February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 10, NUMBER 11, NOVEMBER 1997
Two related papers in Nature, 389(6654), Oct. 30, 1997:
"The Ocean's Productive Deserts," S.C. Doney (NCAR, POB 3000,
Boulder CO 80307; e-mail: email@example.com), 905-906. Comments on the
following paper, which shows, for perhaps the first time, that we can
systematically close the carbon budget for the upper ocean.
"Experimental Determination of the Organic Carbon Flux from
Open-Ocean Surface Waters," S. Emerson (Sch. Oceanog., Univ.
Washington, Seattle WA 98195; e-mail: firstname.lastname@example.org), P. Quay
et al., 951-954. Accurate determination of the flux of biologically
produced organic carbon to deep waters is critical to understanding the
global C cycle and its responses to climate change. This study compares
results from three independent estimates, which show that the typical
carbon export flux in the subtropical ocean, often considered to be a
biological desert, may be responsible for up to half of the global-ocean
biological organic carbon sink.
"Carbon Balance of a Temperate Poor Fen," P. Carroll (Complex
Systems Res. Ctr., Univ. New Hampshire, Durham NH 03824; e-mail:
email@example.com), P. Crill,Global Biogeochem. Cycles, 11(3),
349-356, Sep. 1997.
Field measurements and simple modeling of a Sphagnum dominated
wetland in New Hampshire suggest that if future climate change brings
warmer temperatures and lower water tables to peatland soils, positive
climatic feedback leading to substantial releases of CO2 from
boreal and subarctic peatlands is probable.
Two related papers in Nature, 388(6642), Aug. 7, 1997:
"Inside the Black Box," R. Norby (Environ. Sci. Div., Oak
Ridge Natl. Lab., Bldg. 1059, POB 2008, Oak Ridge TN 37831), 522-523.
Comments on the following research, which shows that exposure of
grasslands to doubled CO2 causes carbon to cycle through the
systems faster but increases carbon accumulation little. Even so, a faster
cycling rate could induce myriad changes in species diversity and
functions, which in themselves could alter the carbon pool.
"The Fate of Carbon in Grasslands Under Carbon Dioxide Enrichment,"
B.A. Hungate (Smithsonian Environ Res. Ctr., Edgewater MD 21037), E.A.
Holland et al., 576-579. Grassland ecosystems exposed to three years of
doubled CO2 show a greater increase in carbon cycling than in
"Variations in the Predicted Spatial Distribution of Atmospheric
Nitrogen Deposition and Their Impact on Carbon Uptake by Terrestrial
Ecosystems," E.A. Holland (NCAR, POB 3000, Boulder CO 80307; e-mail:
firstname.lastname@example.org), B.H. Braswell et al.,J. Geophys. Res.,
102(D13), 15,849-15,866, July 20, 1997.
Widespread deposition of atmospheric nitrogen from industry,
agriculture, and biomass burning can alleviate the nitrogen limitation of
productivity in terrestrial ecosystems, and may increase carbon uptake.
This effect was evaluated with output from five different 3-D chemical
models, used to drive a perturbation model of terrestrial carbon uptake.
Global air pollution appears to be an important influence on the global
carbon cycle, and if this fertilization effect accounts for the "missing"
carbon sink, we would expect significant reductions in the magnitude of
that sink over the next century as terrestrial ecosystems become nitrogen
"Vulnerability of Russian Forests to Climate Changes. Model
Estimation of CO2 Fluxes," A.L. Lelyakin (Inst. Global
Clim. & Ecol., Glebovskaya 20b, 107258 Moscow, Russia), A.O. Kokorin,
I.M. Nazarov, Clim. Change, 36(1-2), 123-133, June 1997.
Uses a model that includes forest age distribution, various carbon
reservoirs, and logging and fires, to estimate a current Russian forest
sink of 160 MtC/yr, a number that will grow to 200-240 Mt/yr in 2010. The
main future uncertainty is forest response to climate change.
