Current warming and likely future impacts - Climate Change: Biological and Human Aspects - page 307

(a) (b) (c)

Fig. 6.6 Rough sketch maps of key aspects of North American climate change for the 21st century under B-a-U scenarios. (a) Mean annual temperature change over the 21st century. Everywhere in

NorthAmericawarms,withwarminggreaterathigherlatitudes.Thisdoesnotmeanitwillbewarmerthere,justthatthewarmingisgreaterthereoverthe21stcentury.(b)Changesinwinter
precipitation.

20%contoursareshown.North
ofthe0%changezoneincreasedsummerprecipitationisexpected.Again,notethat change inprecipitationismapped(notactualprecipitation).ThesouthwestandpartsofthewesternUSA
areexpectedtoseemuchgreaterdroughtthanatpresent.PartsofcentralNorthAmericaareexpectedtoseenetdryingcomparedtothepresent.EvenifprecipitationinpartsofNorthAmerica
remains the same at the end of the 21st century compared to the present, the warmer end-of-21st-century temperature will result in a dryer environment. Compare these sketch maps with
theIPCC2007assessment(WG1,chapter11)andtheUSGCRP2009report(sectiononnationalclimatechange).

− 20%, − 10%, + 10%, + 20%and + 30%contoursareshown.(c)Changesinsummerprecipitation. − 30%, − 20% − 10%,0%, + 10and +