Glacier melt in Alaska is accelerating at an alarming rate
Recent research led by experts at Newcastle University indicates that glacier melt on Alaska’s Juneau Icefield is accelerating faster than previously thought, potentially reaching an irreversible tipping point sooner.
The study, published in Nature Communications, reveals a dramatic increase in glacier loss since 2010.
Concerning acceleration in glacier melt
Study lead author Bethan Davies noted the concerning acceleration in glacier melt, emphasizing the vulnerability of flat, plateau icefields to climate change.
“Alaskan 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,” she said.
Moreover, flatter ice caps and icefields cannot retreat to higher elevations and find a new equilibrium.
Distinct periods of icefield volume change
Using historical records, archival aerial photographs, and satellite imagery, the team identified three distinct periods of icefield volume change since 1770.
Initially, the glacier volume loss was consistent at 0.65-1.01 km³ per year until 1979. From 1979 to 2010, this rate increased to 3.08-3.72 km³ per year.
However, the most alarming increase occurred between 2010 and 2020, when the rate of ice loss doubled to 5.91 km³ per year.
The researchers also found that the rates of glacier area shrinkage were five times faster from 2015-2019 compared to 1948-1979.
Overall, the total ice loss across the Juneau Icefield between 1770-2020 (315.3 ± 237.5 km³) equated to just under a quarter of the original ice volume.
Glacier melt and fragmentation
This increased rate of glacier melt has also been accompanied by increased glacier fragmentation. The team mapped a dramatic increase in disconnections, where the lower parts of a glacier become separated from the upper parts.
Additionally, 100% of glaciers mapped in 2019 have receded relative to their position in 1770, and 108 glaciers have disappeared completely.
An irreversible tipping point
“It’s incredibly worrying that our research found a rapid acceleration since the early 21st century in the rate of glacier loss across the Juneau icefield,” Davies remarked.
“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, potentially pushing glaciers beyond a tipping point into irreversible recession.”
Alaska glacier melt and sea level rise
Alaska contains some of the world’s largest plateau icefields, and their melting is a major contributor to current sea level rise.
The researchers think the processes they observed at Juneau are likely to affect other, similar icefields elsewhere across Alaska and Canada, as well as Greenland, Norway, and other high-Arctic locations.
They also argued that current published projections for the Juneau icefield that suggest ice volume loss will be linear until 2040, accelerating only after 2070, may need to be updated to reflect the processes detailed in this latest study.
Glacier melt is underestimated
“This work has shown that different processes can accelerate melt, which means that current glacier projections may be too small and underestimate glacier melt in the future,” Davies explained.
“What was really exciting about this research was piecing together thousands of archived aerial photographs to extract elevation, which gave us a really detailed insight into the long-term behavior of the icefield,” added Robert McNabb, a lecturer in remote sensing at Ulster University.
This comprehensive study of the Juneau Icefield highlights the accelerating rate of glacier melt and fragmentation, underscoring the urgent need for updated models to predict future impacts on sea level rise.
As climate change continues to affect polar icefields, understanding these processes is crucial for developing effective mitigation and adaptation strategies.
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