Two enormous Antarctic glaciers are breaking loose from the southern continent, potentially threatening coastal cities and regions around the world.

It won’t happen right away, but if both glaciers break free, it could eventually mean the loss of much of the vast West Antarctic ice sheet — and up to a 10-foot rise in global sea levels, reports the Washington Post.

“The new findings published Monday in the Proceedings of the National Academy of Sciences, come from analysis of satellite images,” the Post says.

“They show that a naturally occurring buffer system that prevents the glaciers from flowing outward rapidly is breaking down, potentially unleashing far more ice into the sea in coming years.”

Nearly 98% of Antarctica is covered by ice — representing about 70% of all the fresh water on Earth. The Thwaites and Pine Island glaciers are located on its southwestern coast.

“For several years, scientists have been worried about the retreat and eventual collapse of Thwaites … a Florida-sized plug that holds back the West Antarctic ice sheet from the Southern Ocean,” reports Wired. 

If Thwaites alone were to collapse and melt, it would raise global sea levels by as much as two feet, a singular disaster. Should the entire West Antarctic ice sheet slide into the sea, the rise could reach a catastrophic 10 feet or more.

None of this will happen soon; scientists say the two glaciers are so big, and blocked by a floating ice sheet, that it’s impossible for them to fail completely within the next 100 years.

But the trend is clear, and it could affect the grandchildren of virtually every person alive today.

“The ice shelf is getting weaker,” Dutch scientist Stef Lhermitte told Wired.

“The ice shelf slows down the traffic behind. At the moment you lose the ice shelf, the glaciers are free to flow and discharge their ice into the ocean.”

Here’s a great video from Vos on why scientists are so concerned.