soil and, in some areas,
created vast deserts of salt and pesticides. And consider our desire
to adorn ourselves cheaply in silk by bringing gypsy moths into the
country -- vast stands of diseased and dying trees are the legacy of
that venture. The kudzu vine that chokes native plants and trees in
the Southeast; the rabbits that overran Australia; and the Africanized
bees that have now made their way into the United States, are all
testimony to our inability to gauge and control the effects of grand
eco-engineering schemes. And those are nothing compared to this
proposal.
It is time we stop kidding ourselves. The simple truth is that
it is only by changing our behavior -- and our relationship to the
earth -- that we can effectively address the global environmental
problems we face. Study after study tells us we can make make
significant gains at minimal cost with existing technologies. The need
for such action is clear. The ozone layer is being depleted at an
alarming rate; we need to move quickly to end the use of ozone
destroying chemicals. We continue to experience record warmth, severe
drought, extensive forest fires, and other warning signals consistent
with those long since predicted to accompany the onset of global
warming and climate change; we need to cut our emissions of greenhouse
gases in every sector of the economy. The very threads of the web of
life are being severed as rampant deforestation drives thousands of
species to extinction; we need to preserve and protect sensitive
ecosystems and manage our forests sustainably.
So let's get on with it. I challenge our scientists to use
their insights and creativity to devise ways for us to live in harmony
with nature -- rather than speeding us further along on the collision
course we are currently travelling.
al Dore
Al Gore
United States Senator
Chairman, Senate Subcommittee on
Science, Technology, and Space
PHOTOCOPY
MISC. HANDWRITING
will send
+ hanks
DISCOVER
March 21, 1991
The Honorable Al Gore
United States Senate
393 Russell Senate Building
Washington, DC 20510
Dear Senator Gore:
Enclosed is the most recent issue of DISCOVER. It contains
the article ``Earth on Ice'' on page 54, which we thought
might interest you. On our letters page we like to encourage
an exchange of views about our articles. We'd be happy to
consider any letter that you might want to write.
Thank you for your time.
Sincerely,
Clarence V. Reynolds
Bitoy Hanson
Betsy Hanson
Clarence V. Reynolds
Researchers/Reporters
100%
A FAMILY MEDIA PUBLICATION, 3 PARK AVENUE, NEW YORK, NY 10016 212-779-6200 FAX 212-725-3962
recycled
ALBERT GORE, JR.
393 RUSSELL SENATE OFFICE BUILDING
TENNESSEE
PHONE: 202-224-4944
United States Senate
WASHINGTON, DC 20510-4202
April 16, 1991
Discover
3 Park Avenue
New York, N.Y. 10016
To the Editor:
Responding to your article "Earth on Ice" (April 1991), I must
express my concerns regarding the iron fertilization of phytoplankton
in the Antarctic as a means of lowering atmospheric CO2 levels. The
concept of iron fertilization as a "fix-it" for reversing the
greenhouse effect begs the issue, and proposes a simplistic solution
to a very real and complex problem. Certainly the concept may be
embraced as a means of conducting business as usual, but presenting
iron fertilization as a panacea for this global problem is misleading.
The concept of iron fertilization in the Antarctic has generated
critical research and discussion that question the plausibility and
desirability of adopting such a proposal. Most notable is Peng and
Broecker's (1991) research on ocean dynamics that concludes negligible
to insignificant lowering of atmospheric CO2 by iron fertilization
after 100 years of totally successful fertilization. Their results
suggest that with a "business-as-usual" scenario of fossil fuel CO2
emissions in the next century, the CO2 content of the atmosphere would
be lowered by only about 5-15% below what it would have been without
fertilization.
What are the costs of this concept? As you mention in the
article, the costs of testing the iron fertilization of a small 60
mile X 60 mile square of ocean would run between the tens of millions
of dollars and more than a hundred million. Once begun, the
fertilization process would require even, annual dispersal of iron for
at least 100 years to ensure the retention of carbon. The
fertlization process would involve the use of hundreds of barges and
ships, their transport and upkeep, the purchase of soluable iron, and
the payment of labor -- at an estimate in the billions of dollars
(Borchelt 1990). Given the annual costs of such an operation over a
100 year period, would a lowering of atmospheric CO2 levels by 5-15%
be worth it?
Furthermore, the environmental costs of the iron fertilization
concept need to be fully explored and weighed. Many scientists are
concerned that the long-term ecological effects of iron fertilization
may be devastating. For example, successful fertilization would
increase the amount of organic material in the deep ocean water. In
the worst case scenario, reoxidation of these organic materials would
diminish the supply of oxygen in the Antarctic deep water to the point
of anoxic condition. Repercussions would include the loss of krill
ALBERT GORE, JR.
393 RUSSELL SENATE OFFICE BUILDING
TENNESSEE
PHONE: 202-224-4944
United States Senate
WASHINGTON, DC 20510-4202
eggs and krill upon which whales, seals, squid, fish, and penguins
feed. Such a loss of oxygen in the deep ocean would liken the area to
a devastated and less productive lake environment.
The concept of iron fertilization focuses our attention on short
term "fix-it" approaches in dealing with the greenhouse effect rather
than on changing the attitudes and behaviors that produce CO2
emissions in the first place. If we expended as much money, time, and
energy that the iron fertilization scheme proposes over the next 100
years into reducing the primary production of CO2 emissions, the
problem would be solved -- or, at least, substantially reduced.
Sincerely,
Al Gore
U.S. Senator
REFERENCES:
Peng, T.H., and W.S. Broecker
1991 Dynamical limitations on the Antarctic iron fertilization
strategy. Nature 349: 227-229.
Borchelt, Rick
1990 Enlisting Marine Algae To Ease Global Warming. NewsReport.
December 1990-January 1991: 5-7.
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 publication.
Publications have not been scanned in their entirety for the purpose
of digitization. To see the full publication please search online or
visit the Clinton Presidential Library's Research Room.
THE HUNT FOR BROWN DWARFS
DISCOVER
THE NEWSMAGAZINE OF SCIENCE
APRIL 1991
$2.95
EARTH ON ICE
A Bold Attack on Global Warming
04
37151
0
285567
7
NEWSAND VIEWS
BIOGEOCHEMICAL CYCLES
DAEDALUS
Ironing out greenhouse effects
In two minds
Robin S. Keir
EACH hemisphere of the human brain has
its own specialism. The left hemisphere
it has been proposed that CO. could be
atmospheric and Antarctic surface water
(which dominates the right side of the
removed from the atmosphere and there-
Peo. is maintained at & larger value. The
body) is good at language and logic; the
bv its greenhouse effect reduced by using
consequent reduction in the rate of
right hemisphere (dominating the left side)
the so-called from ypothesis of Martin
increase of atmospheric CO. is also some-
has better spatial awareness and emotional
According to this ideaviton is thellimiting
what greater.
intuition. Daedalus points out how our
nutrient for biological growth in Antarctic
Surely in looking at how to tackle the
view of a knotty problem tends to shift
surface waters. which have abundant
threat of greenhouse warming, we should
cyclically back and forth every few hours or
phosphate: nitrate and silicate: By fertiliz-
not focus on which model of iron fertiliza-
so, This, he says, is our two hemispheres
ing. this area with iron. phytoplankton
non gives the best result (the possibility of
looking at the matter in turn:
growth would be greatly, stimulated. and
undesirable ecological effects put to one
He relates this alternation of mood to our
the surface-water's partial pressure of CO.
side for the moment). but rather we
nostrils, which have to warm and humidify
would lie greatly reduced - by more than
should worry about the increasing rates of
the air before It reaches our lungs. It's a
150 parts per million (pip.m.). But even if
fossil-fuel consumption. The total scale of
hard job. It can drain 5-15 watts of heat
the fertilization were completely success-
fossil-fuel reserves is not known with any
continuously from the warming and wett-
full: the effect on atmospheric CO. would
certainty but most estimates are between
ing surfaces, and the nostrils tend to open
he much smaller according to Peng and
0 and 12 times the present amount of
alternately, a few hours at a time: (You
Broccker on page 227 of this issues Their
carbon in the atmosphere as CO,, mostly
notice this when you have a cold.) Each
model calculations show that after 100
as coal Barring increased uptake by the
hemisphere of the brain puts out only
years of successful fertilization. the atmos-
terrestrial biosphere. which seems un-
about 10 watts of heat. The active 0 11.
pheric CO. content would be reduced only
likely because of deforestation, 70-80 per
draining heat copiously from the hernis-
by about 30 P.P.M. an amount which is
cent of this carbon will accumulate in the
phere close above it, must cool it strongly
The brain is very sensitive to temperature,
PRESERVATION
also small in comparison to the hundreds
atmosphere if it is burned over a period of
PHOTOCOPY
of parts per million- the concentration is
a. few hundred years. regardless of the
growing feverish in the warm and sleepy in
projected to rise during this time owing to
actual history of the CO₂ generation over
the cold. So as each nostril opens up in
fossil-fuel burning
this period When we have consumed
turn, the hemisphere on that side grows
The authors point out that the problem
most of the fossil fuel. the atmosphere will
sleepy, and our mood swings accordingly.
is that the capacity of the Antarctic surface
have reached a level of at least 1.500
In this connection, Daedalus recalls the
water bvitself to take up atmospheric CO
P.P from. its present level of around
traditional yoga exercise of breathing In
is, very small. Therefore this region acts
345 p.p.m. at this point it may not mat-
through one nostril and out the other. The
only as an interface through which addi-
ter whether a sequestering effort reduced
nostril of Inflow gets no relief from warm
tional Owenald be sequestered from the
the atmospheric CO. by 30 p.p.m. or
exhaled breath, and must cool its h
atmosphere and transferred into the large
300 p.p.m.
sphere very strongly - a subtle yogic way
volume of intermediate and deep waters
However, exactly when, the maximum
of opening the mind to new percepti
3:
The rateiof this transfer depends upon the
CO. level will be reached can vary greatly.
Daedalus's psychonasal air-conditioner'
nature of the circulation the speed with
For example, a slowly growing production
provides. each nostril with its own air,
which the upper waters are replaced and
of CO. may result in only a doubling of the
of defined temperature and humidity It
the extent to which they remain in contact
atmospheric content by the year 2100, but
can fire up or chill out either hemisphere
with the atmosphere afterwards
expansion of CO, production at the pre-
at will. Plumbed into the prototype,
The model simulations on page 228
1973 rate of 4.5 per cent a year could lead
DREADCO volunteers are tackling the
(their Fig. 3) illustrate this aspect quite
to levels over. 1:200 p.p.m. by then?
usual psychiatrists' battery of insulting
clearly Initially there is artransitory peri-
Because fossil fuel is a finite resource, we
questions and emotional ordeals. With its
od of few years during which the CO.
will need to find an alternative within the
aid, the sternest logicians are enjoying
partial pressure (P... ) in the surface water
next two or three centuries (sooner if sub-
flights of fancy, while poets buckle down
decreases rapidly and subsequently recov
stantial consumption of coal is to be
to mathematical proofs.
on to within 30 p.m. or so of the atmos-
avoided) The slower that fossil fuel is
The final 'Psyconditioner' will be a
pheric value The latter evidently occurs
burned in the meantime, the better.
special hat with concealed plumbing and
because of rapid exchange of CO: across
Neither iron fertilization nor any other
heat-pump, and integral nose-plece. By con-
the sea surfaces After this transient, the
method of CO. sequestration can be con-
trolling the wearer's nostril-air, it will
surface ni maintains a nearly constant
sidered a serious alternative.
expand his consciousness under full control.
disequilibrium with the atmosphere The
Modern, highly verbal society tends to put
resulting decrease in atmospheric COMs
Robin S: Keir Is at GEOMAR, Forschungs-
the right hemisphere at a disadvantage;
zentrum für Marine Geowlssenschaften an der
quite sligh, the time constant is probably
Christian-Albrechts-Universität zu Kiel, Wisch-
the Psyconditioner will allow anyone to get
of the order of a few hundred years The
hofstrasse 1-3. 2300 Kiel 14, Germany
in touch with his Intuitive nature. Its
Antarene surface ater is Bushed everv
wearer will be able to look at a problem first
years In the en ulation, but for every
1 Martin - Paleocesnography 6. (1990)
logically, then intuitively then (with the
turnover the water takes up only. small
2. Peng: TH & Breecker. W S: Nature 349, 227-229
aid of a special superheater) with fevered
part of the atmospheric CO TRO that the
1991
Wenk t & Siengenthal V In The Carbon Cycle: and
imagination and even with fevered logic
time constant for O. removal is about
Atmospheric CO2: Natural Variations Archeen to Present
At. a picture-gallery* or social function he
100/times the water residence time
(SOE Sundquist. E.T. & Broecker, W. $.) 185-194 (Ameri-
will engage his right hemisphere, while the
can Geophysical Union. Washington DC. 1985).
The result found hv Pengand Broecker
100% Sarmiento. 1. L.& Siegenthaler. U. Nature (In the
small print of an insurance-contract will
is Friund (4.) be somewhat model. dépen-
press)
engross his left one. The most inhibited or
5.
dent Indeed Joes at lusing-a different
Ratty, R: M. & Marland/G in Interactions of Energy and
Climate. (eds Bach,, W., Penkrath J: & Williams, J.),
undisciplined wearer will be able to experi-
circulation pattern through the Antarche
191 212 (Reidet: Dontrecht, 1988)
ence previously suppressed aspects of his
surface region and darger/surface area
Keeling C D. & Bascastow, R.B. in Energy and Climate
72 -95 (National Academy of Sciences. Washington CC,
personality - and suppress them again as
had the diséquilibrium between the
1977)
necessary.
David Jones,
198
NATURE VOL 349 17 JANUARY 1991
PHOTOCOPY
LETTERS TO NATURE
PRESERVATION
duced
possible source for the two-level systems would bei tipping of
The CO2 partial pressure in surface ocean water is influenced
occtral
the central phenyl ring of terphenyl between various allowed
by the extent to which plant growth reduces the total CO₂
and
orientations that are made accessible by disorder in the crystal
content. SCO2 of surface water. The magnitude ofthis reduction
effect
structure" Validation of this model requires detailed tem
depends on the efficiency with which the limiting nutrients
10 be
perature-dependent measurements of the jump rate for a single
phosphate and nitrate are utilized In today's temperate and
turba.
centre over a wide range of temperature in hope of observing
tropical ocean the utilization efficiency is high and therefore the
the characteristic oth(E/2kT) dependence, where E is the
reduction of the CO2 partial pressure. Pco. is near maximum
anner.
energy splitting in an asymmetric two-level model and k is
By contrast. the utilization efficiency is low in the polar oceans
ved to
Boltzmann-s constant
Hence, were a means to be found to increase the efficiency of
juency
ng the
As the spectral jump rates and sizes that we observe are
nutrient utilization in these waters. their CO. partial pressure
uggest
different for different defects; direct observation of this spectral
and in turn that for the atmosphere, could be reduced. Martin
have
diffusion effect would not be possible in any spectroscopy that
and his workers have shown in incubation experiments
averages over many defects. Direct measurement of the
that plant growth rates in waters from polar regions can be
jower
behaviour of individual guest molecules in a glass would lead
greatly accelerated by adding trace amounts of dissolved iron
show
to a clearer understanding of the origins of dynamics in amor-
Iron is an essential micronutrient required for the metabolism
phous solids than is available from ensemble-averaged
of all forms of life; its primary function being cytochrome
from
seem
measurements. Much more intriguing is the fact that we have
formation. Because iron is one of the most particle-reactive
sen spectral jumping in a crystalline environment, where such
elements, its concentration in the sea is very low, with the lowest
width
data
effect is not expected.
values occurring in regions like the Antarctic that are most
removed from the continents
(opent
To date, most of the attention regarding the Manin proposal
either
Received 1 November accepted December 1990
has been focused on its biological aspects and little attention
nearly
1. Moerner, W E: & Kador, L. Priy 5. Rev: Lett, 62, 2535-2538 (1989)
usiline
has been given to the dynamical aspects Even though/successful
2. Kador L: Horne D E. & Moerner W. E. phys. Chem 94, 1237-1248 (1990)
iron fertilization would initially produce up to a twofold
ggests
3 Orit M. & Bernard: J. Phys. Rev. Lett 65; 2716 (1990)
4. Itano W. M. Bargquist 1.C. & Wineland D. J. Science 237, 612-617 (1987)
decrease in the CO₂ partial pressure in Antarctic surface waters.
topose
5. de Vries, H. & Wiersma, D. A. J. chem Phys as, 897-901 (1978)
this reduction might be In the absence of water
where
B Dison R. W& Fayer. M. D. , phys. Chem 2001-2004 (1980)
lically
Stoneham A. M. Rev., mod. Phys 41. 82-108 (1969).
circulation; only an amount of CO. equal to that removed as a
3 Yen. W. M & Seizer: P. M. (eas) Laser. Spectroscopy of Solids (Springer: Bertin. 1981)
result of the initial iron fertilization would be sequestered from
15 may
9 de Vries, M. & Wiereme 5. A , chem. Phys. 72, 1851 1863 (1980).
the atmosphere. In this case, the atmosphere the Antarctic
ns, by
10. de Vries H. & Wiersma, D. A. I chem. Phys 70, 5807-5822 (1979)
11. Gardiner C. W. Handbook of. Stochestic Methods 78-79 (Springer. Berlin, 1983).
surface ocean and the non Antarctic surface ocean would
ssisted
12 Nagoumey W Sandbarg 1 & Denmelt. H. Phys Rev. Lett. 58, 2797-2799 (1986)
nd the
13 Moerner: W. É. & Carter. T. Phys Rev. Lett. 59. 2705-2708 (1987)
14. Patterson F. G: Lee. H W. H Wilson, W. L. & Fayer, M. cnem. Phys 84; 61-60 (1984)
num.
15 Phillips. W.. A. (ed.) Amorphous Solids: Low Temperature Properties (Springer, Berling 1981).
One
16. Sussman AS Phys. kondens Materie 2 146-160 (1964).
CO₂ exchange
Well mixed atmosphere
CO₂ exchange
17 Baudour. L.. Delugeard, Y & Calliaau. H. Acta Crystallogy. 832, 150-154 (1978)
18: Golding B. & Graebner, J.E. in Amorphous Solids Low Temperature Properties (ed. Phillips, W. A.)
0
Surface ocean mixed layers
107-134 (Springer. Berlin. 1981).
75
19 Friedrich 1. & Hearer, D. in Optical Spectroscody of Classes (ed. 2schokke. I.) 148-198 (Reidel,
Dordrecht. 1986).
