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West Antarctic Ice Sheet melt ‘unavoidable’ – study

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Picture: Sarah Dawalibi / AFP – Penguins are seen on January 1, 2010 on the Antartic Peninsula. Helpless emperor penguin chicks perished at multiple breeding grounds in West Antarctica late last year, drowning or freezing to death when sea ice eroded by global warming gave way under their tiny feet, scientists said on August 24, 2023.

By Jessica Corbett

“It looks like we’ve lost control of melting of the West Antarctic Ice Sheet. The bright side is that by recognising this situation in advance, the world will have more time to adapt to the sea-level rise that’s coming.” – BAS researcher Kaitlin Naughten

Even if humanity dramatically reduces planet-heating pollution from fossil fuels, the West Antarctic Ice Sheet faces an “unavoidable” increase in melting for the rest of this century, according to a study published Monday in the journal Nature Climate Change.

The West Antarctic Ice Sheet is the continent’s largest contributor to rising seas and contains enough ice to increase the global mean sea level by over 17 feet, the study explains. Enhanced melting of ice shelves, “the floating extensions of the ice sheet, has reduced their buttressing and caused upstream glaciers to accelerate their flow” toward the Southern Ocean. Ice shelf melting could “cause irreversible retreat” of the glaciers.

Using the United Kingdom’s national supercomputer, scientists ran simulations on ocean-driven melting of ice shelves in the Amundsen Sea. They simulated a historical scenario of the 20th century and four future scenarios: two involving medium and high emissions and two using the goals of the Paris agreement, which aims to keep global temperature rise this century below 2°C, with a more ambitious target of 1.5°C, relative to pre-industrial levels.

“We must not stop working to reduce our dependence on fossil fuels.”

The trio of British Antarctic Survey (BAS) and Northumbria University researchers found that “rapid ocean warming, at approximately triple the historical rate, is likely committed over the 21st century, with widespread increases in ice-shelf melting, including in regions crucial for ice sheet stability”.

“When internal climate variability is considered, there is no significant difference between mid-range emissions scenarios and the most ambitious targets of the Paris agreement,” the study states. “These results suggest that mitigation of greenhouse gases now has limited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet.”

In other words, “it looks like we’ve lost control of melting of the West Antarctic Ice Sheet”, said lead author and BAS researcher Kaitlin Naughten. “If we wanted to preserve it in its historical state, we would have needed action on climate change decades ago.

“The bright side is that by recognising this situation in advance, the world will have more time to adapt to the sea-level rise that’s coming,” Naughten noted. “If you need to abandon or substantially re-engineer a coastal region, having 50 years lead time is going to make all the difference.

“We must not stop working to reduce our dependence on fossil fuels,” she stressed. “What we do now will help to slow the rate of sea-level rise in the long term. The slower the sea-level changes, the easier it will be for governments and society to adapt to, even if it can’t be stopped.”

As Reuters reported Monday:

The collapse of the West Antarctic Ice Sheet is one of nine global climate “tipping points” scientists identified in 2009. The passing of these environmental red lines would be catastrophic for life on Earth. An international team of scientists said in 2022 we may already have passed the point of no return for the West Antarctic Ice Sheet at just 1.1°C of warming above pre-industrial levels.

Tiago Segabinazzi Dotto, a senior research scientist at the UK’s National Oceanography Centre who was not involved in the study, said in a statement that “it is likely that we passed a tipping point to avoid the instability of the West Antarctic Ice Sheet”.

“This work fits with existing evidence that suggests that the collapse of ice shelves in the Amundsen Sea is imminent, such as the Thwaites Ice Shelf,” he continued. “However, the pace of this collapse is still uncertain — it can happen in decades for some specific ice shelves or centuries.”

“The conclusions of the work are based on a single model and need to be treated carefully since different models and even ensembles of the same model can give different responses,” he added, while also emphasising that “this study needs to be taken in consideration for policymakers”.

Other experts who were not involved with the research also regarded its revelations as significant and echoed Naughten’s call for ramping up worldwide efforts tackle the climate emergency by cutting emissions.

“This is a sobering piece of research,” said University of Southampton physical oceanography professor Alberto Naveira Garabato. “It should also serve as a wake-up call. We can still save the rest of the Antarctic Ice Sheet, containing about 10 times as many meters of sea level rise, if we learn from our past inaction and start reducing greenhouse gas emissions now.”

Alessandro Silvano, an independent research fellow at the Natural Environment Research Council (NERC), said that “particularly important will be the future of East Antarctica, where about 90 percent of the Antarctic ice is stored”.

Andrew Shepherd, head of Northumbria’s Department of Geography and Environment and director of the NERC Centre for Polar Observation and Modelling, said that while the “conclusion about the inevitability of West Antarctic Ice Sheet collapse is pessimistic, sticking to 1.5°C of global warming buys us 50 years on the extreme scenario … and even 20 years on sticking to 2°C”.

“This could make all the difference to coastal planners, and so is not to be sniffed at,” he added. “It’s vitally important that these ocean forcing trajectories are translated into projections of ice sheet losses so that we know what sea-level rise to expect.”

The research comes as the international community prepares for COP28, the next major United Nations climate summit, set to be hosted by the United Arab Emirates in Dubai beginning next month.

Jessica Corbett is a senior editor and staff writer for Common Dreams.

This article was first published on Common Dreams