A critical Antarctic glacier is looking more vulnerable as the ice shelf that blocks it from collapsing into the sea is breaking up much faster than before, 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 20km 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.
University of Washington glaciologist and study lead author Ian Joughin said “you can see stuff just tearing apart”.
“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,” he said.
“It's not at all inconceivable that the whole shelf could give way and go within a few years.
“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 per cent 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 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 tonnes of ice – the equivalent of half a metre of sea level rise – and is responsible for about a quarter of the continent's ice loss.
University of California, Irvine ice scientist Isabella Velicogna, who wasn't part of the study, said researchers are keeping a close eye on the two glaciers.
“Pine Island and Thwaites are our biggest worry now because they are falling apart and then the rest of West Antarctica will follow according to nearly all models,” she said.
While ice loss is part of climate change, there was no unusual extra warming in the region that triggered this acceleration, Joughin said.
National Snow and Ice Data scientist Twila Moon said the results continue to highlight the vulnerability of Antarctica, a major reservoir for potential sea level rise.
“Again and again, other research has confirmed how Antarctica evolves in the future will depend on human greenhouse gas emissions.”