February 28, 2007
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A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 8, NUMBER 9, SEPTEMBER 1995
OF GENERAL INTEREST: CARBON CYCLE
"A Large Northern Hemisphere Terrestrial CO2 Sink Indicated by the
13C/12C Ratio of Atmospheric CO2," P. Ciais (CMDL, NOAA, R/E/CG1, 325
Broadway, Boulder CO 80303), P.P. Tans et al., Science, 269(5227),
1098-1102, Aug. 25, 1995.
Uses measurements of isotope ratio to quantify the net removal of CO2 from
the atmosphere by the oceans and by terrestrial plants. Finds a strong
terrestrial sink in the temperate latitudes of the Northern Hemisphere in 1992
and 1993, roughly equal to half the global fossil fuel emissions for those
years. The challenge now is to identify the processes that would cause the
terrestrial biosphere to absorb CO2 in such large quantities.
"Oceanic Transport and Storage of Carbon Emissions," A.A. Keller
(Electric Power Res. Inst., POB 10412, Palo Alto CA 94303), R.A. Goldstein, Clim.
Change, 30(4), 367-395, Aug. 1995.
Experiments with a detailed global carbon cycle model (GLOCO) show that
upwelling velocity in the ocean is an important factor determining the rate of
carbon storage in the ocean; experiments to reduce the uncertainty in this
parameter would be valuable. Examination of the release of carbon in the middle
of the ocean thermocline compared with release to the atmosphere shows that
oceanic burial of a significant fraction of carbon emissions may be an important
management option for limiting the buildup of atmospheric CO2. To stabilize CO2
at 450 ppmv with no ocean burial, the rate of emissions has to be cut
drastically after the year 2010; ocean burial of two gigatons of carbon per year
allows for a smoother transition to alternative energy sources.
"Latitudinal Gradient of Atmospheric CO2 Due to Seasonal Exchange
with Land Biota," A.S. Denning (Dept. Atmos. Sci., Colorado State Univ.,
Ft. Collins CO 80521), I.Y. Fung, D. Randall, Nature, 376(6537),
240-243, July 20, 1995.
Uses a full atmospheric GCM with an advanced representation of CO2 transport
near the ground to show that the interhemispheric gradient of CO2 imposed by
seasonal terrestrial biota is nearly half as strong as that imposed by fossil
fuel emissions. This result implies that CO2 sinks in the Northern Hemisphere
must be stronger than previously suggested.
"Atmospheric Inputs of Dissolved Organic Nitrogen to the Oceans,"
S. Cornell (Sch. Environ. Sci., Univ. E. Anglia, Norwich NR4 7TJ, UK), A.
Rendell, T. Jickells, ibid., 243-246.
Analyses show that dissolved organic N is an ubiquitous and significant
component of precipitation, even in remote marine areas. The results indicate
that the human impact on the global N cycle (and hence marine primary
productivity and carbon burial) may be larger than has been thought.
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