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Uncertainty in crossing time of 2 °C warming threshold over China 被引量:16

Uncertainty in crossing time of 2 °C warming threshold over China
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摘要 The 2 ℃ warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature (SAT) change over China will reach 2℃ rela- tive to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Repre- sentative Concentration Pathways (RCP4.5 and RCPS.5) from the Coupled Model Intercomparison Project Phase 5. The 2℃ threshold-crossing time (TCT) of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a 4-1o- range of inter- model SAT change, the upper and lower bounds of the 2 ℃ TCT could differ by about 25 years or even more. Uncer- tainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensi- tivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 ~C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a cli- mate more sensitive to CO2 forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radia- tion, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT. The 2 °C warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature(SAT) change over China will reach 2 °C relative to the pre-industrial era. To understand the uncertainties,we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Representative Concentration Pathways(RCP4.5 and RCP8.5)from the Coupled Model Intercomparison Project Phase 5.The 2 °C threshold-crossing time(TCT) of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a ±1r range of intermodel SAT change, the upper and lower bounds of the 2 °C TCT could differ by about 25 years or even more. Uncertainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensitivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 °C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a climate more sensitive to CO2 forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region,and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radiation, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.
出处 《Science Bulletin》 SCIE EI CAS CSCD 2016年第18期1451-1459,共9页 科学通报(英文版)
基金 supported jointly by the ‘‘Strategic Priority Research Program–Climate Change: Carbon Budget and Related Issues’’ of the Chinese Academy of Sciences (XDA05110300) the Research Fund for Commonwealth Trades (Meteorology) (GYHY201506012) the National Natural Science Foundation of China (41420104006) the China Postdoctoral Science Foundation (2015M581152)
关键词 2 °C threshold Projection uncertainty China region CMIP5 Climate sensitivity 不确定性分析 中国 时间 区域气候变化 气候敏感性 阈值 变暖 气候模型
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