Scientists have recorded and identified one of the most prominent sounds of a warming planet: the sizzle of glacier ice as it melts into the sea. The noise, caused by trapped air bubbles squirting out of the disappearing ice, could provide clues to the rate of glacier melt and help researchers better monitor the fast-changing polar environments. Geophysicist Erin Pettit, a researcher at the University of Alaska, had often heard popping, crackling sounds while out kayaking in the frigid northern waters. The sounds were also picked up by underwater microphones Pettit set up off the Alaskan coast, and at a much louder volume than above the surface.
“If you were underneath the water in a complete downpour, with the rain pounding the water, that’s one of the loudest natural ocean sounds out there,” she said. “In glacial fjords we record that level of sound almost continually.”
While Pettit suspected the din was caused by melting ice, she couldn’t confirm that hypothesis without a more controlled experiment. So she enlisted the help of Kevin Lee and Preston Wilson, acoustics experts from the University of Texas. Pettit sent the Texas researchers chunks of glacier, which they mounted in a tank of chilled water. Lee and Wilson recorded video and audio of the ice as it melted and were able to match sounds on the recording to the escape of bubbles from the ice.
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