Aug 8 2022Reviewed by Alex Smith
National park managers need to be aware of impending changes to plan for the future as glaciers throughout the world retreat as a result of climate change. Recent research by the University of Washington and the National Park Service analyzes 38 years of change for glaciers in Kenai Fjords National Park, a spectacular jewel about 2 hours south of Anchorage.
Almost half of Kenai Fjords National Park is covered by glacial ice. Glaciers play an important role in sculpting the park’s landscape. Bear Glacier, shown here in September 2019, has retreated more than 5 km (about 3 miles) from 1984 to 2021, according to the new study. The lagoon at the glacier’s base is growing as the glacier retreats. Image Credit: US National Park Service/Deborah Kurtz.
According to the research, which was published on August 5th, 2022, in The Journal of Glaciology, 13 of the 19 glaciers are significantly retreating, while four are largely steady, and two have advanced. Additionally, it identifies patterns in the fastest-disappearing glacier kinds. Numerous glaciers can be found inside the park’s almost 670,000 acres; some end in the ocean, while others do so in lakes or on land.
These glaciers are a big draw for tourism in the park—they’re one of the main things that people come to see. Park managers had some information from satellite images, aerial photos, and repeat photography but they wanted a more complete understanding of changes over time.
Taryn Black, Study Lead Author and Doctoral Student, Earth and Space Sciences, University of Washington
Lake-terminating glaciers, such as the well-known Bear Glacier and Pedersen Glacier, are retreating at the fastest rate, according to the research. Between 1984 and 2021, Bear Glacier receded by 5 km (3 miles), and Pedersen Glacier retreated by 3.2 km (2 miles) over that time.
“In Alaska, much glacier retreat is being driven by climate change. These glaciers are at really low elevation. It’s possibly causing them to get more rain in the winter rather than snow in addition to warming temperatures, which is consistent with other climate studies in this region,” adds Black, who will complete her doctoral degree at the UW this month.
Holgate Glacier, a tidewater glacier that terminates at the ocean, has been moving forward lately. In 2020, local boat captains had mentioned seeing newly exposed land close to the glacier’s edge.
However, the new analysis reveals that the glacier has been moving forward as a whole for nearly five years and seems to advance and retreat in predictable cycles. Most of the other tidewater glaciers’ edges remained largely constant throughout the study period.
The six glaciers that terminated on land all displayed a mixed response, with most retreating, especially during the summer, but at a slower rate than the glaciers that terminated on lakes. The land-terminating Paguna Glacier, which is covered with rock debris from a landslide brought on by the 1964 Alaska earthquake, was the only other glacier to advance throughout the research period. The glacier’s surface is protected from melting by this debris.
Black traced the outlines of each of the 19 glaciers — a total of around 600 outlines — using 38 years’ worth of satellite photos taken in the fall and spring. To locate where the glacier’s margin was, she visually examined each photograph. Black recently calculated the rate of retreat of marine-terminating glaciers in west Greenland using a similar methodology.
The updated statistics for Alaska serve as a foundation for research on how these glaciers may be affected going forward by climate change, which includes increased air temperatures as well as modifications to both the kind and amount of precipitation. Due to their exposure to the humid, warm maritime climate, all of the glaciers in the research are classified as maritime glaciers.
The research has immediate application for park managers. These numbers aid in putting a numerical value on the changes that have been taking place and will continue to affect glaciers and the areas around them.
We can’t manage our lands well if we don’t understand the habitats and processes occurring on them.
Deborah Kurtz, Study Co-Author, US National Park Service, Seward, Alaska
As the park’s Physical Science Program Manager, Kurtz is also interested in the changes to the nearby river, lake, and landscape ecosystems and how to communicate those changes to the general public.
Interpretation and education are also an important part of the National Park Service mission. These data will allow us to provide scientists and visitors with more details of the changes occurring at each specific glacier, helping everyone to better understand and appreciate the rate of landscape change we are experiencing in this region.
Deborah Kurtz, Study Co-Author, US National Park Service, Seward, Alaska
The current research was carried out as part of an internship originally intended to take place at Kenai Fjords National Park. However, Black carried out the study remotely from Seattle and visited local glaciers at Mount Rainier. The study was partly funded by the National Park Service’s Future Park Leaders program, a partnership between the Ecological Society of America and the US National Park Service.
A visit to Mt. Baker's Easton Glacier
A visit to Mt. Baker’s Easton Glacier. Video Credit: University of Washington.
Journal Reference:
Black, T. & Kurtz, D. (2022) Maritime glacier retreat and terminus area change in Kenai Fjords National Park, Alaska, between 1984 and 2021. Journal of Glaciology. doi.org/10.1017/jog.2022.55.
Source: https://www.washington.edu/