Disproportionate magnitude of climate change in United States national parks
Anthropogenic climate change is altering ecological and human systems globally, including inUnited States (US)national parks, which conserve unique biodiversity and resources. Yet, themagnitude and spatial patterns of climate change across all the parks have been unknown.Here, in thefirst spatial analysis of historical and projected temperature and precipitation across all 417USnational parks, we show that climate change exposes the national park areamore than theUS as awhole. This occurs because extensive parts of the national park area are in the Arctic, at high elevations, or in the arid southwesternUS. Between 1895 and 2010,mean annual temperature of the national park area increased 1.0 °C±0.2 °Ccentury (mean±standard error), double theUS rate. Temperature has increasedmost in Alaska and its extensive national parks. Annual precipitation of the national park area declined significantly on 12%of national park area, compared to 3%of theUS.Higher temperatures due to climate change have coincidedwith low precipitation in the southwesternUS, intensifying droughts in the region. Physical and ecological changes have been detected and attributed mainly to anthropogenic climate change in areas of significant temperature increases inUS national parks. From2000 to 2100, under the highest emissions scenario (representative concentration pathway [RCP] 8.5), park temperatures would increase 3 °C–9 °C,with climate velocities outpacing dispersal capabilities ofmany plant and animal species. Even under the scenario of reduced emissions (RCP2.6), temperature increases could exceed 2 °C for 58%of national park area, compared to 22%of theUS.Nevertheless, greenhouse gas emissions reductions could reduce projected temperature increases in national parks by one-half to two-thirds.