Alaska is home to the largest glacier in the world’s piedmont that is, it drops from a mountain and into the plain. However, a new research has found it’s not as huge as we thought. Moreover, its location at a low elevation makes it more prone to melting that could impact the rising sea levels.
The findings are found in an investigation that examines Malaspina Glacier, that spills out of the St. Elias Mountains into an expansive circular lobe on top of an expansive plain that ends short of the ocean.
The research, which was conducted by University of Arizona scientists and published in the Journal of Geophysical Research, utilized specially-designed radars to perform what was effectively, a full body scan that reaches into the Malaspina’s foundation and even into the bedrock underneath the base.
It was found that Malaspina’s volume of ice is 690 cubic kilometers. This is around 30% less than the previous size estimates. The glacier’s two-thirds are located below sea level and the lower portions in the glacier have been submerged by a number of channels that can run up to 350 meters beneath sea level, as the study revealed. In the same way this land-based barrier divides Malaspina from sea is eroding, as the lagoons within it expand. Previous research conducted by researchers from the National Park Service, University of Arizona and UAF suggests there is evidence that the saltwater may already be creeping into the barrier of land, and Malaspina might be changing in what’s referred to as the tidewater glacier.
If the 590 cubic kilometers of ice above sea level melts, it could raise ocean levels by 1.4 millimeters, which is seven times more than the current annual effect on sea levels through Alaska glaciers’ melting according to the study.
The exact date and speed at which Malaspina will melt is still being determined, according to the study’s principal author, Brandon Tober, a University of Arizona geophysics doctoral student. This work is being carried out by the same group that developed the new study comprising members from UAF as well as University of Montana and University of Montana as well as Tober and his University of Arizona colleagues. Tober said he’s hoping that findings that will predict the future of Malaspina will be available before the end of this year.
The Malaspina-scanning study was a as part NASA’s Operation IceBridge, an initiative that ran from 2009 until 2021. The program utilized airborne equipment to monitor sea ice levels glaciers, ice caps and glaciers in both polar regions.
The majority of glacier volume measurements are calculated using calculations from afar, which take into consideration the physical laws of location and their movement over time. However, these calculations are only an estimate, Tober said.
“Really the most effective method of determining this is to to them using radar and then measure them,” he said.
One of the challenges to the radar measurement on Alaska glaciers lies in the fact that at this latitude of temperate the ice is deemed warm, meaning it is a reservoir of water. This water is known to absorb the radio waves utilized by radar, which interferes with any measurements. To solve this issue the Malaspina project employed very low-frequency waves which could penetrate these portions of liquid water Tober explained. The majority of the information used for the study was collected from 2021-based flights and 2021, which created a grid over the glacier. However, there was also use of data from as long as 2013he explained.
Malaspina which is situated in the Wrangell-St. Elias Park National and Preserve It has a size and layout that make it an ideal location for these measurements, Tober said. “It’s the largest chunk of ice that is situated on the broad flat plain” Tober said. Smaller glaciers that are wedged more tightly into mountainous areas are not suitable for radar analyses since the signals could be altered in a complicated topography, he explained.
Alaska has lower than 1 percent global glacier ice however Alaska glaciers contribute a significant amount to the rise in sea levels worldwide that is caused by melting water from land ice. This includes the dice sheets and glaciers and thermal expansion when the oceans warm and their waters occupy more space.
Alaska glaciers provide more than any other land ice source in addition to other sources, including Greenland and Antarctic ice sheets, as per to several recent studies which put Alaska glaciers’ contributions to about 6 or about 7%.
Between 2000 and 2019 about 20% of sea level rise originates caused by the world’s glaciers not including the Greenland as well as the Antarctic sheets. And from that, around 30% of it was due to melting from Alaska glaciers, as reported in an research study in 2021 that was published by the magazine Nature.
This article first appeared in Alaska Beacon and is republished here with permission.
