One of the world's biggest slabs of ice is singing.
Wind blowing over the rough surface of Antarctica's Ross Ice Shelf causes the frigid, France-sized expanse to produce a nearly continuous series of tones, according to research published Tuesday in the journal Geophysical Research Letters.
The tones are too low to be heard by humans, but sped-up renditions have been likened to everything from the haunting drone of a didgeridoo to the soundtrack of a 1950s movie about space aliens.
The discovery of the singing ice came by accident.
To learn more about the ice shelf, which floats on the Southern Ocean next to the Antarctic continent, researchers in 2014 buried dozens of seismic sensors under the shelf's snowy surface. But when the scientists set about to analyze more than two years of data collected by the sensors, they discovered that the shelf's rough surface — what scientists call the firn layer — was almost constantly vibrating.
The scientists also discovered that the frequency of the vibrations changed in response to changing weather conditions on the shelf — when the temperature rose or fell, for instance, and when storms resculpted the shelf's snow dunes.
The firn was "alive with vibration," Douglas MacAyeal, a glaciologist at the University of Chicago, said in a written commentary that accompanied the paper. "This vibration was found to be driven by the wind blowing across the firn layer and interacting with the intrinsic roughness of the surface called sastrugi."
MacAyeal also offered a more poetic description of the sound, comparing it to "the buzz produced by thousands of cicada bugs when they overrun the tree canopy and grasses in late summer."
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Julien Chaput, a geophysicist and mathematician at Colorado State University in Fort Collins and the leader of the research, told NBC News MACH in an email that the sound was "a little like yodeling, except with 10 people all singing in dissonance. It's a little eerie."
But the singing ice is more than a sonic curiosity. Chaput and his colleagues argue in their paper that it might be possible to tap into seismic data to help monitor the health of ice shelves, which have been thinning in response to global warming — and causing sea levels to rise around the world.
Satellite data has proven useful for tracking conditions on ice shelves, but Chaput said seismic monitoring might afford a more nuanced look.
"Our current plans are to data mine all existing Antarctic seismic stations and see if we can get a broad sense of 'snow health' and deploy more stations on vulnerable ice shelves in West Antarctica," he said, adding that the data could prove to be the "canary in the mines" for monitoring polar regions.
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