A vital ice shelf is about to break away from Antarctica's "Doomsday Glacier," further destabilizing one of the world's largest and most vulnerable glaciers.

The Thwaites Glacier is nicknamed the "Doomsday Glacier" because its collapse would send so much ice into the Southern Ocean that global sea levels would rise by 2.1 feet (65 centimeters or 26 inches), flooding coastal communities worldwide. This collapse could take centuries, but there is an imminent threat to Thwaites' eastern ice shelf, which will likely accelerate the glacier's demise.