Escalating socioeconomic exposure to extreme heat in China: A CMIP6-based analysis of future heatwaves across regions and scenarios

The future increased frequency and intensity of heat waves (HWs) across China will exacerbate adverse effects on society and the environment. However, changes in socioeconomic exposure remain underexplored. In this study, climate model outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6), together with population and gross domestic product (GDP) projections were used to investigate projected heat stress and socioeconomic exposure across China and its eight subregions under four shared socioeconomic pathway (SSP) scenarios (SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5) over three periods (2021–2040, 2051–2070, and 2081–2100). Our results indicate a consistent upward trend in the Universal Thermal Climate Index (UTCI) across all scenarios, with intensifying increases over time, peaking at > 6 °C. This suggests a continuous increase in the number of extreme heat events (EHEs) in China. Population exposure to EHEs across the four UTCI thresholds (> 26 °C, > 32 °C, > 38 °C, and > 46 °C) shows an increasing trend. Projections indicate a ∼14-fold increase nationwide, 500-fold increase in Northwest China (NWC), and a 1000-fold in Southwest China (SWC2) under SSP5–8.5 by 2081–2100 compared with current levels. The eastern and southeastern regions, especially the Yangtze River and Pearl River Delta, show significant GDP exposure increases under SSP3–7.0 and SSP5–8.5. Population exposure is mainly driven by climatic effects under severe scenarios, whereas GDP exposure is influenced by interaction effects, particularly under SSP5–8.5 and during the 2090s. This study’s findings offer actionable insights for targeted adaptation in China’s diverse geographies.