Climate Change 2001:
Working Group I: The Scientific Basis
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Figure 3.8: Modelled fluxes of anthropogenic CO2 over the past century. (a) Ocean model results from OCMIP (Orr and Dutay, 1999; Orr et al., 2000); (b), (c) terrestrial model results from CCMLP (McGuire et al., 2001). Positive numbers denote fluxes to the atmosphere; negative numbers denote uptake from the atmosphere. The ocean model results appear smooth because they contain no interannual variability, being forced only by historical changes in atmospheric CO2. The results are truncated at 1990 because subsequent years were simulated using a CO2 concentration scenario rather than actual measurements, leading to a likely overestimate of uptake for the 1990s. The terrestrial model results include effects of historical CO2 concentrations, climate variations, and land-use changes based on Ramankutty and Foley (2000). The results were smoothed using a 10-year running mean to remove short-term variability. For comparison, grey boxes denote observational estimates of CO2 uptake by the ocean in panel (a) and by the land in panel (b) (from Table 3.1). Land-use change flux estimates from Houghton et al. (1999) are shown by the black line in panel (c). The grey boxes in panel (c) indicate the range of decadal average values for the land-use change flux accepted by the SRLULUCF (Bolin et al., 2000) for the 1980s and for 1990 to 1995.

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