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 8, NUMBER 1, JANUARY 1995
OF GENERAL INTEREST: CARBON CYCLE
"Evidence for Interannual Variability of the Carbon Cycle
from the [NOAA/CMDL] Global Air Sampling Network," T.J.
Conway (CMDL, NOAA, 325 Broadway, Boulder CO 80303), P.P. Tans et
al., J. Geophys. Res., 99(D11), 22,831-22,855, Nov.
Extensive weekly sampling between 1981 and 1992 shows that the
global CO2 growth rate has declined from a peak of
~2.5 ppm/yr in 1987-1988 to ~0.6 ppm/yr in 1992. A 2-D model
analysis indicates that the low growth rate in 1992 is mainly due
to an increase in the Northern Hemisphere CO2 sink,
probably in the terrestrial biosphere. One possibility is the
temperature-induced decrease in plant respiration due to cooling
following the Mount Pinatubo eruption. However, the fluctuation
is probably temporary, and a return to a higher growth rate is
Role of Deep Roots in the Hydrological and Carbon Cycles of
Amazonian Forests and Pastures," D.C. Nepstad (Woods Hole
Res. Ctr., POB 296, Woods Hole MA 02543), C.R. de Carvalho et
al., Nature, 372(6507), 666-669, Dec. 15, 1994.
Uses rainfall, satellite and field data to estimate that half
of the closed forests of Brazilian Amazonia depend on deep root
systems to maintain green canopies during the dry season. As deep
roots extract water they also provide carbon to the soil, and
forest alteration that affects depth distributions of carbon
inputs from roots may also affect net carbon storage.
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