"Oceanic Dissolved Organic Carbon Is the Main Sink of Atmospheric CO2,"
V.G. Gorshkov (Petersburg Nuclear Phys. Inst., Gatchina, 188350 Leningrad
District, Russia), World Resource Review, 9(2), 153-169,
Analyzes data on the distribution of prebomb and postbomb 14C in the
ocean, concluding that the production of oceanic dissolved organic carbon
(DOC) has increased twenty-fold during the industrial era, while DOC
destruction has remained unchanged. The resulting increase of DOC mass by
2 Gt/yr coincides with an estimate of carbon release by terrestrial biota
based on land use, and resolves the problem of the "missing"
"Accounting for Biological and Anthropogenic Factors in National
Land-Base Carbon Budgets," D.P. Turner (Forest Sci. Dept., Oregon
State Univ., Corvallis OR 97331), J.K. Winjum et al.,Ambio, 26(4),
220 ff., June 1997.
To compare net CO2 fluxes and identify key research areas,
analyzes data on current land use, rates of land-cover change, forest
harvest levels, and wildfire extent under a common framework for three
countries (the U.S., Former Soviet Union, and Brazil). Continued database
development and close attention to methods of quantifying carbon flux will
be necessary if carbon budget assessments are to be useful for policy
"Cold Season CO2 Emissions from Arctic Soils," W.C.
Oechel (Global Change Res. Group, San Diego State Univ., San Diego CA
92182; e-mail: email@example.com), G. Vourlitis, S.J. Hastings,
Global Biogeochem. Cycles, 11(2), 163-172, June 1997.
Significant amounts of CO2 loss were observed in Arctic
tundra ecosystems of the Alaskan North Slope during the 1993-94 season.
Estimates of annual net CO2 exchange, based on warm season
measurements alone, underestimate the actual magnitude of CO2
"An Integrated Modeling Approach to Global Carbon and Nitrogen
Cycles: Balancing Their Budgets," M.G.J. den Elzen (Global Dynamics &
Sustainable Development, Natl. Inst. Public Health & Environ.-RIVM,
POB 1, NL-3720 BA Bilthoven, Neth.), A.H.W. Beusen, J. Rotmans,Global
Biogeochem. Cycles, 11(2), 191-215, June 1997.
Integrated but simple models of the coupled carbon-nitrogen cycle and
climate show that N fertilization feedback may be important for balancing
the past carbon budget, and that nutrient limitation can seriously limit
CO2 fertilization feedback. Both mechanisms should be examined
in more detailed carbon cycle models, and if the results are confirmed,
should be incorporated into IPCC projections.
"The Decoupling of Terrestrial Carbon and Nitrogen Cycles," G.P.
Asner (CIRES, Univ. Colorado, Boulder CO 80309),BioScience, 47(4),
226-232, Apr. 1997.
Reviews how human influences on land cover and nitrogen supply are
altering natural biogeochemical links in the biosphere, and how the
terrestrial carbon cycle will respond to and influence changes in
atmospheric CO2 and temperature. Although elevated levels of
nitrogen and CO2 are stimulating the uptake of anthropogenic
CO2, the effect is only temporary. The rapidly changing global
nitrogen cycle, with its increasing nitrogen depositon, can also lead to
increases in greenhouse gases such as methane, nitrous oxide, and
tropospheric ozone, which counterbalance the uptake of CO2. As
natural linkages between the terrestrial carbon and nitrogen cycles
continue to deteriorate in coming decades, such changes are likely to
become even more pronounced.
"Historical Variations in Terrestrial Biospheric Carbon Storage,"
W.M. Post (Environ. Scil Div., Oak Ridge Natl. Lab., POB 2008, Oak Ridge
TN 37831; e-mail: firstname.lastname@example.org), A.W. King, S.D. Wullschleger,Global
Biogeochem. Cycles, 11(1), 99-109, Mar. 1997.
Investigates the source of the missing sink needed to balance the
contemporary atmospheric CO2 budget with anthropogenic
emissions, by driving a high-resolution global terrestrial biosphere model
with historical time series of temperature and precipitation and the
historical record of changes in atmosphere CO2. Results
suggest that the temporal evolution of the missing sink over the period
1900-1988 could be a response of the terrestrial biosphere to changes in
climate and CO2 or perhaps changes in climate alone.
