中文摘要：

<正>According to the IPCC Fourth Assessment Re-port (AR4) [IPCC, 2007], the global mean surface tem-perature in 2100 is projected to be 1.1-6.4 C higher than the 1980-1999 mean state, with the best estima-tion of increase at 1.8-4.0 C. It should be noted that

英文摘要：

According to the IPCC Fourth Assessment Report （AR4） [IPCC, 2007], the global mean surface temperature in 2100 is projected to be 1.1-6.4℃ higher than the 1980 1999 mean state, with the best estimation of increase at 1.8-4.0℃. It should be noted that this is the projected range of increase rather than the so-called uncertainties in global warming projection. Specifically, 1.1℃ and 1.8℃ are the lower limit and the best estimation for the B1 emissions scenario （the low emissions scenario）, respectively; while 4.0℃ and 6.4℃ are the corresponding upper limit and the best estimation for the A1F1 emissions scenario （the high emissions scenario）. Therefore,