Projected Increases in Climate Extremes Across Global Vertebrate Diversity Hotspots

Climate change intensifies periods of climate extremes globally, threatening biodiversity. Vertebrates vulnerable to climate extremes are identified by the International Union for Conservation of Nature, though future changes in these species' exposure remain unclear. Using CMIP6 climate models under four shared socioeconomic pathways, we projected changes in extreme drought, heat, and precipitation frequencies between 1974-2014 and 2050-2090 for 1634 terrestrial vertebrates considered threatened by climate extremes, focusing on 33 vertebrate diversity hotspots. Results indicate substantial exposure increases, with tropical regions facing the largest relative increases in extreme heat and drought. Hotspots with fewer vertebrates considered vulnerable to climate extremes often face larger increases in climate extremes, suggesting vertebrate vulnerability within numerous hotspots is understudied. These results highlight the need to widely incorporate climate projections into conservation assessments, and for targeted research on the effects of climate extremes on tropical vertebrates, which may have lower tolerances to climatic change than temperate counterparts.