Projections Of Regional Climate Change In China Under Different Emission Scenarios To Achieve Carbon Neutralit

Based on the model simulation results of the 6th Coupled Model Intercomparison Projection 6（CMIP6）,we define the time period of carbon neutrality by the peak time of CO₂concentration under SSP1-1.9 and SSP1-2.6 scenarios.We investigate the climate change in China during this time period compared with the historical reference period（1995-2014）,and analyze the differences of climate response over China under the influence of the presence or absence of carbon neutrality and the time reaching carbon neutrality using three SSP scenarios（SSP1-1.9,SSP1-2.6,SSP2-4.5）.The reasons for the difference in response are discussed from the circulation changes in East Asia.On this basis,the changes of extreme temperature and extreme precipitation in China are investigated,and the relative changes of risks of extreme events are discussed.The major conclusions are as follows:（1）Based on the peak time of CO₂concentration,the time of global carbon neutrality is determined,which is around 2041 under the SSP1-1.9 scenario and 2063 under the SSP1-2.6scenario.During the carbon neutral period,the areal-mean temperature over China increases significantly compared with the historical reference period.Under the SSP1-1.9/SSP1-2.6scenarios,the annual average temperature increases about 1.16℃/1.53℃,respectively.The average annual temperature and summer temperature increase more significantly in the northern regions of China.Winter temperature rises higher over Plateau and the east of Hu Line.Under the SSP1-1.9/SSP1-2.6 scenarios,the annual mean precipitation increases about6.5%/9.2%,respectively.The changes of annual and summer precipitation are relatively large in eastern China,and the largest increase of winter precipitation is located in the Yellow River and the middle and lower reaches of the Yangtze River.About extreme climate,compared to the historical reference period,extreme temperature and precipitation increase in China during the carbon neutral period.TXx increases the most in the plateau,while TNn increases the most in the plateau and eastern regions.Extreme precipitation,on the other hand,increases more in the northwest and plateau and south of the Yangtze River.（2）Compared with the scenario that achieves carbon neutrality,the SSP2-4.5 scenario that does not achieve carbon neutrality has a greater warming in China under the same time period,and the difference in response between it and the SSP1-2.6 scenario is greater,with a0.62℃increase in annual mean temperature.The areas with larger values of warming increase are mainly located in the northern regions.Meanwhile,compared with the scenario of carbon neutrality,precipitation increases in some northern regions of China under the SSP2-4.5 scenario,and the larger value of precipitation reduction occurs in the southern regions,which may be related to the enhanced downward movement over the southern regions.Compared with the SSP1-2.6 scenario,the extreme temperature increases larger under the SSP2-4.5 scenario,and the risk of hot extremes increase the most in southeast China;the risk of cold extremes decrease the most in northeast China.The spatial distribution of extreme precipitation responses over China with the effect of presence or absence of carbon neutrality is basically consistent with the average precipitation,and the increase is larger in northwest China,risk of extreme precipitation in those regions also increases.（3）Compared with the earlier carbon-neutral SSP1-1.9 scenario,the regional warming in China under the later carbon-neutral SSP1-2.6 scenario is greater,with the annual mean temperature increase of 0.38℃,and the largest value of the increase is mainly located in the plateau region;the increase of precipitation is also greater overall than that of the earlier carbon-neutral SSP1-1.9 scenario,with the annual mean precipitation increase of about 2.6%,which may be related to the slightly stronger regional summer monsoon under the later carbon-neutral scenario.The increase of extreme temperature and precipitation under the SSP1-2.6 scenario is greater than that under the SSP1-1.9 scenario.At the same time,the risks of hot extremes and extreme precipitation increase further when carbon neutrality is achieved late than when it is achieved early.