ABSTRACT Compared with heatwaves that occur only at daytime or nighttime, daytime‐nighttime compound heatwaves (CHWs) cause more severe damage to natural ecosystems and human society. This study aims to investigate the relationship between the frequency of compound heatwaves (CHWF) in the Sichuan–Chongqing (SC) region and the atmospheric apparent heat source (AHS) over the southeastern Tibetan Plateau (TP) during 1985–2014. Furthermore, future changes in this relationship and population exposure to CHWs associated with anomalous AHS are examined using simulations from the Coupled Model Intercomparison Project 6 (CMIP6). Results show that this relationship is projected to strengthen significantly during 2071–2100 under the SSP2‐4.5 and SSP5‐8.5 scenarios, with a larger enhancement in the AHS–CHWs linkage under higher emissions, likely associated with amplified interannual variability of the AHS. However, population exposure to CHWs associated with anomalous AHS in the SC region is projected to increase 2.83‐fold and 2.72‐fold for SSP2‐4.5 and SSP5‐8.5, respectively. Exposure risk levels in eastern SC are also projected to increase by the end of this century, with ultra‐high risk zones emerging and covering 1% (2%) of the area, affecting 11% (17%) of the population, under the SSP2‐4.5 (SSP5‐8.5) scenario. This study highlights the escalating threats of AHS‐related CHWs over the SC region in a warmer future, further underscoring the importance and urgency of implementing emission reduction commitments and climate adaptation strategies.
Chen et al. (2026) studied this question.