As the wind whips across the Antarctic, ice shelves sing to themselves in frequencies too low for human ears to hear.For the first time, scientists have recorded these hums and groans using highly sensitive seismic sensors buried in the snow. The sound is ethereal—an otherworldly hum resonating from our own planet.As part of a new study published Wednesday in Geophysical Research Letters, Julien Chaput, a geophysicist and mathematician at Colorado State University, and her team accidentally discovered the sounds coming from the thick snow layer covering Ross Ice Shelf, Antarctica’s largest ice shelf while studying the movements of the ice shelf and storms farther north. The layer, called the firn, isn’t perfectly smooth, but covered in undulations and hills like sand dunes.Winds make the firn vibrate, creating a flute-like effect across the dunes. But not a melodic, soothing flute—more like a demonic tortured flautist is trapped under the ice.“The firn layer was buzzing with seemingly constant, pulsating vibration,” Douglas MacAyeal, a glaciologist at the University of Chicago, wrote in a commentary about Chaput’s findings. “If this vibration were audible, it would be analogous to the buzz produced by thousands of cicada bugs when they overrun the tree canopy and grasses in late summer.”These seismic sounds aren’t just spooky—continued monitoring could help researchers better understand and track how ice shelves are adapting with climate change. On Wednesday, the National Oceanic and Atmospheric Administration reported that the Antarctic sea ice extent in September was 3.3 percent below average, the second smallest for September on record.“The response of the ice shelf tells us that we can track extremely sensitive details about it,” Chaput said. “Basically, what we have on our hands is a tool to monitor the environment, really. And its impact on the ice shelf.”
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