Alaskan glaciers undergo an extra three weeks of melting for every 1°C of summer warming, study finds

Emerging research suggests Alaska's glaciers may be more exposed to warming than many people assume, as ScienceDaily detailed. In a paper published in Nature, scientists reported that Alaska's glaciers can change rapidly when summers get hot.

What happened?

To document that pattern, the team explained in a news release how it analyzed synthetic aperture radar, or SAR, observations to follow seasonal melt and shifting snowlines on more than 3,000 glaciers statewide from mid-2016 to 2024.

Every 1 degree Celsius (1.8 degrees Fahrenheit) increase in average summer temperature extends glacier melting by roughly three weeks, the scientists revealed.

Led by recent Carnegie Mellon University doctoral graduate Albin Wells, the researchers used Europe's Sentinel-1 radar satellites, which are especially valuable in Alaska because they can collect data through cloud cover and in darkness.

"Our ability to quantify these changes is really important," he said in the release. "Melt extents and snowlines are proxies for glacier mass balance."

That gave scientists a more continuous view of glacier conditions across the year; optical instruments are often used near the end of the melt season.

They also found that brief but intense heat waves stripped away up to 28% more of the snow layer that protects glacier ice in some mountain ranges, leaving the surface more exposed to further melt.

Why does it matter?

More time spent melting generally translates into more total ice loss. That kind of change can reshape landscapes, affect freshwater systems, and intensify the impacts of the warming planet.

The researchers said melt days are a useful way to track this shift since when the number rises, the season of ice loss is lasting longer.

A detailed look at 2019 showed how quickly that can happen. From June 23 to July 10, a heat wave pushed temperatures 20 to 30 degrees above average in many places, and Anchorage reached 90 F.

During that event, glacier snowlines climbed nearly 350 feet above normal, reaching elevations they typically would not hit until about two months later, the researchers found.

When protective snow vanishes sooner, bare ice and firn stay exposed longer, making continued melting more likely.

The authors said in the release that the findings show "the sensitivity of glaciers to short-term climatic variability."

What are people saying?

Wells emphasized the importance of understanding glacier mass balance. 

"These correlations with temperature begin to give a sense for how much melt or snowline retreat we can anticipate under future, warmer climates across the region," he said.

Mark Fahnestock of the University of Alaska Fairbanks Geophysical Institute added that radar solves a major monitoring challenge.

"In optical data, the snowline can be really hard to observe," he said, per the release. "If you're a day late taking your picture, it might have snowed on the entire glacier, and you can't see where the bare glacier ice is down below and where the snow and firn is above."

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