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 2, FEBRUARY 1996
Biological Productivity and Export Production in the Glacial Southern Ocean,"
N. Kumar (Sch. Intl. & Public Affairs, Columbia Univ., New York NY 10027),
R.F. Anderson et al., Nature, 378(6558), 675-680, Dec. 14, 1995.
The results of this study bear on the recent suggestion that atmospheric CO2
levels could be reduced by deliberately stimulating biological activity in
certain ocean regions by adding iron. Examination of radionuclides in marine
sediments shows that during glacial periods over the past 140,000 years,
biological productivity in the Southern Ocean was associated with an increased
supply of iron to surface waters, carried by winds from the Patagonian deserts.
Three items from Global
Biogeochem. Cycles, 9(4), Dec. 1995:
"Terrigenous Fe Input and Biogenic Sedimentation in the Glacial and
Interglacial Equatorial Pacific Ocean," R.W. Murray (Dept. Earth Sci.,
Boston Univ., Boston MA 02215), M. Leinen et al., 667-684. Examines the role of
terrigenous iron input in regulating atmospheric CO2 levels, by
analyzing sediment cores that record deposition through the last six glacial
cycles (~600,000 years). Overall, results show no relationship between
terrigenous iron input and sedimentary sequestering of carbon in this region of
"Toward a Global Estimate of Black Carbon in Residues of Vegetation
Fires Representing a Sink of Atmospheric CO2 and a Source of O2,"
T.A.J. Kuhlbusch (US EPA, 960 College Sta. Rd., Athens GA 30605), P.J. Crutzen,
491-501. Black carbon produced in fires is very resistant to microbial decay and
may represent a substantial carbon sink. This study arrives at estimates of
black carbon production from various types of biomass fires, based on laboratory
experiments. Results show that carbon sequestration in this form reduces
estimates of net carbon flux due to changes in land use by up to 25%.
"On the Contribution of CO2 Fertilization to the Missing
Biospheric Sink," D. Friedlingstein (NASA Goddard Inst. Space Studies, 2880
Broadway, New York NY 10025), I. Fung et al., 541-556. Estimates the biospheric
contribution to the carbon cycle over the industrial period using a global
biospheric model, which is much more comprehensive than the type of model
previously applied to the problem. Results suggest that about two thirds to
three fourths of the 1850-1990 integrated missing carbon sink is due to the CO2
greening of the biosphere. The remainder may be due to the increased level of
nitrogen deposition starting around 1950.
and Production of CO2 in Deep Soils of the Eastern Amazon,"
E.A. Davidson (Woods Hole Res. Ctr., POB 296, Woods Hole MA 02543), S.E.
Trumbore, Tellus, 47B(5), 550-565, Nov. 1995.
Estimates show that 20-30% of CO2 flux from the soil surface is
produced below a depth of one meter by root respiration and microbial decay,
indicating that deep-soil processes are a significant component of carbon
cycling in these deep-rooted ecosystems. About 1% of the stock of soil carbon
found in the 1-8 meter layer turns over annually; land-use changes that affect
rooting depth could significantly affect deep soil carbon stocks over decades to
Uptake by an Undisturbed Tropical Rain Forest in Southwest Amazonia, 1992 to
1993," J. Grace (Inst. Ecology, Univ. Edinburgh, Edinburgh EH9 3JU, UK), J.
Lloyd et al. Science, 270(5237), 778-780, Nov. 3, 1995.
Previous studies suggest that the terrestrial biosphere may be undergoing
fertilization as a result of increasing concentrations of CO2
combined with higher deposition of nitrogen. Extended measurements of CO2
flux over an undisturbed tropical rain forest presented here lead to an estimate
of net carbon absorption by the ecosystem of 8.5 moles per square meter per
in the Tundra, Boreal Forest and Humid Tropical Forest During Climate Change:
Scaling up from Leaf Physiology and Soil Carbon Dynamics," Y.P. Wang (Div.
Atmos. Sci., CSIRO, P.B. 1, Mordialloc, Victoria 3195, Australia), P.J.
Polglase, Plant, Cell, Environ., 18(10), 1226-1244, Oct. 1995.
Calculations based on a general model of ecosystem carbon fluxes show that,
several times during the past 140 years, tundra and boreal forest biomes have
alternately been carbon sources and carbon sinks. More recently, high latitude
warming during 1988 and 1990 caused tundra and boreal forests to be net sources.
Humid tropical forests have generally been a carbon sink since 1960. Under
projected CO2 and temperature increases, the tundra and boreal
forests will emit increasingly more carbon, while the humid tropical forests
will continue to store carbon.
"Land Use Change
and the Carbon Cycle," R.A. Houghton (Woods Hole Res. Ctr., POB 296, Woods
Hole MA 02543), Global Change Biol., 1(4), 275-287, Aug. 1995.