"The Potential Response of Terrestrial Carbon Storage to Changes in
Climate and Atmospheric CO2," A.W. King (Environ. Sci.
Div., Oak Ridge Natl. Lab., Oak Ridge TN 37831; e-mail: email@example.com),
W.M. Post, S.D. Wullschleger, Clim. Change, 35(2), 199227,
Uses a georeferenced model of ecosystem dynamics to explore the
sensitivity of terrestrial C storage to changes in atmospheric CO2
and climate. With a doubling of CO2, the model projects
increases in NPP of 30-36%, and increases in terrestrial ecosystem carbon
"Survey of CO2 in the Oceans Reveals Clues About Global
Carbon Cycle," C.L. Sabine (Geosci. Dept., Guyot Hall, Princeton
Univ., Princeton NJ 08544), D.W.R. Wallace, F.J. Millero, Eos, Trans.
Amer. Geophys Union, 78(5), 49, 54-55, Feb. 4, 1997.
Describes a project involving 10 U.S. universities and national
laboratories working since 1990 to develop a high-quality inorganic carbon
data set for all the world's oceans. The survey, done in collaboration
with the World Ocean Circulation Experiment, has been highly successful,
and data are just starting to become available. (See this Web site:
"Potential for Carbon Sequestration in European Soils: Preliminary
Estimates for Five Scenarios Using Results from Long-Term Experiments,"
P. Smith (Soil Sci. Dept., IACR-Rothamsted, Harpenden, Herts AL5 2JQ, UK;
e-mail: firstname.lastname@example.org), D.S. Powlson et al.,Global Change
Biology, 3(1), 67-79, Feb. 1997.
Uses statistical relationships derived from long-term European
experiments to explore the potential of five scenarios: amendment of
arable soils with animal manure or sewage sludge; incorporation of cereal
straw into soils; afforestation of surplus arable land through natural
regeneration; and a shift to less-intensive use of agricultural land
through increased animal grazing. Concludes that, although efforts in
temperate agriculture can contribute to global carbon mitigation, the
potential is small compared to that available through reducing
anthropogenic CO2 emissions by halting tropical and
sub-tropical deforestation, or by reducing fossil fuel burning.
"Influence of Nitrogen Loading and Species Composition on the Carbon
Balance of Grasslands," D.A. Wedin (Dept. Bot., Univ. Toronto,
Toronto M5S 3B2, Can.; e-mail: email@example.com), D. Tilman,Science,
274(5293), 1720-1723, Dec. 6, 1996.
A 12-year experimental study of nitrogen deposition on Minnesota
grasslands shows that in the short term, nitrogen stimulates growth and
carbon storage in plant tissues. But added nitrogen also pushes the
species mix toward fast-growing, invasive species that are inefficient at
fixing carbon in the long term. (See news articles in Science, pp.
1610-1611, Dec. 6, 1996; New Scientist, p. 16, Dec. 14, 1996; The
New York Times, pp. C1, C12, Dec. 10, 1996; also correspondence in
Science, pp.739-741, Feb. 7, 1997.)
"Two Decades of Carbon Flux from Forests of the Pacific
Northwest--Estimates from a New Modeling Strategy," W.B. Cohen
(Forestry Sci. Lab., USDA Forest Serv., 3200 SW Jefferson Way, Corvallis
OR 97331), M.E. Harmon et al.,BioScience, 46(11), 836-843,
Describes a strategy being developed for estimating regional carbon
fluxes using remotely sensed and spatial biogeoclimatic data, and a pilot
study in the Pacific Northwest of the U.S. that demonstrates its value.
"Temperate Forest Responses to Carbon Dioxide, Temperature and
Nitrogen: A Model Analysis," J.H.M. Thornley (Inst. Terrestrial
Ecol.-ITE, Bush Estate, Penicuik, Midlothian EH26 0QB, UK), M.G.R.
Cannell,Plant, Cell & Environ., 19(12), 1331-1348,
Used the ITE Edinburgh Forest model, one of the most comprehensive
models of its kind, which describes diurnal and seasonal changes of C, N,
and H2O in a fully coupled forest-soil system. Simulated a managed conifer
plantation in upland Britain to examine transient effects on forest growth
of an IS92a scenario of increasing CO2 and temperature over
two future rotations, and the equilibrium effects of all combinations of
increased CO2, mean annual temperature and annual inputs of N.
