Global warming: how stable is the East Antarctic ice sheet?

Science global warming

“East Antarctic Ice Is Very Sensitive”

The study used the latest data and models to predict the future of East Antarctica

The study used the latest data and models to predict the future of East Antarctica

Source: Jan Lenaerts

Unlike the western part of the continent, East Antarctica’s ice has long been considered very stable: scientists are now warning that the region could cause sea levels to rise – by several meters – if greenhouse gas emissions continue to be high.

DThe East Antarctic ice sheet is less stable than has long been thought. If mankind meets the goals of the Paris climate agreement and limits global warming to a maximum of two degrees Celsius, research shows that by far the largest mass of ice on Earth will only slightly melt. In this case, the resulting sea level rise would be less than half a meter by 2500.

However, if the earth warms up, the sea level could rise by several meters, an international research team led by Chris Stokes of Durham University writes in the journal Nature.

The team writes that East Antarctica contains enough ice to raise sea levels by 52 meters. For comparison: the much smaller West Antarctic ice sheet “only” would raise sea level a good 5 meters if it melted completely. From 1992 to 2017, West Antarctica lost 2,000 gigatonnes (billion tonnes) of ice, the equivalent of a 6-millimeter rise in sea level. The loss of ice is mainly due to warm ocean currents.

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drought and melting glaciers

Contrary to the western part of the continent, East Antarctica’s ice has long been considered very stable. The Stokes team has now analyzed the behavior of the ice sheet over the past million years and derived predictions from these findings for the future – each depending on different greenhouse gas emission scenarios.

Accordingly, the concentration of carbon dioxide (CO₂) in the greenhouse gas in the atmosphere was maintained around 3 million years ago at a level close to the present one, i.e. over 400 ppm (parts per million particles).

Scientists from the Mawson Glacier

Scientists from the Mawson Glacier

Source: Richard Jones

During this time, temperatures were 2 to 4 degrees Celsius higher than they are today – about as high as predicted for the end of this century. However, sea level was 10 to 25 meters higher than it is today. It was also due to the recession of ice in Greenland and West Antarctica. However, analyzes of seabed sediments around East Antarctica indicate that this part of the world also contributed several meters to sea level rise during this time.

And 400,000 years ago, after global warming of 1 to 2 degrees, the ice sheet probably retracted about 700 kilometers – causing sea levels to rise by 3 to 4 meters. For comparison: According to the Intergovernmental Panel on Climate Change (IPCC), the average global temperature has increased by about 1.1 degrees since the start of industrialization.

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“A key lesson from the past is that the East Antarctic ice sheet is very sensitive to even relatively little warming,” said co-author Nerylie Abram of the Australian National University in Canberra. “It’s not as stable and protected as we thought.”

The possibility of raising the sea level by several meters

In other words, if greenhouse gas emissions remain high, the ice sheet itself could raise sea level by 1 to 3 meters to 2,300 and 2 to 5 meters to 2,500. Already, research shows that parts of the ice sheet, such as Wilkesland, are losing ice.

A camp in East Antarctica

The camp in East Antarctica “Princess Elizabeth Land”

Source: Nerilie Abram

The team acknowledges that the current understanding is not sufficient to predict at which threshold values ​​for parts of the ice sheet will become unstable. But if we manage to keep global warming below 2 degrees, the sea level rise caused by the East Antarctic ice sheet will remain well below one meter in the coming centuries. “The fate of the largest ice sheet on Earth is largely in our hands,” concludes the team.

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The study uses the latest data and models to predict the future of East Antarctica, says Robert Larter of the British Antarctic Survey, who was not involved.

Prediction is associated with great uncertainty given the long periods of time through the centuries. However, they highlighted the region’s potential to raise sea levels by several meters while greenhouse gas emissions remain high.

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