A previously unknown cause of ice loss from Antarctica’s Thwaites Glacier has been identified in new research.

According to new research, the 80-mile-wide stream of sliding ice at the center of Thwaites Glacier in West Antarctica is likely to expand over the next 20 years, which could accelerate ice loss.

Senior study author Jenny Suckale, an assistant professor of geophysics at the Stanford Doerr School of Sustainability, described the phenomenon as “like a torrential river eating away at the riverbanks and widening in the process.”

Thwaites Glacial Mass is frequently called the “Armageddon glacial mass” in light of its gigantic size and potential to emphatically raise worldwide ocean levels. The Amundsen Sea could be flooded with billions of tons of ice as the planet warms, allowing more inland ice to freely flow to the coast.

Numerous past examinations have analyzed how the icy mass’ speed and thickness are probably going to advance over hundreds of years. The glacier’s width, which influences how much ice falls into the sea at any given time, has received less attention in research. While narrowing could effectively stop ice loss by allowing a new balance of forces, widening the main ice stream, or trunk, could make instability worse.

“The doomsday scenario is merely one of many, many possibilities. At least relative stability is still well within Thwaites Glacier’s capabilities. We’re attempting to get to something more fundamental, which is the nature of the trend: widening, neutralization, and narrowing,”

Senior study author Jenny Suckale, an assistant professor of geophysics at the Stanford Doerr School of Sustainability.

The brand-new study, which came out on March 7 in the Journal of Geophysical Research: Earth Surface, uses numerical modeling to demonstrate how the eastern and western margins of Thwaites Glacier’s main trunk might be affected by its rapid but uneven thinning.

‘Relative soundness’ stays conceivable.
Driven by geophysics Ph.D. understudy Paul Summers, the scientists tracked down that the noticed diminishing of Thwaites Icy mass, along with changes in the slant of its surface and the circumstances at its base, makes the two sides inclined to move a couple of miles outward over the course of the following 20 years.

Summers and colleagues write, “We are considering relatively small changes in driving stress that would realistically occur in the coming two decades.” However, even this slight widening—about 2% of the glacier’s total width—could accelerate ongoing ice loss.

“We ought to be aware if the trend of widening continues and accelerates.” It would imply that we would need to get ready for higher ocean levels,” said Suckale, who is one of many researchers attempting to comprehend the ice sheet and its reaction to environmental change as a feature of the Global Thwaites Glacial Mass Joint effort.

According to existing models, sea levels could rise as much as a few feet or an inch in some places in the coming decades. Suckale stated, “The policy actions you would have to consider from one extreme to the other are completely different.” These policy actions range from enhancing flood management and drainage for infrastructure located close to shorelines to moving entire coastal communities.

Suckale, on the other hand, stated that the “doomsday” scenario is only one of “many, many possibilities.” For Thwaites Glacier, stability—at least relative stability—is still well within the realm of possibility.

Existing ice-loss models, which generally simplify the processes captured in the new research, would need to be updated in order for scientists to determine just how much Thwaites’s disintegration may accelerate as a result of its widening ice stream. We are attempting to comprehend something more fundamental: the nature of the trend. Suckale said, “Widening, neutral, narrowing.”

Monitoring Thwaites like a coming storm

Summers stated that the research team had anticipated that their modeling would demonstrate that the eastern shear margin of the glacier would be the most vulnerable to migration away from the main trunk. They were surprised to learn that the western boundary might also widen in some scenarios.

As part of a team sent by the U.S. Antarctic Program, Summers spent several weeks last year digging up seismic sensors and GPS systems and surveying the ice with ground-penetrating radar. This discovery highlights the significance of expanding research efforts on the western margin in addition to the work that is already focused on the eastern side.

The ice dynamics at Thwaites Glacier have previously been captured in their entirety or predicted hundreds of years into the future by previous models. According to Suckale, scientists have been able to collect so few direct measures of how ice sheets are changing in response to global warming, which creates huge obstacles for testing against real-world data. However, modeling ice sheet evolution and global sea level rise over these longer time scales produces dramatic predictions.

Suckale stated, “We are very deliberately focusing on the next 20 years to enable testability and continued model development.” The model results will be tested against geophysical measurements of ongoing changes at two field sites along the eastern shear margin and at a third field site focused on what’s happening below the main trunk in the next steps.

“It’s similar to climate expectations. You keep an eye on the storms as they approach, updating your forecasts based on the new information. Suckale stated, “I think we need to monitor Thwaites and ensure that we have methods to get that information into the hands of planners.” We don’t need to panic, but we can’t ignore this either.”

More information: Paul T. Summers et al, Migration of the Shear Margins at Thwaites Glacier: Dependence on Basal Conditions and Testability Against Field Data, Journal of Geophysical Research: Earth Surface (2023). DOI: 10.1029/2022JF006958

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