Linkages of Multiple Types of Compound Droughts and Hot Events at the Global Scale

Abstract

Precipitation deficits in the hydrologic cycle lead to various types of droughts, including meteorological, agricultural, and hydrological droughts. The concurrence of different types of droughts and high temperatures, commonly termed compound drought and hot events (CDHEs), including compound meteorological drought-hot events (CMDHEs), compound agricultural drought-hot events (CADHEs), and compound hydrological drought-hot events (CHDHEs), has received increasing attention due to their larger impacts than single events. Although different CDHEs have been evaluated separately, the linkages among them have seldom been quantified. Using monthly hydroclimatic variables, we evaluated spatial variations and temporal linkages of different CDHEs from 1952 to 2021. High frequencies of different CDHEs are observed in regions such as northeastern South America, central Africa, and southeastern China. The strong synchronous linkages among CDHEs, defined as the likelihood of simultaneous CADHEs/CHDHEs conditional on CMDHEs, are observed in low-latitude regions, which are related to drought propagations. Additionally, cascading linkages, defined as the empirical likelihood of subsequent CADHEs/CHDHEs conditional on CMDHEs, are also modulated by temperature persistence. For different climate types, the strongest linkages are observed in equatorial climates, while the weakest linkage is found in snow climates. These findings provide critical insights for developing cross-sectoral mitigation strategies to reduce CDHE-related risks and enhance predictive capabilities for such compound events by considering their temporal linkages under global warming.