Rising Temperatures Will Amplify the Risk of Future Compound Dry–Hot Events over the Mongolian Plateau

Abstract Compound dry–hot events (CDHEs) have been significantly exacerbated under global warming. The Mongolian Plateau, characterized by its distinctive geographical location and high climate sensitivity, serves as an ideal region for understanding CDHEs in continental arid and semiarid environments. Using CRU reanalysis data and the NASA Earth Exchange Global Daily Downscaled Projections for CMIP6 (NEX-GDDP-CMIP6) dataset, we constructed the standardized compound dry–hot index (SCDHI) to quantify CDHE severity. Employing trend analysis, cumulative distribution functions (CDFs), and the Shapley additive explanation model, this study investigated the spatiotemporal characteristics of summer CDHEs under historical and future emission scenarios and attributed CDHE responses to distinct extreme climatic drivers. The results reveal that during the historical period, CDHEs intensified across 99% of the Mongolian Plateau, with 93% of the region exhibiting statistically significant trends. The most substantial changes occurred in the hyperarid zone, where the SCDHI decreased at a rate of 0.0212 yr −1 . Projections under the shared socioeconomic pathway (SSP) 1-2.6, SSP2-4.5, and SSP5-8.5 scenarios suggest continued exacerbation of CDHE severity by the mid-to-late twenty-first century. Notably, higher emission pathways correspond to greater severity, particularly within the southwestern hyperarid zone. While extreme temperatures predominantly influenced historical CDHEs, drought conditions are expected to become dominant in the future. Crucially, maximum temperature remains a pivotal driver of future CDHE intensification, primarily through its regulation of potential evapotranspiration. By comprehensively evaluating the spatiotemporal evolution and underlying mechanisms of CDHEs, this study elucidates the dynamics of extreme climatic events in arid and semiarid regions and provides a robust scientific basis for regional climate adaptation strategies. Significance Statement The frequency of compound dry–hot events (CDHEs) has increased significantly, posing a serious threat to ecosystems and human societies, particularly in vulnerable arid and semiarid regions. This study examines CDHEs over the Mongolian Plateau by constructing the standardized compound dry–hot index (SCDHI) using the NASA Earth Exchange Global Daily Downscaled Projections for CMIP6 (NEX-GDDP-CMIP6) dataset. Through trend analysis, cumulative distribution functions (CDFs), and the Shapley additive explanation (SHAP) model, we comprehensively evaluate the spatiotemporal characteristics of CDHEs under historical and future emission scenarios. Historical analysis indicates that CDHEs over the Mongolian Plateau demonstrate a significant increasing trend. Projections suggest concurrent intensification in both the frequency and severity of CDHEs, with the most pronounced amplification observed in the southwestern arid desert regions. While high temperatures predominantly influenced historical CDHEs, drought conditions are expected to exert a stronger influence in the future, with maximum temperature contributing indirectly through its enhancement of potential evapotranspiration.