World’s largest ice sheet in danger of melting, threatening rising sea levels


The window to protect the world’s largest ice sheet from a dramatic shrinkage is shrinking, scientists say, with troubling new projections suggesting that if greenhouse gas emissions targets are not met, it could lead to sea level rise of up to 16.5% in the long run foot.

The vast East Antarctic ice sheet, roughly the size of the U.S., was thought to be less vulnerable to climate change than the Greenland and West Antarctic ice sheets — where several glaciers have been eroded by warm oceans and are rapidly losing ice water. In recent years, however, research has begun to challenge this view.

The new study, published in the journal Nature, combines recent findings on the potential vulnerability of bedrock and seafloor topography — particularly in areas where glaciers interact with warm water — from analyses of Earth’s past warm periods.

The team from Australia, the UK, France and the US found that if global temperature rise falls below the cap set by the 2015 Paris climate agreement – 2 degrees Celsius above pre-industrial levels – it should mean the ice cap will increase by less than half to 2,500 year, sea level rises by one meter (1.6 feet).Any rise in temperature above that could raise sea levels by as much as 5 m (16.4 ft) over the same period.

“The choices we make today in terms of reducing emissions will be put in place, whether East Antarctica is basically dormant as a very large ice sheet, or we start to initiate some unstoppable changes that will add to what we already face. Sea level rise,” 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 target set in the Paris agreement — limiting global temperature rise to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels — is “Life Support”.

Evidence from seafloor sediments around East Antarctica suggests that some ice sheets collapsed and caused sea levels to rise by several meters during the mid-Pliocene epoch, about 3 million years ago, when temperatures were about 2 to 4 degrees Celsius warmer, the researchers said. than now. About 400,000 years ago, there is evidence that parts of the ice sheet retreated more than 400 miles inland, when temperatures were 1 to 2 degrees Celsius warmer than they are today.

Scientists just discovered a huge new hole in the Antarctic ice sheet

“An important lesson from the past is that the East Antarctic ice sheet is highly sensitive to even relatively mild warming scenarios. It is not as stable and protected as we once thought,” Abram said.

Chris Stokes, a professor of geography at Durham University in the UK and lead author of the study, said satellite observations showed that the ice sheet was thinning and retreating, particularly where glaciers were in contact with warm ocean currents.

“This ice sheet is by far the largest on Earth, equivalent to 52 meters [171 feet] At sea level, it is very important that we do not wake up this sleeping giant,” Stokes said in a statement.

Nick Golledge, a glaciologist at the Antarctic Research Centre in Wellington, New Zealand, who was not involved in the study, said the real concern about East Antarctica is a period beyond the consideration of the paper. Even if greenhouse gas emissions are reduced or stopped, the locked-in heat will still cause receding for thousands of years as the oceans continue to absorb heat from the atmosphere.

“The past warm periods mentioned in the paper help these inferences, but uncertainty remains high,” he said.

Australian scientists will conduct a campaign in the coming years to deepen their understanding of the Denham Glacier region, a 12-mile-wide ice stream that flows through the deepest undersea canyon in East Antarctica’s ice sheet. Scientists have previously warned that the canyon could provide a potential way for the ocean to penetrate deep into the center of Antarctica.

“We know the Moon better than East Antarctica. So we don’t yet fully understand the climate risks that will arise in this region,” said Matt King, co-author of the latest study and an expert on sea level and ice sheet change at the University of Tasmania.

Chris Mooney contributed to this report.

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