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Abstract

Studies on the influences of climate change on biogeochemical cycles and on the key vulnerabilities and the risk from climate change suggest that annual surface temperature rise of 1A degrees C, 2A degrees C and 3A degrees C above the present level would lead to changes in extreme weather and climate events, food production, fresh water resources, biodiversity, human mortality, etc. Here two sets of simulations as performed with seventeen atmosphere-ocean general circulation models (AOGCMs) for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), i.e. the model outputs from the 20th Century Climate in Coupled Models (20C₃M) and from the Special Report on Emissions Scenarios (SRES) emission scenarios B1, A1B and A2, are used to analyze spatial and temporal characteristics of the above values in China over the 21st century. The results indicate that the rate of warming varies from region to region. The above values are reached much later (earlier) when emission amount is lower (higher), and spread of the time when the lower (higher) value is exceeded is narrower (wider) among the three scenarios. As far as the spatial pattern is concerned, the above values are crossed much earlier in northern China and the Tibetan Plateau with respect to the Yangtze-Huaihe River Valley and South China.