Giant cracks push imperilled Antarctic glacier closer to collapse


Giant fractures in the floating ice of Antarctica’s massive Thwaites Glacier — a fast-melting formation that has become an icon of climate change — could shatter part of the shelf within five years, research suggests. If that happens, in what had been considered a relatively stable part of Thwaites, the glacier could release an armada of icebergs and begin flowing much faster into the ocean, funnelling ice that had been resting on land into the sea, where it would contribute to sea-level rise.

For decades, scientists have carefully tracked changes in the Thwaites Glacier, which already loses around 50 billion tonnes of ice each year and causes 4% of global sea level rise. The recently identified fractures are deep, fast-moving cracks in Thwaites’ eastern ice shelf (see ‘Cracking up’). They appeared in satellite images over the past few years and their growth seems to be accelerating.

“I visualize it somewhat similar to that car window where you have a few cracks that are slowly propagating, and then suddenly you go over a bump in your car and the whole thing just starts to shatter in every direction,” said Erin Pettit, a glaciologist at Oregon State University in Corvallis, at the American Geophysical Union (AGU) meeting on 13 December. If Thwaites’ eastern ice shelf collapses, ice in this region could flow up to three times faster into the sea, Pettit says. And if Thwaites were to collapse completely, it would raise sea levels by 65 centimeters.

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