Increased mean annual temperatures in 2014–2019 indicate permafrost thaw in Alaskan national parks

Rising temperatures in the Arctic can result in thaw of permafrost, with widespread implications for ecosystems and infrastructure. We analyzed mean annual air and ground temperatures in the eight northernmost national parks in Alaska using data from thirty-three National Park Service climate monitoring stations and eight National Weather Service stations. Mean annual air temperatures (MAATs) from 2014 to 2019 increased in a stepwise fashion relative to the preceding thirty-year period by at least 1°C at all locations in the study area; the increase was near 2°C in Denali National Park and most of the Arctic Alaska parks and 3°C in the far western coastal areas of the Arctic parks. The increase in mean annual ground temperatures (MAGT) was approximately equal to the increase in MAAT in windswept tundra areas with minimal snow, whereas under deeper taiga and alpine snowpacks the increase in MAGT was about half as large as the increase in MAAT. If the warm temperatures observed during 2014 to 2019 persist, there will be widespread degradation of permafrost in portions of these national parks and in similar environments across Alaska.