Dramatic increase in the probability of 2006-like compound dry and hot events over Southwest China under future global warming

Compound dry and hot events, the combination of high temperature and scarce rainfall, are receiving attention in recent times due to their devastating stress on ecosystems, agricultural production, and public health worldwide. Knowing the risk of compound dry and hot events, particularly for the severe ones on record, is essential for developing effective measures to mitigate the negative impacts. However, most of the existing investigations only focus on the long-term trend of compound dry and hot events during the past decades, and future changes in those record-breaking events remain sparsely reported, especially in China. With a focus on the typical severe compound dry and hot event over Southwest China in summer 2006, this study quantifies the future probability of such compound extreme under various emission and societal development scenarios. Results show that the compound dry and hot event in 2006 is the most severe during 1901-2020, with widespread spatial extent in Southwest China. The observed change in temperature plays a dominant role in the variation of compound severity. Based on Coupled Model Intercomparison Project phase 6 (CMIP6) multi-model simulations, we further show that the maximum ratio of the increase in the area affected by compound dry and hot events to that of 2006 is projected to probably be about twofold under the Shared Socioeconomic Pathway (SSP) 1-2.6 scenario in about 2040, while it would likely climb to nearly triple for the other two scenarios SSP2-4.5 and SSP5-8.5 in about 2060 and 2050, respectively. These findings could provide a support for urgent adaptation and mitigation efforts against compound dry and hot events to mitigate the impact.

Automated summary

Compound dry and hot events, characterized by high temperature and scarce rainfall, have negative impacts on ecosystems, agriculture, and public health worldwide. Understanding the risk of these events, especially the severe ones, is crucial for developing effective measures to mitigate their impacts. However, most existing studies focus on the long-term trends of these events in the past, and there is limited information about future changes, especially in China. This study quantifies the future probability of severe compound dry and hot events in Southwest China, and the results suggest that the severity of these events is expected to increase in the future under different emission and societal development scenarios. Urgent adaptation and mitigation efforts are necessary to address these impacts.