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 5, NUMBER 8, AUGUST 1992
GLOBAL CARBON CYCLE
(See also: Prof. Pubs./Marine Biogeochemistry & Fertilization, this
"Interactions between Carbon and Nitrogen Dynamics in Estimating Net
Primary Productivity for Potential Vegetation in North America," A.D.
McGuire (Marine Biol. Lab., Woods Hole MA 02543), J.M. Melillo et al., Global
Biogeochem. Cycles, 6(2), 101-124, June 1992.
Describes various experiments using the process-based Terrestrial Ecosystem
Model, including evaluation of the importance of interactions between C and N
dynamics in the response of North American forest net primary productivity to an
elevated temperature of 2° C. The linkages between C and N dynamics are
shown to be important in several respects.
"Temperate Forest Ecosystems in the Global Carbon Cycle," R.A.
Sedjo (Resour. for the Future, 1616 P St. NW, Washington DC 20036), Ambio,
21(4), 274-277, June 1992.
Newly available data for all the forests of North America, Europe and the
former USSR allow a reexamination of the recent conclusion that Northern
Hemisphere temperate forests are roughly in carbon balance. Findings indicate
that these forests account for a missing carbon sink of about 0.7 Gt annually, a
size outside of the range of recent estimates that are commonly used for
estimating the global carbon budget.
Three items from Nature, 357(6378), June 11, 1992:
"Packing away Carbon Isotopes," R. Keir (GEOMAR,
Christian-Albrechts Univ., 2300 Kiel 14, Ger.), 445-446. The two independent
studies described in the following articles find that atmospheric _13C during
glacial intervals was probably 0.3%-0.7% lower than in the modern, preindustrial
period. Discusses implications for mechanisms determining CO2 variations between
"Glacial-to-Interglacial Variations in the Carbon Isotopic Composition
of Atmospheric CO2," B.D. Marino (Dept. Earth & Plan. Sci., Harvard
Univ., Cambridge MA 02138), M.B. McElroy et al., 461-466. Samples of a C4 shrub
recovered from packrat middens in the western U.S. show that during the last ice
age CO2 was isotopically light compared to interglacial periods. This result is
attributed to a combination of factors including reduced terrestrial biomass and
decreased productivity of the polar ocean.
"Carbon Isotope Composition of Atmospheric CO2 during the Last Ice Age
from an Antarctic Ice Core," M. Leuenberger (Phys. Inst., Univ. Bern,
Sidlerstr. 5, 3012 Bern, Switz.), U. Siegenthaler, C.C. Langway, 488-490.
Attempts to distinguish between two possible mechanisms which could have reduced
atmospheric CO2 during glacial intervals: more efficient "biological
pumping" of carbon to deep ocean waters, or higher alkalinity in the
glacial ocean as a consequence of changes in carbonate dissolution or
sedimentation. Results are indefinite, but do indicate that changes in the
strength of the biological pump cannot alone have been responsible.
"Carbon Stores in Vegetation," R.A. Kern (Dept. Bot., Duke
Univ., Durham NC 27706), W.H. Schlesinger, ibid., 447-448. Comment on
the importance of soil carbonate in estimates of the global budget.
"Northern Peatlands: Role in the Carbon Cycle and Probable Responses
to Climatic Warming," E. Gorham (Dept. Ecol., Univ. Minnesota, Minneapolis
MN 55455), Ecolog. Applic., 1(2), 182-195, May 1991.
Discusses various uncertainties in the carbon and methane budgets of boreal
peatlands, particularly for the former USSR. Satellite monitoring of open water
in the peatlands of the West Siberian Plain and the Hudson/James Bay Lowland may
detect early effects of global warming on these regions.
"Carbon Dioxide Budget in a Temperate Grassland Ecosystem," J.
Kim (Dept. Agric. Meteor., Univ. Nebraska, Lincoln NE 65803), S.B. Verma, R.J.
Clement, J. Geophys. Res., 97(D5), 6057-6063, Apr. 20, 1992.
Eddy correlation measurements of CO2 flux combined with simulated data show
that CO2 exchange between the experimental ecosystem and the atmosphere is
highly variable. Drought, a frequent occurrence in the region, can change the
ecosystem from a source to a sink for CO2. Results suggest the importance of
below-ground biomass in estimating net primary productivity.
"The Global Carbon Dioxide Flux in Soil Respiration and Its
Relationship to Vegetation and Climate," J.W. Raich (Dept. Botany, Iowa
State Univ., Ames IA 50011), W.H. Schlesinger, Tellus, 44B(2),
81-99, Apr. 1992.
Reviews measured rates of soil respiration from terrestrial and wetland
ecosystems to define the annual global CO2 flux from soils, to identify
uncertainties, and to investigate influences on soil respiration rates.
Evaluates human impacts on respiration rates, particularly land use, soil
fertilization, irrigation and drainage, and climate changes. Increased soil
respiration with global warming is likely to provide a positive feedback to the
"Global Carbon Dioxide Emission to the Atmosphere by Volcanos,"
S.N. Williams (Dept. Geol., Arizona State Univ., Tempe AZ 85287), S.J. Schaefer
et al., Geochim. Cosmochim. Acta, 56(4), 1765-1770, Apr. 1992.
Calculates emissions from subaerial volcanoes using CO2/SO2 from volcanic
gas analyses and SO2 flux. Volcanic CO2 presently represents only 0.22% of
anthropogenic emissions, but may have contributed to significant greenhouse
effects at times in the Earth's history. Models of climate response to CO2
increase may be tested against geological data.
"Continuous Shipboard Measurement of the pH of Surface Seawaters, and
Derivation of the Corresponding Record of pCO2," E.C.V. Butler
(Marine Labs., CSIRO, GPO Box 1538, Hobart, Tasmania 7001, Australia), D.J.
Mackey, Sci. Tot. Environ., 112(2-3), 165-175, Mar. 1992.
Explains the technique, and discusses measurements of pH and estimates of pCO2
in the Tasman Sea that reveal regions where the two parameters are highly
correlated with temperature and salinity.
"Forest Biomass in Brazilian Amazonia--Comment," P.M. Fearnside
(Inst. Nacl. Pesquisas, Caixa Postal 478, BR-69011 Manaus, Brazil), Interciencia,
17(1), 19-27, Jan.-Feb. 1992.
Describes a variety of adjustments that should be made to the estimates of
biomass by Brown and Lugo using forest volume data collected by the RADAMBRASIL
Project and the U.N. FAO. Revised estimates indicate a substantial contribution
to greenhouse emissions from deforestation in Brazilian Amazonia.
"Oceanic Sinks for Anthropogenic CO2," C.L. Sabine (Dept.
Oceanog., Univ. Hawaii, Honolulu HI 96822), F.T. Mackenzie, Intl. J. Energy,
Environ., Econ., 1(2), 119-127, 1991.
Discusses the impact of human activities on the geological cycle of CO2,
quantifies the major oceanic sinks of anthropogenic CO2, and reassesses the
oceanic sink of CO2 owing to dissolution of calcium carbonate, using data from
the Hawaiian Archipelago. Fluxes associated with the last process may become
greatly enhanced in the future if society continues its present practices.
"A Simple Inverse Carbon Cycle Model," T.M.L. Wigley (Clim.
Res. Unit, Univ. E. Anglia, Norwich NR4 7TJ, UK), Global Biogeochem. Cycles,
5(4), 373-382, Dec. 1991.
Derives a practical and efficient inverse model from the convolution
integral form of a carbon cycle model. An example shows how modeled
land-use-change emissions over 1765-1989 vary with assumptions made regarding
the efficiency of oceanic uptake.
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