The growing threat of spatially synchronized dry-hot events to global ecosystem productivity

Compound hazards, like simultaneous occurrence of unusually dry and hot (DH) weather, cause cascading socio-economic damages that surpass univariate hazards. In the context of agricultural production, DH events triggered by pressure and moisture flux anomalies are responsible for some of the most severe agricultural losses across the globe. Most analyses focus on characterizing compound events in individual regions, and the extent of spatial synchrony of DH events and their impacts on crop production has yet to be quantified. Here, using observation-based gridded precipitation and temperature data, we find that the frequency of widespread spatial synchrony–defined as five or more regions simultaneously experiencing DH events–has increased nearly ten-fold over the past four decades, while confined events are declining. This rapid synchronization, especially in recent decades, reflects a non-linear response to global warming. At global scale, substantially larger productivity losses are observed during widespread DH events as compared to the spatially confined DH events. Wheat cropland exhibits the strongest losses during synchronized DH events, followed by maize, with weaker effects for rice. The results highlight the importance of considering the growing occurrence of spatially widespread DH events in assessments of agricultural risk, alongside analyses of individual regional extremes.