ACKNOWLEDGEMENTS. We thank M. Orrit for providing a copy of his manuscript prior to publication
Depth ocean (m)
Antarctic (10%)
Diffusion-zone
This work was supported in part by the US Office of Naval Research
Non-Antarclic (90%)
1cm
Dynamical limitations on the
2,000
Antarctic iron fertilization
W
strategy
Well mixed sea
T-H. Peng* & W. $. Broeckert
4,000
Environmental Sciences Division, Oak Ridge National Laboratory,
Oak Ridge, Tennessee 37831. USA
CO2 exchange
Well.mixed atmosphere
CO. exchange
1 Lamont-Doherty Geological Observatory. Columbia University, Palisades,
0
Surface ocean mixed layers
New York 10964, USA
75
MARTIN et al. have proposed an ingenious means by which the
rise in stmospheric CO2 content generated by the burning of fossil
Antarctic could be stimulated by the addition of dissolved iron,
Depth in (m)
Antarclic (10%)
Diffusion zone
is that plant production In the nutrient-rich surface waters of the
Non Antarctic 190%)
Iem
fuels and deforestation might be partially compensated. The idea
thereby reducing the CO₂ partial pressure In these waters and
2,000
allowing CO2 to flow from the stmosphere into the Antarctic
W
Ocean. We have used a box model callbrated with translent tracer
data to examine the dynamical aspects of this proposal, and
Well mixed deep
conclude that after 100 years of totally successful fertilization the
CO₂ content of the atmosphere would be lowered by only 10 ± 5%
4,000
below what It would have been la the absence of fertilization So
0
F.IG. 1 Linked vertical advection and diffusion model used to ovaluate the
if after 100 years the CO₂ content of the atmosphere were 500 µatm
response to iron fertilization of Antarctic surface waters The upper panel
without fertilization, it would be between 425 and 475 patm with
shows the case where the water upwelled in the Antarctic is transferred
full fertilization. In other words, If our model callbration is correct,
laterally to the non-Antarctic surface ocean The lower panel shows the
single
even if iron fertilization worked perfectly it would not significantly
case where this upwelled water is converted to deep water and transferred
centre
reduce the atmospheric CO2 content.
directly to the model's deep reservoir
227
NATURE VOL 349 17 JANUARY 1991
PHOTOCOPY
LETTERS TO NATURE
PRESERVATION
3.0
10
Ocean as measured during the GEOSECS surveys of the world
a
100
ocean 10 These results show that the Antarctic waters contain
2.5
far less bomb-produced radiocarbon than invaded this region
from the atmosphere.' By contrast, the temperate region of the
2:0
Southern Hemisphere ocean has an inventory exceeding the
0
PO, kg
amount received by invasion. This excess roughly balances the
1.5
deficiency in the Antarctic. This pattern can only be explained
by upwelling in the Antarctic coupled with lateral transport to
1.0
the adjacent temperate regions!! The upwelling rate required
to explain the Antarctic deficiency is 15 m yr (ref. 11). As the
low bomb-radiocarbon water in the Antarctic. Ocean covers
0.5
10% of the total ocean area, this corresponds to a flux of 17 SV
(17 10° -52
0.0
0
500
1,000
1,500
2.000
In addition to upwelling. account must be taken of the extent
2,400
of vertical mixing. The mean penetration depth of the bomb
h
radiocarbon for the fifteen GEOSECS radiocarbon profiles for
100
latitudes south of 49°S is 260 m (ref. 11): This extent of penetra-
tion into the upwelling plume can be explained using a vertical
2,300
10
eddy diffusivity of 5 (the steady-state tracer penetra
tion depth into such a plume would be 630 m). Hence, if this
0
CO2 (fimol
interpretation of the homb-radiocarbon data is correct, the
2,200
volume of water immediately beneath the Antarctic surface
available for CO., storage is only 2.2> 1016 m² (630 3.5x
10" m') or 1.8% of the ocean's volume, a volume too small to
2:100
house a significant amount of excess CO2 Thus it is the fate of
the upwelled water that matters. Additional storage capacity
will be provided by that portion of the upwelling water that is
2.000
converted to notiom water along the southern fringe of the
0
500
1,000
1:500
2.000
Antarctic or to intermediate waters along the northern fringe of
Depth (m)
the Antarctic.
We devised a simple model to test our ideas Two box
FIG: 2. Vertical distribution of a PO, and 5 100, in the Antarctic column
before the onset of fertilization (dashed line) end" 10 and 100 years after
diffusion columns' are linked by an overlying atmosphere and
the onset of fertilization for the scenário where water is upwelled at the
an underlying deep sea (see Fig. T): One column represents the
rate of 174 Svrand transferred to the deep sed.
Antarctic and the other the non-Antarctic region of the ocean
Each column is capped by a mixed layer 75 m deep. These mixed
layers are underlain by diffusion zones 2,000 m thick Beneath
rapidly reach a new equilibrium, leaving the atmosphere with
the diffusion zone is a single well mixed deep reservoir: The
a CO₂ content only slightly lower than it had before fertilization.
area of the Antarctic column was taken to be 10% of the ocean
To achieve a significant reduction of the atmosphere CO.
total The actual effective area of nutrient-rich water in the
content the surface waters of the Antarctic must he replaced
Antarctic is 16% of the ocean area (out to 45° S). We adopted
frequently from below.
a somewhat lower area to compensate for the fact that iron
Thus the critical issue is the rate of vertical mixing in the
fertilization cannot work during the lightless winter months.
Antarctic Ocean. Traditional thinking is that deep ocean water
During these periods vertical mixing will return the CO₂ partial
upwells in this region A portion of this upwelled water moves
pressure to its fertilization value.
beneath the Antarctic's sea-ice fringe where it is densitied by
We set the vertical eddy diffusivity in the Antarctic column
brine release causing it to sink back into the deep sca. The
at Meints and that in the non-Antarctic column at 1 cm2 S
remainder moves to the north Part is converted to intermediate
The upwelling rate in the Antarctic column was set at 17 $v
water which penetrates northward into the Atlantic Pacific and
(15 vr Because we do not have information with which to
Indian oceans at a depth of 1,000 m. The remainder is mixed
apportion the late of the upwelled water we studied two limiting
into the temperate surface water.
cases in the first the water is transferred entirely to the surface
Confirmation of the upwelling hypothesis comes from the
of the non-Antarctic column. In the second it: is transferred
inventories of bomb produced radio arbon in the Antarctic
entirely to the deen reservoir:
350
350
15
266
Peo 34
280
FIG, 3 Model runs for an Antarctic upwelling the of 4.St
300
265
300
252
Surface non Antarctic
Left-hand panel shows the case where the upwelled water
Is transferred to the surface of the Antara (II Orean and
the right-hand panel- shows the Case
250
Atmosphere
water is transferred to the deep sea Iri cach case tetails
successful fertilization is conducted for years First
the steady conditions before fertilization THE en
has
Antarctic surface waters is nearly identical 1/1 USA for the
20°
200
atmosphere
Surface Antarctic
150
150
50
100
0
50
100
Time (yr)
228
NATURE VOL 349 17 JANUARY-1991
PHOTOCOPY
LETTERS TO NATURE
PRESERVATION
vorid
We started our calculation with the carbon cycle in a steady
12: Geschger, H., Siegenthaler: U., Schotterer: & Gugelman A Tellue 27.168.192.(1975)
ntain
state The residence times for PO₄ with respect to biological
13. Foster, T: DH& Welss R. F Antaict 74, 7611988)
14: Stouffer Manabe $ & Bryan: K Nature: 342. 660-652 (1989)
gion
removal from the surface reservoirs were set to vield 1.6 umol
of the
per kg PO₂ in the surface water above the Antarctic column and
ACKNOWLEDGEMENTS Discussions with. Sarmiento prompted this study He also pointed 0.4 an
important mistake in our paper We had assumed that the reductions obtained foi a steady state
MI the
no PO. in the surface waters of the non-Antarctic column. The
atmosphere with 280 p.m. CO2 applied directly to the enthropogenically perturbed etmosphere
:S the
regeneration function for falling organic debris was set to yield
Samiento pointed out that this is not correct. We have carried out CO, Increase models and found
that the percentage change in CO₂ partial pressure and not the absolute change that remaine
ained
PO depth profiles similar to those observed (the choice of this
approximately the same. We have done the perturbation celculations and find that this:19 if
ort to
regeneration function has no influence on the result of the
correct This work was supported by the Lawrence Livermore National Laboratory Exxon Corporation
uired
calculation of the atmospheric CO₂ response to iron fertiliz-
and the Carbon Dioxide Research Program (W.S.B.) and by the U.S. Department of Energy (T.H.P.)
through a;joint contract Martin Marketta Energy Systems:inc
is the
ation). The atom ratio of carbon to phosphorus in the organic
overs
matter falling from the surface mixed layer was 130. We then
17 Sv
adjusted the ECO-/alkalinity ratio in the model ocean to yield
an atmospheric Pco of 280 platm.
Control of pore-water chemistry
-
xtent
We simulated a totally successful iron fertilization by greatly
bomb
decreasing the residence time (with respect to biological
the base of the Florida escarpm nt
es for
removal) of PO. in Antarctic surface water. bringing its PO₄
netra
content to near zero, and continued the iron fertilization for 100.
by processes within the platform
ertical
vears. Figure 2 shows the evolution of the vertical distributions
netra
of PO. and ECO₂ in the Antarcticicolumn for the deep-transport
Jeffrey P. Chanton*, Christopher S. Martens
if, this
case The total PO. in the water column remains unchanged but
& Charles K. Paull
1, the
a bulge of excess 200, appears, representing the CO2 transfer-
urface
red from the atmosphere to the Antarctic water column. In the
Marine Science Program and Department of Geology
lateral-transfer scenario (see Fig. 3), the atmospheric CO2 con-
University of North Carolina Chapel Hill, North Carolina 27599. USA:
nall to
tent drops ever more slowly, reaching an asymptote patm
Date of
lower than the initial value: In the deep-transfer scenario the
PORE waters collected from seep sediments hosting active
ipacity
decrease continues, reaching -34 µatm after 100 years. The
chemosypthetic communities tend to be rich in sulphide, chloride
that is
reason for the difference is that in one case the surface water
and ammonium and depleted in sulphate relative to the concentra-
of the
from the Antarctic is transferred to the surface of the non-
tions in sea water. To Investigate the source of the energy-rich
inge of
Antarctic region, allowing the excess CO₂ to re-enter the atmos-
compounds and the processes causing low sulphate concentrations
phere, whereas in the other this water is removed to the deep
in seep-sediment pore waters, we have measured the suiphur Isotope
box
sea, isolating it from the atmosphere.
composition, 8³⁴S, of pore waters from seep sediments at the base
:re and
As a sensitivity test we have changed the upwelling rate for
of the West Florida escarpment. The isotopic composition of pore-
nts the
the deep-transfer case. A rate of 8:7 Sv yields a drop in atmos-
water sulphate remains approximately constant as Its concentration
ocean
pheric Peo. of 28 palm and that of 34.8.Sv a drop of 47 patm.
is depleted, Indicating that processes within the Florida platform.
mixed
The question naturally arises as to what would happen if iron
rather than microbial processes at seep sites, control pore-water
Beneath
fertilization were terminated Our model shows that any reduc-
chemistry in these sediments. The composition of the seep brines,
firs The
tion in atmospheric CO: content accomplished by the fertiliz-
deduced from a linear mixing model, provides Information on
ocean
ation would be lost, on more or less the same timescale as it
processes deep within the platform.
in the
was gained.
Dense biological communities living on highly sulphidized
dopted
Clearly, the key to the evaluation of. the iron-fertilization
sediments found at the 3,280-m-deep base of the Florida escarp:
(at iron
scheme is the rate of vertical overturn in the Antarctic. If our
ment are supported by chemosynthetic processes that use
nonths
interpretation of the bomb-radiocarbon record is correct, then
reduced substrates seeping from the highly jointed limestone
partial
this process is too slow to create a significant decrease in the
cliff forming the edge of the Florida platform (Fig. 1). These
CO. content of the atmosphere. The distribution of freons in
seeps occur along at least 10% of the escarpment base. Sedimen
(column
the Antarctic water column offers further evidence in this regard.
tary pore waters beneath the large populations of mussels and
cm
The single published freon section11, a meridional traverse across
tube worms are enriched in ammonium (up to 2mM), radio
SV
the Atlantic sector of the Antarctic, shows that the freon con-
carbon-depieted biogenic methane (up to 10 mM) and sul
which in
centration for the entire water column between 500 m below the
phide (up to 5.7 mM). Sediments consisting of 30% sulphide.
limiting
surface and 500 m above the bottom is <6% of the surface
minerals have been reported⁹. The acidity generated by sea-floor
surface
concentration. Although we have not formally modelled freons,
oxidation of dissolved sulphide has been suggested as one
insferred
this result is broadly consistent with the dynamics adopted here.
mechanism for undercutting and croding the edge of the carbon
In any case. such surveys offer constraints on the rates of both.
ate continental margin²:
deep. and intermediate-w formation. As such information
We collected sediment cores in these chemosynthetic com
IS critical to the evaluation of temperature buffering of the
munities with the submersible Aluin. The pore waters were
reenhouse warming by the Antarctic Ocean14, as well as to
expressed from sediments by pressure filtration. Depth profiles
Bustion of the iron fertilization scheme, its procurement
of pore-water concentrations show chloride and ammonium
34
should be placed high on the list of environmental research
enrichment and corresponding sulphate depletion relative to
priorities.
overlying sea water (Fig. 2). Both pore-water sulphate and
52
ammoniumare linearly correlated with pore-water chloride con
centrations (Fig. 3), indicating conservative mixing between sea
water and a sulphate-depleted, ammonium-rich brine The
Reduced Subtember Seceived 16 November 1990
chloride-sulphate trend yields a value of 27.5% for a sulphate
Begin. R Chem Enging News 24 1990).
concentration of zero, suggesting that this is the chlorinity of
Martin IN & Fitzwater E Nature 331. 341 343 (1988)
the brine exiting the platform at the sea floor. The equation
& Gardon R M Deep Sea Res. 35. 177-196,(1988)
Marchdays Gordon R M Fitzwater 5. & Broenkow W. W. Deep See Res 36, 649-680 (1989).
fitting the chloride-ammonium data yields a value of 2.2.mM
Marger, M. Doroon R M & Fitzwater. S. Nature 346, 156-158 (1990).
for the concentration of ammonium in the suiphate-depleted
Mattin. FM Palaeoceanigraphy 8. 1-13 (1989).
Deacon G t. R Discovery Pep 15. 125-152 (1937).
brine.
6 H & Starver M Rediocarbon 22. 25-53 (1980)
00
9 Student M 6 Ostluno o Radiodarbon 22. 1:24 (1980).
10 Storer M & Outlund H.G Radiocarbon (1983).
Present address: Department of Oceanography, Figrida State University Tallahassee Florida 32306
11 Brogover Wash Peng. 1.11 Ostiund G. & Stuiver, M. 2. geophys Res 90, 6953-6970 (1985)
USA
ARY 1991
NATURE
VOL
349
17
JANUARY
1991
229
GLOBAL ENVIRONMENTAL CHANGE REPORT
tion growth will be in the Third
dramatically with both the changing
blooms in the Adriatic, are concerned
World. What is unexpected is that
balance of fish species and the in-
about the impact on the food chain.
the data show developing countries
creased water quality.
Oceanographers and atmospheric
are already major sources."
The authors note that many other
scientists say that the phytoplankton
The English edition of World
lakes in the Sudbury region showed
may simply release most of the carb-
Resources 1990-91 is available for
increased pH after SO₂ emissions
on back rather than sinking to the
US $20.95 from World Resources In-
declined, and they conclude that "con-
ocean floor. And some policy
ditions suitable for the survival and
analysts worry that if every industry
stitute Publications, PO Box 4852,
could fill a tanker with iron to atone
Hampden Station, Baltimore, MD
reproduction of lake trout and other
for its carbon sins, few would take ex-
21211, USA. For overseas orders, or
acid-sensitive organisms can return
for information on editions in Rus-
without liming or other ameliorative
pensive and restrictive measures to
treatments."
keep emissions down."
sian, Spanish, Arabic, Japanese, Ger-
man, or Chinese, contact WRI at
But a number of US agencies have ex-
1709 New York Avenue NW,
Algae-CO₂ Connection
pressed interest in Martin's proposal,
Washington, DC 20006. Tel: +1-202-
Draws Ironic Attention
and Anderson reports that the Nation-
638-6300; Fax: +1-202-638-0036.
al Research Council will hold a con-
A report in the 10 May issue of Na-
ference on this topic (to follow up a
ture (vol. 345, pp. 156-157) by John
Reducing Industrial
conference held last December) later
Martin of the Moss Landing Marine
Emissions Can Reverse
this year.
Laboratory (Moss Landing, Califor-
Effects of Acid Rain on
nia, USA) indicates that iron could be
Lakes
UK Opens New Climate
a major limiting factor for phytoplank-
Research Center
According to a report in the 31 May
ton. A lack of iron "prevents [the
issue of Nature, acidified lakes are
algae] from blooming and using up
On 25 May, UK Prime Minister Mar-
capable of rapid biological recovery
the luxuriant supplies of major
garet Thatcher opened the
when industrial emissions are
nutrients found in vast areas of the
Meteorological Office's Hadley Cen-
reduced. This means that simply cut-
southern ocean."
ter for Climate Prediction and Re-
ting back on SO₂ emissions may have
This in itself is not terribly controver-
search, at Bracknell, UK. According
direct benefits for acid-endangered
to the Met Office, the immediate re-
sial. Martin has found that levels of
lakes; elaborate schemes for liming
iron are extremely low in southern
search goals of the new center are to:
and otherwise neutralizing lake pH
oceans, and he provides a note at the
1) predict global climate change to
may be unnecessary.
the year 2100; 2) provide the founda-
end of his paper indicating that sub-
The authors, J.M. Gunn and W.
sequent experiments in the Ross Sea
tion for improved predictions of
have indeed stimulated phytoplank-
regional climate change; and 3) pro-
Keller, of the Ontario Ministry of
vide a focus for national research
Natural Resources and the Ontario
ton productivity.
programs relevant to the prediction of
Ministry of Environment, respective-
But Martin has gone a step further.
climate change. The center will be
ly, monitored water quality and
Since increased phytoplankton ac-
funded at £5.5 million (US $9.2 mil-
biological characteristics of a lake
tivity will take CO₂ out of the air, he
lion) per year.
near Sudbury, Ontario (Canada) from
reasons, why not add a lot of iron to
1978 to 1988. Average yearly SO₂
The center will coordinate Met Of-
the oceans to combat climate change?
emissions from the Sudbury metal
fice climate research efforts, and will
This proposal, reminiscent.of
smelters dropped from over one mil-
act in concert with other UK research
biomanipulation projects to reverse
lion metric tons in 1975-79 to
institutions.
lake eutrophication by introducing
718,000 tons in 1988. The average
new fish species, has met with a
For more information, contact the
pH during the study period rose from
wide range of reactions, and a lot of
Hadley Center, Meteorological Of-
5.4 in 1980 to 5.9 in 1988.
attention.
fice, London Road, Bracknell,
Lake trout reproduced successfully in
Berkshire, UK RG12 2SZ. Tel: +44-
As Christopher Anderson notes in the
the lake after pH rose above 5.5, and
344-856655; Fax: +44-344-854942.
