Summary/Abstract
This peer-reviewed study uses geographical data for approximately 36,000 marine and terrestrial species and climate projections to 2100 to show that area of each species’ geographic range in which it is at risk for exposure to dangerously high temperatures is expanding abruptly. On average, more than 50% of the exposure projected for a species will occur in a single decade. This is true both on land and in the ocean. The number of species at risk of exposure to extreme temperatures doubles from about 15% under a 1.5º C warming scenario to more than 30% under a 2.5º C scenario. This exposure to extreme temperature has the potential to drive mass die-offs and population declines of many species, causing cascading ecosystem impacts that will impact natural resources on which human societies depend. The expanding area over which species are threatened by extreme temperatures increases the risk of local and global extinctions. The rapid speed of this change is especially concerning, because it will provide less time for species to respond via evolution or dispersion, and less time for humans to implement conservation or adaptation policies.