An ice shelf in East Antarctica roughly the size of New York City has collapsed, marking the first such event in human history, scientists said on Friday.

The ice shelf that collapsed held the Conger and the Glenzer glaciers, and was a nearly 1,200 square kilometres wide. The collapse, which was captured by satellite images, took place between March 14 and 16 after a freakish period of climate change-induced high temperatures in the region, when average temperatures were 70 degrees Fahrenheit warmer than usual.

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“The Glenzer Conger ice shelf presumably had been there for thousands of years and it’s not ever going to be there again,” said Peter Neff, a scientist from the University of Minnesota.

For those unaware, ice shelves are gigantic pieces of floating ice attached to land that take millennia to form and act as levees that hold back ice from flowing into the ocean and causing sea level rise.

However, both Neff and Catherine Walker of the Woods Hole Oceanographic Institute said that point of concern was not the amount of ice lost in the collapse, but the place where it happened.

For decades, researchers had thought that East Antarctica was relatively stable, in comparison to West Antarctica which is fast losing ice.

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However, the collapse of the Glenzer Conger ice shelf has challenged that assumption, and more collapses in East Antarctica could see sea levels rise by as much as 160 feet.

“East Antarctica is starting to change. There is mass loss starting to happen,” said Helen Amanda Fricker, co-director of the Scripps Polar Center at the University of California San Diego, adding, “We need to know how stable each one of the ice shelves are because once one disappears…some of that water will come to San Diego and elsewhere.”