31 May issue of Nature, "Biologists,
invertebrate populations changed
noting the deadly effects of algal
6
8 JUNE 1990
VOL II, NO. 11
GLOBAL ENVIRONMENTAL CHANGE REPORT
ness of weatherization and commer-
after 1997 while adding an additional
reducing methane emissions from
cial tax incentive and loan programs.
900 megawatts of renewable energy
animal wastes), capturing methane
sources in the region by 2005. On
from landfills, reducing transporta-
State transportation options include
the sink side, ODOE proposes plant-
tion fuel use and natural gas use, and
setting (and enforcing) a 55 mile per
ing large areas of unstocked or under-
reducing gas emissions from coal
hour speed limit statewide, convert-
productive timberlands. Boosting
mines.
ing Oregon private and public vehicle
recycling programs would also help
fleets to natural gas, converting all
Written comments on the strategy are
decrease CO2 emissions.
intra-city buses in the state to natural
due by 10 December; for a copy of
gas by the year 2005, and a number
For other greenhouse gases, ODOE
the energy plan, contact John Savage,
of initiatives to reduce vehicular use
proposes mandatory recycling of
Administrator, Policy and Planning
in the city of Portland. Electricity op-
CFCs, reducing methane emissions
Division, Oregon Dept. of Energy,
tions include a moratorium on new
from cattle (through low-methane
625 Marion Street NE, Salem, OR
coal power plants in the region, and
diets, reducing beef consumption, in-
97310. Tel: +1-503-378-4040; Fax:
phasing out some existing coal plants
creasing reproductive efficiency, and
+1-503-373-7806.
Science Update
Northern Lake Ecology
nutrient), which along with the
of responsible scientists and policy-
Disrupted by Climate
temperature rise caused certain
makers are seriously considering it as
Warming
phytoplankton populations to grow.
an option to complement anthropo-
The scientists also recorded a slight
genic emissions reductions. The
Some of the most severe effects of
increase in the phytoplankton species
NRC workshop summary emphasizes
greenhouse warming are expected in
diversity. On the other hand, the
that there are still many unanswered
high northern latitudes, where the
longer ice-free season and decreased
questions, and scientists will most
temperature change is predicted to be
snowfall, the clearer water (a result
likely perform a "Transient Iron Ex-
greatest and the ecosystems are easily
of the lowered runoff), and the in-
periment" (TIE) to settle key uncer-
stressed. A new report, appearing in
creased wind velocity, combined to
tainties. The TIE would begin some-
the 16 November issue of Science
increase the depth of the warm-water
time in the next 3-5 years, and would
(vol. 250, pp. 967-970), gives an em-
layer. This is bad news for cold-
involve spreading iron over 400
pirical preview of climate change's
loving species such as lake trout,
square kilometers of the Antarctic
impact on boreal lakes and their sur-
which may die out in the more shal-
Ocean. Preliminary assessments indi-
rounding watersheds.
low lakes as the growing warm layer
cate that the TIE would have no nega-
Over the past 20 years, according to
compresses or eliminates the cold,
tive environmental consequences.
the report, average air and water tem-
oxygen-rich layer near the bottom.
As GECR reported in the 9 Novem-
peratures in the Experimental Lakes
Regardless of the cause of the warm-
ber issue (vol. II, no. 19, pp. 4-5), the
Area of northwestern Ontario, Canada,
ing trend recorded by Schindler et al,
maximum impact of a totally success-
have risen 2°C. Coincident with this
their study represents a landmark
ful, intensive iron fertilization pro-
change has been a decline in precipi-
analysis of how a real ecosystem
gram would be significant, but not
tation and runoff, and a dramatic in-
responds to a real change in climate.
enormous given the scale of the
crease in the time it takes for lakes to
project. The NRC workshop found
replenish lost water - from 4.6 years
More on Iron Fertilization:
that iron fertilization over an area of
to over 20 years. The droughts have
The NRC Workshop
40 million square kilomcters (18 mil-
increased the occurrence of fires in
On 29-31 October in Irvine, Califor-
lion square miles) would result in an
the watershed, resulting in greater
wind velocities over the lakes.
nia, the US National Research Coun-
uptake of 1 gigaton of carbon annual-
cil (NRC) held a workshop on marine
ly. That's a healthy 1/6 of the total
The effects of these changes on the
algal productivity and carbon dioxide
amount of carbon released by burn-
lakes are complex. The research
assimilation. NRC released a
ing fossil fuels today (1/8 - 1/9 of
team, led by David Schindler of the
workshop summary on 16 November.
total anthropogenic emissions when
University of Alberta (Edmonton, Al-
deforestation is factored in), though
berta, Canada), found that lower
While some observers have objected
as one scientist pointed out, it's only
water levels in the lake studied led to
to the idea of enhancing CO₂ removal
1/28 of the amount some studies
an increase in nitrogen (a key
by phytoplankton, a growing number
project for fossil carbon emissions in
VOL. II, NO. 22
21 NOVEMBER 1990
5
GLOBAL ENVIRONMENTAL CHANGE REPORT
the mid-21st century with uncon-
policy analysts working on climate
tific and Industrial Research, report
strained growth. Fertilization would
change issues: How does one choose
that transmission of UV light through
have to take place annually for at
the most reliable estimate?
sea ice is naturally the greatest during
least 100 years to ensure that the carb-
the austral spring, when the ice is
Fortunately, methane experts M.A.K.
on isn't just released back into the at-
Khalil and R.A. Rasmussen of the
relatively transparent.
mosphere through upwelling, and
Oregon Graduate Center (Beaverton,
Unfortunately, early spring is also the
such a program would require spread-
Oregon, USA) have come up with
time when ozone depletion is at its
ing 1-5 million tons of iron each year
guidelines. Presenting their analysis
most severe. Trodahl and Buckley
over the area.
in a recent issue of Tellus (vol. 42B,
say that the shallow ozone hole of
Particularly interesting at the NRC
pp. 229-236), Khalil and Rasmussen
1988 enhanced the net UV dose
workshop was the discussion of
find that a realistic budget should
under the ice by a factor of ap-
potential ecological side effects. Gus-
portray the anthropogenic fraction of
proximately four over pre-1975
tav Paffenhofer of the Skidaway In-
total methane emissions at between
levels. The 1987 and 1989 (and
stitute of Oceanography (Savannah,
40-70%, and total current emissions
presumably the 1990) holes yielded
Georgia, USA) noted that krill - a
at between 420-620 teragrams per
about a ten-fold UV enhancement
vital food for whales, squid, fish, seals,
year. Only two of the 11 global
over the pre-1975 levels.
and penguins - might increase with
methane budgets they looked at met
Ken Ryan, a colleague of Buckley's
the rising phytoplankton populations.
these conditions. Which two? One
at the Department of Scientific and
But he warned that as greater amounts
was their own 1983 study (Khalil and
Industrial Research, told GECR that
of carbon sink toward the ocean
Rasmussen, Journal of Geophysical
he'd just returned from a trip to Ant-
floor, microbial activity in the deeper
Research, vol. 88, pp. 5131-5144),
arctica where he studied the response
ocean might increase, diminishing
and the other was a 1988 paper by
of algae to the increased UV doses.
the supply of oxygen. Krill eggs dev-
Cicerone and Oremland (Global
Ryan said he recorded depressed
clop at depths of several hundred to a
Biogeochemical Cycles, vol. 2, pp.
algal growth rates in every experi-
thousand meters, and a lack of oxy-
299-327).
ment he performed, but his prelimi-
gen there "could mean certain death
Khalil and Rasmussen base their
nary results did not show the effects
[and] an eventual crash or greater
criteria on observed features of the
worsening significantly with higher
diminution of the krill population
global methane cycle. Significantly,
doses.
Copies of the NRC Bicoastal Session
they note that methane sinks may be
Summary of the Marine Algal Produc-
declining somewhat (see GECR, 8
Global Average
tivity and Carbon Dioxide Assimila-
December 1989, pp. 4-5), which may
Temperatures in 1990
tion Workshop are available from Dr.
have led to a somewhat longer atmos-
Could Reach Record High
Oskar R. Zaborsky, Director, Board
pheric lifetime for the gas.
As GECR's 26 October Hotline sec-
on Biology, National Research Coun-
tion noted, the global average temper-
cil, 2101 Constitution Avenue NW,
Study Yields First
ature trend for 1990 shows that - so
Washington, DC 20418-0001, USA.
Measurement of UV
far, at least - 1990 could end up
Several articles on iron fertilization
Penetration of Antarctic
being the warmest year since the mid-
will also appear in November issue of
Sea Ice
1800s. Here are a few more details:
Global Biogeochemical Cycles (vol.
Studies published two years ago
On 11 October, Phil Jones of the
4, no. 1), published by the American
show that algae living on the under-
Geophysical Union.
University of East Anglia (Norwich,
side of sea ice surrounding Antarctica
UK) told a US Senate panel that the
are sensitive to ultraviolet (UV) radia-
Most Methane Budgets
temperature record for the first eight
tion. These algae are important,
Appear Unrealistic
months of 1990 "should easily make
since they may account for up to 30%
it the warmest year yet recorded."
Over the past 10 years, researchers
of the primary food production in the
The first few months were exception-
have published nearly a dozen
region; disruptions in their population
ally warm, especially March.
separate estimates of methane emis-
could have serious effects on the An-
sions from anthropogenic and natural
tarctic ecosystem.
And on 22 October, Jim Angell of the
sources. These estimates range wide-
US National Oceanic and Atmos-
In the November issue of Geophysi-
ly in both their figures for total emis-
pheric Administration announced that
cal Research Letters (vol. 17, no. 12,
sions and in their ratios of
the global average surface air
pp. 2177-2179), H.J. Trodahl and
anthropogenic emissions to total
temperature in the early part of this
emissions. This presents a dilemma
R.G. Buckley of, respectively, New
year was the warmest on record.
Zealand's Victoria University and the
that's quite familiar to scientists and
March, April, and May temperatures
New Zealand Department of Scien-
6
21 NOVEMBER 1990
VOL. II, NO. 22
A 'GERITOL SOLUTION
Enlisting Marine Algae
To Ease Global Warming
ach year, combustion of
workshop participants calls for "fer-
E
fossil fuels, deforestation,
tilizing" large areas of the world's
and other human and
oceans with iron, an essential nutri-
natural activities release
ent for marine plants that is appar-
eight or nine billion tons of carbon
ently in short supply in many oceanic
in the form of carbon dioxide —
waters.
into the Earth's atmosphere. This car-
bon dioxide is a key player in current
Life in the Sea
concern about global warming; as a
Of primary interest to the 40 scien-
"greenhouse gas," it has the effect of
tists and others who gathered at the
trapping heat and preventing it from
Academies' Beckman Center in Irv-
radiating back into space.
ine, Calif., were marine algae. To
In addition to reducing carbon
many, algae are best known as the
Grant Heilman
emissions, scientists have theorized
stringy mats of green scum that form
Sargassum (brown algae)
about ways to recapture some of the
in stagnant pools. But algae - and
carbon that is being released. One of
especially marine algae - are a
California kelp, can reach lengths of
the most innovative ways - boosting
highly variable, often beautiful group
nearly 100 feet.
the amount of carbon dioxide used
of plants.
Other macroalgae float unattached
by marine algae during photosynthe-
Microalgae form the bulk of the
in the sea. A good example is Sar-
sis - was a topic of a workshop in-
oceans' plankton, typically micro-
gasso Weed. which forms dense mats
October sponsored by the Research
scopic plants that drift with sea cur-
across much of the Sargasso Sea in
Council's Board on Biology to answer
rents or, sometimes, have limited
the tropical Americas.
key ecological and economic ques-
powers of locomotion.
What all these algae have in com-
tions about the feasibility of this ap-
At the other end of the size spec-
mon is that they are plants that live
proach. Francisco Ayala of the Uni-
trum are the macroalgae. the familiar
by photosynthesis. In the presence of
versity of California, Irvine, chaired
"seaweeds." These may be rooted to
sunlight, water and nutrients, they
the meeting.
rocks and are the green, brown and
are able to take up carbon dioxide
Often dubbed the "Geritol solu-
red masses that frequently wash
from the atmosphere and use the car-
tion," one technique studied by
ashore when pulled loose from their
bon to create sugars, starches and
anchor. The largest marine alga,
December 1990-January 1991
5
other carbohydrates. They release
in the atmosphere, workshop partici-
Ecological Impact
oxygen in the process.
pants concluded. If the algae in iron-
The impact of iron fertilization on the
poor areas of the ocean reached their
The Iron Hypothesis
marine environment was one of the
peak productivity. they could remove
The surface of the sea typically has
critical questions generated by the
by photosynthesis about 2 billion
plenty of sunlight and carbon dioxide
workshop group. The algae species
tons of the 5 billion to 6 billion tons
for algae to utilize in photosynthesis.
that currently make up the algal
pumped into the atmosphere annu-
But some scientists believe that cer-
populations in the open ocean are
ally by the combustion of fossil fuels.
tain nutrients might be lacking in
species adapted to iron-poor condi-
However, so little is known about
parts of the ocean that limit the abil-
tions; these would almost certainly be
ity of algae to reach their maximum
supplanted by other algae species
productivity.
with unknown repercussions in the
Increased algal productiv-
food web, said William Sunda of the
John Martin of Moss Landing
ity could have the benefit of
National Marine Fisheries Service of
(Calif.) Marine Laboratories has pro-
posed that iron may be a "limiting"
significantly reducing the
the National Oceanic and Atmos-
nutrient for almost one-fifth of the
amount of carbon dioxide
pheric Administration.
world's oceans. While iron is one of
in the atmosphere.
Other organisms in the open-ocean
the most abundant metals in the
community also could be adversely
Earth's crust, it is extremely insoluble
the mechanics of the carbon cycle in
affected, explained Gregory Mitchell
the ocean and the biology and ecol-
of the Marine Research Division of
in seawater. It is carried to the ocean
primarily by wind and suspended in
ogy of the organisms involved that
Scripps Institution of Oceanography.
streams and rivers that feed into the
there is no way of accurately predict-
Krill, for example, are tiny crusta-
sea.
the or environmental con-
ceans that feed on phytoplankton.
In the open ocean far from land,
sequences of fertilizing large areas of
They make up the bulk of the diet of
the ocean with soluble iron, confer-
many fish and of some whales and
little iron is available to the algae that
grow there.
ees agreed.
therefore are a critical link near the
If iron were introduced into these
Workshop participants recom-
bottom of the food chain. One might
areas - principally Arctic, Antarctic
mended that a pilot project move
expect their populations to burgeon
and equatorial waters - the result
forward after about two more years
as algae populations grow, he said.
of laboratory research. The pilot
However, the eggs of krill hatch at
should be a marked increase in algal
growth and productivity. Martin
project would involve one research
considerable depths in the ocean. If
reasoned.
vessel periodically spraying soluble
much organic matter from increased
iron on a 400-square-kilometer
algal populations falls from the ocean
The Carbon Cycle
patch of ocean near Antarctica.
surface to these middle levels and de-
Increased algal productivity could
Workshop attendées said there
composes, these waters might be-
have the benefit of significantly re-
would be no major environmental
come deprived of oxygen. Young krill
ducing the amount of carbon dioxide
consequences for a project of this
might die for lack of oxygen. "We just
magnitude.
6
NewsReport
don't know for sure what the impact
might be," he said.
Even if environmental problems
were somehow surmounted, impos-
ing engineering problems remain.
A team of researchers from the E.I.
du Pont de Nemours and Co. - Ed-
ward Howard and Thomas O'Brien --
calculated some of the logistics and
cost.
cost. For a 600-square-mile area, one
would need special barges to haul the
ferrous chloride (soluble iron) at a
cost of $2.5 billion plus maintenance.
They said a flotilla of hundreds of
barges and ships would be required
to transport and distribute the iron,
each operating 365 days a year. Add
to this the cost of the iron solution
itself and the labor involved, and the
proposed bill mounts rapidly.
Macroalgae
Grant Heilman
Mass farming of macroalgae also was
discussed by the meeting partici-
are anchored. Fertilizers would be
Kelp (brown algae) farms would
pants. Compared to microalgae,
sprayed over the kelp periodically to
remove some atmospheric carbon.
however, the contributions of larger
help them grow, and the kelp plants
seaweeds to increased carbon uptake
themselves - composed mostly of
Undaunted by the engineering diffi-
would be minimal, conferees agreed.
carbon in the form of starches and
culties posed by both macroalgae and
Kelp already has been the subject of
carbohydrates - would be chemi-
microalgae "farming," conferees
considerable experimentation.
cally converted into methane and the
agreed that research should proceed.
Wheeler North of the California In-
remaining carbon somehow sunk to
"We need to resolve questions re-
stitute of Technology has been con-
the ocean's depths.
gardless of the ultimate utility of any
ducting some of this research.
However, North noted that experi-
ocean fertilization scheme," they
While microalgae usually are free-
mental designs with which he has
wrote in a summary prepared during
floating, most seaweeds are attached
worked have not been adequate. Of-
the meeting. "The area is socially rele-
to rocks or other substrates. North
ten, the kelp get tangled up in the
vant and intellectually engaging."
envisions submerged platforms
towing or anchor lines and become
- Rick Borchelt
towed by barges on which the kelp
no more than a ball of shredded
seaweed.
7
December 1990-January 1991
R1
THE WASHINGTON POST
THE WASHINGTON POST INDEX
SCIENCE
NOTEBOOK
Rising energy demand in
Temple Hills man among
Fighter Chavez gets little
Third World threatens
four area homicide victims
B5
D4
Oceanography: Problems With 'Geritol Solution'
recognition, money
economies, report says
A7
Martin Luther King remem-
Preview of tonight's college
Suspect in rare books theft
bered for taking stand
basketball games
D8
to go on trial
A8
L
ast summer scientists proposed an
growth would not be sustained because in
against war
B5
Bullets return home from
Jurors' work frees man they
Violations cited at Maryland
D9
imaginative but radical solution to
the Southern Ocean, the surface waters,
long, tough road trip
where all the action is, are not replaced
found guilty of murder
A10
health department
B5
Notebook: Alarie does well
the buildup of carbon dioxide in the
TWA blames weak economy,
News from around the re-
playing for Grant
D9
atmosphere, which many researchers
quickly enough by deeper water that
gulf situation for layoffs
A12
Geddes overtakes Sheehan
fear could lead to global warming.
contains other needed nutrients such as
gion, in capsule form
B5
Officials encouraged by lay-
Holiday schedules and
for Jamaica golf victory
D11
Why not, they asked, dump hundreds
phosphorus and nitrogen.
ing of condor eggs
A12
what's open and closed
B5
of thousands of tons of iron fertilizer
In other words, the algae in the
News from around the na-
tion, in capsule form
WASHINGTON BUSINESS
into the ocean and SO create a giant
surface water might have all the iron
A12
OBITUARIES
bloom of marine algae? The growing
they need, but there may not be enough
algae would suck carbon dioxide out of
mixing of the exhausted surface water
Banks and S&Ls suffering
WORLD
Claudio Villar, 79, former
from troubled loans
the atmosphere and sequester it in the
and nutrient-rich deep water to sustain
1
heavyweight boxer
B4
Depositors are wary of fed-
sea. The algae in the Southern Ocean
accelerated growth.
