Alaskan Glaciers in a Warming Climate

Glaciers across Alaska are undergoing rapid mass loss, with implications for sea-level rise, natural hazards, water resources, and more. Here, we utilize new snowline and melt extent observations of Alaskan glaciers at high spatiotemporal resolutions to improve projections to 2100. Specifically, we incorporate these observations into the calibration scheme for the large-scale Python Glacier Evolution Model (PyGEM), and subsequently simulate future changes under various climate scenarios. We estimate that glaciers in Alaska will lose 49 ± 17% to 73 ± 26% of their 2015 mass by the end of the century, depending on the future climate. Nearly all small glaciers (<1 km2) will disappear by 2100 regardless of the climate scenario, along with the smallest glacierized subregions of Alaska, namely, the Brooks and Talkeetna ranges. Across larger subregions, negative mass balance is projected to peak in the middle of the 21st century for the modest future warming scenario (i.e., SSP1-2.6), while negative mass balance continues to increase to 2100 for the most aggressive future warming scenario (SSP5-8.5). Much of these changes are attributed to increasing temperatures that cause greater melt in addition to a shift in early-winter precipitation from snow to rain which reduces accumulation and enhances melt by exposing the underlying ice earlier in the next ablation season. Of the remaining glaciers in 2100, 15%–60%, depending on the future climate, have no accumulation area and are thus committed to disappearance. Overall, the widespread loss of glaciers in Alaska by 2100 has implications on ecology, water resources, natural hazards, and tourism across the region.