Alaska glaciers may hit irreversible melting point sooner than expected

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.

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.

“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, published in the journal Nature Communications, 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.

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.

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 US Forest Service, or about the size of Rhode Island.

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.