Soviet forces attack Latvian
John C. Morgan, 76, in-
eral insurance system
1
around Antarctica appear to be starving
Wallace Broecker of Columbia
building, killing four
A1
spired "Twelve O'Clock
Rudolph A. Pyatt Jr.
3
for iron. Scientists half-jokingly called
University and T. H. Peng of Oak Ridge
Lithuanian parliament is
High"
B4
Wash Biz
3
their scheme the "Geritol Solution."
National Laboratory conclude that "even
symbol of defiance
A13
Malcolm Maloof, 39, with
Lawyers
5
Alas, the Geritol Solution might not
if iron fertilization worked perfectly, it
Talks on Soviet troop move
National Rehabilitation
Amtek program helps im-
Hospital
work. According to a computer
would not significantly reduce
from Poland hit snag
A13
B4
migrants develop careers
6
China presses trials of pro-
simulation reported in the current issue
atmospheric carbon dioxide content."
Regional Report
7
A14
Dividends
7
of the journal Nature, a spurt of algal
-William Booth
democracy activists
STYLE
South African judge rules on
Indicators
8
death squads
A18
Anger among blacks, and an
GMU institute puts painting
antidote
C1
firm on right track
9
Entomology: A New Anti-Cockroach Weapon
THE FEDERAL PAGE
Opera: Menotti's "Saint of
Jane Applegate
9
Bleecker Street"
C1
New chief of Ticketron to
Medical journals and flow of
TV Preview: "Line of Fire,"
emphasize better service
10
n the ongoing war against
information studied
A19
"The Last to Go" and
Appointments
11
cockroaches-which has engaged an
Northeastern
PBS's "The Sixties"
C2
Business Law
12
endless variety of poisons, baits,
governors
seek release of more fed-
Jonathan Yardley on colum-
Power Computing
15
booby-trapped "motels" and bedroom
eral energy money
A19
nists and self-control
C2
Personal Computing
16
slippers-scientists have found a new
Early release of Medicare
Opera: NYC's "Figaro" at
Bankruptcy Filings
17
ally: The breeze.
funds sought
A19
new George Mason hall
C3
Contracts
18
Dance: ABT's "Coppelia" on
Insider Transactions
24
In research conducted by the
Saturday
C3
Business Calendar
24
Agriculture Department's insect
Experts believe that roaches, which
EDITORIAL/OP-ED
Book World: "Rediscovering
Computer Calendar
24
research lab in Florida, scientists
must stay moist to survive, find that a
America"
C3
Washington Investing
29
installed equal numbers of roaches on
constant breeze dries them out.
Editorials, Letters to the
Personalities: Effi Barry
Selected area stocks
30
two sides of an attic. Air vents were
Researchers suggest that home
Editor
A20
talks about her book
C3
Economic index
33
installed on one side; the other was left
builders make sure that attics and wall
Op-ed: Evans and Novak,
Style Plus: Martin Luther
Money market funds
34
Washingtoon
A21
unventilated. In two weeks, most of the
voids are well ventilated.
King Jr.'s dream
C5
Foreign stocks
37
Charles McC. Mathias on
insects had fled to the still side. Why?
-Malcolm Gladwel
Actor Robert Young's ap-
Martin Luther King.
parent suicide attempt
C6
Charles M. Lichenstein
Arts Beat: The shifting
Number of Pages Today
120
and Paul M. Joyal on sin-
sands of political comedy
C7
Pharmacology: Alcohol and Aspirin a Bad Mix
Jack Anderson
B8
gling out Arab Ameri-
Theater: "The Island," at
Ask Beth
B6
cans. Frank H. Wu gives
American Showcase
C7
Around the Nation
A12
the perspective of a Chi-
Around the Region
T
here are few things aspirin can't
But, according to the scientists, this
B5
was because the studies were
nese American
A21
do. In addition to fighting
SPORTS
Books
C3
conducted on people drinking on an
B6
headaches, arthritis and sundry other
Bridge
empty stomach. In those cases, without
TERS TO NATURE
ke place. In all cases no significant anisotropy is observed,
carbon in the Southern Ocean, where concentrations of the
indicating that melting is necessary to obtain alignment.
nutrients P and N are high, can lead to alterations of atmospheric
Our method has several advantages over existing techniques.
CO₂ in excess of 100 p.p.m.4⁻⁷ Recently, it has been suggested
The temperatures and magnetic fields required during sample
that biological production in these regions may be limited by a
preparation are relatively modest. The direction of the crystal
restricted supply of iron8⁻¹¹. Although the hypothesis that iron
orientation can be controlled carefully and easily. In addition,
is the ultimate limiting factor there is controversial we adopt
because of the relatively rapid cooling rates used during the
it here to obtain upper-limit estimates of the possible reduction
thermal treatment cycle, the sample production times are sig-
in atmospheric CO2. Because the ratio of iron to carbon incor-
nificantly shorter than those commonly experienced in melt-
porated in plants is rather low, between 1:10,000 and
texture-growth techniques If the alignment is due to the
1:100,00 the amount of iron required to carry out this
presence of anisotropic magnetic particles into a liquid, the
fertilization is relatively modest: ~10⁶ tons of iron per year
efficiency of the process will depend on the size and the number
assuming that all the iron goes into organic matter. Our model
of nuclei that are aligned by the field, and consequently on the
study differs from that of Peng and Broecker¹⁷ in the area
heating rate, the time and the temperature of the annealing and
fertilized (16% of the world ocean rather than 10%), and in that
the cooling rate, all of which govern the grain growth. The
we include scenarios with anthropogenic CO2 emissions for
process could be adapted for industrial production of textured
which we find that fertilization has a greater effect-than when
samples and may prove to be generally applicable to all magnetic?
we assume no man-made emissions.
substances that have a residual magnetic anisotropy at high
We consider there to be three factors that exert the most
temperature.
important control on the response of atmospheric, CO₂ to an
HILDA Model
Received 17 October 1990; accepted 8 January 1991.
1. Farrel, D. E. et al. Phys. Rev. B 38, 4025-4027 (1987).
2. Livingston, J. D., Hart, H. R. Jr & Wolf, W.P. J. appl. Phys. 64, 5806-5808 (1988).
Atmosphere
3. Nakagawa, Y., Yamasaki, H., Obara, H. & Kimura. Y. Jap. I appl. Phys. 28, L547-L550 (1989).
4. Lees, M. et al. in Proc. Int. Conf. 'From Modern Superconductivity Towards Applications' (ed.
Tournier, R. & Suryanarayanan, R.) 49-54 (IITT International Gournay-sur-Marne, 1990).
5. De Rango. P., Lees, M., Lejay, P., Sulpice. A. & Tournier, R. in Proc. Int. Conf 'From Modern
Superconductivity Towards Applications' (ed. Tournier. R. & Suryanarayanan. R.) 21-26 (IITT
g,
gh
International, Gournay-sur-Marne. 1990).
6. Miljak, M., Collin, G. & Hamzic. A. J. Mag Mater. 76 & 77, 609-611 (1988).
0
7. Jin, S. et al. Appl. Phys. Lett. 52, 2074-2076 (1988).
LS
HS
8. Salama, K., Selvamanickam, V., Gao, L. & Sun, K. Appl. Phys. Lett 54, 2352-2354 (1989)
9. Meng. R. L. et al. Nature 345, 326-328 (1990).
75
10. Schulz, L. G. J. appl. Phys. 20, 1030 (1949).
u
Estimates of the effect of
Fp
Fₚ
Southern Ocean iron fertilization
Depth (m)
K
W
on atmospheric CO2
q
concentrations
F. Joos*, J. L. Sarmiento & U. Siegenthaler*
Interior
HD
* Physics Institute, University of Bern, CH-3012 Bern, Switzerland
3,800
+ Atmospheric and Oceanic Sciences Program, Princeton University,
Princeton, New Jersey 08544, USA
84%
16%
Area
IT has been suggested¹⁻ that fertilizing the ocean with iron might
FIG. 1 Structure of the model used for our study. which is based on a model
offset the continuing increase in atmospheric CO2 by enhancing
developed by G. Shaffer (personal communication) and one of US (J.L.S.).
the biological uptake of carbon, thereby decreasing the surface-
The ocean interior is resolved by a vertical stack of boxes connected by
ocean partial pressure of CO₂ and drawing down CO2 from the
advection (w) and diffusion (K): The high-latitude regions are simulated by
atmosphere. Using a box model, we present estimates of the
two well-mixed boxes which are connected to each other by mixing (u):
maximum possible effect of iron fertilization, assuming that iron
The parameter q is a rudimentary representation of the ven on
is continuously added to the phosphate-rich waters of the Southern
of the interior oceans by high-latitude waters. The model parameters
Ocean, which corresponds to 16% of the world ocean surface. We
obtained by fitting bomb and natural . 14C are:
find that after 100 years of fertilization, the atmospheric CO₂
465 + 7,096 exp m)/253 m² yr⁻¹; (equiva-
lent to s⁻¹); (69.8
concentration would be 59 p.p.m. below what it would have been
0.00186 (79.5 10⁶ gas-exchange rate (g₁, gn) at 280 p.p.m.=
with no fertilization, assuming no anthropogenic CO2 emissions,
15.1 mol yr⁻¹: ocean surface area 3.62 depth of
and 90-107 p.p.m. less when anthropogenic emissions are included
layer = average depth of ocean =3,800 m. We solve CO vation
in the calculation. Such a large uptake of CO₂ is unlikely to be
equations for the perturbation of phosphate and CO₂ = Cactual
achieved in practice, owing to a variety of constraints that require
with an initial condition for Cpert. of 0 everywhere. The relation between
further study; the effect of iron fertilization on the ecology of the
changes of 2CO₂ and Pco₂ is calculated using the equations of Peng et
Southern Ocean also remains to be evaluated. Thus, the most
al.²⁴. The phosphate and carbon removed from the surface high-latitude
effective and reliable strategy for reducing future increases in
box are regenerated to the dissolved form in the deep box below (dashed
atmospheric CO₂ continues to be control of anthropogenic
arrows, Fo perturbation flux of particulate carbon and phosphorus). A small
amount of this excess phosphate makes its way through the
to
emissions.
low-latitude surface waters, where it is removed and regenerated below
A flux of dead biogenic organic matter from the ocean surface
with an exponential scale depth of 1,160 m obtained from a fit to oceanic
continuously transports carbon (and nutrients) to depth and
nutrient data by G. Shaffer and J.L.S. Multiplying the resulting phosphate
thus influences the surface concentration of total dissolved inor-
fluxes by the C:P Redfield ratio (130) gives the corresponding carbon fl
ganic carbon (ΣCO₂). Model studies have shown that variations
LS, low-latitude surface; HS, high-latitude surface; and HD, high-latitude deep
in the efficiency of biological uptake and export of organic
boxes.
772
NATURE VOL 349 28 FEBRUARY 1991
LETTERS TO NATURE
TABLE 1 Projected changes in atmospheric CO2 partial pressures resulting from various scenarios beginning in 1990
After 50 years
After 100 years
Effect of
Effect of
A
B
fertilization
C
D
fertilization
Scenario*
Unfertilized
Fertilized
(B-A)
Unfertilized
Fertilized
(D-C)
High-latitude area fraction= 9.7%+
Initialized at pre-industrial levels
Our model
0
-26
-26
0
-39
-39
-
0
-34
-34
Peng and Broecker
-
-
Constant-emission
80
46
-34
156
98
-58
-68
Business-as-usual
150
114
-36
430
362
High-latitude area fraction=16.0%
Initialized at pre-industrial levels
0
-41
-41
0
-59
-59
Constant-emission
79
24
-55
151
61
=90
Business-as-usual
146
88
-58
417
310
-107
The scenario which is initialized at pre-industrial levels of atmospheric CO₂ has no anthropogenic. source of CO₂ to the atmosphere, thus the CO₂
drawdown by the ocean results in a reduction below the initial pre-industrial value of 278.3 p.p.m. In the 'constant-emission' scenario, atmospheric CO₂
content is prescribed using observations until 1990²³, after which the CO₂ emission to the atmosphere is fixed at the model-determined value of
in 1990. In the "business-as-usual' scenario, the atmospheric CO₂ content is prescribed until 1989 after which the annual emission increases according
to the IPCC büsiness-as-usual scenario²², in which the man-made emissions increase linearly with time from in 1990 to 22.4 Gt in
2100. The 1990 atmospheric CO₂ partial pressure is 355 p.p.m.
+ The area fraction of 9.7% in our model corresponds to the same area in m² as chosen by Peng and Broecker¹⁷.
# The Peng and Broecker¹⁷ model is initialized at 280 p.p.m. and has a phosphate reduction of 1.6 mmol m⁻³. The result given here is for their scenario
with 17.5 10⁶ of water upwelling in the high latitudes and being placed directly into the deep ocean.
enhanced carbon uptake resulting from iron fertilization. First
from the natural ¹⁴C background; the data in the Southern Ocean
is the reduction in average Σ CO₂ per unit area that occurs when
are scanty, especially from pre-bomb time; and the bomb inven-
fertilization is started. We take the supply of phosphate from
tories south of 46°S show considerable variation. Instead, we
depth as a reasonable guide to the maximum potential biological
checked our model with high-latitude CFC-11 observations,
uptake of carbon, although we recognize that light supply, our
obtaining a standing crop of 1,976-nmol for 1984, compar-
ability to spread iron efficiently over the large ocean areas
able to an estimate of 1,950 ± 550 nmol obtained for the
involved, the behaviour of the ocean ecosystem, and other
same period from measurements south of 46°S by Weiss et al.²⁰
processes may interfere long before the phosphate is depleted.
in the South Atlantic, by the Pacific Marine Environmental
(Carbon cycling is linked to that of phosphate through the
Laboratory of the National Oceanic and Atmospheric
Redfield ratio of C: = 130 in organic matter.¹⁸) Second is the
Administration in the South Pacific (R. H. Gammon and D.
area over which the fertilization occurs. We use a recent analysis
Weisgarver, personal communication), and by R. Weiss (per-
of National Oceanic Data Center phosphate data (S. Levitus
sonal communication), also in the South Pacific:
and R. G. Najjar, personal communication) to estimate that the
Figure 2 summarizes results from the iron fertilization assum-
Southern Ocean's (>30°S) water volume in the depth range
ing the business-as-usual and constant-emission CO₂ scenarios.
0-75 m with phosphate 1.0 mmol amounts to 15.8% of the
Without fertilization, the increase in atmospheric CO₂ from its
world ocean volume in the same depth range. The average
1990 value of 355 p.p.m. is 146 p.p.m. after 50 years, and
phosphate content of this volume is 1.63 mmol m⁻³. We therefore
417 p.p.m. after 100 years in the business-as-usual scenario (Fig.
take the-high-latitude box of our 'standard' model to consist of
2a). When iron fertilization is initiated, an additional flux of
16% of the world ocean area (with 9.7% as an alternative case
organic carbon out of the high-latitude surface box is stimulated.
corresponding to the area used by Peng and Broecker¹⁷), and
Its size is approximately constant at 5.5 Gt C yr⁻¹ after an initial
we determine the enhancement to the biological production by
peak in the first year. This increased carbon flux leads to a
forcing a reduction of phosphate by 1.5 mmol m⁻³ in the surface
massive decrease in the high-latitude surface Pc₀₂ (see Fig. 2b),
box of this area. Third is the reduction in CO₂ partial pressure
and a resulting enhancement of atmospheric CO₂ uptake so that
resulting from a given carbon removal. We have found that this
the atmospheric CO₂ now increases by only 88 p.p.m. after 50
is considerably larger at high rather than at low CO₂ levels
years (60% of the increase in the unfertilized scenario) and by
because of the nonlinear relation between Pc₀₂ and CO2. We
310 p.p.m. after 100 years (74% of the increase in the unfertilized
use three different anthropogenic CO₂ emission scenarios to
scenario). The decrease in atmospheric Pc₀₂ resulting from iron
examine the contribution of this nonlinearity, one in which the
fertilization reduces the low-latitude air-sea difference so that
ocean and atmosphere are initialized at the pre-industrial value
the response of the low latitude regions is opposite in sign to
of 278 p.p.m. with no anthropogenic sources, a 'constant-
that of the high latitudes (Fig. 2b). After 100 years, the additional
emission' scenario, and a 'business-as-usual' scenario (see Table
CO₂ flux from the atmosphere to the high-latitude box in the
1 legend for descriptions of the scenarios).
iron fertilization scenario is 2.65 Gt This is partly
The rate at which atmospheric CO₂ is taken up by the oceans
balanced by a reduction of 0.51 Gt C yr⁻¹ in the low-latitude
also depends on the rate at which the ocean circulation and
uptake of anthropogenic CO2, for a net annual oceanic uptake
mixing transport to the abyss the excess CO₂ that invades the
of 2.13 Gt C yr⁻¹ due to iron fertilization.
fertilized region from the atmosphere. As discussed below, we
The effect of the nonlinearity of the carbon chemistry
find that this factor is less critical than those mentioned above.
equations can be discerned by comparing the three scenarios
Figure 1 shows the model we use to simulate the ocean circula-
shown in Table 1. The constant-emission scenario with fertiliza-
tion and mixing. Parameter values are obtained by fitting the
tion of 16% of the world ocean shows a reduction of 90 p.p.m.
model to pre-bomb ¹⁴C observations as well as the GEOSECS
in the increase of atmospheric CO₂ resulting from 100 years of
bomb inventory. estimates of Broecker et al.¹⁹ (U.S. and F.J., to
iron fertilization, compared with 59 p.p.m. for the scenario
be published elsewhere). However, the bomb inventory estimates
initialized at 278 p.p.m. The further increase in atmospheric CO₂
in the Southern Ocean were not considered adequate for use in
in the business-as-usual scenario has a still larger effect:
the fitting exercise because the bomb signal is not easy to discern
107 p.p.m. The dependence on the prevailing atmospheric CO2
NATURE: VOL 349 28 FEBRUARY 1991
773
LETTERS TO NATURE
concentrations can be understood when considering that Pco₂
iron fertilization of ~60%. Broecker²¹ argues that their choice
depends in a nonlinear way on Σ CO2. The higher the atmo-
of the smaller area was intended to compensate for the fact that
spheric concentration of CO2, the larger the change in oceanic
much of the Antarctic is in darkness during part of the year.