Details eight major conclusions, which may lead to decreases or increases
of growth. Projected increases in CO2 and temperature (IS92a)
are likely to increase net ecosystem productivity and carbon sequestration
in temperate forests.
"Oceanic Carbon Dioxide Uptake in a Model of Century-Scale Global
Warming," J.L. Sarmiento (Program in Atmos. & Oceanic Sci.,
Princeton Univ., Princeton NJ 08544),Science, 274(5291),
1346-1350, Nov. 22, 1996.
In a model of ocean-atmosphere interaction that excluded biological
processes, global warming substantially reduced the oceanic uptake of
atmospheric CO2, primarily through the weakening or collapse
of the ocean thermohaline circulation. Such a large reduction in uptake
would have a major impact on the future growth rate of atmospheric CO2.
Simulations incorporating biological effects show that they could largely
offset this reduction, but the magnitude of the offset is difficult to
quantify with present knowledge.
"Historical Biomass Burning: Late 19th Century Pioneer Agriculture
Revolution in Northern Hemisphere Ice Core Data and Its Atmospheric
Interpretation," G. Holdsworth (Arctic Inst. of North America, Univ.
Calgary, Calgary AB T2N 1N4, Can.; e-mail gholdswo@acs. ucalgary.ca), K.
Higuchi et al.,J. Geophys. Res., 101(D18), 23,317-23,334,
Oct. 27, 1996.
Ice core data from Yukon and Greenland from about 1750 to 1950 show a
clear atmospheric signal of an episode of biomass burning between about
1850 and 1910, which has been referred to elsewhere as the Pioneer
Agriculture Revolution. The relationships of this finding to other types
of climatic data are explored. It appears that factors associated with the
burning, such as changes in surface albedo and atmospheric dust and smoke,
caused local cooling and temporarily negated any radiative gas greenhouse
"Atmospheric Gas Concentrations over the Past Century Measured in Air
from Firn at the South Pole," M. Battle (Grad. Sch. Oceanog., Univ.
Rhode Island, Naragansett RI 02882), M. Bender et al.,Nature, 383(6597),
231-235, Sep. 19, 1996.
In contrast to the past few years, calculations based on the data
indicate that, the terrestrial biosphere was neither a source nor sink of
CO2 between about 1977 and 1985. This implies that carbon
losses from deforestation were approximately balanced by net CO2
"Late Pleistocene Charcoal in Tropical Atlantic Deep-Sea Sediments:
Climatic and Geochemical Significance," D.J. Verardo (Dept. Environ.
Sci., Univ. Virginia, Charlottesville VA 22903), W.F. Ruddiman,Geology,
24(9), 855-857, Sep. 1996.
Charcoal, presumably from forests, is a surprisingly significant
component of the sampled sediment, and is linked to the growth and decay
of high-latitude ice sheets. [The discovery may force scientists to revise
models used to predict how the planet wi ll respond to climate change; see
New Scientist, p. 15, Sep. 14, 1996.]
Special issue. Tellus, 48B(4), ca. 180 pp., Sep.
1996. Contains 12 papers from the CO2 symposium, The
Breathing of the Earth-Observational Constraints for Models of the
Terrestrial Biosphere (Boulder, Colorado, July 1995). Topics include
observational networks, modeling, and observational analysis.
"A Carbon Budget for Brazil: Influence of Future Land-Use Change,"
P. Schroeder (ManTech Environ. Res. Corp., US EPA, 200 SW 35th St.,
Corvallis OR 97333),Clim. Change, 33(3), 369-383, July
Develops an estimate of Brazil's biotic CO2-C budget for the
period 1990-2010, using a spreadsheet accounting model based on three
major components: a conceptual model of ecosystem C cycling; a recently
completed satellite-based vegetation classification; and published
estimates of C density for each of the vegetation classes. Three
alternative projections of land-use change through 2010 show Brazil to be
a C source in the range of 3-5 ? 10-9 MgC.
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