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Pine Island Glacier Ice Shelf Tears, Accelerating Key Thinning of Antarctic Glacier | NSF

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Pine Island Glacier’s ice shelf tears, accelerating key thinning of the Antarctic glacier

From 2017 to 2020, large icebergs on the edge of the pack ice broke off

The Pine Island Glacier ends with pack ice that floats in the Amundsen Sea.

June 28, 2021

For decades, the ice shelf helping to hold back one of Antarctica’s fastest glaciers, the Pine Island Glacier, has gradually thinned. Analysis of satellite images reveals a more dramatic process in recent years. From 2017 to 2020, large icebergs at the edge of the pack ice broke off and the glacier accelerated.

Since floating ice shelves help hold a glacier’s largest ground mass, the recent acceleration due to a weakened edge could shorten the timing of the eventual collapse of the Pine Island Glacier into the sea. the Funded by the National Science Foundation of the United States A study by researchers at the University of Washington and the British Antarctic Survey has been published in the journal Scientists progress.

“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go a lot faster than expected,” said lead author Ian Joughin, a glaciologist at the Applied Physics Laboratory at the University of Washington. “The processes we had studied in this region were leading to irreversible collapse, but at a fairly measured pace. Things could be much steeper if we lost the rest of the pack ice.”

The Pine Island Glacier contains approximately 180 trillion tonnes of ice, the equivalent of 0.5 meters or 1.6 feet of sea level rise globally. It is already one of the main sources of Antarctica’s contribution to sea level rise, causing about one-sixth of a millimeter of sea level rise each year, or about two-thirds of an inch. per century, a rate that should increase. If he and the nearby Thwaites Glacier accelerate their flow into the ocean and release their grip on West Antarctica’s largest ice cap, the world’s seas could rise several feet over the next several centuries.

Glaciers have gained attention in recent decades as their ice shelves have thinned; warmer ocean currents have melted the underside of the ice. From the years 1990 to 2009, the movement of the Pine Island Glacier out to sea accelerated from 2.5 miles per year to 4 kilometers per year, or from 1.5 miles per year to 2.5 miles per year. The glacier’s speed then stabilized at this higher rate for nearly a decade.

The results show that what happened more recently is a different process, related to internal forces on the glacier.

“The pack ice appears to be tearing apart due to the acceleration of the glacier over the past ten or twenty years,” Joughin said.

The Pine Island Ice Shelf is important because it helps hold back the relatively unstable West Antarctic Glacier, in the same way that the curved buttresses of Notre Dame Cathedral support the mass of the cathedral. Once these foothills are removed, the slow-moving glacier can flow to the ocean more quickly, contributing to the rising seas.

“What is particularly striking about the recent disintegration of the Pine Island Glacier is that it takes place against the backdrop of several millennia of relative stability,” said Paul Cutler, program director in the NSF’s office of polar programs. . “The international research community is very focused on what these new developments mean for future sea level.”


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