Changes in climate are driving widespread landscape changes in northern ecosystems, altering the size and distribution of wildlife populations over multi‐decadal time scales. Extreme weather events are also expected to become more common over time, affecting a variety of species, and mountain ungulates may be particularly susceptible because they occupy habitats with particularly harsh winter weather conditions. To explore the impacts of weather conditions and adverse weather events as population drivers, we surveyed Dall's sheep throughout their latitudinal range in Alaska and assessed lamb production and population trend in relation to end of the continuous snow season (CSS) as a measure of spring onset. In 2013, spring onset was extraordinarily late, providing an opportunity to directly assess the impacts of variability in weather on sheep population dynamics. We hypothesized that the timing of the end of the CSS would have greater impacts in arctic areas where conditions are presumably most limiting. We found that lamb production was negatively related to the annual timing of the end of the CSS and was near 0 in arctic areas in 2013. The 2013 event was also associated with ~40–70% declines in overall sheep numbers in arctic areas, indicating adult survival was also impacted. Overall, our results suggest that expected increases in adverse weather events may have direct, lasting impacts on mountain ungulate populations and that these impacts can be expected to be most extreme for populations occurring at northern range limits where growing season conditions are most restricted.

Observational networks are important for an improved understanding of ecohydrological processes and for improving gridded climate products, yet few studies employing these networks have been undertaken at higher latitudes. We evaluated physiographic controls on summer temperature in Denali National Park and Preserve in Alaska, United States while accounting for synoptic temperature conditions, finding shallow minimum temperature lapse rates, effects of solar radiation, and interactions between physiography and synoptic conditions. Average temperature from monthly gridded climate data was overall warmer than observed while lapse rates from observed data were somewhat steeper and more variable over time than gridded data.

Abstract. Recent observations of near-surface soil temperatures over the circumpolar Arctic show accelerated warming of permafrost-affected soils. The availability of a comprehensive near-surface permafrost and active layer dataset is critical to better understanding climate impacts and to constraining permafrost thermal conditions and its spatial distribution in land system models. We compiled a soil temperature dataset from 72 monitoring stations in Alaska using data collected by the U.S. Geological Survey, the National Park Service, and the University of Alaska Fairbanks permafrost monitoring networks. The array of monitoring stations spans a large range of latitudes from 60.9 to 71.3∘ N and elevations from near sea level to ∼1300 m, comprising tundra and boreal forest regions. This dataset consists of monthly ground temperatures at depths up to 1 m, volumetric soil water content, snow depth, and air temperature during 1997–2016. These data have been quality controlled in collection and processing. Meanwhile, we implemented data harmonization evaluation for the processed dataset. The final product (PF-AK, v0.1) is available at the Arctic Data Center (https://doi.org/10.18739/A2KG55).

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.