Global Synchronization of Compound Drought and Hot Extremes

Compound drought–heatwave events (CDHEs) are becoming more frequent across several regions at the same time, heightening global climate risks, yet the processes that lead to their synchronized emergence remain poorly understood. Further, to assess how the governing drivers of synchrony have evolved, we employ statistical approaches to quantify the relative contributions of climatic oscillations and anthropogenic warming to CDHE occurrences. In this study, CDHEs are detected using the Blended Dry and Hot Index (BDHI), and their co-occurrence patterns are analyzed through a global complex-network approach that identifies statistically significant teleconnections. Complex network analysis reveals persistent synchronization hubs in the Amazon, West Africa, the Mediterranean, Southeast Asia, and northern Eurasia, highlighting regions where hot–dry extremes tend to cluster in time. Results also indicate that, although ENSO has historically played a major role in widespread CDHE clusters, its influence has weakened considerably in recent decades.  In contrast, anthropogenic warming exhibits a consistently increasing and statistically significant effect, elevating the baseline probability of CDHEs even during weak or neutral ENSO conditions. Overall, our findings demonstrate a climate-system shift toward warming-dominated synchronization dynamics, in which background warming increasingly overrides natural variability. This transition heightens the risks of simultaneous climate shocks across continents, with major implications for disaster preparedness and global food–water security.