Mountains around the world are home to glaciers, massive rivers of ice and snow carved into the rugged terrain.

But as the climate warms, many of those glaciers are melting quickly — and some may already be doomed to melt away entirely.

“We found that the glaciers are losing a significant amount of mass and that it’s really controlled by the amount of temperature increase that we see in the future,” says David Rounce, an environmental engineer at Carnegie Mellon University.

He and his colleagues recently found that if the world warms four degrees Celsius by the end of the century, more than 80% of all glaciers could disappear.

All that melting would contribute to rapidly rising sea levels. Plus, it would eliminate a key source of fresh water for billions of people who live downstream from those glaciers.

But their research also found that if the world can limit warming to just 1.5 degrees, about half of the world’s glaciers could be saved.

“Any reductions we can have in reducing that temperature increase will have a big impact on preserving our glaciers,” Rounce says.

Currently, the world is on track to warm nearly three degrees, so a lot more work is needed to protect these precious rivers of ice.

Reporting credit: Ethan Freedman/ChavoBart Digital Media