Pc₀₂ for a given reduction of Σ CO₂ due to iron fertilization
We attempted to compensate for this effect by fertilizing the
(see Fig. 2c). We find that the percentage reduction in atmos-
ocean for only six months of the year. The CO₂ uptake in the
pheric CO₂ concentration which would occur after 100 years of
business-as-usual case went down from 107 p.p.m. to 88 p.p. m.
iron fertilization decreases with higher CO₂ levels (21% for
far less than the drop to 68 p.p.m. which occurs when using the
pre-industrial initialization, 14% for the business-as-usual
smaller area.
scenario). This is in contrast to the assertion of Peng and
To be effective, iron fertilization has to be applied con
Broecker¹ that the relative reduction is constant.
tinuously so that the atmosphere-ocean system does not revert
Peng and Broecker¹⁷ emphasize that the key to evaluating the
to its unfertilized state. This is shown in Fig. 3, which show
impact of iron fertilization is the rate of vertical exchange in
what happens if iron fertilization is terminated after 50 years
the Southern Ocean. We find that the uncertainty in the calibra-
At 50 years the ocean in the business-as-usual iron fertilization
tion of the high-latitude transport parameters u and W gives
simulation has taken up 57.9 p.p.m. more CO₂ than the non
error limits of +14% -24% for the absolute value of the iron-induced
fertilized ocean. If fertilization is stopped-at this point, the
reduction in atmospheric CO₂ for the pre-industrial scenario.
difference between the fertilized and-non-fertilized scenarios
Therefore, the precise magnitude of the vertical exchange seems
reduces to 35.5 p.p.m. after 100 years.
not to be as critical as uncertainties in other processes. This is
Changes in the Earth's equilibrium temperature are
also supported by the fact that Peng and Broecker's result agrees
logarithmically related to the atmospheric CO₂ content, with a
well with ours for the same pre-industrial scenario (Table 1),
doubling of CO₂ leading to an equilibrium warming of between
although their high-latitude vertical exchange, which is cali-
1.5 °C and 4.5 °C, with a preferred value of 2.5 °C (ref. 22): A
brated with bomb-produced radiocarbon, is considerably
useful index of the significance of a given CO₂ increase is the
weaker than our vertical exchange calibrated by oceanic distri-
factor In (Pco₂/278)/In (2) which, multiplied by 2.5.°C, will give
bution of CFC-11.
the equilibrium warming resulting from a given CO₂ increase
The effect of ocean area is readily apparent from the results
Thus, the atmospheric CO₂ concentration of 771 p.p.m. reached
summarized in Table 1. An increase in the fertilized area from
by 2090 in the business-as-usual scenario will give an equilibrium
9.7% to 16% leads to an almost linear increase in the effect of
warming of 3.7 °C. The 107-p.p.m. additional oceanic uptake
900
Business as usual scenarios
a
0
800
b
Low lat
Atmospheric CO₂ concentration (p.p.m.)
700
as usual
CO₂ (p.p.m.)
-50
600
Business
High lat.
500
400
100
Constant
High lat.
emission
300
200
1900
1950
2000
2050
2100
150
Year
1900
1950
2000
2050
2100
Year
1,000
c
800
PCO₂ (p.p.m.)
600
FIG. 2 a, Future atmospheric CO2 concentration in the business-as-usual
and constant-emission scenarios. The solid line is our prediction without
iron fertilization, the dashed line shows what might occur with iron fertiliza-
tion. b, The air-sea CO₂ difference of the iron-fertilized business-as-usual
400
scenario (dashed-lines) and the non-fertilized business-as-usual, scenario
(solid lines). C, Dependence of the partial pressure of CO2 on CO₂ In
high-latitude surface water (T=-0.22°C). With Increasing CO2 concentra-
tions, the slope of the curve increases, and so does the change in Pco₂ for
200
a given change in ΣCO₂
0
-100
-50
0
50
100
150
Perturbation 2CO₂ (umol kg )
774
NATURE VOL 349 28 FEBRUARY 1991
LETTERS TO NATURE
900
estimate the CFC inventories. R. Fink developed our carbonate system algorithm and R. Slater helped
with the phosphate data analysis. J, R. Toggweiler and J. Orr provided helpful comments on the
manuscript. FJ. and U.S. acknowledge the hospitality of the Atmospheric and Oceanic Sciences
Program during their extended visit to Princeton. This work was funded by subcontracts with Martin
800
Marietta Systems, Inc., under contract with the Carbon Dioxide Research Division, US Department of
Energy: by a follow-up contract directly from the Carbon Dioxide Research Division of the Department
of Energy: and by the National Science Foundation.
Atmospheric PCO₂ (p.p.m.)
700
Business
as usual
Biases from natural sulphurization
600
in palaeoenvironmental recon-
500
struction based on hydrocarbon
400
biomarker distributions
Constant
Math E. L. Kohnen, Jaap S. Sinninghe Damsté
300
emission
& Jan W. De Leeuw
200
Organic Geochemistry Unit, Faculty of Chemical Technology and Materials
1900
1950
2000
2050
2100
Science, Delft University of Technology, De Vries van Heystplantsoen 2,
2628 RZ Delft; The Netherlands
Year
FIG. 3 The effect of stopping iron fertilization after 50 years (dotted line)
BIOMARKERS (chemical fossils) are sedimentary organic com-
is depicted for the business-as-usual and constant-emission scenarios. The
pounds whose basic skeletons suggest an unambiguous link with
solid line is the unfertilized scenario; the dashed line is the scenario for
known contemporary natural products, and were synthesized by
continuous fertilization.
biota present at the time of the deposition of the sediment. These
compounds are commonly used to assess palaeoenvironmental
resulting from iron fertilization gives an equilibrium warming
conditions of deposition of Recent and ancient sediments¹⁻³ Satur-
of 3.1.°C instead. On the other hand, the unfertilized constant-
ated hydrocarbons are relatively easy to analyse and contain a lot
emission scenario, which reaches 505 p.p.m. in 2090, gives a
of geochemical information, and are therefore the most widely
significantly smaller equilibrium warming of 2.2 °C, °C, which is
used class of biomarkers in palaeoenvironmental reconstruction
reduced to 1.4 °C with the 90 p.p.m. additional oceanic uptake
Hydrocarbon biomarkers are biosynthesized as such or are derived
resulting from iron fertilization. These numbers can be compared
from functionalized biosynthetic lipids, such as alkenes, alcohols
with the 0.9 °C equilibrium warming that can be expected from
and acids, by diagenetically induced defunctionalization. Func-
the present atmospheric CO₂ content of 355 p.p.m. It should be
tionalized lipids may, however, also undergo an abiogenic reaction
kept in mind that the transient warming is smaller than, and
with hydrogen sulphide or polysulphides ('natural sulphurization")
not necessarily proportional to the equilibrium warming, due
during the early stages of diagenesis, and this may lead to selective
primarily to the uptake of heat by the ocean.
removal of specific hydrocarbon biomarker precursors. Here we
The most important conclusion we draw from our calculations
investigate the influence of natural sulphurization on hydrocarbon
is that, although the effect of iron fertilization is large enough
biomarker signatures in immature sediments from Italy and off
to justify further study, the effect of a significant change in the
Peru. We show that, if not taken properly into account, this process
emissions of CO₂ is even larger. We emphasize the preliminary
may lead to a severe bias in the interpretation of the geological
nature of our calculations and the fact that all the assump-
record.
tions we have made have been biased so as to yield an upper
Sedimentary functionalized lipids react with reduced sulphur
limit.
species (H₂S and HS) to form organic sulphur compounds
(OSCs) and sulphur-bound lipid moieties in macromolecules
(see ref. 6 for a review). The onset of sulphurization of organic
Received 5 November 1990; accepted 5 February 1991.
matter is controlled by the reactive iron (for example, ferri-
1. Booth, W. Washington Post A1 20 May (1990).
hydrite and haematite) content of the sediment; because organic
2. Baum, R. Chem. Engrig News 68, 21-24 (1990).
3. Martin, J. H., Fitzwater, S. E. & Gordon, R. M. Global biogeochem. Cycles 4, 5-12 (1990).
matter reacts with reduced sulphur more slowly than do sedi-
4. Knox. F. & McElroy, M. B. 1 geophys. Res. 84, 2503-2518 (1984).
mented iron minerals and thus does so only after reactive iron
5. Siegenthaler, U.& Wenk, T. Nature 308, 624-626 (1984).
oxides have first been converted to iron sulphides: In the region
6. Sarmiento, J. L & Toggweiler, J. R. Nature 308, 621-624 (1984).
7. Sarmiento, J. L. Toggweller, J. R. & Najjar, R. Phil. Trans R Soc. A325, 3-21 (1988).
of upwelling in the Peru margin, sulphur incorporation into
8. Martin, J. H. & Fitzwater, S, E. Nature 331, 341-343 (1988).
sedimentary organic matter starts in the top metre of the sedi-
9. Martin, J. H. & Gordon, R. M. Deep-Sea Res. 35, 177-196 (1988).
10. Martin J. H., Gordon, R. M., Fitzwater, S. & Broenkow, W. W. Deep-Sea Res. 36, 649-680 (1989).
ment column', indicating that this process occurs in the early
11. Martin, J. H. Paleoceanography 5, 1-13 (1990).
stages of diagenesis. Moreover, the identification of OSCs in a
12. de Baar, H. J. W. et al. Mar. Ecol. Prog. Ser. 65, 105-122 (1990).
13. Banse, K. Limnol. Oceanogr. 35, 772-775 (1990).
Recent Black Sea sediment (age 3-6x 10³ yr) also points to an
14. Dugdale, R. C, & Wilkerson, F.P. Global biogeochem. Cycles 4, 13-20 (1990).
early diagenetic sulphurization of organic matter⁸. Ten Haven
15. Anderson, G: & Morel, F. M. M. Limnol. Oceanogr. 27, 789-813 (1982).
16. Morel, F. M., & Hudson, R. J. in Chemical Processes in Lakes (ed. Stumm, W.) 251-270 (Wiley,
et al.⁹ examined the extracts of almost 100 thermally immature
New York, 1985):
deep-sea sediments and found that approximately 70% of the
17. Peng. T.H. & Broecker, W.S. Nature 349, 227-229 (1991).
samples contain OSCs. The widespread occurrence of OSCs,
18. Toggweiler, J.R. & Sarmiento, J.L. in The Carbon Cycle and Atmospheric CO₂: Natural variations
Archean to Present Vol. 32; Geophysical Monograph Series (eds. Sundquist. E. T. & Broecker,
and the fact that reduced inorganic sulphur species are present
W. S.) 163-184 (American Geophysical Union, Washington, DC. 1985).
in any anoxic organic-matter-containing Recent marine sedi-
19. Broecker, W. S. Peng, T.-H., Ostlund, G. & Stuiver, M. 1 geophys Res. 90, 6953-6970 (1985).
20. Weiss, R. F., Bullister, J. L, Warner, M. J., Van Woy, F. A. & Salameh, P. K. Ajax Expedition
ment¹⁰, suggest that natural sulphurization of specific func-
Chlorofluorcarbon Measurements (Scripps Institution of Oceanography Reference 90-6, La Jolla,
tionalized lipids is a ubiquitous process. It seems inevitable that
1990):
this selective removal of the precursors of hydrocarbon bio-
21. Broecker, W. S. Global biogeochem Cycles 4, 1-2 (1990).
22. Houghton, T., Jenkins, G.I. & Ephraums, J.J. (eds) Climate Change, The IPCC Scientific Assessment
markers will alter the hydrocarbon biomarker distribution in
(Cambridg, University Press, 1990).
immature sediments, and thus the interpretation of the geologi-
23. Siegenthaler, U.& Deschger, H. Tellus 398, 140-154 (1987).
24. Peng. T. H. Takashi T. & Broecker, W. S. Tellus 399, 439-458 (1987).
cal record as revealed by their apparent distribution. Hydro-
carbon biomarkers are used in many (palaeo )environmental
ACKNOWLEDGEMENTS. We appreciate the great help given to FJ. by M. Warner in setting up OUT
CFC runs, and his generosity and that of R. Gammon in helping us to obtain the CFC date needed to
reconstruction studies of immature sediments and of par-
775
NATURE VOL 349 28 FEBRUARY 1991
GLOBAL ENVIRONMENTAL CHANGE REPORT
tion of net CO₂ emissions by 1-2%
Methane Emissions from
emissions "may account for half of
per year starting now would be re-
Lakes Increase as Air
the observed trend of H2," and
quired." This still amounts to at least
Pressure Drops
biomass burning, oxidation of non-
a 20-50% cut in CO₂ over the next
methane hydrocarbons, and various
According to a report in the 25 Oc-
20-50 years, but the stepwise, year-to-
anthropogenic activities could ac-
tober issue of Nature (vol. 347, pp.
year approach makes the target seem
count for much of the rest.
718-719), the bubbles of methane
less painful and uses a time frame
that routinely escape from lakes may
The 27 October issue of Science
politicians can understand.
become larger and more frequent
News quotes F. Sherwood Rowland
More Precise Temperature
during periods of low air pressure.
of the University of California, Irvine,
as saying that methane oxidation
Estimates Unlikely, Say
According to the study's authors,
should add "significantly more water
Researchers
Mark Mattson and Gene Likens of
vapor to the stratosphere than would
In what US climatologist Stephen
the Institute of Ecosystem Studies,
increasing levels of hydrogen, posing
Schneider described as "the only orig-
Millbrook, New York, USA, more
an even greater threat to the ozone
inal piece of climate science" that he
than half the methane fluxes from a
layer." Rowland, famous for his
saw presented at the Second World Cli-
New Hampshire lake during 64-day
early work on CFCs and the ozone
mate Conference, UK researchers Tom
sampling period in 1989 occurred
layer, has begun to focus much of his
Wigley and Sarah Raper explained
during a heavy rainfall on 5 August,
attention on greenhouse gas emissions.
that better estimates of the climate's
and a tropical storm on 23 September.
equilibrium response to an equivalent
Mattson and Likens also cite carlier
Iron Fertilization to
doubling of CO₂ are unlikely to
research that reported gas releases
Remove CO2: What's the
emerge in the next few decades.
from soils during low-pressure
Potential?
If the current observed warming of
events; if climate change eventually
As GECR reported on 8 June (p. 6),
0.5°C resulted entirely from an en-
increases rainfall in certain areas, and
US scientist John Martin and col-
hanced greenhouse effect, the re-
increases the frequency of tropical
leagues have proposed a way to
searchers say, then a doubling of CO₂
storms, then this methane response
reduce atmospheric CO₂ concentra-
should result in a warming of only
represents a potentially significant
tions by enhancing plant productivity
1.25 - 1.55°C. Adding the very real
positive warming feedback.
in Antarctic waters. Although the
factors of natural climate variability
southern ocean is rich in nutrients,
and data uncertainties widens the
Molecular Hydrogen
algae there are limited by a lack of
range to 0.65 - 4.05'C. This range be-
Increase May Pose Threat
iron; adding iron to the ocean would
comes even broader when the effects
to Ozone Layer
stimulate algal growth and take more
of ocean circulation changes, solar
The atmospheric concentration of
CO₂ out of the atmosphere.
variation, and sulfate aerosols are in-
molecular hydrogen (H2) has in-
But how much more? A new es-
cluded. Sulfates, according to
creased to a little over 500 parts per
timate, by T.H. Peng and Wallace
Wigley and Raper, may have offset
billion since its estimated pre-in-
Broccker of Oak Ridge National
the greenhouse contribution to warm-
dustrial level of around 200 ppb.
Laboratory (Oak Ridge, Tennessee,
ing by as much as one third, which
And according to a report in the 25
USA) and the Lamont-Doherty
means that SO₂ reductions currently
October issue of Nature (vol. 347, pp.
Geological Observatory (Palisades,
underway in many Northern Hemi-
743-745), H2's concentration has in-
New York, USA), respectively, con-
sphere countries could result in a con-
creased by about .5% per year bc-
cludes that "after 100 years of totally
siderably larger warming than might
tween 1985 and 1989. Because H₂
successful fertilization, the atmos-
otherwise be expected.
oxidizes to form water vapor, and be-
phere's CO₂ content would be
cause an increase in water vapor in
Wigley and Raper point out that no
lowered by 30 parts per million [give
the stratosphere may lead to an in-
matter what global-mean tempera-
or take 10 ppm]." In other words, ac-
tures do over the next few decades,
crease in polar stratospheric clouds,
cording to Peng and Broecker, if CO2
the H₂ trend could be bad news for
they won't reduce the range of uncer-
were to reach 500 ppm in the year
the ozone layer.
tainty in estimates of the climate's
2090 under business as usual, a strict
response to a CO₂ doubling. And,
Why is molecular hydrogen increas-
program of fertilization over the en-
significantly, they claim that at least a
ing? According to the study's
tire century would lower the con-
2.5°C warming can be expected even
authors, M.A.K. Khalil and R.A. Ras-
centration to 455-485 ppm. Peng
if the temperatures remain unchanged
mussen of the Oregon Graduate In-
told GECR that the relationship isn't
for the next 15 years.
stitute (Beaverton, Oregon, USA),
linear - most of the effect occurs in
the 1% per year increase in methane
the carly stages of fertilization, and
VOL. II, NO. 19
12 OCTOBER 1990
5
GLOBAL ENVIRONMENTAL CHANGE REPORT
over a shorter time horizon (50
Study Finds High Levels
enough to stabilize its global con-
years), the atmospheric CO₂ con-
of Methane in Eastern
centration, "and eliminate any further
centration would still be lowered by
European Cities; Leaks
incremental contribution of this gas
20-25 ppm. However, Peng cau-
Blamed
to the atmospheric trapping of in-
tioned that the estimate is very op-
frared radiation."
F. Sherwood Rowland and colleagues
timistic, and assumes the process of
from the University of California at
The IPCC's scientific report quotes a
fertilization and CO₂ removal works
Irvine report in the 4 October issue of
figure of 15-20%; Rowland bases his
"100% perfectly." More realistically,
Nature (vol. 347, pp. 432-433) that
calculation on the fact that methane
CO₂ concentrations might be lowered
recent methane levels in Berlin,
has increased an average of 1% per
by only 15 ppm over the next 50-100
Budapest, Krakow, and Prague were
year during the 1980s, and that its at-
years through an intensive fertiliza-
"substantially higher than those
mospheric lifetime is about 10 years.
tion program.
characteristic of most US cities."
According to Rowland, "improved
The two scientists will present the
Rowland, who along with Mario
controls on the tranmission of natural
results of their study at the Fall 1990
Molina first brought the ozone-deplet-
gas, particularly in eastern Europe
meeting of the American Geophysi-
ing potential of CFCs to light, says
and Asia, offer a promising oppor-
cal Union, to be held in San Francis-
that leakage during natural gas trans-
tunity to slow the global build-up of
co from 3-7 December.
mission is probably the culprit.
methane..." See GECR's 22 June
Rowland says a 10% reduction in
issue, p. 6) for a related article.
global methane emissions should be
Industry Watch
US to Facilitate
fact that each industry is concerned
prepared a strategy that calls for
with its own specific issues will make
100,000 megawatts (MW) of wind
Coordination of Industry's
it hard to duplicate the broad
generating capacity to be installed in
Global Change Research
programmatic scale that CEES has es-
the EC by the year 2030. EWEA
Efforts
tablished for the Global Change Rc-
produced the strategy on contract
The Committee on Earth and Environ-
search Program. GECR should note
with the European Commission, and
mental Sciences (CEES, formerly
that PIGI's program would focus
its recommendations are based on an
CES), the government body that es-
mainly on basic research, not on ef-
appraisal of technological develop-
tablished and oversees the US Global
forts to mitigate global change.
ments, realistic costs, a comparison
Change Research Program, is trying
with conventional power generation,
to organize a similar program for US
Henderson and colleagues are or-
and reviews of markets, budgets, and
industry research on global change.
ganizing a workshop to be held 11-13
subsidies.
