The Antarctic ice sheet is melting in a new, troubling way that scientific models used to project future sea-level rise have not taken into account, suggesting that current forecasts may significantly underestimate the problem, according to a study by young.
British Antarctic scientists have found that warm ocean water is seeping beneath the ice sheet at its “grounding line” – the point at which the ice rises from the seabed and begins to float – causing accelerated melting that could lead to at a turning 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 push a system past a point of no return.
Melting works like this: the relatively warm ocean water opens up cavities in the ice, allowing more water to seep in, which causes more melting and the formation of larger cavities, etc.
A small increase in ocean temperatures could have a very large impact on the amount of melting, the study found. As climate change warms the oceans, the process accelerates.
“You get this kind of runaway response,” said Alex Bradley, an ice dynamics researcher at BAS and lead author of the paper. It acts as a tipping point, he told CNN, “where you can have a very sudden change in how much melting is happening in these places.”
That tipping point would play out through a faster flow of ice into the oceans, a process not currently included in models of future sea-level rise, Bradley said, suggesting “our projections of sea-level rise may be significant underestimates,” he added.
The implications would not be felt immediately, according to the study, but would see higher sea level rise accumulate over tens and hundreds of years, threatening coastal communities around the world.
The study does not provide a time frame for when the tipping point might be reached, nor does it provide figures for how much sea level rise can be expected. But the region is extremely important: the Antarctic ice sheet already sheds an average of 150 billion metric tons of ice each year and, in its entirety, holds enough water to raise global sea levels by about 190 feet (about 58 meters).
The study is not the first to show Antarctica’s vulnerabilities to the climate crisis. A wealth of research points to the vulnerability of West Antarctica in particular, particularly the Thwaites Glacier, known as the Doomsday Glacier for the catastrophic impact it could have on sea level rise.
But what surprised Bradley about the study, which used climate modeling to understand how this melting mechanism could affect the entire ice sheet, is that some of the most vulnerable glaciers were those in Antarctica Eastern.
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 take a closer look at the physical processes that occur in grounding zones “.
“But this is a very complex, poorly observed region, and much more research and field observations are needed,” he warned, including establishing the processes that control the intrusion of ocean water beneath the ice and exactly how that affects melting. the ice.
Recent research from West Antarctica found that melting at the base of the glaciers was actually lower than expected because it was being suppressed by a layer of colder, fresher water – although scientists still found a 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 it needs to be viewed alongside more recent findings, including the mechanisms of ice melt. as well as the tides of influences. have in pumping seawater under the ice.
Bradley hopes the study will spur more research into which regions may be most at risk and give added impetus to policies to tackle the climate crisis. “With every little increase in ocean temperature, with every little increase in climate change, we get closer to these tipping points,” he said.
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