Figure 3.10: Projections
of anthropogenic CO2 uptake by process-based models. Six dynamic global
vegetation models were run with IS92a CO2 concentrations as given in
the SAR: (a) CO2 only, and (b) with these CO2 concentrations
plus simulated climate changes obtained from the Hadley Centre climate model with
CO2 and sulphate aerosol forcing from IS92a (Cramer et al., 2000).
Panel (b) also shows the envelope of the results from panel (a) (in grey). (c)
Ten process-based ocean carbon models were run with the same CO2 concentrations,
assuming a constant climate (Orr and Dutay, 1999; Orr et al., 2000). A further
six models were used to estimate the climate change impact on ocean CO2
uptake as a proportional change from the CO2-only case. The resulting
changes were imposed on the mean trajectory of the simulations shown in panel
(c), shown by the black line in panel (d), yielding the remaining trajectories
in panel (d). The range of model results in panel (d) thus represents only the
climate change impact on CO2 uptake; the range does not include the
range of representations of ocean physical transport, which is depicted in panel
(c).