February 1991 on industry's "current
CEES has sct up an informal working
and planned research that's relevant
According to EWEA President David
group, the Private Industry-Govern-
to the Global Change Research Pro-
Lindley, wind energy currently
ment Interface (PIGI), to act as a
gram." Interested parties should con-
provides about 365 MW in Europe,
communication point between
tact Henderson at The Gcosat Com-
with 250 MW of that being produced
government and industry; the next
mittee Inc., 601 Elm Street, Room
in Denmark. Denmark's Energy
step, says Dr. Frederick Henderson of
438C, Norman, OK 73019, USA.
2000 plan requires wind power to in-
the Geosat Committee in Norman,
Tel: +1-405-325-3329; Fax: +1-405-
crease to 10% of the country's total
Oklahoma, is to help industry or-
325-3327.
energy production by the year 2000,
ganize a research steering committee
up from 2% today. The Netherlands
that parallels CEES. Henderson ac-
European Wind Energy
has set a goal of 1,000 MW of wind
knowledges that coordinating in-
Pushes for Major
energy capacity by the year 2000,
dustrial research efforts may be quite
Increases in Capacity
and is currently soliciting bids for
difficult, particularly if PIGI aims to
Seeing an opportunity for growth in
250 MW worth of new turbines. Ger-
be comprehensive. According to
the face of the European
many plans to add 250 MW of wind
Geraldine Cox, vice president of the
Communities' commitment to reduce
energy by the year 2000, and is offer-
Chemical Manufacturers Association
CO2 emissions, the European Wind
ing major subsidies (US $0.9 per
and chair of the Global Climate
Energy Association (EWEA) has
kw/h to wind farmers); Italy wants
Coalition's research committee, the
6
12 OCTOBER 1990
VOL. II, NO. 19
cations
Sci. 288 A, 115 (1988).
G. W. Viele, Eds. (Geological Society of America,
Table 1. Schematic representation of t]
28. R. L. McMaster et al., Geology 8, 496 (1980).
Boulder, CO, 1989), PP. 537-553.
1, field
experimental treatments (4). All plots with
29. S. Mosher, Tectonics 2, 327 (1983).
39. W. R. Muehlberger and P. R. Tauvers, in ibid., pp.
kangaroo rats removed (-) were compared 1
at con-
30. B. H. Reck and S. Mosher, J. Geol. 96, 677 (1988).
673-680.
ssively
31. R. E. Zartman, and O. D. Hermes, Earth Planet. Sci.
40. J. Pindell and J. F. Dewey, Tectonics 1, 179 (1982).
all other plots (+), except those with I
Lett. 82, 305 (1987).
41. P. Bird, J. Geophys. Res. 83, 4975 (1978); Tectono-
spectabilis removed.
during
32. S. L. Dean, B. R. Kulander, J. M. Skinner, Geol.
physics 50, 307 (1978).
ysis is
Soc. Am. Bull. 100, 299 (1988).
42. P. A. Ziegler, Tectonophysics 126, 303 (1986).
Numb
eozoic
33. J. Rodgers, The Tectonics of the Appalachians (Wiley-
43. D. H. Tarling, Proc. Ussher Soc. 4, 233 (1979); R.
Treatment
of
Interscience, New York, 1970).
Van der Voo, personal communication.
nerica,
plots
34. P. Geiser and T. Engelder, Geol. Soc. Am. Mem.
44. We benefited from field discussions with H. Maher
158, 161 (1983).
and A. Dennis. A. Dennis, T. Engelder, W. R.
35. R. D. Dallmeyer, Am. J. Sci. 289, 812 (1989).
Unmanipulated control
2 (+)
Muchlberger, S. Schamel, W. E. Sharp, J. Shervais,
36. J. H. McBride and K. D. Nelson, Geol. Soc. Am.
All rodents removed
A. Snoke, R. Van der Voo, and H. Williams read
2 (-)
Bull. 100, 436 (1988).
All rodents and all ants
early versions of the manuscript. This work has been
2 (-
158, 19
37. S. A. Graham et al., ibid. 86, 273 (1975); J.
supported by the National Science Foundation
removed
Wickham el al., Geology 4, 173 (1976); K. D.
grants EAR 8508123 and EAR 8803833 to D.T.S.
Kangaroo rats removed
2
1.
Nelson et al., Tectonics 1, 413 (1982); R. J. Lillie et
Additional support has been provided through De-
Kangaroo rats and
2 (-
77); R.
al., Am. Assoc. Pet. Geol. Bull 67, 907 (1983).
partment of Geological Sciences, University of
Pogonomyrmex ants
Duachita
38. W. A. Thomas and G. H. Mack, Geol. Soc. Am.
South Carolina teaching assistantships and a Grant-
removed
W.A.
Bull. 93, 6 (1982); G. H. Mack, W. A. Thomas, C.
in-Aid of Research from the American Association
ciety of
A. Horsey, J. Sediment. Petrol. 53, 931 (1983); W.
Dipodomys spectabilis removed
2
of Petroleum Geologists to P.E.S.
3.
All ants removed
A. Thomas, in The Appalachian-Ouachita Orogen in
2 (+
full. 88,
the United States, R. D. Hatcher, Jr., W. A. Thomas,
26 June 1990; accepted 19 September 1990
Pogonomyrmex ants removed
2 (+
Seed addition
8 (+)
DC. Am.
A. Liu,
).
9, 809
dii, and D. merriami; or just the largest an
ghanian
Control of a Desert-Grassland Transition by a
behaviorally dominant kangaroo rat, D
Carolina
Geolog-
Keystone Rodent Guild
spectabilis. An initial analysis of varianc
blogical
(ANOVA), with plots as the sample units to
avoid "pseudoreplication" (6), showed tha
JAMES H. BROWN AND EDWARD J. HESKE
treatments in which all rodents or all kanga
forton,
T. Se-
roo rats had been removed were similar to
ological
Twelve years after three species of kangaroo rats (Dipodomys spp.) were removed from
each other in the plant variables analyze
Excur-
lumbia,
plots of Chihuahuan Desert shrub habitat, density of tall perennial and annual grasses
below. They differed significantly from a
Geology
had increased approximately threefold and rodent species typical of arid grassland had
other treatments, except D. spectabilis re
ibid., p.
colonized. These were just the most recent and dramatic in a series of changes in plants
moval. In addition, there were no detectable
and animals caused by experimental exclusion of Dipodomys. In this ecosystem
effects of ant removal or seed addition treat
)uachita
kangaroo rats are a keystone guild: through seed predation and soil disturbance they
ments on these plant variables. Therefore
W.A.
have major effects on biological diversity and biogeochemical processes.
the eight plots where all kangaroo rats wer
ciety of
absent were compared to the 14 plots wher-
19, 537
HE BIOLOGICAL DIVERSITY AND
T
of southeastern Arizona (4, 5). Twenty-four
all kangaroo rats were present in the follow
7, 433
biogeochemical processes that char-
plots, each 0.25 ha in area (50 by 50 m),
ing analyses. The two plots from which jus
pl. Soc.
acterize an ecosystem depend on in-
were fenced with fine wire mesh and as-
D. spectabilis had been removed were exclud
her, Jr.,
teractions of the organisms with each other
signed at random to experimental manipu-
ed from the analyses, because the vegetation
United
and with their abiotic environment. The
lations. Treatments included removal of
G. W.
parameters were often intermediate between
oulder,
presence or absence of certain kinds of or-
some or all rodent or ant species and addi-
the two treatment classes and the limited
ganisms, called "keystone species" (1), can
tion of millet seeds (Table 1). Access of
replication did not permit statistical resolu-
1319
dramatically alter the structure and dynamics
different rodent species to appropriate plots
tion.
of ecological systems. In most ecosystems,
was controlled by cutting holes of different
Long-term removal of kangaroo rat
vertebrate animals account for only a small
sizes at ground level in the fences surround-
caused a dramatic change in habitat, fron
of the
fraction of the biomass and energy flow (2),
ing the plots. Populations of rodents, ants,
desert shrubland to grassland (Fig. 1). Ef
nont of
but through predator-prey, competitive,
birds, and plants were monitored systemat-
fects of Dipodomys on vegetation were ana
r., Ed.
South
and mutualistic interactions with other spe-
ically at a grid of permanent sample sites
lyzed by ANOVA, not only comparing plot:
1987),
cies and by causing physical disturbance they
within each plot. Between 4 and 16 Septem-
where kangaroo rats had been removed tc
can have disproportionately large effects on
ber 1989, in order to better characterize
plots where kangaroo rats were present, but
Oliver,
3).
habitat structure, species composition, and
plant cover inside and immediately outside
also comparing transects inside and imme-
Progeny
biogeochemical processes (2, 3). We show
each plot, all plant species were counted at
diately outside the plots where kangaroo rats
la and
that long-term experimental removal of a
logical
10-cm intervals along eight 25-m transect
had been removed (Fig. 2). Tall-statured
al Sur-
guild of three kangaroo rat species from a
lines: four inside transects began 8 m from
perennial and annual grasses colonized the
desert ecosystem initiated changes that have
the center of the plot and ran outward
open spaces between the shrubs and in-
'g. 22,
led to the conversion of the habitat from
toward each corner; after a gap of 2 m on
creased approximately threefold in the ab-
), 853
shrubland to grassland.
either side of the fence, the other four
sence of kangaroo rats. Much of this re-
n, Jr.,
In 1977, experiments were begun on an
transects continued for another 25 m out-
sponse can be attributed to two species: the
alluvial outwash plain with diverse desert
side the fence.
3, 999
perennial Eragrostris lehmanniana, which in-
shrub vegetation in the Chihuahuan Desert
In ten plots, one of three different combi-
creased more than 20-fold, and the annual
3).
nations of desert rodent species was exclud-
Aristida adscensionis, which increased ap-
i, 735
Department of Biology, University of New Mexico,
ed (Table 1): all rodents; three species of
proximately threefold. There were comple-
Am. J.
Albuquerque, NM 87131.
kangaroo rats, Dipodomys spectabilis, D. or-
mentary changes in two species of short
250
21 DECEMBER 1990
REPORTS 1705
nnual grasses (Bouteloua aristidoides and B.
same period, seed-eating birds decreased
30
Inside
Dipodomys removed
arbata); these were significantly less abun-
their foraging on plots with rodents re-
1:
Dipodomys present
lant where kangaroo rats had been re-
moved in comparison with plots where kan-
noved. Tridens pulchella, a short-statured
garoo rats were present (8). This was asso-
20
pecies and the only perennial grass that was
ciated with an increase in herbaceous (both
captured
10
tommon on the site when the experiments
grass and forb) vegetation and a decrease in
vere begun, was the only abundant species
the amount of bare ground, conditions that
10
that did not show a significant response to
made it more difficult for the birds to harvest
cangaroo rat removal. The net result of
the available seeds. Six to 12 years after the
excluding either all rodents or all three Di-
experiment was begun, and in response to
the increase in grass cover documented
0
bodomys species for 12 years was a dramatic
increase in the cover of tall grasses.
above, six species of rodents that are charac-
That kangaroo rats are a keystone guild in
teristic of arid grasslands differentially colo-
Cover (%)
30
Outside
this ecosystem is further demonstrated by
nized the grassy plots where kangaroo rats
other changes that occurred on plots where
had been removed (Fig. 3). Finally, we have
Fig.
rodei
they were removed. During the first 10 years
noted, but not quantified, greatly increased
20
funct
after initiation of the experiments, large-
accumulation of litter and longer persistence
perer
seeded winter annual plant species had in-
of snow on the plots where kangaroo rats
shade
creased (Fig. 1), some by as much as several
were absent.
ized
Two processes, seed predation and soil
10
thousand times, and small-seeded winter
viven
annuals decreased on plots with rodents and
disturbance, appear to be responsible for the
repre
kangaroo rats removed (5, 7). During this
changes in this desert ecosystem that were
spp.
both
0
ERIN
PERG
ARAD
ANNG
BOAR
BOBA
Vegetation type
may
Fig. 2. Effects of removing kangaroo rats (Di-
lishn
podomys) on densities of perennial and annual
birds
grasses. Plotted are mean values (±SE) of the
distu
percentage of cover for Eragrostris lehmanniana
(ERLE), all other tall perennial grass species
rats
(PERG), Aristida adscensionis (ARAD), all other
tence
tall annual grasses (ANNG), and the short annual
color
grasses Bouteloua aristidoides (BOAR) and B. bar-
speci
bata (BOBA). (Top) Data from transects inside
Al
plots where kangaroo rats were either present or
removed; asterisks indicate significant differences
size-:
between kangaroo rat removal and other plots.
soil
(Bottom) Data from transects immediately out-
dant.
side these plots. Asterisks indicate statistically
significant differences between transects inside
repo
cated
and outside plots where kangaroo rats were pres-
ent or absent. (ANOVA, with plots as units of
differ
replication;
*P
V
0.05,
^
0.01,
V
imen
0.001.)
trans
certai
caused by removing kangaroo rats. Selective
abser.
foraging by kangaroo rats for large seeds is
betw
sufficient to explain the shorter-term re-
when
sponses to our experiments (5, 9). Large-
grazil
seeded winter annual plants increased in
cause
response to their release from rodent preda-
shrut
tion, and asymmetrical competition from
effect
these dominant large-seeded species then
kang:
caused the decrease in the small-seeded win-
exclu:
ter annuals. Increased availability of seeds
prodi
and reduced competition from kangaroo
horse
rats may account, at least in part, for the
ed fro
colonization of kangaroo rat removal plots
no si;
Fig. 1. Photographs across
the fences surrounding plots
by the granivorous Reithrodontomys rodents
been
from which kangaroo rats
(Fig. 3). Physical disturbance appears to
In
were removed (left side of
have played the major role in the longer-
nism
fence). (Top) Increase of the
term responses to removal of kangaroo rats.
ecosy.
yellow-flowered, large-seed-
ed annual, Lesquerella gordo-
During their foraging, food caching, and
single
nii, 5 years after kangaroo rat
burrowing activities, kangaroo rats make
ically
removal. (Bottom) Increase
runways through the vegetation and move
roo r.
in rall-statured annual and
large quantities of soil, creating many shal-
behav
perennial grasses 13 years af-
ter kangaroo removal.
low pits and little mounds. This disturbance
lis) h:
SCIENCE, VOL. 250
21 DE
1706
and distribution of other desert rodents (4,
Brown, in Pattern and Process in Desert Ecosystems, W.
150
12), but it required the removal of all three
G. Whitford, Ed. (Univ. of New Mexico Press,
Albuquerque, 1986), p. 51.
species to cause wholesale changes in vege-
3. J. A. Estes and J. F. Palmisano, Science 185, 1058
tation. On the other hand, the eight com-
(1974); S. R. Carpenter, J. F. Kitchell, J. R. Hodg.
Rodents captured
son, BioScience 35, 634 (1985); J. C. Castilla and L.
100
mon and several rare species of desert ro-
R. Duran, Oikos 45, 391 (1985); R. J. Naiman, C.
dents that remained after kangaroo rats had
A. Johnston, J. C. Kelley, BioScience 38, 753
been removed clearly did not play the same
(1988); J. Pastor et al., ibid, P. 770.
4. J. H. Brown and J. C. Munger, Ecology 66, 1545
keystone role and were not able to prevent
(1985).
50
the conversion of desert to grassland.
5. J. H. Brown et al., in Community Ecology, J. Dia-
Twenty-five years after the concept of
mond and T. J. Case, Eds. (Harper & Row, New
York, 1986), p. 41.
"keystone species" was first introduced, ex-
6. S. H. Hurlbert, Ecol. Monogr. 54, 187 (1984).
0
(DO KID)
amples have been found in a number of
7. D. W. Davidson, D. A. Samson, R. S. Inouye,
0
20
40
60
taxonomic groups and habitat types (1, 3).
Ecology 66, 486 (1985); D. A. Samson, T. E.
Philippi, D. W. Davison, in preparation.
Grass cover (%)
It remains, however, to develop a general
8. D. B. Thompson et al., Ecology, in press.
Fig. 3. Number captured per plot since 1983 of
conceptual framework that will predict
9. J. H. Brown and D. W. Davidson, Science 196, 880
rodent species typical of grassland habitat as a
which kinds of organisms play key roles in
(1977); J. H. Brown et al., Annu. Rev. Ecol. Syst.
10, 201 (1979); R. S. Inouye, G. S. Byers, J. H.
function of mean percentage of cover of all tall
different kinds of ecosystems. Native species
Brown, Ecology 61, 1344 (1980).
perennial grasses plus Aristida adscensionis. Un-
shaded symbols represent only the most special-
are increasingly being eliminated from local
10. J. R. Hastings and R. M. Turner, The Changing Mile
(Univ. of Arizona Press, Tucson, 1965); D. Sheri-
ized grassland species, Sigmodon hispidus, S. ful-
habitats and larger regions as a result of
dan, Descrification of the United States (Council on
viventer, and Baiomys taylori; shaded symbols
human activities. It is critical to develop a
Environmental Quality, U.S. Government Printing
represent the above species plus Reithrodontomys
theoretical basis for assessing the effects of
Office, Washington, DC, 1981).
spp. Least-squared regression lines are fitted, and
11. E. J. Heske and M. Campbell, Southwest. Nat., in
these species on ecosystems so that, if extir-
both are statistically significant (P < 0.0001).
press; see also R. M. Chew, Am. Midl. Nat. 108,
pation of keystone organisms cannot be
159 (1982); B. A. Roundy and G. L. Jordan,
Southwest. Nat. 33, 425 (1988).
avoided, their roles can be replaced by other
12. M. A. Bowers et al., Oecologia 72, 77 (1987).
may facilitate decomposition of litter, estab-
native or exotic species or by active ecosys-
13. We thank L. Valle, P. Mazzolini, and many other
lishment of many annuals, and foraging of
tem management.
people for assistance with the fieldwork, S. Mistry
al
for help with the statistical analyses, C. Crawford, L.
birds (8). Conversely, the reduction in soil
Hawkins, M. Molles, and M. Taper for comments
he
disturbance following exclusion of kangaroo
REFERENCES AND NOTES
on the manuscript, and the National Science Foun-
la
es
rats promoted the establishment and persis-
dation (most recent Grant BSR-8718139) for sup-
1. R. T. Paine, Am. Nat. 100, 65 (1966);
ibid.
