Spatial compounding of droughts and hot extremes across southwest and east China resulting from energy linkages

Abstract

The concurrence of droughts and hot extremes at the same location can lead to immense damagesto water resources, agriculture, and ecosystems. However, assessment of simultaneous occurrences of the two extremes at multiple regions, which can lead to amplified impacts due to socioeconomic linkages such as energy transmission, has been limited. In this study, we first demonstrated the characteristics of this type of compound extremes based on droughts in Southwest China (SC) and hot extremes in East China (EC) during 2022. We then evaluated changes in the frequency and duration of this type of compound extremes in historical periods from 1979 to 2022. Finally, we projected changes in these characteristics during the future period (2025–2044) based on simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Results showed that droughts in the SC (associated with hydropower losses) and hot extremes in the EC (associated with surging electricity) peaked in July-August 2022, which constituted the spatially compounding droughts and hot extremes (CDHEs). For the historical period, the spatial CDHEs have occurred several times, including the summer of 1994, 2006, 2016, and 2022. Future projections showed that the frequency and duration of this type of CDHEs may increase in the future compared with the rare occurrences in historical periods, which largely results from substantial increases in hot extremes in EC. This study provides useful insights into the adaptation measure of compound droughts and hot extremes in China, which can be beneficial for energy security in a changing climate.