World’s largest ice sheet at risk of melting, threatens rising sea levels

World's largest ice sheet at risk of melting, threatens rising sea levels
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Scientists say the window to protect the world’s largest ice sheet from significant shrinkage is narrowing, with worrying new predictions that it has the potential to trigger sea level rises of up to 16½ feet in the long term if not Greenhouse gas emission targets are met.

The Great East Antarctic Ice Sheet, which is about the size of the United States, It used to be considered less vulnerable to climate change than the Greenland and West Antarctic ice sheets, where several glaciers have been rapidly losing ice as they advance. undermined by warm ocean water. In recent years, however, research has began to emerge defiant that view

The last To studypublished in the journal Nature, combined recent findings on potential vulnerabilities in bedrock and underwater topography, particularly in areas where glaciers interact with warm water, with an analysis of warm periods in Earth’s past.

The team of researchers from Australia, Britain, France and the United States found that if global temperature increases are below the upper limit set by the 2015 Paris climate agreement (2 degrees Celsius above pre-industrial levels), that should mean the ice sheet adds less than half a meter (1.6 feet) to sea level by the year 2500. Any rise above that temperature has the potential to raise sea level as much as 5 meters (16.4 ft) during the same period.

“The decisions that we’re making today in terms of emissions reductions will establish whether East Antarctica remains largely dormant as a very large ice sheet, or whether we start to set in motion some unstoppable changes that will add to the problem of rising emissions. sea ​​level that we’re already facing,” Nerilie Abram, a climate scientist at the Australian National University and co-author of the study, said in an interview.

UN Secretary-General António Guterres warned earlier this year that the more ambitious goal set out in the Paris agreement, to limit global temperature rise to 1.5 degrees Celsius (2.7 degrees Fahrenheit) per above pre-industrial levels, it is “On life support.”

The researchers said evidence from seafloor sediments around East Antarctica indicates that part of the ice sheet collapsed and contributed to rising sea levels by several meters during the mid-Pliocene era, about 3 million years ago. years, when temperatures were 2 to 4 degrees Celsius higher. .that now. About 400,000 years ago, there is evidence that some of the ice sheet retreated more than 400 miles inland, at a time when it was 1 to 2 degrees Celsius warmer than it is now.

Scientists Just Discovered a Massive New Vulnerability in the Antarctic Ice Sheet

“A key lesson from the past is that the East Antarctic Ice Sheet is highly sensitive to even relatively modest warming scenarios. It is not as stable and protected as we once thought,” Abram said.

Chris Stokes, a geography professor at Britain’s Durham University and lead author of the study, said satellite observations have suggested the ice sheet is thinning and retreating, particularly where glaciers are in contact with warm ocean currents.

“This ice sheet is by far the largest on the planet, containing the equivalent of 52 meters [171 feet] sea ​​level and it’s really important that we don’t wake up this sleeping giant,” Stokes said in a statement.

Nick Golledge, a glaciologist at the Antarctic Research Center in Wellington, New Zealand, who did not work on the study, said the real concern for East Antarctica is the period beyond what the paper considers. Even when greenhouse gas emissions slow or stop, the amount of heat locked up will lead to a reversal over millennia, as the ocean continues to absorb heat from the atmosphere.

“The recent warm spells mentioned in the paper help with these inferences, but the uncertainties remain very large,” he said.

Australian scientists are embarking on a campaign over the next few years to deepen their understanding of the Denham Glacier region, a 12-mile-wide stream of ice that flows over the deepest underwater canyon of the East Antarctic Ice Sheet. Scientists have warned that the canyon could provide a potential pathway for the ocean to infiltrate deep into central Antarctica.

“We understand the Moon better than East Antarctica. So we don’t yet fully understand the climate risks that will emerge from this area,” said Matt King, co-author of the latest study and a member expert in sea level and ice cover change at the University of Tasmania.

Chris Mooney contributed to this report.

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