If you ever find yourself on Antarctica's largest ice shelf, you won't hear much besides the whistle of the wind. But there's another sound that rumbles across the frozen plain, and humans have been unable to listen to it until recently.
This audio clip released by the American Geophysical Union was recorded on Antarctica's Ross Ice Shelf—a slab the size of Texas. In a news release, researchers compare the haunting tones to those of a flute or "the pounding of a colossal drum." The sound is actually made by wind shifting massive snow dunes and causing the ice sheet beneath them to vibrate. The frequency is too low to be detected by the naked ear, so the scientists sped up the 2015 recording below about 1200 times.
As the researcher describe in their newly published study in the journal Geophysical Research Letters, they discovered the Antarctic song by accident. They installed 34 seismic sensors beneath the Ross Ice Shelf's deep layer of snow in late 2014 in order to track its movements. It didn't take long for them for them to realize that the ice produces a near-constant humming tone that's unrelated to its gradual shift toward the sea.
In addition to sounding cool, the vibrations also convey valuable information about the state of the ice shelf at any given time. The position of the snow dunes and air temperatures at the surface both determine the specific pitch of the glacial tones. By studying which conditions correspond to which pitches, climate scientists can better monitor the stability of the ice—which is essential as more ice chunks break away from the continent each year.