A commissioned review. Compares various estimates of net carbon flux between
land and the atmosphere, showing that much of the variability results from
differences in approach. If evaluated carefully, these differences may help
increase our understanding of the net carbon balance in terrestrial ecosystems.
"Soil and Biomass
Carbon Pools in Model Communities of Tropical Plants Under Elevated CO2,"
J.A. Arnone III (Dept. Botany, Univ. Basel, Schönbeinstr. 6, CH-4056 Basel,
Switz), Ch. Körner, Oecologia, 104(1), 61-71, 1995.
Reports experiments conducted in greenhouses with somewhat nutrient-limited
model communities of moist tropical plant species. Finds that: enormous amounts
of carbon can be deposited in the ground that are not normally accounted for in
estimates of net primary productivity and net ecosystem productivity; any
enhancement of carbon sequestration under elevated CO2 may be
substantially smaller than is currently believed; species dominance in plant
communities is likely to change under elevated CO2, but changes may
"Role of Russian
Forests in the Global Carbon Balance," T.P. Kolchugina (Dept. Civil Eng.,
Oregon State Univ., Corvallis OR 97331), T.S. Vinson, Ambio, 24(5),
258-264, Aug. 1995.
The absence of a common approach to quantifying terrestrial carbon has
resulted in substantial discrepancies in regional, national and global
estimates. One of the most dramatic examples is flux estimates for Russian
forests, which differ by two orders of magnitude. This paper presents a
comprehensive system of accounting which shows that the sequestration of carbon
in Russian forests is substantial, about 0.66 Pg carbon per year in the late
1980s and early 1990s. About a third this amount was returned to the atmosphere
through logging and forest fires.
Two related items in
Nature, 376(6543), Aug. 31, 1995:
"Is the Ocean Losing Nitrate?" L.A. Codispoti (Ctr. Coastal Phys.
Oceanog., Old Dominion Univ., Norfolk VA 23529), 724. Discusses how the
following paper adds to the evidence that the present-day ocean is losing fixed
nitrogen, which implies lower plant productivity and lower oceanic uptake of CO2.
Increased denitrification could result if schemes to fertilize the ocean with
trace metals led to an increased flux of organic material to deep layers.
"Large Changes in Oceanic Nutrient Inventories from Glacial to
Interglacial Periods," R.S. Ganeshram (Dept. Oceanog., Univ. British
Columbia, Vancouver BC V6T 1Z4, Can.), T.F. Pedersen et al, 755-758. Nitrate is
an oceanic nutrient that can be regulated by changes in the rate at which it is
degraded by bacteria (denitrification) in oxygen-deficient subsurface waters.
Nitrogen isotope ratios in marine sediment cores taken from the eastern tropical
North Pacific Ocean show that water-column denitrification was greatly
diminished during glacial periods. A consequent increase in the oceanic nitrate
inventory could have contributed to the well-documented decrease in atmospheric
CO2 during glacial periods.
in the Partial Pressure of Carbon Dioxide in Coral Reef Water," H. Kayanne
(Dept. Geog., Univ. Tokyo, Hongo, Tokyo 113, Japan), A. Suzuki, H. Saito, Science,
269(5221), 214-216, July 14, 1995.
Coral reefs are considered to be a source of atmospheric CO2
because of their high calcium carbonate production and low net primary
production. However, direct measurements of partial pressure on a Japanese
island reef show that the reef flat area is a net sink for CO2,
suggesting that the net organic production exceeded net calcium carbonate
production during the observation periods.
Two items from Chemosphere,
29(5), Sep. 1994:
"Prehistoric Anthropogenic Wildland Burning by Hunter-Gatherer
Societies in the Temperate Regions: A Net Source, Sink or Neutral To the Global
Carbon Budget?" M.K. Anderson (Hall Ctr. for Humanities, Univ. Kansas,
Lawrence KS 66045), 913-934. Demonstrates the need for more intense
multi-disciplinary study of prehistoric "hunter-gatherer" burning
patterns in temperate regions, using California as an example. Presents an
approach for better defining patterns of anthropogenic wildland burning in
various regions of North America at the time of Euro-American contact. Physical,
social and biological scientists should work together to examine global warming
in a broader historical context to explore this question, which has profound
implications for global warming mitigation policies.
"Biomass Utilization in Households and Industry: Energy Use and
Development," D.O. Hall (Div. Life Sci., King's Coll., London W8 7AH, UK),
F. Rosillo-Calle, J. Woods, 1099-1119. The historical importance of
biomass-related carbon releases through human activities is increasingly
recognized, but the available data are insufficient for full evaluation. This
paper re-examines the role of past and present biomass energy use (including its
relation to population and environment), and potential anthropogenic carbon
releases from biomass, with particular attention to land use changes, biomass
burning, and industrial uses.
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