Ice shelf protecting Antarctic glacier is breaking up faster

 Ice shelf protecting Antarctic glacier is breaking up faster

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The floating ice shelf acts like a cork in a bottle for the fast-melting glacier and prevents its much larger ice mass from flowing into the ocean

WASHINGTON

A critical Antarctic glacier is looking more vulnerable as satellite images show the ice shelf that blocks it from collapsing into the sea is breaking up much faster than before and spawning huge icebergs, a new study says.

The Pine Island Glacier’s ice shelf loss accelerated in 2017, causing scientists to worry that with climate change the glacier’s collapse could happen quicker than the many centuries predicted. The floating ice shelf acts like a cork in a bottle for the fast-melting glacier and prevents its much larger ice mass from flowing into the ocean.

That ice shelf has retreated by 20 kilometers between 2017 and 2020, according to a study in Friday’s Science Advances.

The crumbling shelf was caught on time-lapse video from a European satellite that takes pictures every six days.

“You can see stuff just tearing apart,” said study lead author Ian Joughin, a University of Washington glaciologist.

“So it almost looks like the speed-up itself is weakening the glacier….And so far we’ve lost maybe 20 per cent of the main shelf.”Between 2017 and 2020, there were three large breakup events, creating icebergs more than 8 kilometers long and 22 miles 36 kilometers wide, which then split into lots of littler pieces, Joughin said.

There also were many smaller breakups. “It’s not at all inconceivable that the whole shelf could give way and go within a few years,” Joughin said. “I’d say that’s a long shot, but not a very long shot.” Joughin tracked two points on the main glacier and found they were moving 12% faster toward the sea starting in 2017.

“So that means 12 per cent more ice from Pine Island going into the ocean that wasn’t there before,” he said. The Pine Island Glacier, which is not on an island doesn’t have pine trees, is one of two side-by-side glaciers in western Antarctica that ice scientists worry most about losing on that continent. The other is the Thwaites Glacier.

Pine Island contains 180 trillion tons of ice the equivalent of half a meter of sea level rise —and is responsible for about a quarter of the continent’s ice loss.

Agencies

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