,
port of the research program.
er
tence of tall grasses, and this in turn favored
103, 91 (1969).
al
colonization by specialized grassland rodent
2. R. M. Chew, Ohio J. Sci. 74, 359 (1974); J. H.
25 June 1990; accepted 3 October 1990
species.
le
Although kangaroo rats presumably cause
or
es
size-selective seed predation and extensive
s.
soil disturbance wherever they are abun-
&
dant, the kind and magnitude of changes
Characterization of "Peak E," a Novel Amino Acid
ly
reported here would probably not be dupli-
de
Associated with Eosinophilia-Myalgia Syndrome
cated if kangaroo rats were removed from
S-
of
different kinds of desert habitats. Our exper-
imental site is near the zone of natural
ARTHUR N. MAYENO,* FENG LIN, CHRISTOPHER S. FOOTE,
transition from desert to grassland, so that
DAVID A. LOEGERING, MATTHEW M. AMES, CRAIG W. HEDBERG,
certain abiotic conditions or the presence or
GERALD J. GLEICH
e
absence of keystone species can cause a shift
is
between alternative vegetation types. Else-
Epidemiologic studies strongly associate eosinophilia-myalgia syndrome (EMS) with
e-
where in the southwestern United States
ingestion of tryptophan containing a contaminant ("peak E"). Prior reports have
e-
grazing by domestic livestock is known to
suggested that peak E is the di-tryptophan Nα-aminal of acetaldehyde. Spectral and
in
cause degradation of arid grassland to desert
chemical studies now demonstrate that peak E is 1,l'-ethylidenebis[tryptophan]. This
a-
shrubland (10). At our site, however, the
novel amino acid may be the etiological agent responsible for EMS, or it may be a
m
effects on vegetation of the exclusion of
marker of a still unidentified causal agent.
in
kangaroo rats in combination with livestock
Nα-aminal of acetaldehyde (4, 5). We present
C
exclusion were much greater than those
is
produced by the exclusion of cattle and
A
S OF AUGUST 1990, EMS WAS LINK-
chemical and spectral data which show that
ed to 27 deaths and over 1500 cases
peak E is actually the isomeric l'-ethyli-
Ю
horses alone. Grazing livestock were exclud-
(1). Epidemiological studies (2, 3)
denebis[tryptophan] (1).
ie
ed from our entire 20-ha site since 1977, but
have associated EMS with the ingestion of
Peak E was isolated by high-performance
ts
no significant change in vegetation has yet
L-tryptophan (Trp) produced by a single man-
liquid chromatography (HPLC) (3). Fast
ts
been detected across the fenceline (11).
ufacturer, suggesting that a contaminant is
atom bombardment-mass spectrometry
to
In the present case the "keystone" orga-
responsible for EMS. Recently we reported the
(FAB-MS) revealed peaks at mass-to-charge
r-
nism whose removal caused large changes in
discovery of a contaminant (peak E) in the Trp
ratios (m/z) of 157, 231 (base peak), and
S.
ecosystem structure and dynamics was not a
samples consumed by EMS patients that was
435 ([M + High-resolution FAB-MS
id
single species, but a guild of three taxonom-
absent in the Trp consumed by asymptomatic
gave a mass of 435.2041, consistent with
ke
ically related and ecologically similar kanga-
controls (3). A significant association exists
the molecular formula C₂₄H₂₇N₄O₄.
ve
roo rat species. Removal of the largest and
between the presence of peak E and EMS-
The proton nuclear magnetic resonance
il-
behaviorally dominant of these (D. spectabi-
associated Trp (3, 4). Two groups have previ-
(¹H NMR) spectrum of peak E in D₂O (6)
ce
lis) had significant effects on the abundance
ously reported that peak E is the di-tryptophan
was similar to that of Trp in terms of
50
21 DECEMBER 1990
REPORTS 1707
THE
NTERPARLIAMENTARY
CONFERENCE ON THE
DROW
GLOBAL ENVIRONMENT
boxtles I HD.
tel carf. ul Roina
1/25/91
whole theory of Fe seeding
avore from 38 bottles 100.
X
will be a box re: this
Stray X he released soon.
in their glibal work
I
EARTH ON ICE
John Martin's idea is simple and ingenious,
and some say it's crazy.
If you dump iron in the ocean,
he says, you can draw carbon dioxide
out of the atmosphere-
and cool down an overheating planet.
BY ROBERT KUNZIG
OSS Landing on Monterey
deep. Some people who heard about his
M
Bay is a knot of antique
idea got enthusiastic, and he is now
stores and a harbor tight
pestered by people who have iron to get
with boats that still fish
rid of. Others, particularly environmen-
the bay for albacore and
talists, got mad. The National Research
salmon. From a distance,
Council has convened two workshops
though, from the coast highway or from
on Martin's idea. The American Society
the artichoke fields of the Salinas Val-
of Limnology and Oceanography just
ley, what you see of Moss Landing are
held a special symposium for the sec-
the twin stacks of the Pacific Gas and
ond time in its history. Martin has ap-
Electric power plant. They dominate the
peared on Good Morning America. The
village like cathedral spires. And on a
upshot of these learned discussions is
hot summer day, when air conditioners
that Martin's idea may work or it may
in central California are pumping furi-
not; but it is certainly worth investigat-
ously, the PG&E stacks are spewing
ing, and it is certainly no joke.
4,300 tons of carbon into the atmo-
Somehow this bluff, shy but outspo-
PHOTOGRAPH BY ANDY FREEBERG: MICROGRAPH BY DEE BREGER, LAMONT-DOHERTY GEOLOGICAL OBSERVATORY
sphere. From the Moss Landing Marine
ken man has managed to convince his
Laboratories, which stand on the sand
peers that it is worth talking about fertil-
spit that protects the harbor from the
lizing the Antarctic sea surface with a
bay, John Martin, the director of the
shipload of iron-that the single-cell
labs, can gauge the region's demand for
algae that float there might grow like
electricity just by looking up at the
crazy and in the process draw carbon
stacks. Martin thinks he may have a
dioxide out of the atmospheric green-
way of getting some of that carbon back
house. What accounts for Martin's per-
out of the atmosphere. He says we might
suasiveness? It is not charisma, though
do it by dumping a few hundred thou-
there is a disarming Yankee directness
sand tons of iron into the ocean around
about him. And it is not just that
Antarctica.
everyone these days seems to want to
When Martin first made this sugges-
talk about the greenhouse effect. The
tion a few years ago, he was half joking.
impact of Martin's idea really stems from
"I got into this mess by shooting my
its simplicity-and from the solid data
mouth off," he says. But now he's in
that back it up.
John Martin at Moss Landing: Fertilize the ocean with iron, he says, and the
phytoplankton-floating single-cell plants-will bloom. Inset: An electron
micrograph shows a type of phytoplankton called a diatom; this one is relatively
large-.001 inch long. More diatoms are on the following pages.
DISCOVER
APRIL
1991
55
would have blown
everybody would scream at him, 'You
out every window
stupid old man!' He just completely
"I'm not much of
in Panama City. So
infuriated a lot of people, and so they
a
that kind of slowed
didn't want to believe him."
a scientist. My
them down. But it
Martin and his assistants, though, de-
was an interesting
cided to heed Patterson's advice. They
strength is
project, and a tre-
started taking off their shoes before en-
mendous amount
tering the laboratory so they wouldn't
imagination-I
of research came
track in metal-rich dirt. They wrapped
S
out of it."
each bottle of seawater in three plastic
can imagine what's
Martin's own re-
bags. They kept the laboratory under
S
search involved tak-
positive pressure, with filtered air com-
going on in the ocean."
ing samples of
ing in and fans blowing out, so that no
plankton-the sea's
dust grains would waft in when the
floating population
door was opened. They even switched
of tiny plants and
to the brand of laboratory tissue that
Dumping iron in the Antarctic, if it
animals-from all over the Gulf of Pan-
Patterson recommended as being partic-
ever happens, would not be the weird-
ama and measuring their metal content.
ularly metal-free. "Our big goal in life,"
est project Martin has ever been in-
He found that the water and the plank-
says Martin, "was to get one damn num-
volved in. In 1966, at age 31, he left the
ton contained ample amounts of metals
ber for lead that Patterson would believe-
University of Rhode Island with a Ph.D.
already, which suggested to the Atomic
in plankton, in sea lions, in water, or
in oceanography and took a job with the
Energy Commission that a little radioac-
whatever. So we started doing all this,
Atomic Energy Commission. He was sent
tive metal wouldn't do much harm. Mar-
and it was amazing. All of a sudden all
to Panama to work on Project Plow-
tin got pretty good at these measure-
these things started to fall into place.".
share-the goal of which was to dig a
ments, or so he thought at the time. But
In Panama Martin had found that
second, sea-level canal through the isth-
in 1970, when he took a job at the
many metals were naturally abundant
mus by detonating a chain of 150 or so
Hopkins Marine Station, a Stanford out-
in seawater. Now he found that he had
atom bombs. "What you do is, you set
post on the Monterey peninsula, he was
been wrong. When he cleaned up his
the devices up across Panama, and you
tired of plankton ("They're cruddy
procedures and, eliminated sources of
touch them off, and it's just like a wave
things"), and he was tired of metals. He
contamination, the water turned out to
in the ground," says Martin. "You end
wanted to switch to something new.
be a lot purer. What's more, such metals
up with a depression half a mile wide
A colleague pointed out that his tim-
as were in it were distributed in an
and banks on either side.
ing was all wrong. The early 1970s were
orderly way. Before, when researchers
"But when you blow off all these
a time of swelling popular concern about
took samples of the water column at
underground shots, some radioactivity
the effects of heavy metals in the envi-
progressively greater depths, the con-
is going to fall out on the sea surface.
ronment. Caltech geochemist Clair Pat-
centration of a metal would fluctuate
And so they wanted to find out how
terson, in particular, was warning about
wildly and inexplicably. Now it followed
much of this was going to be taken up
the pervasiveness of lead pollution and
a smooth profile, generally increasing
by the food chain and eventually be-
the dangers of lead poisoning. The
toward the metal-rich mud on the bot-
come a human health hazard. In the old
Roman Empire had fallen, he said, not
tom. Things made sense.
days of atomic testing they used the
to the Visigoths and the Huns, but to
In the ensuing years Martin and his
'specific activity' approach, which said,
lead poisoning. Prodded by his colleague
group measured lots of different metals.
the more of a stable element there is to
at Hopkins, Martin read Patterson's pa-
They measured manganese in seawater.
dilute the radioactive element, the safer
pers. They convinced him he should
They measured mercury and cadmium
you are. In other words, if you're a sea
stay in the trace-metal business. When
in sea lions, sea otters, and sewage.
creature and you've got in the water an
he moved to Moss Landing in 1972, he
Those measurements were comparatively
atom of radioactive zinc and a hundred
set up a trace-metals lab.
easy because there isn't much manga-
atoms of stable zinc, the chances will be
But Patterson proved to be a difficult
nese, mercury, or cadmium floating
a hundred to one that you'll take up the
role model. "About the mid-seventies,"
around to contaminate a sample: Later
stable element. So they wanted to know
Martin recalls, "Patterson started telling
Martin's group measured lead, which
how much stable zinc was in the water,
everybody, 'Your numbers are all bad.
was harder; it was still being spewed
and iron, and all these other things."
You're contaminating your samples.
out by cars running on leaded gasoline.
Today Martin describes himself as an
When you try to measure lead in water
The biggest challenge of all, however,
environmentalist, and he thinks nuclear
or in plankton, everywhere you look or
was iron. Martin had measured it in
power plants are dangerous. But two
touch is contaminated with lead that's
Panama, but those numbers, he had
decades ago the idea of nuclear excava-
flowing out of exhaust pipes, and if you
long since realized, were far too large.
BY DEE LAMONT-DOHERTY OBSERVATORY
tion didn't strike him as strange. "It
could put on this special pair of glasses,
Iron is highly insoluble in seawater; it
didn't particularly bother me, I guess.
you'd see lead all over the room.' And
tends to glom on to organic particles
Anyway, the bottom line was you have
Patterson is enough of a strong individ-
and sink to the bottom. So the amount
PHOTOGRAPH GENE FELDMAN,
a big mountain range in Panama, and if
ual to go into a room full of scientists
of iron in the water column had to be
you knocked down the mountain, it
and say, 'You're all full of crap!' Then
very small. But nobody had been able
56
DISCOVER
APRIL
1991
to say exactly how small, because con-
them all the main nutrients-the ni-
is a warmth to the man, although it
tamination was almost impossible to
trates and phosphates-they need to
doesn't bubble.
avoid.
grow. Yet the nutrients go unused. The
But Martin is also known for irritat-
"Every time you get a speck of dirt,
phytoplankton never bloom. That is,
ing his peers. It is not just that he is
that's five percent iron," says Martin.
their population never explodes, as it
competitive. He doesn't seem to feel he
"And of course man uses iron for every-
does, say, in the North Atlantic, where
belongs to the club. "I'm not much of a
thing. When you make a plastic bottle,
the sea surface turns green each spring.
scientist," he says. "I don't have a very
it's usually extruded onto a stainless
Why? In his talk that day Frost offered
scientific mind-you know, math and
steel form-there's this hot plastic flow-
the conventional explanations: there is
all that. My strength is imagination-I
ing over stainless steel, and some of that
not enough light in the Antarctic, he
can imagine what's going on in the
stainless steel is picked up in the plas-
said; or it is too cold; or else the phyto-
ocean. I guess I'm right-brained. Right-
tic." Even the plastic bottles in the labo-
brained people tend to get weeded out
ratory, then, were not to be trusted as
of science, and it's too bad. I knew a guy
far as iron was concerned.
at Rhode Island who was brilliant, but
But after ten years of being
he could never get his Ph.D. He just
washed in nitric and hydro-
wasn't able to concentrate long
chloric acid-which is the
enough on one thing. He
procedure Martin's team
would get bored."
follows with all the im-
Martin is impatient
plements and even the
with complex analytic
walls in their all-
arguments. He likes
plastic lab-a filthy,
simplicity. And he
iron-infested bottle
likes to needle peo-
can get pretty
ple. So after Frost
clean. In a nut-
finished explaining
shell, that is the
how Antarctic zoo-
secret of how Mar-
plankton could
tin's colleague
keep the phyto-
Mike Gordon fi-
plankton in check,
nally succeeded, in
Martin went up to
the early 1980s, in
him. "And more or
measuring the first
less in jest I said,
reliable profile of iron
'Aw, baloney, it's just
in seawater: he finally
iron deficiency.' And he
had a clean enough bot-
didn't want to hear that.
tle. By then Martin had re-
It was too simple."
tired from lab work. Reluc-
Martin doesn't remember
tantly, he had also quit going to
what made him think of iron
sea. Over the years the polio he
deficiency. Other people had
contracted in college in 1954 has made
thought of it, too; the idea was in the
him progressively less mobile, and now-
air. Martin's wisecrack, though, was a
adays he spends most of his time sitting
kind of wishful boast-the wish being
down, either in a wheelchair or behind
Phytoplankton already bloom
that the subject he had devoted his
his desk. He has chronic pain. Gordon
in the Antarctic, as this satellite
career to might prove important in some
and another colleague, Steve Fitzwater,
image shows (red and yellow),
broader context. Back at Moss Landing
have taken over the hands-on work. It is
but chiefly near the coast.
he decided to try to deliver on his boast.
slow, craftsmanlike work, and it requires
He knew that phytoplankton, like
dexterity. It is work that can be undone
plankton are kept in check by tiny,
every other living organism, need iron
by a single errant dust grain.
grazing animals, the zooplankton.
to survive. Iron is an essential cog in the
"So Mike showed me this iron pro-
It was after Frost's talk that Martin
cell's synthetic machinery. Phytoplank-
file, casting pearls before swine," Martin
first decided to shoot his mouth off.
ton need iron to make chlorophyll, the
recalls, "and I kind of ignored it." But
molecule with which they capture sun-
then in December 1986, at a conference
PHOTOGRAPH COURTESY GENE FELDMAN, NASA/GSFC
artin is well liked by those
light. They need it to make nitrate re-
in San Francisco, he heard Bruce Frost
of the University of Washington give a
M
who know him well; his as-
ductase, the enzyme with which they
sistants are former students
reduce nitrate to a form suitable for
talk about an old problem in biological
who have stayed with him for
incorporation into proteins. Most funda-
oceanography. In some regions of the
years. The voice that sounds
mental of all, they need it to make
ocean, such as the Antarctic, the float-
gravelly and short over the phone be-
DNA, the stuff of their genes. So in
ing single-cell plants, or phytoplankton,
comes gravelly and friendly and even
principle it was possible for a phyto-
are notorious underachievers. Upwell-
self-deprecating in person. The eyes twin-
plankton population to be hobbled by a
ing currents from the deep ocean bring
kle, and now and then they smile. There
lack of iron.
DISCOVER
APRIL
1991 57
no shortage of iron
clean lab-whatever they do, they don't
in the water.
let it touch the deck, because it might
"This is a real pain.
But the winds
pick up a few atoms of iron that it
that blow over the
would take back down on the next trip.
It's on a rolling ship,
Antarctic cross al-
"This is a real pain in the ass," says
most no land that
Martin, who goes to sea vicariously.
and maybe the deck
isn't covered by ice.
