Researchers in Antarctica have discovered that the frozen continent’s ice shelves produce an audible sound when the wind passes over the surface snow, a haunting song from a landscape that remains alien to the majority of us. The researchers also found that the "song" changes as the surface conditions of the ice changes — meaning that this Antarctica aria might become useful in tracking the effects of climate change on the ice at the bottom of the Earth.
For two years, researchers from the American Geophysical Union monitored data gathered from 34 high-sensitivity seismic sensors implanted under the snow on Antarctica’s largest ice shelf, the Ross Ice Shelf. The researchers found that as the wind blows over the firn snow, a granular layer that helps protect the underlying ice from melting, it produces a constant, low level sound above 5 hertz. As surface condition change, the pitch of the sound also changes, producing a variety of different frequencies — sounds that might be used to monitor the ice without having to maintain a constant presence on a remote ice shelf the size of France.
"It’s kind of like you’re blowing a flute, constantly, on the ice shelf, with each note change indicating a major structural change," according to research team member Julien Chaput, of Colorado State University. "Either you change the velocity of the snow by heating or cooling it, or you change where you blow on the flute, by adding or destroying dunes. And that’s essentially the two forcing effects we can observe."
The Ross Ice Shelf itself covers an area of 193,363 square miles (500,809 square km), making it difficult to monitor in its entirety, a fact that compounds the initial difficulty in accessing the remote region to begin with. The importance of monitoring of ice shelves, especially those found in Antarctica, has been increasing as global warming progresses: ice shelves act as dams that keep the land-based glaciers that feed them stable, and when these shelves collapse the glaciers they were supporting tend to flow rapidly into the ocean, as was the case when the Larsen B ice shelf collapsed in 2002, accelerating sea level rise.
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