Rapid climatic changes are emerging as a major threat to native species and ecosystems in the United States. Temperatures across the United States have already increased an average of 1.8oF, with Alaska warming at nearly twice the rate of the lower 48 states (USGCRP 2017). The decade 2010-2020 was the hottest in recorded history, and the five warmest years on record all have occurred since 2015 (NOAA 2020). Beyond an increase in average temperature, however, several other climate-related factors are of ecological significance, including changes in precipitation patterns (longer and more severe droughts, more intense rainfall events), more powerful storms and hurricanes, longer and more frequent heat waves, melting of permafrost, and rising sea levels. Changing climatic factors in turn have cascading ecological impacts, which include shifts in the distributional range of plant and animal species, shifts in breeding seasons and other lifecycle events including migrations, and disruption of interactions among interdependent species (e.g., pollinators) (Staudinger et al. 2013). Climate-related impacts are also being documented at the ecosystem level, with changes occurring in the species composition of many habitats, in ecosystem processes, such as water and nutrient cycling, and even in the structure of the ecosystem, such as conversion of forest to shrub or grassland (Grimm et al. 2013).
Several species already have been listed under the Endangered Species Act primarily as a result of climate change-related threats, including polar bear (Ursus maritimus), bearded seal (Erignathus barbatus), and several species of coral (e.g., Acropora palmata and A. cervicornis). Many other federally listed species are regarded as sensitive to climate change (Delach et al. 2019), complicating their recovery prospects, and numerous other species are considered climate-vulnerable and could experience declines to a level where ESA protections may be warranted. Rapid and accelerating climatic change increasingly is becoming a defining concern for biodiversity conservation and wildlife management (Stein et al. 2013, Inkley and Stein 2020).
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Author
Bruce Stein, Ph.D., Chief Scientist and Associate Vice President
National Wildlife Federation