GLACIER OF THE LAST JUDGMENT | Tides are ‘vigorously’ eroding Antarctica’s huge Thwaites Glacier
Recent research into the melting of Antarctica shows alarming results. High-resolution satellite radar data showed warm, high-pressure seawater penetrating sea ice. Giant Thwaites Glacier Antarctica (also called Doomsday Glacier)which accelerates its melting and can cause growth sea level much more than previously thought. If this glacier were to melt completely, sea levels across the planet would rise by 60 centimeters.
In a study published in Proceedings of the National Academy of SciencesA team led by the University of California, Irvine (USA) explains that widespread contact between ocean water and a glacier (a process that is repeated throughout Antarctica and Greenland) causes “vigorous melting” and may lead to overestimation of global sea level rise projections.
The Thwaites Glacier is 120 kilometers wide at its point of contact with the sea and extends from West Antarctica to the sea basin. Warming air and water around Thwaites is causing it to melt, but now we’re looking at something much worse. The water below Thwaites, on the ocean floor, warms the ice faster. which would significantly speed up the rate of melting.
The glaciologists relied on data collected from March to June 2023 by the Finnish commercial satellite mission ICEYE. The ICEYE satellites form a “constellation” in polar orbit around the planet and show the evolution of the Thwaites Glacier in great detail.
“These ICEYE data provided a series of long-term daily observations that closely match tidal cycles,” said senior author Eric Rignot, a professor of systems science at the University of California, Irvine.
Ice blast from below
Thanks to ICEYE they noticed that Water penetrates under the glacier every day and lifts it from the bottom of the sea., before the weight of the 1.2 kilometer thick glacier causes it to subside again. The cycle repeats with the tides for the first 2 to 6 kilometers of the glacier, but when the Sun and Moon align, creating stronger tides, they can reach another six kilometers. This causes short-term accelerated heating that accumulates over time.
Michael Wollersheim, director of analysis at ICEYT, said in a statement: “Until now, some of nature’s most dynamic processes have been impossible to observe in sufficient detail or with sufficient frequency for us to understand and model them. Observing these processes from space and using satellite radars provides InSAR measurements Accurate to the centimeter with daily frequencyeven up to three times a day, and represents an important step forward.
Rignot said seawater reaching the base of the ice sheet, combined with fresh water from geothermal flow and friction, accumulates and “has to flow somewhere.” In fact, water spreads through natural conduits or accumulates in cavities, creating enough pressure to lift the ice sheet.
“There are places where the water is almost under pressure from the ice overlying it, so it only takes a little more pressure to push the ice up,” Rigno said. “The water then compresses enough to raise a column of ice over half a mile long.”
And it’s not just sea water. For decades, Rignot and his colleagues have been collecting evidence of the impact of climate change on ocean currents that push warmer seawater toward the coasts of Antarctica and other polar ice regions.
Salt water does not freeze down to -2°C.
Circumpolar deep waters are salty and have a lower freezing point than normal.. While fresh water freezes at zero degrees Celsius, salt water only freezes at minus two degrees, and that small difference is enough to promote “vigorous melting” of basal ice, the study found.
Co-author Christine Dow, a professor at the School of the Environment at the University of Waterloo in Ontario, Canada, said: “Thwaites is the most volatile site in Antarctica and represents the equivalent of a sea level rise of 60 centimeters.. The concern is that “we are underestimating the rate at which the glacier is changing, which will have devastating consequences for coastal communities around the world.”
Reference Study: https://www.pnas.org/doi/10.1073/pnas.2404766121
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