A comparison of 11 coupled climate-carbon cycle models shows unanimous agreement that more anthropogenic carbon will remain in the atmosphere as the efficiency of natural carbon sinks on land and in the oceans is reduced in the coming decades. Current atmospheric CO2 concentration of about 385 ppmv is projected to reach 700 to 1000 ppmv by 2100 (see 1.2a). Climate change will tend to release land and ocean carbon to the atmosphere, but the magnitude of this response remains highly uncertain. Much of this uncertainty is due to incomplete understanding and model representation of ecosystem carbon cycling processes and climate-induced changes in these processes. Based on current knowledge and modeling methods, different models project dramatically different futures for carbon uptake by land (see 1.2b) and ocean (see 1.2c). More observational and experimental data are needed to constrain these models and decrease the large uncertainties in future projections of climate-induced changes in the carbon cycle.
Credit or Source: Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science. science.energy.gov/ber/
U.S. DOE. 2008. Carbon Cycling and Biosequestration: Report from the March 2008 Workshop, DOE/SC-108, U.S. Department of Energy Office of Science. (p. 6) (website)