Atmospheric Science

Carbon Budgeting

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Science  29 Nov 2002:
Vol. 298, Issue 5599, pp. 1681
DOI: 10.1126/science.298.5599.1681a

Forests take up an average of more than 2 gigatons of fossil-fuel-generated carbon per year. Because relatively few measurements of CO2 fluxes have been made over entire continents, it is difficult to determine whether temperate forests in the Northern Hemisphere or tropical forests represent the largest carbon sink. Such measurements are difficult because each day there is alternate uptake and release of CO2 by vegetation, and because there may be surface fluxes of CO2 over the landscape.

In an attempt to overcome such difficulties, Chou et al. present a conceptual framework for using atmospheric measurements made with aircraft to determine fluxes of CO2 from a continental land area. Using measurements of CO2, O3, and CO made over central and eastern Amazonia late in the wet season of 1987, the carbon budget of a substantial area of central Amazonia was shown to be close to balance. Below 3 km, regional fluxes of CO2 cause atmospheric concentration gradients that can be quantified by systematic aircraft soundings, which should provide important input for global studies of CO2 uptake. — HJS

J. Geophys. Res. 107, 4614 (2002).

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