With that, the question was no longer whether the West Antarctic Ice Sheet would disappear, but when. When those glaciers go, sea levels will rise by more than a meter, inundating land currently inhabited by 230 million people. And that would be just the first act before the collapse of the entire ice sheet, which could raise seas 5 meters and redraw the world’s coastlines. This makes West Antarctica’s ice sheet the most vulnerable to collapse. A heaping dome of ice, the ice sheet flows outward under its own weight through tentacle-like glaciers.