Climate warming is transforming the underwater soundscape

Faster sound transmission in the oceans due to climate change will alter the underwater soundscape marine organisms rely on for survival. New research published by the American Geophysical Union reveals that climate change will significantly alter how sound travels underwater, as sound waves move faster and farther in warmer water.

The new global study demonstrates how changes to ocean soundscapes could impact essential activities of marine life. The ocean soundscape is made of vibrations produced by living organisms, waves and cracking ice, and human caused sound such as ship traffic and resource extraction. 

“We calculated the effects of temperature, depth and salinity based on public data to model the soundscape of the future,” said study lead author Alice Affatati. These factors all affect how fast and how far sound travels in water.

Two “acoustic hotspots” of sound speed increases are predicted in the east of Greenland and in the Northwest Atlantic Ocean, East of Newfoundland. 

These hotspots can expect the most change at 50 and 500 meter depths, where the average speed of sound is likely to increase by more than 1.5%, or approximately 25 meters per second by the end of the century.

Marine animals use sound to communicate and navigate their underwater world. Changes in sound speed can impact day to day activity such as finding food and mates, avoiding predators and even migrating.

“The major impact is expected in the Arctic, where we know already there is amplification of the effects of climate change now. Not all the Arctic, but one specific part where all factors play together to give a signal that, according to the model predictions, overcomes the uncertainty of the model itself,” said author Stefano Salon.

To consider how these changes impact species, the study also modeled vocalizations of the North Atlantic right whale, a critically endangered species inhabiting both north Atlantic acoustic hotspots. This found that  whales’ typical “upcall” at 50 Hertz is likely to travel farther in a warmer future ocean.

“We chose to talk about one megafauna species, but many trophic levels in the ocean are affected by the soundscape or use sound,” Affatati said. “All these hotspots are locations of great biodiversity.”

This study has inspired future work to combine the global soundscape with anthropogenic impacts in the oceans to identify areas of combined stressors, or direct needed observational research.

The study is published in the journal Earth’s Future.

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By Katherine Bucko, Earth.com Staff Writer