Land‐Feedbacks‐Driven Dry‐Hot Mutual Reinforcement Extends Global Compound Drought‐Heatwave Durations

Abstract Under global warming, numerous compound events have emerged, yet the physical linkages between the two factors often remain unclear. The increasing frequency of droughts and heatwaves has raised the likelihood of compound drought and heatwave events (CDHE) worldwide, accompanied by frequent long‐lasting mega‐CDHE posing serious exposure risks. Nevertheless, the mechanisms governing CDHE duration remain poorly understood. Here, we propose a compound mechanism that prolonged CDHE durations, beyond the contribution of atmospheric dynamics. This mutual reinforcement loop initiates a “T‐D” (temperature‐to‐drought) moisture process: sustained high temperatures and low precipitation increase the vapor pressure deficit, intensifying atmospheric evaporative demand and meteorological drought. Subsequently, a “D‐T” (drought‐to‐temperature) energy process occurs as drought alters surface energy partitioning, reducing evaporation, latent heat flux, and soil heat capacity, thereby raising soil temperature and reinforcing land‐atmosphere feedback. Locally dry soils extend the Soil moisture (SM)‐temperature feedback, which amplifies air temperatures and prolongs CDHE duration through three principal pathways: enhanced sensible heat flux (globally, 0%–19%), increased skin temperature (notably in northern Europe, Africa, and Australia, 0%–16%), and surface pressure modifications affecting temperature advection (in Europe, Africa, and Australia, 0%–5%). Meanwhile, an additional energy‐related pathway involves local SM‐evaporation coupling, which modulates atmospheric moisture advection, and downward longwave radiation, thereby influencing CDHE. Thus, the compound mechanism of intensified dry‐hot reinforcement—driven by land feedback and associated thermodynamic processes—is necessary to drive long‐lasting CDHE, operates beyond the contribution of atmospheric dynamics, and should be incorporated into CDHE predictions.