Escalating heatwave exposure of the elderly across China

With the increasing frequency of heatwaves and a growing aging population, the number of older adults exposed to extreme heat has risen sharply. However, most existing studies assess heatwave exposure for the general population, with limited attention to the elderly. Despite the accelerating demographic shift and escalating climate risks, few studies in China have specifically examined the exposure of the elderly to heatwaves. Addressing these gaps, this study assesses the spatiotemporal dynamics of heatwave exposure among the elderly using historical and projected temperature data under multiple Shared Socioeconomic Pathways (SSPs). Heatwaves were identified based on the Excess Heat Factor (EHF), and exposure was calculated by integrating high-resolution temperature, aging rate, and population datasets. The results indicate that the national average frequency of heatwaves is projected to approach or exceed 30 days from 2041 to 2100, with significant increases observed across more than 67% of the country. Elderly population exposure to heatwave increased from 3.93 million person-days in 2001 to 10.74 million in 2020, with climate effect alone contributing 51.67% to this increase. By 2100, the exposure is projected to reach 116.08 million person-days under SSP2-4.5 and 239.12 million person-days under SSP5-8.5, with the interaction effect between climate change and demographic aging accounting for 60.37 % and 69.53 % of the increase, respectively. This highlights a shift from climate-driven exposure in the historical period to a dominance of interaction effect in the future. These findings underscore the urgent need for tailored adaptation measures to protect vulnerable elderly populations from intensifying heatwave risks.