Atmosphere-biosphere exchange of CO(sub[2])

Abstract The current rate at which the concentration of atmospheric carbon dioxide is increasing is well known and easily measured. What is less clear is the relative role of terrestrial ecosystems and oceans in sequestering carbon. Limits to our understanding of the global carbon balance prevent us from giving unequivocal answers to such seemingly innocuous questions as: how much carbon dioxide is being taken up by the oceans; how much carbon dioxide is being released from soils and vegetation as a result of natural changes and deforestation? Progress in closing the carbon budget must rely on an interdisciplinary approach which relates and integrates observations made at different spatial and temporal scales. When made in combination with detailed biophysical field experiments such observations can reveal the atmospheric and biophysical variables which control carbon dioxide exchange.