Spatiotemporal evolution of heatwaves and their impact on excess mortality in China: A historical analysis and future projection based on observations and CMIP6 simulations

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Heatwaves represent a significant meteorological hazard with profound societal impacts. Based on the ground observation data from National Climatic Data Center (NCDC) and simulated meteorological data from Coupled Model Intercomparison Project Phase 6 (CMIP6), the temporal and spatial evolution of heatwaves in China was analyzed, and the past, present and future heatwaves in Wuhan were quantitatively evaluated, as well as the impacts on excess mortality.Overall, heatwaves primarily occurred in Xinjiang, central China, East China, South China and parts of Southwest China, showing clear spatial heterogeneity. Projections suggest that heatwaves will expand to affect all regions of the country, with significantly longer exposure durations. Under the three Shared Socioeconomic Pathway scenarios, both the annual duration and excess mortality in Wuhan are projected to show fluctuations with an overall increasing trend. After 2040, the differences in mortality among the three scenarios become more pronounced. In the high economic growth scenario, society may experience exposure to heatwaves for up to four months annually, leading to a substantial increase in mortality risks. Under the low emission, the moderate emission and high emission scenarios, the projected annual increase in heatwave-attributable excess mortality in Wuhan is approximately 4.85, 30.61, and 670.87 deaths per 1 million people, respectively.