FIGURE 4.6 Geographical patterns of percentage precipitation change per 1°C of global annual average warming, for the whole world (top) and over North America (bottom). From left to right: patterns of changes in precipitation averaged over the whole calendar year or over boreal winter (December, January, and February) or summer (June, July, and August). Patterns are obtained by scaling end-of-21st-century percentage changes in precipitation (compared to end-of-20th-century climatology) by global average annual *warming* over the same period for the 18 CMIP3 models whose output is available for all three SRES scenarios A2, A1B, and B1. White regions are where less than two-thirds of the models agree over the sign of the change.

FIGURE 4.6 Geographical patterns of percentage precipitation change per 1°C of global annual average warming, for the whole world (top) and over North America (bottom). From left to right: patterns of changes in precipitation averaged over the whole calendar year or over boreal winter (December, January, and February) or summer (June, July, and August). Patterns are obtained by scaling end-of-21st-century percentage changes in precipitation (compared to end-of-20th-century climatology) by global average annual *warming* over the same period for the 18 CMIP3 models whose output is available for all three SRES scenarios A2, A1B, and B1. White regions are where less than two-thirds of the models agree over the sign of the change.



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