Glaciers in the Juneau Icefield in southeastern Alaska are melting at a faster rate than previously thought and may reach an irreversible tipping point sooner than expected, according to a study published on Tuesday. Home to more than 1,000 glaciers, the snow covered area is now shrinking 4.6 times faster than it was in the 1980s, according to a new study.
Researchers at Newcastle University in England found that glacier loss in the icefield, located just north of Alaska’s capital city of Juneau, has accelerated rapidly since 2010.
Glacier melt is a major contributor to rising sea levels, a threat to coastal settlements worldwide. Current rates of ice melt could result in a permanent decline of Juneau Icefield, researchers said.
Researchers meticulously tracked snow levels in the nearly 1,500-square mile icy expanse going back to 1948 with added data back to the 18th century. It slowly shriveled from its peak size at the end of the Little Ice Age around 1850, but then that melt rate sped up about 10 years ago, according to a study in Tuesday’s Nature Communications.
“As glacier thinning on the Juneau plateau continues and ice retreats to lower levels and warmer air, the feedback processes this sets in motion is likely to prevent future glacier regrowth,” Bethan Davies, senior lecturer at Newcastle University and the study’s lead, said in a press release.
In the study, researchers found that the icefield’s volume shrank between 2010 and 2020 at twice the yearly rate recorded from 1979 to 2010.
Juneau Icefield, which runs along Alaska’s border with the Canadian province of British Columbia, has lost a little less than a quarter of its earlier ice volume, according to records going back to 1770, the researchers said. The press release did not give an estimate of when the icefield could completely disappear at its current rate of volume loss.
Every glacier in Juneau Icefield mapped in 2019 had receded relative to their position in 1770, and 108 glaciers had disappeared completely.
“Alaskan icefields – which are predominantly flat, plateau icefields – are particularly vulnerable to accelerated melt as the climate warms since ice loss happens across the whole surface, meaning a much greater area is affected,” said Davies.
It’s melting so fast that the flow of ice into water from now averages about 50,000 gallons every second, according to study co-author Mauri Pelto, a professor of environmental science at Nichols College in Massachusetts.
Scientists have long warned that warming global temperatures, driven by the release of greenhouse gases from the fossil fuel industry, are eating away at glaciers and ice sheets around the world, contributing to higher sea levels that threaten populous coastal cities.
Only four Juneau icefield glaciers melted out of existence between 1948 and 2005. But 64 of them disappeared between 2005 and 2019, the study said. Many of the glaciers were too small to name, but one larger one, Antler glacier, “is totally gone,” Pelto said.
Alaska climatologist Brian Brettschneider, who was not part of the study, said the acceleration is most concerning, warning of “a death spiral” for the thinning icefield.
An icefield is a collection of glaciers, while an ice sheet is something continent-wide and only two of those remain, in Greenland and Antarctica. The most famous glacier in the Juneau icefield is the Mendenhall Glacier, a tourist hotspot. The Arctic is warming about four times faster than the rest of the globe with Alaska warming 2.6 degrees (1.5 degrees Celsius) since 1980, according to federal weather data.
Alaska contains some of the world’s largest icefields, including the Juneau Icefield, which ranks as the fifth largest in North America. The icefield is about 1,500 square miles, according to the U.S. Forest Service, or about the size of Rhode Island.
“When you go there the changes from year-to-year are so dramatic that it just hits you over the head,” Pelto said.
Pelto first went to the Juneau icefield in 1981 to try to make the U.S. ski team and has continued to study it since, giving up competitive skiing for research.
“In 1981, it wasn’t too hard to get on and off the glaciers. You just hike up and you could you could ski to the bottom or hike right off the end of these glaciers,” Pelto said. But now they’ve got lakes on the edges from melted snow and crevasses opening up that makes it difficult to ski, he said.
It’s also now like a staircase of bare rocks there, Pelto said. White snow and ice reflect the sun’s heat, the dark rocks absorb it, making the ground warmer, melting more snow in a feedback effect that amplifies and accelerates the warming-triggered melt, the study said.
“The tipping point is when that snow line goes above your entire icefield, ice sheet, ice glacier, whichever one,” Pelto said. “And so for the Juneau icefield, 2019, 2018, showed that you are not that far away from that tipping point.”
Even if all the snow in the Juneau icefield would melt, and that’s a long way away, it would not add much to global sea levels, Pelto said. But it is a big tourist destination and cultural hot spot, Davies said.
“It is worrisome because in the future the Arctic is going to be transformed beyond contemporary recognition,” said Julienne Stroeve, a University of Manitoba ice scientist who wasn’t part of the study. “It’s just another sign of a large transformation in all the ice components (permafrost, sea ice, land ice) that communities depend on.”
Five different outside experts said the research made sense and fits with other observations. Michael Zemp, head of the World Glacier Monitoring Service, said it shows “that we need urgent and tangible actions to save at least some of the remaining ice.”
“We’re 40 years from when I first saw the glacier. And so, 40 years from now, what is it going to look like?” Pelto said. “I do think by then the Juneau icefield will be past the tipping point.”
The researchers believe the same conditions thinning the Juneau plateau could affect similar icefields across Canada, Greenland, Norway and other high-Arctic locations. Current projections suggest Juneau Icefield’s volume loss will remain consistent until 2040 and accelerate again after 2070, but the researchers believe those projections may need to be updated to reflect their study’s findings. (Reuters/AP)
