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 10, OCTOBER 1992
GLOBAL CARBON BUDGET
Four items from Nature, 358(6389), Aug. 27, 1992:
"Diminishing Oxygen," W.S. Broecker (Lamont-Doherty Geol. Observ.,
Palisades NY 10964), J.P. Severinghaus, 710-711. Discusses the background for,
and implications of, the results presented in the following paper by Keeling and
"Seasonal and Interannual Variations in Atmospheric Oxygen and
Implications for the Global Carbon Cycle," R.F. Keeling (NCAR, POB 3000,
Boulder CO 80307), S.R. Shertz, 723-727. Measurements using a new
interferometric technique show that the O2 content of air varies seasonally in
both the Northern and Southern Hemispheres, and is decreasing from year to year.
The seasonal variations provide a new basis for estimating global rates of
biological organic carbon production in the ocean, and the interannual decrease
constrains estimates of the rate of anthropogenic CO2 uptake by the oceans.
"Thermal Skin Effect of the Surface Ocean and Its Implications for CO2
Uptake," J.E. Robertson (Plymouth Marine Lab., Prospect Pl., West Hoe,
Plymouth PL1 3DH, UK), A.J. Watson, 738-740. The upper 1 mm or so of the oceans
represents a cool "skin," with a temperature gradient such that the
surface is generally cooler than the bulk mixed layer by about 0.3° C.
Accounting for this temperature difference results in a calculated increased
global uptake of about 0.7 Gt C yr-1, helping to bring into closer agreement the
oceanic CO2 uptake determined by different methods.
"Phytoplankton Productivity in the North Pacific Ocean since 1900 and
Implications for Absorption of Anthropogenic CO2," P.G. Falkowski
(Brookhaven Nat. Lab., Upton NY 11973), C. Wilson, 741-743. Increases in
phytoplankton biomass reported recently for the central North Pacific could be
important in the global carbon budget if they are widespread. However,
historical records of Secchi depth data show that any widespread increases are
too small to have a significant effect on the rise in atmospheric CO2.
"Sensitivity of Terrestrial Carbon Storage to CO2-Induced Climate
Change: Comparison of Four Scenarios Based on General Circulation Models,"
T.M. Smith (Dept. Environ. Sci., Univ. Virginia, Charlottesville VA 22903), Clim.
Change, 21(4), 367-384, Aug. 1992.
Estimates using Holdridge Life-Zone Classification show an increase in the
area occupied by forests for all four scenarios. Terrestrial C storage increases
0.4-9.5% above estimates for present conditions, representing a potential
reduction of 4-85 ppm in elevated atmospheric CO2.
Discussion on the potential of Southern Ocean birds and mammals to respire
CO2 to the atmosphere, Science, 257(5067), 259-260, July 10,
Comments on "The Significance of Coral Reefs as Global Carbon
Sinks--Response to Greenhouse," Glob. Plan. Change, 5(4),
"A Perturbation Simulation of CO2 Uptake in an Ocean General
Circulation Model," J.L. Sarmiento (Atmos. & Oceanic Sci., Princeton
Univ., Princeton NJ 08544), J.C. Orr, U. Siegenthaler, J. Geophys. Res.,
97(C3), 3621-3645, Mar. 15, 1992.
Atmospheric pCO2 was prescribed for the period 1750-1990 using the
combined Siple ice core and Mauna Loa records. For 1980-1989, the calculated
average flux of CO2 into the ocean, added to the observed atmospheric increase,
totals 5.1 Gt yr-1. This is comparable to the estimated fossil CO2 production,
implying that other sources and sinks (such as deforestation, enhanced growth of
land biota, and changes in the ocean C cycle) must be approximately in balance.
Letter discussing research presented at a recent workshop on balancing the
carbon budget, Science, 257(5066), 11, July 3, 1992.
"Carbon Storage in Upland Forests of the Lake States," D.F.
Grigal (Dept. Soil Sci., Univ. Minnesota, St. Paul MN 55108), L.F. Ohmann, Soil
Sci. Soc. Am. J., 56(3), 935-943, May-June 1992.
A study of C in the biomass, forest floor and mineral soil of Lake States
forests indicates that C storage can be influenced by forest management.
Patterns of C storage in these moist temperate ecosystems are not as strongly
influenced by climatic variables as in grasslands to the west.
"Calcium Carbonate in Surface Sediments of the Deep Ocean Floor,"
M.J. Kennish (Inst. Marine Sci., Rutgers State Univ., New Brunswick NJ 08903),
R.A. Lutz, Rev. Aquatic Sci., 6(3-4), 183-202, 1992.
Reviews the oceanic carbonate system, which has sparked renewed interest in
the context of increasing atmospheric CO2, and the accumulation and dissolution
of calcium carbonate in seafloor sediments of the major ocean basins. The
primary controls on the observed distribution patterns of calcium carbonate are
(in addition to depth) surface productivity, dissolution, and dilution by
noncarbonate and nonbiogenic sediment.
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