Figure 22: Simple model
results: (a) global mean temperature projections for the six illustrative SRES
scenarios using a simple climate model tuned to a number of complex models with
a range of climate sensitivities. Also for comparison, following the same method,
results are shown for IS92a. The darker shading represents the envelope of the
full set of thirty-five SRES scenarios using the average of the model results
(mean climate sensitivity is 2.8°C). The lighter shading is the envelope based
on all seven model projections (with climate sensitivity in the range 1.7 to 4.2°C).
The bars show, for each of the six illustrative SRES scenarios, the range of simple
model results in 2100 for the seven AOGCM model tunings.
(b) Same as (a) but results using estimated historical anthropogenic forcing are
also used. [Based on Figures
9.14 and 9.13b]