RACHEL MARTIN, HOST:
If a glacier cracks and nobody hears it, does it still make a sound?
GRANT DEANE: Yes, it's like they're speaking to us. But it's a language that we don't yet understand well.
MARTIN: That's Grant Deane. He's a researcher at the Scripps Institution of Oceanography and one of the authors of a new study that interprets the acoustics of glacial melting.
DEANE: Oh, they moan, and they groan, and they crackle and rumble and fizz. And they have all kinds of amazing sounds that they make.
MARTIN: So Deane and his team set out to find what the glaciers are saying. They used underwater microphones to record the sound of massive sheets of ice breaking away from glaciers. And they used time lapse photography to observe how the glaciers changed above water.
(SOUNDBITE OF GLACIAL CALVING)
MARTIN: That is called calving. The study published in the journal Geophysical Research Letters found that there are three types of glacial calving, each with their own distinct sound.
DEANE: Imagine, if you will, a wall of ice in the ocean, and it extends from pretty much the bottom of the fjord, through the water and then on up into the air.
MARTIN: The ice can fall off above the water in a clean break or in a messy crumble. When it breaks off beneath the surface, it is almost impossible to see.
DEANE: But the sound propagates very well. So although we can't see the calving event, we can hear it.
MARTIN: That means Dean and the other researchers can tell how much ice is breaking off and ultimately how much it's contributing to global sea level rise.
DEANE: But we also want to be able to predict in 50 years from now how much ice is going to be melting into the ocean. And that is a far more subtle thing.
MARTIN: By listening to the glaciers, Deane says they may just reveal their secrets.
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