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Continued warming to put one-third of Antarctic ice shelves at risk of collapse

A long crack is seen across the Larsen C Ice Shelf, as seen by the Operational Land Imager on the NASA/USGS Landsat 8 spacecraft in 2017, is one of the largest remaining shelves in Antarctica -- but researchers are worried about the threat that warmer temperatures pose to its health. File Photo by NASA/UPI
A long crack is seen across the Larsen C Ice Shelf, as seen by the Operational Land Imager on the NASA/USGS Landsat 8 spacecraft in 2017, is one of the largest remaining shelves in Antarctica -- but researchers are worried about the threat that warmer temperatures pose to its health. File Photo by NASA/UPI
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April 7 (UPI) -- If global temperatures reach 4 degrees Celsius above preindustrial levels, more than a third of Antarctic's ice shelves will be at risk of collapse, according to new models detailed Thursday in the journal Geophysical Research Letters.

Modeling the potential collapse of Antarctica's ice shelf is key to forecasting global sea level rise, said climate scientists at Britain's University of Reading.

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The new simulations showed, specifically, that more than two-thirds of the ice shelf on the Antarctic Peninsula would be at risk of collapse under a severe warming scenario.

Conversely, if warming is limited to 2 degrees, simulations suggest the risk of collapse along Antartica's coast can be halved and accelerated sea level rise can be avoided.

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Should the continent's ice shelves collapse, Antarctica's interior ice sheet would become increasingly exposed to warm air and water, further accelerating melt rates and sea level rise.

While the collapse of a third of Antarctica's ice shelves sounds dramatic, paleoclimate data suggests ancient warming events have previously triggered the rapid loss of ice shelves, ice sheets and glaciers.

Currently, Antarctica's ice shelves serve as a protective buffer, insulating interior glaciers from warm water currents and rising atmospheric temperatures.

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The ice shelves also work like a dam, counteracting gravity's influence on southern continent's interior ice.

Even without continued warming, destabilization of Antarctica's ice shelf would guarantee accelerated melt rates and sea level rise for a century or more.

"We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly," study lead author Ella Gilbert, climate scientist at the University of Reading in Britain, said in a press release.

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"Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modeling techniques to fill in the finer detail and provide more precise projections," said Gilbert, a climate scientist at the University of Reading.

"The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise," Gilbert said.

Gilbert developed the new models to isolate the effects of warming trends on the fracturing process inside Antarctica's ice shelf. The simulations considered three global warming scenarios: warming of 1.5, 2 and 4 degrees Celsius.

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Every year, meltwater runoff cleaves holes and crevices in the large expanses of ice that stretch into the Southern Ocean. New snow and refrozen meltwater often fills theses gaps, but when meltwater rates outpace new snow, these gaps can grow larger and larger.

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Eventually, these widening crevices can cause parts of the ice shelf to collapse.

In 2017, this process caused a massive iceberg to cleave into the ocean from Antarctica's Larsen C ice shelf, leaving the shelf vulnerable to further breakdown.

In 2002, Larsen C's neighbor, the Larsen B ice shelf, disintegrated in the wake of a similarly dramatic breakaway.

The newest simulations showed that the Larsen C, Shackleton, Pine Island and Wilkins ice shelves are most at risk of collapse under accelerated warming scenarios.

"If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades," Gilbert said. "Limiting warming will not just be good for Antarctica -- preserving ice shelves means less global sea level rise, and that's good for us all."

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