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 9, NUMBER 9, SEPTEMBER 1996
Carbon Exchange and Intra-annual Atmospheric CO2 Concentrations
Predicted by an Ecosystem Process Model and Three-Dimensional Atmospheric
Transport Model," E.R. Hunt Jr. (Dept. Bot., Univ. Wyoming, Laramie WY
32071; e-mail: email@example.com), S.C. Piper et al., Global Biogeochem.
Cycles, 10(3), 431-456, Sep. 1996
Used a generalized terrestrial ecosystem process model to simulate the
global fluxes of CO2 that result from photosynthesis, autotrophic
respiration and heterotropic respiration. Predictions agreed to an encouraging
degree in phase and amplitude with observed atmospheric CO2
concentrations for 20° to 55° N latitude, the zone where most data
are available. In the tropics and high northern latitudes the agreement was
poor. The methodology presented here allows terrestrial ecosystem models to be
tested globally, not by comparisons to homogeneous plot data, but by seasonal
and spatial consistency with a diagnostic vegetation model and atmospheric CO2
Stores in Oregon and Washington Forest Products: 1900-1992," M.E. Harmon
(Dept. Forest Sci., Oregon State Univ., Corvallis OR 97331), J.M. Harmon et al.,
Clim. Change, 33(4), 521-550, Aug. 1996.
This new model for estimating carbon stored in forest products considers the
manufacture of raw logs into products and their fate during use and disposal.
Pools examined were long- and short-term structures, paper supplies, mulch, open
dumps and landfills. Of the 1,692 Tg of carbon harvested during the selected
period, only 23% is currently stored, mostly in long-term structures and
landfills.. Most carbon release has occurred during manufacture and this may
help to account for the lack of sensitivity of forest products models. The fate
of paper and wood wastes appears to be a key focus for future research.
"An Efficient and
Accurate Representation of Complex Oceanic and Biospheric Models of
Anthropogenic Carbon Uptake," F. Joos (Physics Inst., Univ. Bern, CH-3012
Bern, Switz.; e-mail: firstname.lastname@example.org), M. Bruno et al., Tellus,
48B(3), 397-417, July 1996.
Proposes an ocean mixed-layer pulse response function that characterizes the
surface to deep ocean mixing in combination with a separate equation describing
air-sea exchange. This avoids the problem arising from nonlinearities of carbon
chemistry and gives more accurate results. Found that difference between the
complete Princeton 3-D model and its pulse substitute is better than 4% for
cumulative uptake of anthropogenic carbon for the period 1765 to 2300.
Global Carbon Cycle Observing System: A Plan to Decipher Today's Carbon Cycle
Based on Observations," P.P. Tans, P.S. Bakwin (ERL R/E/CG1, NOAA, 325
Broadway, Boulder CO 80303; e-mail: email@example.com), D.W. Guenther, Global
Change Biology, 2(3), 309-318, June 1996.
One of 14 papers selected from a workshop, Strategies for Monitoring and
Modelling CO2 and Water Vapour Fluxes over Terrestrial Ecosystems
(Mar. 1995, Valle d'Aosta, Italy). Presents a design to continuously monitor
transfers of carbon between the atmosphere and the terrestrial biosphere and
oceans on large spatial scales. Considering the expected signal-to-noise ratio,
a cost effective method would be to perform repeated measurements of the mixing
ratios of trace gases at more sites than the present geographical coverage, a
process that can be done by applying existing technology.
Two related items in
Clim. Change, 33(1), May 1996:
"Accounting for the Missing Carbon Sink with the CO2
Fertilization Effect," H.S. Kheshgi (Corporate Res. Labs., Exxon Res. Co.,
Annandale NJ 08801), A.K. Jain, D.J. Wuebbles, 31-62. Estimates the magnitude of
the biospheric sink with a simple carbon cycle box model, assuming that the past
missing carbon sink was due to the CO2-fertilization effect. Then
uses the model to project the future role of this sink in the carbon budget
under a variety of scenarios, finding that it could rival the oceanic sink in
the next century.
"The CO2 Fertilization Factor and the 'Missing' Carbon
Sink: An Editorial Comment," A.A. Keller (Stanford Univ., Stanford CA
94304), 63-68. The role of simple carbon cycle models such as the one used in
the previous paper is to point us in the correct direction, by defining the
magnitude of the response and to provide interim answers to policy makers. But
closing the "missing carbon sink" debate will require high resolution
models with multiple components.
British Cattle Herd," P. Smith (Soil Sci. Dept., IACR-Rothamsted,
Harpenden, Herts AL5 2JQ, UK), J.U. Smith, D.S. Powlson, Nature,
381(6577), 15, May 2, 1996.
