How Sound Can Help Scientists Track Earth's Vanishing Glaciers

Illustration for article titled How Sound Can Help Scientists Track Earth's Vanishing Glaciers
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Our planet is a symphonic masterpiece. Whales, rivers, water birds, springs, and ice all there for the listening, and they sound spectacular. But humans are changing the planet’s tune and adding discordant notes to the natural score.


That’s particularly true for the polar regions, where glaciers tumble down from Greenland and Antarctica’s ice sheets into the oceans. Those glaciers have been melting at a quickening clip, and researchers have chronicled the sound of their disappearance for years. But a new study published in Geophysical Research Letters makes the case that scientists could actually use those sounds to get a better handle on how fast the ice is melting. Glacier sounds could help inform what’s going on in areas that are hard to observe via satellite, as well as what’s happening under the water’s surface.

“It is clear that we need to keep the finger on the pulse, by conducting glacier monitoring programs and forecasting future changes,” Oskar Glowacki, a postdoctoral researcher at Scripps Institution for Oceanography at UC San Diego, told Earther. “But while it is easy to look at glaciers from the space using satellites, it is difficult or even impossible to study ice melting that takes place below the sea surface.”

Glowacki and his colleagues undertook a case study in Hornsund Fjord near Svalbard, Norway where Hans Glacier tumbles down into the fjord and calves icebergs year after year. To listen to the glacier and its icebergs, they put hydrophones, tiny, waterproof listening devices, underwater over the course of three summers.

The thing about glacial ice is it’s not like ice in your freezer. For an ice cube, you just pour tap water in a tray and freeze it. Glacial ice forms when snow falls each winter and gets compacted under its own weight. That process leaves tiny air pockets, unlike your average freezer-made ice.

When it melts, those bubbles create tiny sonic explosions. In Glowacki’s recordings, you can hear those thousands of explosions as the ice disintegrates in a riot of sizzles, hisses and pops. Close listening to the recordings reveal subtle differences in how different forms of ice melt under different conditions, though.


Glacier melt caused a near constant stream of sound somewhere between white noise and the sound of rain falling on a lake. But as icebergs melted, the sound was more varied, almost like a babbling brook or “sizzling popcorn or frying bacon” in Glowacki’s estimation. The researchers were able to tease out the source of the sounds by tracking the icebergs as they passed by on a boat, and through a statistical analysis of the noises they recorded over time.


The sounds also reveal that the side of icebergs exposed to currents—where more heat is exchanged between the water and ice—is noisier than the backside. That means there’s potentially a direct relationship between the sound of melt and how warm the water is.

This is the first study to tease out those differences, and the findings offer a path forward to refining our understanding of ice melt as oceans warm further. Glowacki said the next step is to better quantify the relationship between melt sounds and water temperature, as well as how the sounds bounce off the ocean floor and surface alike. But if the technique can be refined, it may be used not just in Norway but in Greenland and Antarctica, which contain much bigger stores of ice.


Beyond science, there’s also something more meta about the research. Stepping back from its applications, the sounds themselves are a record of this peculiar time on Earth.

Matthew Burtner, a composer the University of Virginia who has featured glacier sounds in his pieces, told Earther that the glaciers are “expressive instruments of our time, played by the human population as a force of global warming. When we hear those signature glacial sounds we can imagine the global system and our place in it.”


And right now, our place is one where we’re one of the dominant sources of landscape change.

Managing editor at Earther, writing about climate change, environmental justice, and, occasionally, my cat.


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Whenever I think of geophysics and soundwaves, I think of “Thumpers.”

Maybe the geologists and geophysist doing the published study above were hearing the sound of a track mounted thumper truck doing seismic surveys somewhere in the Arctic looking for oil:

Basically the plate in the middle of the truck starts pounding on the ground to create sound waves to travel through the ground and back up to sensors. Some asshole back in the day at college started up one of those parked in the geophysics yard. Took it for a joyride and started thumping away. Blasted out some windows in the nearby town. I think it was a geologist. Probably a geologist.