The melting of Alaska’s Juneau Icefield, home to more than 1,000 glaciers, is accelerating, with the snow-covered area shrinking 4.6 times faster than it was in the 1980s, according to a new study.
Researchers kept close track of snow depth in the nearly 1,500 square mile icy plain going back to 1948 with added data back to the 18th century. It slowly shrank from its peak size at the end of the Little Ice Age around 1850, but then that rate of melting accelerated about 10 years ago, according to a study in Tuesday Nature communication.
“What happens is that if the climate is changing“We’re going to have shorter winters and longer summers,” lead researcher on the study Bethan Davies, a glaciologist at Newcastle University in England. “We’re going to have more melt, a longer melt season.”
A group of people enjoy the view of Mendenhall Glacier on June 8, 2023, in Juneau, Alaska. (AP Photo/Becky Bohrer, File)
According to Mauri Pelto, co-author of the study and a professor of environmental science at Nichols College in Massachusetts, it’s melting so fast that the flow of ice to water now averages about 55,000 gallons per second.
“In fact, between 2000 and 2020, we are losing more ice from glacier shrinkage in Alaska than anywhere else in the world,” Davies said.
Only four Juneau Icefield glaciers melted between 1948 and 2005. But 64 of them disappeared between 2005 and 2019, the study found. Many of the glaciers were too small to name, but one larger one, Antler Glacier, “is completely gone,” Pelto said.
Alaska climatologist Brian Brettschneider, who was not involved in the study, said the acceleration is most concerning and warned of a “death spiral” for the thinning ice field.
An ice field is a collection of glaciers, while an ice sheet is something that extends across the entire continent, of which there are only two left, in Greenland and Antarctica. The most famous glacier in the Juneau Ice Field is the Mendenhall Glacier, a tourist attraction. The Arctic is warming four times faster than the rest of the world According to federal weather data, temperatures in Alaska have risen 2.6 degrees (1.5 degrees Celsius) since 1980.
People walk on a frozen Mendenhall Lake, with the Mendenhall Glacier in the background, Feb. 18, 2024, in Juneau, Alaska. (AP Photo/Becky Bohrer)
“When you go there, the changes from year to year are so dramatic that it just overwhelms you,” Pelto said.
Pelto first went to the Juneau ice field in 1981 to try to make the U.S. Ski Team. He has continued to study the sport since then, but has retired from competitive skiing to pursue research.
“In 1981, it wasn’t that hard to get up and down the glaciers. You could just hike up and you could ski down or hike all the way off the end of these glaciers,” Pelto said. But now they have lakes at the edges of melted snow and crevasses that make it hard to ski, he said.
It’s also a kind of bare rock staircase there now, Pelto said. White snow and ice reflect heat from the sun, and the dark rocks absorb it, warming the ground and causing more snow to melt in a feedback effect that amplifies and accelerates the warming-induced melt, the study found.
The key is the snow level. Below the snow line, snow can disappear in the summer, but there is snow above it year-round. That snow line keeps moving up, Pelto said.
The shape of the Juneau Ice Field, which is fairly flat, “makes it vulnerable to certain tipping points,” because large areas suddenly become more susceptible to melting as the snow line moves up, Davies said.
“The tipping point is when that snow line comes up above your entire ice field, ice cap, ice glacier, whatever it is,” Pelto said. “And so for the Juneau Ice Field, 2019, 2018, showed you’re not that far from that tipping point.”
Even if all the snow in the Juneau Icefield melted, which is still a long way off, it wouldn’t add much to global sea level, Pelto said. But it’s a major tourist destination and cultural hotspot, Davies said.
“It’s concerning because the Arctic is going to be transformed beyond recognition in the future,” said Julienne Stroeve, an ice scientist at the University of Manitoba who was not involved in the study. “It’s just another sign of a major transformation in all the ice components (permafrost, sea ice, land ice) that communities depend on.”
Davies said the team was able to build such a long-term picture of the ice field’s melting using satellite imagery, aircraft overflights, photographs stored in barrels in a warehouse and historical local measurements. The team was able to piece it all together like a giant jigsaw puzzle, with most of the pieces almost entirely white.
Five different outside experts said the study was meaningful and fit with other observations. Michael Zemp, head of the World Glacier Monitoring Servicesaid it shows “that we need urgent and tangible action to save at least some of the remaining ice.”
“It’s been 40 years since I first saw the glacier. And what will it look like in 40 years?” Pelto said. “I think the Juneau Ice Field will be past the tipping point by then.”
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