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Fifth National Climate Assessment - Read the Report

Climate-driven changes in heat stress increase extinction risk across some animal populations

Animals that depend on external sources of body heat (for example, fish and reptiles) are known as ectotherms and are especially sensitive to shifts in climate conditions outside the range they are accustomed to. However, risk assessments often focus on changes in average temperature, ignoring the effects of shifts in temperature variability over time on population health. To provide a fuller picture of how heat risks to ectotherm populations might evolve as the climate changes, researchers funded by NSF and NASA integrated fine-scale climate projections from the latest generation of Earth System Models into an ecological model that simulates the effects of heat stress on 38 globally distributed ectotherm species (Duffy et al., 2022). The study revealed complex regional changes in population stability over the twenty-first century but a universal increase in extinction risk and suggests that temperate species may face higher risk than tropical species. These results highlight the importance of accounting for the effects of projected changes in average temperatures, as well as the variance of temperature, to accurately predict global responses of species to warming.