Ice shelves perform a vital function in slowing down the rate of glacier melt in Antarctica, so scientists keep an eye on them for signs of collapse. And as the continent's largest, the Ross Ice Shelf is particularly important. After monitoring seismic activity over a few years, researchers noticed that the Ross Ice Shelf is "singing" – and listening out for changes in that song could be an early warning system for potential problems.
As temperatures rise, glaciers are melting at an increasing pace, but ice shelves are doing their part to slow that process down. Unfortunately, these ice shelves are themselves collapsing, which speeds up the rate of glacial melt and, in turn, sea level rise. Last year, a giant iceberg calved off the Larsen C ice shelf, and now continuously-sprawling cracks threaten to destabilize the rest of the ice shelf.
Roughly the size of France, the Ross Ice Shelf is crucial to keeping the southern continent together, so monitoring it is of particular interest to scientists. To do so, 34 seismic sensors were buried beneath the thick snow that blankets the shelf, allowing researchers to monitor its structure and how it moves.
After analyzing data gathered between late 2014 and early 2017, researchers noticed that the snow dunes atop the ice shelf were almost always vibrating. On closer inspection, it seems that the wind blasting across the surface is responsible, creating a constant hum too low for human ears to pick up.
But it wasn't just a one-note song. The pitch changed with the weather, vibrating at different frequencies with storm winds and as the surface temperature rose and fell.
"It's kind of like you're blowing a flute, constantly, on the ice shelf," says Julien Chaput, lead author of a study describing the work. "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 research suggests that using sensitive seismic stations to monitor these vibrations could help scientists understand how the ice shelf is responding to the changing climate.
Increasing the frequency of the sounds, the team turned the Ross Ice Shelf's "song" into something we can hear. The eerie results sound like the kind of natural "music" often heard from objects in space. Listen for yourself in the video below.
The research was published in the journal Geophysical Research Letters.
Source: American Geophysical Union
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