Global intensification of flash droughts in the past and future

Flash droughts have raised a wide concern in recent years. Besides many regional analyses, global distributions of flash droughts have been discussed in a few studies. With certain differences due to different drought indices or datasets, a few hotspots consistently show increasing flash droughts among studies. However, to date, there is no global picture on whether flash droughts have been intensified, or whether the intensification will continue into the future. Here we propose a method to quantify the intensification of global flash droughts, and investigate the historical trends (trends in the past 60 years) by using global reanalysis data and CMIP6 climate models with or without human-induced climate change. The human fingerprint can be identified for the global trends, which suggests the important role of anthropogenic intensification of global flash droughts in the past. Moreover, future projection of flash drought is also carried out over IPCC SREX regions by using CMIP6 future scenarios. The results show that intensification of flash droughts is projected to continue across most regions, with larger increase under higher emission scenarios. This raises an urgent need to adapt to the intensifying flash droughts in the future.