The melting of Alaska's Juneau icefield, home to more than 1,000 glaciers, is accelerating. The snow covered area is now shrinking 4.6 times faster than it was in the 1980s, according to a new study.
Researchers meticulously tracked snow levels in 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
鈥淲hat鈥檚 happening is that as , we鈥檙e getting shorter winters and longer summers,鈥� study lead author Bethan Davies, a glaciologist at Newcastle University in England. 鈥淲e鈥檙e having more melt, longer melt season.鈥�
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.
鈥淚n fact, glacier shrinkage in Alaska from the year 2000 to the year 2020, we're losing more ice in Alaska than anywhere else,鈥� Davies said.
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, 鈥渋s totally gone,鈥� Pelto said.
Alaska climatologist Brian Brettschneider, who was not part of the study, said the acceleration is most concerning, warning of 鈥渁 death spiral鈥� 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 The Arctic is warming about with Alaska warming 2.6 degrees (1.5 degrees Celsius) since 1980, according to federal weather data.
鈥淲hen you go there the changes from year-to-year are so dramatic that it just hits you over the head,鈥� 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.
鈥淚n 1981, it wasn鈥檛 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,鈥� 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.
Key is the snow elevation line. Below the snow line, snow can disappear in the summer, but there's snow cover year-round above. That snow line keeps moving upward, Pelto said.
The shape of Juneau's icefield, which is rather flat, 鈥渕akes it vulnerable to particular tipping points鈥� because once the snow line moves up, large areas are suddenly more prone to melt, Davies said.
鈥淭he 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.鈥�
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.
鈥淚t is worrisome because in the future the Arctic is going to be transformed beyond contemporary recognition,鈥� said Julienne Stroeve, a University of Manitoba ice scientist who wasn't part of the study. 鈥淚t's just another sign of a large transformation in all the ice components (permafrost, sea ice, land ice) that communities depend on.鈥�
Davies said the team was able to get such a long-term picture of the icefield鈥檚 melting from satellite images, airplane overflights, pictures stored away in drums in a warehouse and historical local measurements, stitching them all together like a giant jigsaw puzzle with most of the pieces 小蓝视频 nearly all white.
Five different outside experts said the research made sense and fits with other observations. Michael Zemp, head of the , said it shows 鈥渢hat we need urgent and tangible actions to save at least some of the remaining ice.鈥�
鈥淲e鈥檙e 40 years from when I first saw the glacier. And so, 40 years from now, what is it going to look like?鈥� Pelto said. 鈥淚 do think by then the Juneau icefield will be past the tipping point.鈥�
___
Read more of AP鈥檚 climate coverage at
___
Follow Seth Borenstein on X at
___
The Associated Press鈥� climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP鈥檚 for working with philanthropies, a list of supporters and funded coverage areas at .
Seth Borenstein, The Associated Press