"This is hard. It's on a rolling ship, and
So they drop on the
maybe the deck is icy-it's terrible. But
is icy-it's terrible.
ocean almost no
it guarantees a clean sample."
dust and almost no
With the clean samples they collected
But it guarantees
iron. In the Antarc-
in the Gulf of Alaska, Martin's team did
tic and in other
a simple experiment. They measured
a clean sample."
places far from dry
the amounts of iron and nitrate in the
land, Martin rea-
water and found that, according to the
soned, phytoplank-
best estimate of phytoplankton require-
ton would have to
ments, the plankton didn't have enough
B
Martin's problem, though, was that plank-
make do with what little iron was al-
iron to use all the nitrate. Then they
ton get by on extremely small amounts
ready in the water. And if Gordon's
divided the samples into two groups.
of iron. Just how small is not known
measurements from the cruise. to Ha-
One group they fertilized with iron; the
precisely. But the best estimate is that
waii were representative, that was very
other they left alone. They watched the
they use, at most, one atom of iron for
little iron indeed-less than a millionth
bottles for four and a half days. At the
every 10,000 atoms of carbon, every
of an ounce in a cubic yard of seawater.
end of that period the bottles with the
1,500 atoms of nitrogen, and every 100
Even for a frugal plankter, that's just not
added iron contained nearly nine times
atoms of phosphorus. It didn't seem
enough.
as much chlorophyll-a measure of the
likely, on the face of it, that there could
The thing to do, then, was to see
total mass of phytoplankton-than the
be areas where the phytoplankton had
whether Gordon's measurements held
unfertilized bottles. The idea that phyto-
plenty of the nutrients that they need
up elsewhere in the ocean. In the sum-
plankton may be limited by iron defi-
plenty of but were unable to bloom for
mer of 1987 Martin had a cruise sched-
ciency had its first solid support.
o
lack of a few measly atoms of iron.
uled to the Gulf of Alaska to make some
This past year Martin's team went to
p
And yet Martin soon found evidence
manganese measurements. But man-
the Antarctic-"the big enchilada," as
to back up his claim. It was buried
ganese was old hat now. Martin's troops
he puts it. The Southern Ocean is 8
among the debris on his chronically
went after iron instead. They did the
million square miles of nutrient-rich
disorganized desk. Bob Duce, an atmo-
same sort of experiments they've been
water fed by vigorous upwelling cur-
spheric chemist at the University of Rhode
repeating in different places ever since.
rents. Every year, during the six months
Island and an expert on atmospheric
On each of these cruises Gordon and
of sunlight, phytoplankton bloom pro-
C
dust, had recently sent him a paper. In it
Fitzwater bring along their own clean
fusely in a narrow band along the Ant-
Duce estimated that more than half the
mini-lab-it's the size of a small house
arctic coast. Those blooms support vast
iron in the open ocean comes from dust
trailer-and set it up on deck. They use
herds of krill, shrimplike creatures that
V
settling out of the atmosphere, as op-
special 30-liter sampling bottles that go
are in turn the daily bread of seals,
S
posed to being upwelled from the deep
through the sea surface closed (so the
penguins, and whales. Away from the
with the other nutrients. Then Martin
inside won't get
unearthed the iron measurements that
coated with bilge
Gordon had made on a cruise from
water or fuel) and
California to Hawaii. Gordon's numbers
then snap open
MICROGRAPHS BY DEE BREGER LAMONT-DOHERTY GEOLOGICAL OBSERVATORY. PHOTOGRAPH COURTESY JOHN MARTIN
suggested that, if anything, Duce was
automatically at 30
underestimating the importance of at-
feet. The bottle is
mospheric iron: there was so little iron
lowered on Kevlar
in the open ocean that about 95 percent
line, because ordi-
of the plankton's requirements must
nary steel wire
come from dust.
might contaminate
The circuit closed in Martin's mind:
the water around
Where there's no dust, there's no iron.
the bottle. And
Except for shallow coastal waters, where
when the bottle
the sea surface is close to the iron-rich
comes back up,
mud on the bottom, the distribution of
now weighing more
iron in the ocean is controlled by the
than 100 pounds,
geometry of winds and landmasses, par-
Gordon and Fitzwa-
ticularly arid landmasses. In the equato-
ter either load it
rial Atlantic, for example, winds sweep-
onto a plastic cart
ing off the Sahara carry dust as far west
or manhandle it di-
as Barbados. All along that path there is
rectly over to the
Far from the Antarctic coast diatoms are sparse
58
DISCOVER
APRIL
1991
coast, however, the Southern Ocean is
a back-of-the-enve-
much less fertile. The major nutrients
lope calculation.
are there, the temperature and sunlight
If 300,000 tons
are similar, but the plankton don't bloom.
of iron were broad-
Gordon and Fitzwater did iron-
cast in the ocean
fertilization experiments in the Ross Sea,
surrounding Ant-
near the McMurdo base. They found
arctica over a six-
that adding iron to a bottle of seawater
month growing sea-
taken from near the shore didn't help
son, he figured, it
the phytoplankton much. That made
would allow the
sense; there was already plenty of iron
phytoplankton to
in the water. It came from the bottom
convert all the avail-
mud, and from atmospheric dust that
able nutrients-in-
had fallen on the glaciers over many
cluding 2 billion
years and then got dumped in the ocean.
tons of carbon-
But a few hundred miles offshore the
into new organic
story was different. When Gordon and
matter. Those 2 bil-
Fitzwater added iron to a seawater sam-
lion tons would
ple there, they got a fourfold increase in
come from carbon
the amount of organic matter in the
dioxide that had dis-
On the Antarctic cruise Martin's clean lab got a little chilly.
bottle. "There was hardly any growth
solved out of the
without iron," says Martin. "And with it
atmosphere into the surface waters. In
with 280 parts per million in the nine-
the stuff really took off."
other words, they would come right out
teenth century and 350 today. The same
Now the evidence for Martin's iron-
of our greenhouse.
ice cores show that the amount of dust
limitation hypothesis was strong. And
Much of that carbon, Martin assumed,
settling onto the Antarctic-and hence
in the world of biological oceanography,
would sink to the bottom of the ocean-
the amount of up to 50 times
this was big news-a new paradigm,
in the form of plankton corpses or plank-
greater during the Ice Age. The world
one oceanographer called it. But a new
ton parts or fecal pellets excreted by the
was drier then, with vast deserts and
paradigm about phytoplankton was
things that eat phytoplankton. Oceanog-
stronger winds that carried dust out to
hardly enough to get Martin on televi-
raphers know this carbon sinking goes
sea. All that iron-rich dust, Martin
sion. There was one more step to take.
on all over the world; they call it the
claims, may have led to massive plank-
It was a logical step, and actually
biological pump. They don't really know
ton blooms in the Antarctic, which
Martin had been referring to it all along
how important it is. But they think that
pumped carbon out of the atmosphere,
in his papers. If adding iron to a bottle
right now it may take as much as 3
which made the world colder.
causes the phytoplankton in the bottle
billion tons of carbon each year-half of
If Martin is right, the amount of iron
to bloom, then you ought to be able to
all the carbon we pump into the atmo-
in seawater-something he spent more
fertilize the ocean itself. It wouldn't take
sphere annually with our power plants
than a decade learning how to measure
very much iron to fertilize the whole
and cars-and put it out of harm's way
correctly-has a decisive impact on
Southern Ocean, because phytoplank-
in the deep ocean. All Martin suggests is
Earth's climate. "You give me half a
ton don't need very much. Martin did
that it might be possible to speed up the
tanker full of iron," Martin said this past
pump in places
May, shooting off his mouth again, this
where, for lack of
time to a Washington Post reporter,
iron, it isn't run-
"and I'll give you another ice age."
ning up to speed.
The pump may
artin wasn't recommending an-
have worked faster
bles of ancient air
M
other ice age, of course, and
before, he says. Bub-
he doesn't truly think he could
deliver one. He was just try-
extracted from Ant-
ing to get a point across. "I
arctic ice cores re-
don't waffle," he says. But for quite a
veal that the car-
while after that remark he almost
bon dioxide level in
wished he did.
the atmosphere has
Martin's idea has been attacked from
fluctuated with the
all angles. If there were huge blooms of
advance and retreat
phytoplankton in the Antarctic during
of the ice sheets.
the Ice Age, for example, some evidence
During the Ice Age
of them ought to be preserved in sedi-
the carbon dioxide
ments on the ocean floor. The dominant
concentration was
type of phytoplankton today are dia-
only 200 parts per
toms, which have hard shells of opal.
but when iron is added to the water they multiply.
million, compared
This past year researchers at the Lamont-
DISCOVER
APRIL
1991
59
millionths of an
Martin responds, somewhat testily,
"I don't want
ounce per square
that he has in fact seen copepods hap-
yard, and a steady
pily grazing in his test bottles. But the
supply would some-
to go down in
whole argument irritates him. "They
how have to be
take a very simple thing and make it
maintained in the
history as Martin's
complex," he says of these critics. "And
face of its. natural
if you get into complexities, you can
tendency to sink
Mistake-the guy
make all these arguments. If you keep it
out of the surface
simple, you just say, 'Hey, I got two
waters. Martin
who ruined the
bottles, right, and in this one I'm going
speaks vaguely of a
to put a little bit of iron and in this one
supertanker with a
ecosystem."
I'm not. And I'm going to sit here and
huge fan on deck;
watch it for a week and see what hap-
iron dust coming
pens.' And at the end of the week you
up from the hold
hold it up to the light and you can see
on a conveyor belt
all these glinting cells. And this one over
Doherty Geological Observatory looked
would be cast by the fan into the stiff
here, the one without iron, has nothing
for opal in sediment cores from the
Antarctic winds. Alternatively, he says,
in it. To my way of thinking you have a
Southern Ocean. They found plenty in
perhaps some sort of time-release pel-
very dramatic effect."
recent sediments, but in Ice Age sedi-
lets might work. No one really knows.
Martin would like to stop arguing. He
ments they found almost none-just
No one knows either what effect the
would like to start preparing for what he
the opposite of what Martin would pre-
iron would have on the Antarctic envi-
considers the ultimate test of his hy-
dict. "This is one of the big flaws in my
ronment. The ocean would not turn to
pothesis: fertilizing a small square of
hypothesis," says Martin. Perhaps, he
green mush, but iron fertilization might
ocean, perhaps 60 miles on each side. It
says, the Ice Age phytoplankton were
favor some species over others and
would take a couple of years, as he sees
mostly soft-bodied species that don't
thereby alter the food web in unforesee-
it, to thoroughly research the test area,
fossilize, rather than diatoms.
able ways. Martin thinks the simplest
to map its currents and its weather
Then there is the question of whether
outcome is the most likely one: the iron
patterns and its patterns of life. Only
Martin's back-of-the-envelope calcula-
would produce more diatoms and more
then would the crop dusters or military
tions are at all accurate-whether iron
krill, which eat diatoms, and thus more
cargo planes come in and start spraying
fertilization would get rid of as much
seals, penguins, and whales. ("When I
iron. Meanwhile squads of oceanogra-
atmospheric carbon dioxide as he
get real facetious, I say I'm not inter-
phers would be waiting on ships to
your
thinks. The Antarctic upwelling currents,
ested in the CO₂ problem, I'm interested
monitor the effects.
it has been suggested, might keep most
in repopulating the world's whale
The experiment would not come
of the plankton-fixed carbon from sink-
stocks.") But it's also possible the iron
cheap-it would certainly cost tens of
ing; then the carbon would be quickly
would yield blooms of organisms that
millions of dollars, and perhaps more
recycled into the atmosphere by bacte-
krill don't eat and that would outcom-
than a hundred million: The funding
ria, which break down organic matter. If
pete the diatoms. In that case the krill-
agencies are wary. But in spite of all the
that is true, then dumping iron in the
based food web would collapse.
flak Martin has taken, support for such
Antarctic would have only a negligible
Martin thinks all these concerns are
a test seems to be growing among his
impact on the greenhouse effect. People
valid. They are not his area of expertise,
fellow oceanographers. In the end his
who specialize in making theoretical
and he doesn't pretend to have the an-
data are hard to ignore.
models of the ocean are now arguing
swers. He is not suggesting, he stresses
Yet in the end there is also an argu-
the point. Martin is not a modeler. He
again and again, that we dump iron in
ment against iron fertilization that no
prefers to let them duke it out.
the ocean now. He is only arguing for
amount of data can answer. There is
The modelers do agree on two things,
focused research into the possibility.
something fundamentally wrong, some
however. One is that iron fertilization
The one criticism that gets under his
people would say, with the whole idea
would at best be a palliative-never a
skin comes from people who say he
that we should attempt to "fix" nature
cure-for the greenhouse effect. Even if
hasn't really shown that phytoplankton
on so grand a scale. Wrong because we
it worked perfectly, it would remove
are limited by iron-from people, in
will surely foul it up; wrong because it
less carbon from the atmosphere each
other words, who question his data or
is not our place. Does Martin not com-
year than we are now putting in, not to
his interpretation of the data. Perhaps,
mit the sin of pride?
mention what we have put in already.
these people argue, adding iron to a
"We're already involved in the big-
The other point of agreement is that
bottle of seawater doesn't really make
gest experiment ever," Martin responds.
iron fertilization would not be a one-
the phytoplankton grow better. Perhaps
"We're finding out what's going to hap-
shot deal; it would have to be repeated,
the bottle just didn't happen to include
pen if we dump three billion tons of
year after year, until we stop burning
any of the large zooplankton, called
CO₂ into the atmosphere every year.
fossil fuels. Nor would it be just a mat-
copepods, that graze on the plants and
That is the biggest manipulation of the
MICROGRAPH BY DEE GEOLOGICAL OBSERVATORY
ter of pushing a few rusting cars over
keep their population in check. With no
environment ever. What I argue is we're
the side of a ship. The iron would have
grazers, it would look like the plants
going to keep doing this. And we'd
to be broadcast extremely thinly, a few
had bloomed.
better know about ways, if we have to,
60
DISCOVER
APRIL
1991
Over the past 160,000
years, whenever the
amount of iron-rich
dust falling onto the
Antarctic has gone
Age of ice
up, the amount of
(thousands of years)
carbon dioxide in the
20
40
60
80
100
120
140
160
atmosphere has gone
down, and vice versa.
The data come from
300
100
CO
a 7,000-foot-deep
Iron
Antarctic ice core;
the deeper the
CO concentration
(parts per million)
75
250
ice, the older it
is. The iron peaks
50
Iron concentration
(parts per billion)
at about 18,000 and
160,000 years ago
200
correspond to ice-
25
age peaks. Martin
thinks dust falling out
of the atmosphere
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
caused Antarctic
Depth of ice
phytoplankton to
(feet)
bloom, taking up
carbon dioxide and
cooling the planet.
to take CO₂ out of the atmosphere.
you could go down there and add the
Liebig, the nineteenth-century German
"The Chinese are not burning their
iron and not disturb the environment,
chemist. Liebig discovered the law of
coal right now, but they have massive
then I'd say go ahead and do it."
the minimum, which states that a plant
reserves. As they industrialize they're
will not grow unless it has its minimum
going to want to use that coal. They're
artin hasn't been spending
requirement of each essential nutrient.
not going to say, 'Gee, gang, we're going
M
much time at Moss Landing
Liebig's law has always fascinated
to use solar power so we don't put out
lately. The earthquake in Oc-
Martin. Now he thinks he has discov-
greenhouse gases.' The average Chinese
tober 1989 destroyed his lab-
ered the first marine example of it, and
peasant wants to have electricity and a
oratories-pulled the rug right
he would like very much to prove it
refrigerator and maybe a motorbike-
out from under the low stucco building,
conclusively. The iron-fertilization idea,
these people want to have the same
damaging it so heavily it had to be
he hopes, will help convince the public,
crap we've got, and they're going to use
condemned. Martin and most of the
his peers, and the funding agencies that
what they've got available. CO₂ is not
other researchers have moved to Sali-
the work is important. But Martin ad-
going to go down next year, or level off
nas, into temporary quarters provided
mits that it makes him a little nervous.
next year. It's going to go up by at least
by San Jose State University. But Gor-
"It's scary," he says. "I don't want to
three billion more tons, and the next
don is still at Moss Landing, doing iron
go down in history as Martin's Mistake-
year three billion more and probably
analyses in the shadow of PG&E; he's
as this guy who advocated adding iron,
five. So by sixty years from now, you
set up a clean lab in a trailer with
and they did it, and it completely ruined
may be going up ten or fifteen or twenty
equipment salvaged from the ruins. "We
the ecosystem. What I want is to do the
billion tons a year. The purists say iron
were very lucky," says Martin. "No one
ocean experiment, and prove that iron
PHOTOGRAPH BY BRIAN GRAPH DATA PROVIDED BY JOHN MARTIN
fertilization is crap, and we shouldn't
was hurt, and we didn't lose any of our
is limiting-and then retire.
even think about it-we should be con-
equipment or samples. You lose your
"When you work with trace elements,
serving. That's very true. But what if we
data and you're out of business."
you'd like to think they're really impor-
get into a situation where global warm-
It's now three decades since Martin
tant. But then you say, 'Who are you
ing really does occur?
first got interested in trace metals. That
kidding-they're not important.' These
"I'd see an ethical problem if we
was back in graduate school, when he
are the conversations you have with
could go down and fertilize the Antarc-
read about sheep in Australia whose
yourself. And then, all of a sudden:
tic and remove the CO2, but in the
wool fell off because of vitamin B₁₂
'Jesus! It looks like it is important. What
process we would kill all the whales and
deficiency. The deficiency was traced to
the hell do I do now?"
the penguins. Then I'd say, 'Don't do it.
a lack of cobalt, and it was cured by
Man has created this, he can stew in his
adding tiny amounts of cobalt to each
Senior editor Robert Kunzig wrote
own juice. Leave the whales alone.' But
acre of pasture. It was also back then
"The Man Who Weighs Dinosaurs"
on the other hand, if it turned out that
that Martin learned about Justus von
in the October issue.
DISCOVER
APRIL
1991 61
not
global
April 22, 1991
In my opinion,
Discover Magazine
3 Park Avenue
New York, N.Y. 10016
To the Editor:
John Martin proposes iron fertilization of the Southern
Ocean as at least a partial solution to the threat of global warming.
("Earth On Ice", April 1991) He's got it exactly wrong. Our
manhandling of the environment created the problems we face; it in no
-way- is part of the solution.
It would be easy to attack Martin's suggestion on technical
grounds: There is evidence that iron is not the limiting nutrient in
the oceans; very recent research shows that, even if adding iron would
increase plankton populations, the net amount of carbon sequestered
would be modest; massive amounts of money and other resources would
have to be mustered if the program were to be even marginally
successful in achieving its objectives.
hubris
fundamental
But my opposition to Martin's suggestion runs much deeper. The
proposal is dangerous because it plays to wishful thinking that there
is no need for change; and that, with a little creative engineering,
we can out-smart nature once again. The truth, however, is that we
cannot, without serious repercussions, continue our campaign of re-
creating the environment.
in the design of one civilization;
You would think we would have learned that lesson by now. This
is certainly not the first time we have undertaken such technological
"fixes". Our determination to produce crops in areas not suited to
produce them, for example, has poisoned the soil and, in some areas,
created vast deserts of salt and pesticides. And consider our desire
to adorn ourselves cheaply in silk by bringing gypsy moths into the
country vast stands of diseased and dying trees are the legacy of
that venture. The kudzu vine that chokes native plants and trees in
Thinks
the Southeast; the rabbits that overyran Australia; and the brown
illegal
trout that threatened the entire Yellowstone Lake ecosystem, are all
testimony to our inability to gauge and control the effects of our grand
eco-engineering schemes. And those were nothing compared to this proformal.
It is time we stop kidding ourselves. The simple truth is that
it is only by changing our behavior -- and not by further changing our
on
environment that we can effectively address the global
can
relation
environmental problems we face. Study after study tells us we/make
to
make significant gains at minimal cost with existing technologies. The
eart
need for such action is clear. The ozone layer is being depleted at an
alarming rate; we need to move quickly to end the use ozone destroying
chemicals. We continue to experience record warmth, severe drought,
interduction of Africarized has
of
the web of
warning with to globalin and change
to
extensive forest fires, and intense storm activity; We we need cut our
emissions of greenhouse gases in every sector of the economy. The
very threads of life are being severed as rampant deforestation drives
thousands of species to extinction; we need to preserve and protect
sensitive ecosystems and manage our forests sustainably.
So let's get on with it. I challenge our scientists to use
their insights and creativity to devise ways for us to live in harmony
with nature -- rather than speeding us further along the collision
course that we have already begun to travel.
are currently travelling
on