Limiting future warming reduces drought exposure for terrestrial vertebrates

Abstract

Ambitious conservation efforts are needed to curb biodiversity loss as drought severity intensifies globally. Here, we assess the exposure of resident terrestrial vertebrates within global biodiversity hotspots to drought severity surpassing the extremes experienced during their pre-industrial history. We show that 22.5% of threatened terrestrial vertebrates (especially reptiles and amphibians) have recently experienced drought severity exceeding their historical extremes across at least half of their current geographic range. Under an intermediate greenhouse gas emission scenario (Shared Socioeconomic Pathway 2-4.5), this proportion is projected to reach 36.5% by the latter half of the 21st century, with mid-latitude dryland biodiversity hotspots facing the most severe drought exposure. Importantly, a low-warming future (Shared Socioeconomic Pathway 1-2.6) will reduce exposure estimates of species by 8.5% compared to Shared Socioeconomic Pathway 2-4.5, highlighting the urgency of ambitious climate mitigation. However, as future drought exposure is projected to increase across most biodiversity hotspots, and many exposed regions face inadequate protection and substantial social burdens, expanding adaptive conservation without compromising local well-being is essential. Our findings offer spatial guidance for prioritizing conservation and adaptive strategies in biodiversity hotspots, contributing to global biodiversity targets.