Simulation Evaluation And Prediction Of Extreme Temperatures In The "Silk Road Economic Belt" Based On The CMIP6 Model

The risk of extreme climate change with global warming has seriously affected the common development of China and the countries that participate in the construction of the "Silk Road Economic Belt".Under the the situation of global warming,projecting the extreme temperature change over this belt provides a scientific basis for risk assessment and decision-making on climate change,and is of great significance to ensure the long-term sustainable development on the "Silk Road Economic Belt" and the security of China's overseas investment.Employing phase 6 of the Coupled Model Intercomparison Project(CMIP6)simulations and extreme temperature indices defined by the Expert Team on Climate Change Detection and Indices,we firstly evaluate the performance of the CMIP6 models in this region,and then project the spatial patterns of changes in extreme temperature in different periods under Shared Social-economic Pathway scenarios and at different global warming levels.The conclusions are drawn as follows:(1)The results show that the performance of the CMIP6 models in simulating the indices of coldest day(TXn),coldest night(TNn),summer days(SU),tropical nights(TR),and frost days(FD)are good.Therefore,the simulations of these five indices could be applied to projection.For the indices which the deviation between the CMIP6 model simulations and observations is large,such as hottest day(TXx)and warmest night(TNx),,their simulations is corrected through the variance scaling method and then could be used in projection.(2)Overall,TXn,TNn,SU,TR,TXx and TNx show an increasing trend and FD a decreasing trend,consistent with global warming in the future.The responses to global warming tend to be strongest in high latitudes for TXn and TNn,in high latitudes and high-altitude areas for FD,and in some low-latitude areas for SU and TR.However,the spatial distribution characteristics of response for TXx and TNx are not obvious(3)At the local scale over Silk Road Economic Belt,where the change is larger than the regional median level,the changes in extreme temperature indices at 1.5°C of global warming above pre-industrial levels are projected to be reduced by 25%–55% and 55%–85%,respectively,compared with the situation at 2.0°C and 3.0 warming.If global warming could be controlled to within 2.0°C,the changes in extreme temperature indices over Silk Road Economic Belt would be reduced by up to 60% compared with the situation at 3.0°C warming.Therefore,if global warming can be controlled to within a low warming target,the risk of extreme temperature change will be greatly reduced in these regions.