Antarctica faces a "tipping point" of melting as oceans warm: study June 27, 2024

Sea level rise occurs when melting ice outpaces the formation of new ice (Mathilde BELLENGER)

By AFP - Agence France Presse

Antarctica faces a "tipping point" of melting as oceans warm: study

By Linda GIVETASH

Scientists have discovered a new tipping point towards the "runaway melting" of Antarctica's ice sheets, caused by the intrusion of warm ocean water between the ice and the land on which it sits, according to a study published on Tuesday.

Although this type of melting has been studied previously, the models used by the United Nations' Intergovernmental Panel on Climate Change (IPCC) to project the impact of global warming on Antarctica have not yet taken this phenomenon into account.

They have also systematically underestimated the loss of ice observed so far, said the study, published in the journal Nature Geoscience.

As ocean temperatures rise due to man-made global warming, Antarctica's ice sheets are melting, threatening rising global sea levels and endangering coastal communities.

"Increases in ocean temperature can lead to the crossing of a tipping point, beyond which unlimited ocean water intrudes under the ice sheet through an uncontrolled melting process," said the study.

Antarctica's ice sheets sit on bedrock and extend beyond the coast to float in the sea.

Previous studies have shown that warm seawater is seeping into the "grounding zone" - where land and ice meet - and further inland, under the floating ice.

As the water warms, even fractionally, the intrusion accelerates from short distances of 100 meters (330 feet) to tens of kilometers (miles), melting the ice along the way by heating it from below, explained the study's lead author, Alexander Bradley.

"Every tenth of a degree (of warming) brings these kinds of processes closer together, these tipping points closer together," said Bradley, a researcher at the British Antarctic Survey.

The risk of rising sea levels arises when accelerated melting outstrips the formation of new ice on the continent.

Some areas of Antarctica are more vulnerable to this process than others due to the shape of the landmass, which has valleys and cavities where seawater can accumulate under the ice.

The Pine Island glacier, currently Antarctica's largest contributor to sea level rise, is at high risk of melting due to the slope of the land, which allows more seawater to enter, according to the study.

Scientific models need to be updated to take into account the melting element to better predict the risk of sea level rise in the future and prepare for it, Bradley said.

"And this emphasizes the need for urgent climate action to prevent these tipping points from being crossed," he added.

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