Global Warming

126 Climate changein the twenty-firstcenturyand beyond

(a)

Change in temperature relative to model’s global mean

Much greater than average warming

Greater than average warming

Less than average warming

Inconsistent magnitude of warming Dec-Jan-Feb

Jun-Jul-Aug

60N

30N

EQ

30S

60S

180 120W 60W 0 60E 120E 180

Change in global mean temperature (°C)

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Change in temperature for scenario A2

Figure 6.5Projections for the SRES scenario A2 for the period 2071–2100

relative to 1961–1990 from an ensemble of nine different ocean–atmosphere

general circulation models. (a) The annual mean change of temperature in◦C

shown by the shading. The boxes show an analysis of inter-model consistency in

regional relative warming (i.e. warming relative to each model’s global average

warming) for winter and summer seasons. Regions are classified as showing

either agreement on warming in excess of forty per cent above the global mean

annual average (much greater than average warming), agreement on warming

greater or less than the global mean annual average (greaterorless than average

warming) or disagreement amongst models on the magnitude of regional

relative warming (inconsistent magnitude of warming). A consistent result from at

least seven of the nine models is defined as being necessary for agreement. The

global mean average warming of the models used are in the range 1.2 to 4.5◦C

for this scenario. (b) The boxes show an analysis of inter-model consistency in

regional precipitation change for winter and summer seasons. Regions are

classified as showing agreement on change of greater than+20% (large

increase), between+5% and+20% (small increase) and more than−20% (large

decrease), or disagreement (inconsistent sign). A consistent result from at least

seven of the nine models is defined as being necessary for agreement.