Why must some species move toward the poles or higher elevations as temperatures rise?

As temperatures rise due to global warming, many species are shifting their geographic ranges toward the poles or higher elevations to remain within their suitable climate envelopes—the specific range of temperatures and conditions they require to survive.12

Because most organisms are adapted to long-term seasonal climate patterns, they have limited physiological capacity to withstand sudden, significant increases in temperature. Moving toward cooler habitats, such as higher latitudes or mountaintops, allows these species to escape heat stress and maintain their necessary thermal environment.312

However, this migration is not always successful. Species with small geographic ranges, particularly those already living on mountaintops, face a critical threat because they have nowhere else to go as their habitats become too warm. Furthermore, even for mobile species, human-made barriers like highways and cities can impede their ability to reach these cooler areas. Ultimately, if a species' suitable climate envelope shrinks to nothing, it faces an increased risk of extinction.21