Temporal And Spatial Variation And Impacts Of Drought In China Based On CMIP6 Multi-model

In order to better prevent and reduce drought disasters and effectively manage water resources,it is of great significance to study the temporal and spatial variations of drought and its impact in China,including different climatic regions.In this study,we take China as the research object.Based on the meteorological factors such as temperature,precipitation,wind speed and so on in 20 global climate model simulations from CMIP6,we analysed the spatiotemporal variations of drought and its impacts in China using the self-calibrated Palmer Drought Severity Index(sc PDSI)calculated by both Thornthwaite and Penman-Monteith method during the historical period(1961-2014)and the future(2015-2100).What's more,based on the two variables including PET and precipitation,we analysed the key influencing factors of drought evolution over China during the historical period and the future.Finally,we used the population and GDP data under the shared social path of four Shared Socio-economic Pathways(SSPs)for further analysis of the impact of drought on population and GDP.The main findings are as follows:1.The scPDSI drought index calculated by both Thornthwaite and Penman-Monteith showed that the drought intensity,area and the monthly occurrences would increase in China.There is a high consistency between two different sc PDSI drought indices calculated by Thornthwaite and Penman-Monteith respectively during 1961-2014(except that the variation of drought area in temperate semi-humid region is quite different).However,there is a significant difference between Thornthwaite and Penman-Monteith in the prediction of future drought.In the future(2015-2100),the sc PDSI drought index calculated by Thornthwaite showed that there would be large areas of drying trends in China under most scenarios except SSP1-2.6.Quite evidently,the sc PDSI drought index calculated by Thornthwaite overestimates the drought condition for future projection,espescially under SSP3-7.0 and SSP5-8.5.This is because Thornthwaite approach is sensitive to temperature and overestimates the characteristics of drought in the context of climate warming.2.By analyzing the contribution of precipitation and PET to linear trend of sc PDSI,we concluded that precipitation is the key influencing factor of drought in most areas of China.From history to the future,the water cycle mechanism in some regions will change.The South is mainly controlled by precipitation(decrease)in the historical period,leading to it drying,while the region will still be drying in the future(except for SSP1-2.6),but it will be controlled by PET(increase).The arid region in the historical period is controlled by precipitation(increase),leading to it wetting.Under SSP1-2.6,the arid region will be controlled by PET(increase),leading to it drying.3.Under SSP1-2.6?SSP2-4.5 and SSP5-8.5,population exposure to drought will increase before 2040 s,and then gradually decrease.In most areas,population factors have a greater impact on population exposure to drought.The temperate humid region may become future hot spot,as climate factors contribute a greater proportion to the population exposure to drought.At the same time,with the rapid development of social economy,the GDP in China will grow rapidly.Under the four scenarios,the economic exposure to drought in China will increase,especially in the South.In the relative contribution of GDP and climate factors to the economic exposure to drought,GDP factor is highly dominant.