New Studies Show Antarctic Glaciers Far More Vulnerable To Heat & Fracture Than Previously Thought
Two new studies have added to the fears that West Antarctic ice shelves ( specifically the Amundsen Sea embayment that includes Pine Island, Thwaites, Haynes, Pope, Smith, and Kohler glaciers.) the corresponding glacier are degrading rapidly from the upwelling of warm ocean water on the shelf underbelly. Scientists fear that melting is doubling in the region from two recently discovered phenomena, tidal pumping and saltwater intrusion.
Wired Magazine has the story, and it is as fascinating as it is terrifying. Neither the tidal pumping nor saltwater intrusion is in any climate model, suggesting that the disintegration of the buttressing effects of ice shelves would vanish, and sea-level rise accelerates. It could happen so fast that scrapers as far away as Houston, Texas could topple due to subsidence. Researchers used data from the TanDEM-X and COSMO-SkyMed radar satellites and ground-penetrating radar. This latter technology sends pings through the glaciers and reviews what bounces back. Explosions are sometimes used to analyze seismic data. Synthetic aperture radar interferometry was used to scan three West Antarctic glaciers, the Pope, Smith, and Kohler, all in the Amundson Sea embayment in West Antarctica. The study was published in Nature Science. In theory, these small glaciers by themselves could take down west Antarctica.
Think of an ice shelf as a cork that’s keeping the rest of the glacier, that ice sheet, from sliding into the ocean. The Florida-sized Thwaites Glacier, for instance, is known as the “Doomsday Glacier” for good reason: It’s attached to a seamount off the coast and is holding back ice that would raise global sea levels by two feet if it all melted. Last month, scientists reported that Thwaites’ ice shelf could crumble in three to five years.
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But current glacier melt models don’t account for a phenomenon called tidal pumping. Whenever the tide rises, it heaves Thwaites’ ice sheet upward, allowing relatively warm seawater to rush farther upstream underneath the glacier. That drives melting along its belly, making the ice sheet more prone to fracture. “It means that warm water that is at the bottom of the glacier can infiltrate up to several kilometers upstream,” says University of Houston physicist Pietro Milillo, who is studying Antarctic glaciers. “And all of a sudden you start realizing, ‘Wait a minute! The models that actually predict the future state of the glaciers do not have these kinds of phenomena. They basically have a grounding line that is fixed.’”
The measurements are dire. In 2017, Pope’s grounding line fell back over two miles in just three and a half months. Between 2016 and 2018, Smith logged a mile and a quarter retreat a year, while Kohler pulled back three quarters of a mile. And when that grounding line starts retreating, it initiates a cascade of catastrophes: The more of the glacier’s underside that’s exposed to seawater, the more melting. “Once you trigger a subtle retreat, they're going to just keep retreating and retreating, which means that they're going to keep speeding up,” says Milillo. “Speeding up the glacier acts like a chewing gum: The glacier thins, and by thinning also you have a speed-up, because while not in contact with the bed, there is less resistance to the flow. Which means the glacier [movement] will accelerate and in turn will inject more ice into the ocean.”
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https://www.dailykos.com/stories/2022/2/18/2080989/-Warm-seawater-is-being-squeezed-past-West-Antarctic-grounding-lines-melting-even-the-inland-ice
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