East Antarctica’s Denman Glacier has retreated nearly 3 miles over the past two decades, losing 268 billion tons of ice between 1979 and 2017, according to a new study published in the journal Geophysical Research Letters. If the glacier were to melt completely, it holds enough water to raise global sea levels by about 5 feet.

The 9,266-square-mile glacier currently fills Antarctica’s deepest canyon. As it melts, water is traveling from the canyon into the ocean. Scientists warn the shape of the ground under the ice makes it very susceptible to rapid climate-driven collapse. Not only would this raise sea levels globally, the unblocked canyon could also serve as a pathway for ocean water to penetrate inland and further melt ice sheets.

“The configuration of the bed of the glacier makes this one of the weakest spots in east Antarctica,” Virginia Brancato, a NASA scientist and lead author of the new study, told The Washington Post. “If I have to look at East Antarctica as a whole, this is the most vulnerable spot in the area.”

For a long time, scientists focused their attention on West Antarctica, which has warmed more quickly than East Antarctica and experienced much more rapid ice melt in recent decades. But new research has shown that East Antarctica, which holds much more ice than the west and therefore poses a greater threat to global sea levels, is not as stable as once thought. To learn more about this growing body of research on East Antarctica, click here.

