High exposure of United States national parks to anthropogenic climate change and applications of new spatial data to adaptation

Anthropogenic climate change is altering ecosystems globally, including in national parks and other protected areas that are essential for conserving global biodiversity. Spatial patterns and magnitudes of climate change across the national parks of the United States (U.S.) have been unknown, however, due to the lack of a consistent spatial analysis of climate across all the parks. Furthermore, achieving the mission of the U.S. National Park Service to conserve resources unimpaired for future generations would benefit from spatial data on climate change trends, which would inform resource management decisions under climate change. We have addressed these information needs through the first spatial analysis of historical and projected temperature and precipitation trends across the 417 U.S. national parks. Our results show that temperature increases have been twice as high and areas of significant precipitation decreases have been higher in the national park area than in the U.S. as a whole in the period 1895-2010. This derives from the extensive area of national parks at high latitudes and elevations and in arid lands. We downscaled the coarse-scale climate projections to a spatial resolution of 800 m to provide data that is more useful for resource management decisions. Under the highest emissions scenario (RCP8.5), temperatures in the period 2000-2100 could increase at five times historical rates. Reducing greenhouse gas emissions from human sources would reduce the future exposure of national parks, although even under the reduced emissions scenario (RCP2.6), more than half of the national park area could experience temperature increases that exceed the 2ºC Paris Agreement goal. Our results provide data for analyses of historical changes and future vulnerabilities of ecosystems to wildfire increases, glacial melt, invasive species, biome shifts, and other disturbances. National parks are taking steps to use the new data to develop comprehensive park plans that account for potential future scenarios, guide conservation of refugia, target prescribed burning, and develop other adaptation measures to protect ecological integrity under human-caused climate change.