Melting causes faster ice loss at tidewater glaciers, releasing pressurized bubbles
INDUSTRIAL SOCIAL OF AMERICA
CREDIT: JOHNSON, VISHNU AND DEANE
SEATTLE, December 3, 2021 – As world temperatures rise, tidewater glaciers are receding and melting, releasing air trapped in the ice. Scientists can listen to air release and potentially use sound to help them assess the impact of climate change on ice sheets.
During the 181st meeting of the Acoustical Society of America, to be held November 29-December 29. 3, Hayden Johnson, from the University of California, San Diego, will discuss how sound can can be used to estimate the melting of ice caused by climate change. The talk, “Spatial Shifts in Sound Fields Due to Submarine Melting in Ice Bays,” will take place on Friday, December 3, at 11:45 a.m. Eastern at the Hyatt Regency Seattle.
Hari Vishnu, from the National University of Singapore, Grant Deane, from the Scripps Institution of Oceanography, and their research team investigated the thawing of ice that creates bubbles of distinct sound pressure underwater.
The air trapped with the ice beneath the glacier’s surface becomes a compressed, pressurized bubble rock mixture all the way to the glacier’s terminus. The glacier’s ice contains ancient gas bubbles that can have a pressure of up to 20 atmospheres and produce detectable sounds as they emanate as the ice melts.
“We observed that the intensity of sound produced by the molten terminal tended to increase as the water temperature increased,” said Deane. “This makes sense, because we expect the terminal to dissolve faster in warmer water, release bubbles more quickly into the ocean, and produce more sound.”
The team found that as the recording plate was moved further away from the glacier, the variation in sonic melt did not follow a uniform trend.
Furthermore, the sound intensity at different glaciers converges to different degrees. These observations indicate that the shape of the glacier-ocean interface, the temperature and salt composition of the underwater acoustic channels, and the presence of drift ice impact the recorded acoustic measurements. .
Their experiments will allow monitoring the effects of climate change on glaciers.
“Underwater acoustic recording from a melting terminus opens the door to long-term acoustic monitoring of ice loss and its relationship to water temperature,” said Deane. “The end game here is setting up long-term recording stations for underwater sound around glaciers like those in Greenland and Svalbard, to monitor their stability over time.”
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