O Antarctic ice sheet is melting in a new and worrying way that scientific models used to project future sea level rise have not taken into account, suggesting that current projections may be significantly underestimating the problem, according to a new study.
Scientists from the British Antarctic Survey have discovered that warm ocean water is leaking under the ice sheet at its “grounding line” – the point at which the ice rises from the sea floor and begins to float – causing accelerated melting that could lead to an inflection point, according to the report published Tuesday in the journal Nature Geoscience.
A tipping point refers to the threshold at which a series of small changes accumulate to take a system beyond a point of no return.
Melting works like this: relatively warm ocean water opens cavities in the ice, allowing more water to penetrate, which causes more melting and the formation of larger cavities, and so on.
A small increase in ocean temperatures could have a very large impact on the amount of ice melt, the study concluded. As climate change warms the oceans, the process accelerates.
“You get this kind of runaway feedback,” said Alex Bradley, an ice dynamics researcher at BAS and lead author of the paper. It behaves like a tipping point, he told CNN, “where you can have a very sudden change in the amount of melting that’s happening in these places.”
This tipping point would occur through a faster flow of ice into the oceans, in a process that is not currently included in models of future sea level rise, Bradley said, suggesting that “our sea level rise projections may be significant underestimates,” he added.
The implications would not be felt immediately, according to the study, but would see an even greater rise in sea levels, accumulating over tens and hundreds of years, threatening coastal communities around the world.
The study does not provide timelines for when the tipping point might be reached, nor does it provide figures on how much sea level rise can be expected. But the region is extremely significant: the Antarctic ice sheet already releases an average of 150 billion metric tons of ice every year and, in its entirety, contains enough water to raise global sea levels by about 190 feet (about 58 meters).
The study is not the first to highlight Antarctica’s vulnerabilities to the climate crisis. A series of research points to the vulnerability of West Antarctica in particular, especially the Thwaites Glacier, known like the doomsday glacier due to the catastrophic impact it could have on rising sea levels.
But what surprised Bradley about this study, which used climate models to understand how this melting mechanism could affect the entire ice sheet, is that some of the most vulnerable glaciers were those in East Antarctica.
Eric Rignot, a professor of Earth system science at the University of California, Irvine who was not involved in the research, told CNN that the study “encourages us to look more closely at the physical processes occurring in grounding zones.”
“But this is a very complex and poorly observed region and much more research and field observations are needed,” he warned, including establishing what processes control the intrusion of ocean water under the ice and exactly how this affects ice melt. .
Recent research from West Antarctica found that melting at the base of glaciers was actually below expectedbecause it was being suppressed by a layer of cooler, fresher water – although scientists still found rapid retreat.
Ted Scambos, a glaciologist at the University of Colorado Boulder, said the new model developed by BAS scientists “is potentially very important” but should be analyzed in conjunction with more recent discoveries, including ice melt mechanisms as well as the impacts of tides. have to pump seawater under the ice.
Bradley hopes the study will spur more research into which regions may be most at risk and give additional impetus to policies to address the climate crisis. “With every little increase in ocean temperatures, every little increase in climate change, we get closer to these tipping points,” he said.
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