Climate scientists and geologists have been keeping a close eye on Antarctica for years, using the icy continent as a barometer for many effects of climate change. Most recently, attention has been directed to the Nansen ice shelf, a 30-mile-long by 20-mile-wide floating sheet of ice that may not be part of Antarctica for much longer. Scientists are watching, and waiting, as a crack first spotted in 2013 worsens, threatening to severe the ice shelf from the rest of the continent.

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Nansen ice shelf, or ice sheet as it is sometimes referred, measures approximately twice the size of Manhattan. Images captured by NASA’s Operational Land Imager (OLI) on the Landsat 8 satellite in December 2013 first showed a crack in the ice shelf, raising concerns about the future of Nansen’s stability. New imagery (above) obtained by OLI show the crack has grown, and now stretches nearly the entire width of the ice shelf. The crack itself is also visibly wider, making it evident to scientists that it is only a matter of time before the giant ice formation will break free and float into Terra Nova Bay in the Southern Ocean, an area that is typically relatively free from ice.

Related: New study warns that Antarctica’s ice safety band is melting closer to the point of no return

There are many ice shelves around the perimeter of the cold continent, ranging in size. Nearby, the Drygalski Ice Tongue stretches nearly 50 miles out into the sea, but doesn’t show signs of imminent danger the way Nansen does. Christine Dow and Ryan Walker, scientists at NASA Goddard, visited the ice shelf in November and December 2015, and Dow says they are trying to understand what caused the crack to form in the first place, in an effort to predict what will happen in the future with this and other ice shelves. “I’m really interested to see whether this feature is occurring because of the topography around the ice shelf, or whether it was initially created by surface water flowing into a small ice surface crack,” she said. “We’re planning an intensive survey of this feature in the coming years and will hopefully get a handle on the causes.”

Via Gizmodo and NASA

Lead image via McKay Savage, images via Jesse Allen/NASA and Christine Dow/NASA