West Antarctica: Part of the ice sheet will melt 'inevitably'

Europe 1 with AFP / Photo credit: ESMEE VAN WIJK / CSIRO / AFP 18:08 p.m., October 23, 2023

The melting of West Antarctica's ice is expected to accelerate dramatically in the coming decades and could raise sea levels even if the world meets its commitments to limit global warming, according to a study published Monday. Researchers from the British Antarctic Survey, who led the new study, warned that humanity had "lost control" of the fate of ice shelves, the gigantic frozen structures floating on the margins of the main ice sheet that play a stabilising role in holding back the drift and melting of glaciers in the ocean.

Climate 'tipping point'

Antarctica has already experienced accelerated ice loss in recent decades and scientists have said the West Antarctic ice sheet — which contains enough water to raise sea levels by several meters — could be approaching a climate "tipping point." The researchers found - using computer modelling - that faster melting of ice shelves is already inevitable in the coming decades due to warming oceans.

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Even in a scenario where greenhouse gas (GHG) emissions are reduced and warming remains within the Paris Agreement's most ambitious goal of 1.5 degrees Celsius above pre-industrial levels, their results are roughly identical. The study, published in the journal Nature Climate Change, looked at the process of melting by ocean waters beneath floating ice shelves in the Amundsen Sea. Even in the best-case scenario, ocean warming could be three times faster in the <>st century than in the <>th century.

"Alarm bell"

Kaitlin Naughten, lead author of the study, said the researchers had "every reason to expect" that melting ice would contribute to sea level rise — which is already expected to reach a meter by the end of the century — although they had not specifically studied it. "The melting of the West Antarctic ice shelf is one of the effects of climate change that we are likely to have to adapt to," she said. Millions of people around the world currently live in low-lying coastal areas and some "coastal communities will either have to build around them or be abandoned," she added.

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According to Alberto Naveira Garabato, professor of physical oceanography at the University of Southampton, the study is "sobering". "This illustrates how our past choices have likely resulted in a substantial melting of the West Antarctic ice sheet and the consequent rise in sea levels, to which we will inevitably have to adapt as a society over the decades and centuries to come," he told the Science Media Centre. But he points out that it is also a "wake-up call" to reduce GHG emissions to avoid other severe climate consequences, including the melting of the East Antarctic ice sheet, which is currently considered more stable.

A limited study

The authors of the study note that while a major reduction in emissions would not make much difference to the loss of the West Antarctic ice sheet this century, it could nevertheless have a large impact in the longer term, since the ice sheet will likely take centuries or even millennia to fully respond to climate change.

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Jonathan Bamber, a professor at the University of Bristol's School of Geographic Sciences, notes that the study is somewhat limited because the researchers used only one ocean model and did not explicitly investigate the effect of warming waters on sea levels. "This part of West Antarctica contains enough ice to raise sea levels by more than a meter. So it's important to understand how it will evolve in the future," Jonathan Bamber, who was not involved in the research, told the Science Media Centre.