Differential sensitivities of three types of compound drought and heatwave events to human-induced climate change across the globe

Compound drought and heatwave (CDHW) events threaten ecosystems, water security, and human health through mutually reinforcing thermal and hydrological stress. Using CMIP6 multi-model simulations, we quantify influences of human-induced climate change on three CDHW types (i.e., precipitation-based (CMDH), runoff-based (CHDH), and soil-moisture-based (CSDH)) by isolating greenhouse gas, aerosol, and natural forcings (1960-2014). Greenhouse gas forcing emerges as the dominant driver of global CDHW intensification, with CSDH showing the strongest and most coherent amplification of CDHW frequency and severity. Aerosols partially offset warming-induced increases, particularly in monsoon regions. Interpretable machine learning reveals temperature as the primary driver, with precipitation and vapor pressure deficit playing event-dependent roles. Future projections (2015-2100) under high-emission pathways indicate significant severity growth (6.8%, 9.4%, and 15.4% for CMDH, CHDH, and CSDH on average) and sharply rising population exposure (with slope of 0.22, 0.23, and 0.65 for CMDH, CHDH, and CSDH) concentrated in tropical and temperate regions. These findings highlight the urgency of aggressive mitigation and adaptation strategies that address the compound nature of climate extremes and the spatial heterogeneity of anthropogenic impacts.