Decades of change: how climate is affecting glaciers

As glaciers retreat due to climate change, managers of national parks need to know what’s on the horizon to prepare for the future. A new study led by the University of Washington has measured 38 years of change for glaciers in Kenai Fjords National Park. The 670,000-acre park hosts various types of glaciers that terminate in the ocean, in lakes, or on land.

The researchers identified trends in the glacier types that are disappearing the fastest. The results showed that 13 of the 19 glaciers show substantial retreat, four are relatively stable, and two have advanced. 

“These glaciers are a big draw for tourism in the park – they’re one of the main things that people come to see,” said study lead author Taryn Black, a UW doctoral student. “Park managers had some information from satellite images, aerial photos, and repeat photography but they wanted a more complete understanding of changes over time.”

Lake-terminating glaciers, which include the popular Bear Glacier and Pedersen Glacier, are retreating fastest. Bear Glacier retreated by five kilometers (three miles) between 1984 to 2021, and Pedersen Glacier retreated by 3.2 kilometers (two miles) during the same time period. Glacier retreat in Alaska is 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,” said Black.

One surprising finding was that Holgate Glacier has advanced in recent years. Local boat operators had reported seeing newly exposed land near the glacier’s edge in 2020. The new analysis shows that the overall glacier has been advancing for five years, and appears to go through regular cycles of advance and retreat. The edges of most of the other tidewater glaciers were relatively stable over the study period.

The six land-terminating glaciers all showed an intermediate response, with most retreating in summer months, but at a slower rate than the lake-terminating glaciers. The Paguna Glacier is covered in rock debris from the 1964 Alaska earthquake which insulates the glacier from melting. It was the only glacier to advance during the study period. 

These findings provide a baseline to study how climate change – including warmer air temperatures and changes in precipitation – will continue to affect these glaciers. 

The study can support park managers by helping to quantify the changes that have been occurring. “We can’t manage our lands well if we don’t understand the habitats and processes occurring on them,” said study co-author Deborah Kurtz of the U.S. National Park Service in Seward, Alaska.

“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.”

The study was conducted as part of an internship originally intended to take place at Kenai Fjords National Park. Instead, Black did the research remotely from Seattle and visited local glaciers at Mount Rainier. The project was partially funded by the National Park Service’s Future Park Leaders program, a partnership between the Ecological Society of America and the U.S. National Park Service.

The findings are published in the Journal of Glaciology.

Image Credit: U.S. National Park Service

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By Katherine Bucko, Earth.com Staff Writer