Global expansion of compound drought–heatwave risk

The increasing frequency of compound drought and heatwave (CDHW) events poses a growing threat to water security, agriculture, and ecosystems. However, the evolution, expansion, and spatial reorganization of CDHW hotspots across global land regions remain largely unexplored. Here we track more than 2500 CDHW events using a three-dimensional connected-component (CC3D) labeling approach and show that CDHWs, often treated as spatially stationary extremes, exhibit systematic displacement over time. Larger and longer-lasting events tend to travel farther and faster, expanding the spatial footprint of compound heat and moisture stress. Most contiguous events persist for 6–12 days, displace by up to ~500 km, and reach peak daily spatial extents of 2–5 × 10⁵ km². Migration is strongest in the Northern Hemisphere mid-latitudes and is predominantly eastward. We identify emerging hotspots of increasing CDHW migration potential across the European Plains, western North America, the Amazon, the West African Sahel, Central Asia, and northern Australia. These shifts are linked to evolving large-scale atmospheric circulation and are reinforced by downstream drying through reduced moisture transport and strengthened land–atmosphere coupling. Increasing CDHW migration potential over agricultural landscapes may expand exposure to compound heat and moisture stress, particularly in grazing-dependent regions vulnerable to pastureland-to-scrubland transitions. This study shows that compound drought-heatwave events exhibit systematic displacement over time, with larger and longer-lasting events tending to travel farther and faster, especially in the Northern Hemisphere mid-latitudes, with a dominant eastward direction.