Respective contributions of precipitation and potential evapotranspiration to long‐term changes in global drought duration and intensity

Abstract

Climate change has resulted in an increase in drought in most global land areas, mainly due to a decrease in regional precipitation (P) or an increase in potential evapotranspiration (PET) induced by climate warming. However, knowledge on the contributions of P and PET to long-term changes in global drought duration and intensity is still limited. In this study, we quantitatively analysed the respective contributions of P and PET to long-term drought duration and intensity on a global scale, using standardized precipitation evapotranspiration index (SPEI) and different inputs of P and PET. The results showed that the mean drought duration and intensity experienced an increasing trend in most global land areas during 1950-2020, especially in western United States, eastern Amazon, Mediterranean region, Africa, western Asia, and northeastern Asia. The contributions of P and PET to historical drought evolution vary from regions. The results show that while increasing PET has extensive contribution to drought increase, regional increases in long-term drought duration and intensity are largely determined by the variability in P, and the contribution of P to the increase in long-term drought can even reach 100%. This study has great implications in improving physical understanding of long-term drought evolution under climate change.