Antarctic Ice Shelf Thins from Above and Below to Cause Sea Level Rise

What's causing the thinning of one of Antarctica's largest ice shelves? That's a question that's been debated for over a decade. Now, researchers have taken a closer look at the Larsen C Ice Shelf to learn a bit more about this thinning ice.

The Larsen A and Larsen B ice shelves actually collapsed in 1995 and 2002. In contrast, the Larsen C Ice Shelf is still present; however, it's thinning from both its surface and beneath. For years, researchers have been unable to determine whether it was warming air temperatures or warmer ocean currents causing this melting. Now, though, researchers may have the answer.

The scientists combined satellite data and eight radar surveys that were captured over a 15-year period from 1998 to 2012. In the end, they found that the Larsen C Ice Shelf lost an average of 4 meters of ice and had lowered by an average of one meter at the surface.

"What's exciting about this study is we know that two different processes are causing Larsen C to thin and become less stable," said Paul Holland, the lead author of the new study, in a news release. "Air is being lost from the top layer of snow (called the firn), which is becoming more compacted-probably because of increased melting by a warmer atmosphere. We know also that Larsen C is losing ice, probably from warmer ocean currents or changing ice flow. If this vast ice shelf-which is over two and a half times the size of Wales and 10 times bigger than Larsen B-was to collapse, it would allow the tributary glaciers behind it to flow faster into the sea. This would then contribute to sea-level rise."

The findings reveal that two processes are causing the ice to melt. This is particularly important to note when it comes to predicting future sea level rise in the area.

The findings are published in the journal The Cryosphere.

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