A commonly suggested solution to the U.K.'s crisis involving bovine
spongiform encephalopathy ("mad cow disease") is to move all cattle to
new pasture after eradication of the disease. This article attempts to quantify
the possible impact of this scenario on soil carbon content and on nitrate
leaching. If permanent grasslands were plowed for arable crops there would be
significant and long-lasting environmental effects, including losses in soil
Two related items in
Nature, 381(6579), May 16, 1996:
"A Quickening on the Uptake?" M. Bender (Grad. Sch. Oceanog.,
Univ. Rhode Island, Kingston RI 02881), 195-196. The following paper is the
second landmark contribution from Keeling et al. on the distribution of oxygen
concentration in air and its implications for the CO2 budget. The
flux terms they calculate (using the O2/N2 ratio) are in good agreement with
estimates from tracer methods. Possible causes for rapid uptake in northern
biota they find include CO2 fertilization of land biosphere,
nitrogen fertilization from industrial emissions, and warmer temperatures and
"Global and Hemispheric CO2 Sinks Deduced from Changes in
Atmospheric O2 Concentration," R.F. Keeling (Scripps Inst. Oceanog., La
Jolla CA 92093), S.C. Piper, M. Heimann, 218-221. Carbon sinks are missing in
both the global and the Northern Hemispheric carbon budgets, suggesting that
northern land biota may be missing sink. This study presents an extensive data
set for the ratio O2/N2 which shows simultaneous trends in this ratio in both
Northern and Southern Hemispheres. For 1991-1994, the global oceans and the
northern land biota each removed the equivalent of ¸30% of fossil fuel CO2
emissions, while the tropical land biota were not a strong source or sink.
Gradient in Carbon Turnover Times in Forest Soils," M.I. Bird (Sch. Earth
Sci., Australian Natl. Univ., Canberra, ACT 0200, Australia), A.R. Chivas, J.
Head, Nature, 381(6578), 143-146, May 9, 1996.
Analyzes carbon isotope contents and ratios in particulate organic carbon
samples from low altitude, non-water-stressed forests. A marked latitudinal
gradient supports the proposition that high-latitude forest soils have the
capacity to act as a net sink for anthropogenic CO2 on decadal time
Ocean Carbonate Budgets for the Global Carbon Cycle," P.M. Holligan (Dept.
Oceanog., Univ. Southampton, Southampton SO17 1BJ, UK), J.E. Robertson, Global
Change Biology, 2(2), 85-95, Apr. 1996.
A commissioned review that examines the role of biologically driven fluxes
of organic and inorganic carbon in modifying the carbon dioxide chemistry of the
oceans, and the corresponding implications for partitioning of CO2
between atmosphere and ocean. Some of the topics presented are: recent estimates
of and uncertainties in marine carbonate fluxes; the need to account for the
carbonate pump and subtle interactions between organic and inorganic carbon
cycling in addition to accounting for the role of ocean biota; the significance
of carbonate formation and dissolution; and the effects of global change on the
marine carbonate system.
Between Soil Carbon and Atmospheric Carbon Dioxide Driven by Temperature Change,"
S.E. Trumbore (Dept. Earth System Sci., Univ. California, Irvine CA 92717), O.A.
Chadwick, R. Amundson, Science,
272(5260), 393-396, Apr. 19, 1996.
Comparison of 14C in pre-1963 and contemporary soils along an elevation
gradient in the Sierra Nevada, California, revealed rapid (7-65 years) turnover
for 50-90% of the carbon in the upper 20 cm. Carbon turnover times increased
with elevation (decreasing temperature), a trend, consistent with that from
other locations, indicating that temperature is a dominant control of soil
carbon dynamics. When extrapolated to large regions, the observed relation
between carbon turnover and temperature suggests that soils should be
significant sources or sinks of atmospheric CO2 in response to
global temperature changes.
Two related items in
Nature, 379(6566), Feb. 15, 1996:
"Iron Grip on Export Production," A. Longhurst (Biological
Oceanog., Bedford Inst. Oceanog., Dartmouth NS B2Y 4A2, Can.), 585-586. The
following paper and one by Kumar et al. (Nature, 1995) have added to our
understanding of the factors that control the rate of oceanic carbon uptake by
phytoplankton, showing that over some of the ocean the controlling factor is
iron. We need to understand how this occurs in order to predict phytoplankton
response to even higher levels of CO2 than those already being
produced from anthropogenic sources. Models of algal growth must also include
iron transport and supply to quantify the response of the ocean to changing
global climate regimes, or to predict where iron limitation may occur in the
larger regions now thought to be nitrate limited.
"Control of Community Growth and Export Production by Upwelled Iron in
the Equatorial Pacific Ocean," K.H. Coale (Moss Landing Marine Labs., POB
450, Moss Landing CA 95039), S.E. Fitzwater et al., 621-624. Surface water
measurements show that the main iron source to equatorial waters at 140° W
is from upwelling waters, not solely from atmospheric deposition as has been
"Coral Reefs and
Carbon Dioxide," Science, 271(5253), 1298-1300, Mar. 1,
Comments and a reply by H. Kayanne concerning his suggestion that coral
reefs might serve as a sink, not a source, for atmospheric CO2.
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