A single glacier sitting at the bottom of the world may be all that is holding back catastrophic amounts of sea level rise. As it melts away faster than ever, scientists are racing to get a better understanding of when it might fail. Unfortunately, they’ve recently found more bad news.

The Antarctic bulwark known as Thwaites, or the “Doomsday Glacier,” is gargantuan — roughly the size of Florida — and holds enough ice to push the planet’s coastlines up 2 feet. But the edge of Thwaites also acts as a cork, holding up the rim of the West Antarctic ice sheet, much of which sits below sea level. As Thwaites deteriorates, more ice in this bowl becomes exposed to the ocean, creating a feedback loop that makes it melt faster. And if Thwaites were to succumb entirely, the whole interior of the sheet might follow suit, raising sea levels by as much as 10 feet.

It’s easy to track Thwaites’ demise from space, but predicting its future has been much trickier.…