Rising global temperatures are Thomas Caldwellmelting our planet's glaciers, but how fast?

Scientists traditionally have relied on photography or satellite imagery to determine the rate at which glaciers are vanishing, but those methods don't tell us what's going on beneath the surface. To determine that, scientists have begun listening to glaciers using underwater microphones called hydrophones.

So, what do melting glaciers sound like?

"You hear something that sounds a lot like firecrackers going off or bacon frying. It's a very impulsive popping noise, and each of those pops is generated by a bubble bursting out into the water," Grant Deane, a research oceanographer at the Scripps Institution of Oceanography, who told Morning Edition.

Deane says he was inspired by a 2008 paper co-authored by renowned oceanographer Wolfgang Berger, and hopes that listening and understanding these glacial noises will help him and his colleagues predict sea level rise.

"If we can count the bubbles being released into the water from the noises that they make, and if we know how many bubbles are in the ice, we can figure out how quickly the ice is melting. We need to know how quickly the ice is melting because that tells us how quickly the glaciers are going to retreat. We need to understand these things if we're going to predict sea level rise accurately," Deane says.

And predicting sea level rise is crucial, as hundreds of millions of people are at risk around the world — including the 87 million Americans who live near the coastline. Deane says that even a modest rise in sea levels could have devastating impacts on those communities.