An Insight into Ice

Glaciers are a magnificent part of the landscape of Kenai Fjords National Park. They are responsible for carving the park's fjords, they nourish downstream ecosystems, and they provide recreational opportunities for visitors to the park. Although glaciers may appear to be permanent, unchanging features—things that change very slowly are often said to move at "a glacial pace"—glaciers are actually quite dynamic, changing in size in response to changes in their environment. How do we know that glaciers are changing in size? One method is to use photographs, taken by people on the ground or from satellites in space. By comparing photographs of the same location from different dates (repeat photography), we can monitor how glaciers change over time. Explore the new story map below to learn more.

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Maritime glacier retreat and terminus area change in Kenai Fjords National Park, Alaska, between 1984 and 2021

Abstract

Glacier change in Kenai Fjords National Park in southcentral Alaska affects local terrestrial, fresh water and marine ecosystems and will likely impact ecotourism. We used Landsat 4–8 imagery from 1984 through 2021 to manually map lower glacier ice margins for 19 maritime glaciers in Kenai Fjords National Park. Of these glaciers, six are tidewater, three are lake-terminating, six are land-terminating and four terminated in more than one environment throughout the study period. We used the mapped ice margins to quantify seasonal terminus position and areal change, including distinguishing between ice loss at glacier termini and along glacier margins. Overall, 13 glaciers substantially retreated (more than 2σ), 14 lost substantial area and only two underwent both net advance and area gain. The glaciers that had insubstantial length and area changes were predominantly tidewater. Cumulatively, the lower reaches of these 19 glaciers lost 42 km² of ice, which was nearly evenly distributed between the terminus and the lateral margins. The rapid rate of glacier change and subsequent land cover changes are highly visible to visitors and locals at Kenai Fjords National Park, and this study quantifies those changes in terms of glacier length and area.

Black, T. and D. Kurtz. 2022. Maritime glacier retreat and terminus area change in Kenai Fjords National Park, Alaska, between 1984 and 2021. Journal of Glaciology, 1-15.