Temperature-induced shift in 21st-century Amazon droughts

Abstract The Amazon Basin (AB) has been experiencing a transition in hydroclimatic extremes induced by climate change; however, the relative contributions of precipitation deficits versus rising atmospheric evaporative demand (AED) remain poorly understood. Here, we analyzed and ranked AB droughts from 1980 to 2024, revealing that the 2023/24 event was unprecedented, affecting 88% of the basin with a magnitude four times greater than the average top-5 droughts. Notably, other years since 2020 also appear in the top rankings, underscoring how extreme conditions have persisted and intensified since the beginning of the decade. Our analysis of the AED contribution suggests a regime shift occurring during the 21st century. While earlier droughts were primarily precipitation-driven, the post-2005 era is characterized by a temperature-driven regime, where climate change-induced warming increases AED, acting as the primary intensifying mechanism for exceptional drought events. This intensification is further linked to sea surface temperature anomalies in the Tropical Indian, Tropical Pacific, and North Atlantic oceans.