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Though photographs may present the barren landscapes of Antarctica as eerily calm and peaceful, at least when no storms are raging, the largely lifeless continent and the ice shelves surrounding it produce a medley of bizarrely beautiful sounds. As noted by Earther, the frozen region’s ambient sounds include the Rice Crispies-like crackle of melting ice releasing long-trapped air bubbles to the steady groans, screeches, and pops of massive floating ice sheets shifting and breaking apart as they buckle under the weight of fresh snow in the winter or melt during the summer.
The only catch is that you might not be able to hear all the notes in this spectacular natural symphony if you’re listening with human ears, because many occur on timescales or at frequencies that are not compatible with our auditory abilities. But if you have the right equipment to first capture and then remix the acoustic waves, a whole new soundtrack can be revealed. On top of being really cool to listen to, these recordings help scientists better understand the climatological and geologic processes that shape the Antarctic.
In an astounding new example, a team led by Julien Chaput of Colorado State University and the University of Texas, have revealed how the "songs" created by vibrations in the Ross Ice Shelf can be used to continuously monitor the changing conditions within the ice mass' top five meters (16.4 feet).
“Deploying sensitive seismographs across Earth’s largest ice shelf (the Ross Ice Shelf) for 2 years, we discovered that the shelf nearly continuously sings at frequencies of ?ve or more cycles per second, excited by local and regional winds blowing across its snow dune-like topography,” they wrote in their paper, now published in Geophysical Research Letters. “We ?nd that the frequencies and other features of this singing change, both as storms alter the snow dunes and during a (January 2016) warming event that resulted in melting in the ice shelf’s near surface.”
The Texas-sized ice shelf floats on the Southern Ocean, fused to the mainland off western Antarctica. From this position, the shelf – itself composed of glacier ice that spilled out from the interior of the landmass – acts as a buttress to lessen the flow of ice melt that occurs each warm season. Climate change-driven increases in temperatures have already caused other ice shelves to thin and recede, resulting in sea level rise from unblocked glacier drainage. Currently holding back enormous glaciers that would contribute 5 meters (16.4 feet) of sea level rise if introduced into the water, researchers are anxious for ways to measure the integrity of the Ross Ice Shelf.
As part of that endeavor, Chaput and his colleagues had buried 34 extremely sensitive seismographs under the snow on the ice’s surface and analyzed the vibrations recorded between late 2014 and early 2017.
Installation of a seismic station near the northern edge of the Ross Ice Shelf, with a solar halo created by fine ice crystals created by spray from the nearby Southern Ocean. Rick Aster.
Soon into the project, the team realized that the snowy coating on the shelf is, in fact, vibrating nearly constantly from the effects of heating and wind. And, similar to a musical instrument, different tones are created when different forces act upon it.
"It's kind of like you're blowing a flute, constantly, on the ice shelf," Chaput said in a statement. "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," he said. "The response of the ice shelf tells us that we can track extremely sensitive details about it."
