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West Antarctic Ice Sheet unlikely to reverse retreat

"What happened roughly 10,000 years ago might not dictate where we're going in our carbon dioxide-enhanced world," said researcher Reed Scherer.

By Brooks Hays
The West Antarctica Ice Sheet reached its maximum extent, shown in green, at the end of the last ice age. It reached its minimum extent some 10,000 years ago, seen in red. A buttressing effect triggered some rebound, as marked by orange, representing a modern grounding line. Photo by Albrecht/PIK
The West Antarctica Ice Sheet reached its maximum extent, shown in green, at the end of the last ice age. It reached its minimum extent some 10,000 years ago, seen in red. A buttressing effect triggered some rebound, as marked by orange, representing a modern grounding line. Photo by Albrecht/PIK

June 15 (UPI) -- A new study of the West Antarctic Ice Sheet during the Holocene suggests the ice sheet is unlikely to reverse its accelerating retreat as it has in the past.

At the end of the last ice age, warming temperatures caused ice masses in Antarctica to shrink. But, around 10,000 years ago, the West Antarctic Ice Sheet surprisingly rebounded. New research suggests the loss of mass allowed for crustal uplift. As the continent rose, the ice sheet began to self-stabilize.

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Analysis of the phenomenon -- detailed this week in the journal Nature -- suggests such a reversal of fortune is unlikely to happen again.

"Given the speed of current climate-change from burning fossil fuels, the mechanism we detected unfortunately does not work fast enough to save today's ice sheets from melting and causing seas to rise," Torsten Albrecht, researcher at the Potsdam Institute for Climate Impact Research, said in a news release.

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Until now, scientists thought the retreat of the West Antarctic Ice Sheet was continuous. But new models showed the ice sheet's behavior was more complicated.

"When I observed the re-growth in our numerical computer simulations of Western Antarctica, I first thought this might be a flaw -- it looked so different from what you find in the text books," Albrecht said. "So I started figuring out the involved interactions between the ice, ocean and Earth and their typical time scales."

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A radar survey of the ice sheet's ancient layers, led by Jonathan Kingslake and colleagues from Columbia University's Lamont-Doherty Earth Observatory, revealed cracks where scientists didn't expect them.

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The cracks suggested the ice had been rapidly stretched and compressed, evidence of periods of retreat and regrowth. When a team of scientists led by Reed Scherer from Northern Illinois University examined sediments from beneath the ancient ice layers, they arrived at a similar conclusion.

Researchers believe the rising peaks of the mountains beneath the West Antarctic Ice Sheet provided a "buttressing" effect. This effect requires time to have an impact and encourage ice regrowth.

"What happened roughly 10,000 years ago might not dictate where we're going in our carbon dioxide-enhanced world, in which the oceans are rapidly warming in the polar regions," Scherer said. "If the ice sheet were to dramatically retreat now, triggered by anthropogenic warming, the uplift process won't help regrow the ice sheet until long after coastal cities have felt the effects of sea level rise."

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