As climate change accelerates, effectively monitoring and managing the growing impacts on biodiversity is an urgent priority. Here, we identify the exposure of species to unprecedented heat to evaluate the potential impact of 2024-the hottest year on record-across >33,000 vertebrate species worldwide. One in six (5,368) species were exposed to unprecedented temperatures across >25% of their range-68% more species than in 2023. Most (81%) species exposed in 2023 were also exposed in 2024, potentially compounding risks. For the first time, widespread species were exposed to extreme temperatures across >10% of their ranges. We propose using these exposure estimates to inform monitoring and mitigation efforts to avoid the worst impacts of climate change.
Keywords: 2024; early warning; extinction debts; extreme climate; thermal exposure.