Increases of Compound Hot Extremes Will Significantly Amplify the Population Exposure Risk Over the Mid–High Latitudes of Asia

Abstract

Based on Coupled Model Intercomparison Project phase 6 (CMIP6) simulations, we found that the frequency and intensity of daytime–nighttime compound hot extremes (HEs) in the mid-high latitudes of Asia (MHA) are expected to increase. The most significant increase is anticipated under the shared socioeconomic pathway (SSP) 5-8.5, while the smallest increase is expected under SSP1-2.6. Notably, unlike the decreasing trends of independent HEs since 2050 under the high emission scenarios, the compound HEs, which comprise the largest proportion, are expected to continuously increase and intensify. To better understand the impact of these changes on human society, we also focused on changes in population exposed to HEs. The findings reveal that population exposure to compound and nighttime HEs is projected to increase most rapidly under SSP3-7.0, with estimates indicating increases of 10.06 and 3.80 times, respectively, by the end of the century. The most significant increases are expected in the mid-latitudes, where changes in HEs are most pronounced. Climate change is the primary driver behind the rising population exposure to compound and nighttime HEs, with its impact expected to grow over time. Conversely, exposure to daytime HEs is primarily influenced by population changes, particularly in urban areas. Therefore, effective climate change mitigation and adaptive strategies are crucial to reducing future population exposure to HEs in MHA.