A significant icefield in Alaska is melting faster than previously believed, and it may eventually hit an irreversible tipping point sooner than expected, according to a research carried out in the Newcastle University.
The study discovered that since 2010, there has been a significant rise in glacier loss on Juneau Icefield, which is located on the border between Alaska and British Columbia, Canada. The team, comprising academic institutions from the UK, USA, and Europe, examined data dating back to 1770 and discovered three separate eras in the variation of icefield volume.
They observed that between 1770 and 1979, the annual rate of glacier volume loss was roughly constant, ranging from 0.65 to 1.01 km3, and between 1979 and 2010 it increased to 3.08 to 3.72 km3. When the rate of ice loss doubled to 5.91 km3 annually between 2010 and 2020, there was a notable acceleration.
Specifically, the study—which was published in Nature Communications—found that, compared to 1948–1979, the rates of glacier area decrease throughout the icefield were five times greater between 2015 and 2019. In the Juneau icefield, the total amount of ice lost between 1770 and 2020 (315.3 ± 237.5 km3) was equivalent to slightly less than 25% of the initial ice volume.
Specifically, the study—which was published in Nature Communications—found that, compared to 1948–1979, the rates of glacier area decrease throughout the icefield were five times greater between 2015 and 2019. In the Juneau icefield, the total amount of ice lost between 1770 and 2020 (315.3 ± 237.5 km3) was equivalent to slightly less than 25% of the initial ice volume.
There has been a rise in glacier fragmentation to go along with the faster pace of glacier depletion. The group observed a sharp rise in disconnections, or the splitting of a glacier's upper and lower sections. In addition, 108 glaciers have entirely vanished and 100% of the glaciers mapped in 2019 have receded in comparison to their positions in 1770.
The study's senior lecturer at Newcastle University, Dr. Bethan Davies, led the research and expressed concerns, saying:
The study's senior lecturer at Newcastle University, Dr. Bethan Davies, led the research and expressed concerns, saying:
"Our research found a rapid acceleration since the early 21st century in the rate of glacier loss across the Juneau icefield. Since ice loss occurs along the entire surface, a significantly larger area is impacted, Alaskan icefields, which are primarily flat, plateau icefields, are especially vulnerable to accelerated melt as the temperature warms.
"The Juneau Plateau's glacier thinning is likely to prevent future glacier regrowth and may even push glaciers beyond a tipping point into irreversible recession as ice retreats to lower levels and warmer air. Moreover, flatter ice caps and icefields are unable to retreat to higher elevations and find a new equilibrium."
Some of the greatest plateau icefields in the world are found in Alaska, and their melting is a key factor in the present rise in sea level. The scientists believe that the processes they saw in Juneau are probably going to have an impact on other comparable icefields in Alaska and Canada, as well as Greenland, Norway, and other high-Arctic regions.
Some of the greatest plateau icefields in the world are found in Alaska, and their melting is a key factor in the present rise in sea level. The scientists believe that the processes they saw in Juneau are probably going to have an impact on other comparable icefields in Alaska and Canada, as well as Greenland, Norway, and other high-Arctic regions.
Additionally, they note that the Juneau icefield's already published estimates, which predict ice volume loss to be linear until 2040 and accelerate only after 2070, may need to be adjusted to take into account the processes included in this most recent study.
Dr. Davies stated: "This work has demonstrated that different processes can accelerate melt, which implies that current glacier projections may be too low and underestimate future glacier melt."
Dr. Robert McNabb, a lecturer in remote sensing at Ulster University, stated:
"This research was particularly interesting because it allowed us to extract elevation from thousands of old aerial pictures, giving us a really precise understanding of the icefield's long-term history.
"It was something like assembling the world's most difficult jigsaw puzzle to piece together this archive of images, which was gathered between 70 and 50 years ago, but the clarity of the imagery allowed us to recreate the icefield elevation during the pre-satellite era for the first time. Longer term archives, such as this one, are extremely significant because they help us better understand the thresholds at which change might accelerate, as seen by the Juneau Icefield."
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