The Sounds of the Planet Melting
If a glacier melts, will it make a sound?
Glacial melt on an Icelandic beach. Image: Nick/Flickr.
Climate change is a noisy thing. Ever heard a glacier calve? Even if you haven't been to Greenland, you likely know just how thunderous the downward crash of building-sized hunks of ice really is.
But it's global warming's subtler soundtrack, shot through with the otherwise hushed tone of a single icicle dripping, say, that not only fills out a fuller, grimmer picture of what's happening as global temperatures continue to climb, a scenario driven largely by humans. If we capture its sonic profile, the collective din of our planet's retreating ice masses could hold keys to understanding the true scope of climate change—and if it's not too late, what we can do about it.
Our best shot at cooling down just might be by recording the sounds the Earth makes as it melts.
Just ask Gustavo Valdivia and Tomás Tello. Earlier this summer Valdivia and Tello, an anthropologist and experimental musician, respectively, set out for Peru's Quelccaya Ice Cap with a modest kit of lo- and hi-fi analog and digital field recording devices. They were after the far-flung sounds of the melting glacier, the idea being to "establish new approaches to questions of climate change," as they write in a guest post on GlacierHub.
And guess what? The death rattles of Quelccaya do not sound like, well, death rattles: An icicle drips. A brook, chilled inside a cave, babbles. Caught up in this easy stream is a pebble, ping-ponging gently down the mountain. This would be soothing stuff, if it didn't belie the fact that Quelccaya, the biggest tropical ice sheet on Earth, is in trouble.
They came out with a 10-track "sonic narration" of the encounter with the ailing glacier, which you can listen to here. They couldn't be more literal with their track titles. Take track four, above: "Water stream next to glacier with drops from icicle melting."
As they got deeper into the excursion, Valdivia and Tello got more and more creative in how they captured the final gasps of Quelccaya. At one point, they full-on stuck an underwater microphone right into a melt stream:
If anything, by utilizing consumer hydrophonic technology Valdivia and Tello are signal boosting a broader project that uses seafloor listening posts to chart the loudest naturally-occurring aquatic environment: the snap, crackle, and pop of ice melting off glacial fjords below the surface.
Up in Alaska, Kevin Lee and Preston Wilson, two acoustic experts with the University of Texas, use a network of hydrophones that they installed off the coast to listen to these sounds, which are the result of trapped bubbles of air that manage to escape.
According to Lee and Wilson, the bulk of the sounds they've so far captured come from bubbles that oscillate as they're spewed from the ice. These bubbles, borne of layer after layer of snow crystals that have trapped small air pockets, build up pressure. As more snow accumulates, the more the snow compacts into ice; the bubbles have nowhere to go, until they manage to wiggle their way out.
"A bubble when it is released from a nozzle or any orifice will naturally oscillate at a frequency that's inversely proportional to the radius of the bubble," Lee told Wired UK.
The researchers hope these field recordings of ice melting in glacial fjords can be brought to bear on time-lapse photography, another crucial tool in modern climate science, as Wired reports.
It's all part of the Glacier Acoustics Project, a pilot study headed up by Erin Pettit, a geophysicist at the University of Alaska who collaborates with Lee and WIlson.
As Pettit explains in the above video, the goal is to place the sounds of freshwater discharges that shoot out underneath glaciers in the context of a glacier's dynamic processes. These pulses are driving dramatic sea-level rise, but we still really have no idea how large these floods are, or how often they occur. That's because this happens deep in fjords, right in the firing line of calving glaciers. Not exactly the easiest, safest environment to pitch instruments.
Hydrophones, and underwater acoustics generally, let them observe the action from a safe distance, a mile or two out of harm's way. The hydrophones she and her team use to pick up these pulses operate on their own. The hydrophones' docks are anchored to the ocean floor, such that the mics themselves suspend roughly 100 meters above the ocean floor.
Electronically, the hydrophones are programmed to perk up every few of minutes, listen for four seconds, and then process the sonic data in a way that a single mic can tell if "there's anything interesting happening," in Pettit's words. Should something interesting happen, she goes on, the hydrophone will stay on, recording more data.
It might sound like strictly hard science, but it's worth noting that the humanities can help make sense of some of this data. Here's Jonathan Pearl, a musicologist at City University of New York, on his work sonifying data on Greeland's ice melt gathered by climatologist Marco Tedesco:
And then there's Katie Paterson. Back in 2007, Paterson, then a student at the Slade School of Art in London, dropped a hydrophone into a lagoon at the edge of Iceland's Vatnajokull Glacier. Here's what that sounded like:
Back in Peru, high up in the Andes, experts estimate that what took well over 1,500 years to amass into what we know today (formerly knew?) as the Quelccaya glacier has melted away almost entirely in just 25 years. For their part, Valdivia and Tello hope to return soon, with even more recording gear in tow.
In the end, the question shouldn't be, If a glacier melts, will it make a sound? But rather, As glaciers melt, what are they telling us?