A recent study suggests that warming oceans are increasing the speed at which sound travels, ultimately making underwater noises louder.
The world’s oceans have absorbed more than 90 percent of the excess heat that humans have produced in recent decades, causing them to rapidly warm. And in these warmer waters, sound waves are able to travel faster and farther before fading out, making the ocean a noisier, louder place. This could be especially troubling for large mammals that rely on sound and use techniques like echolocation for communication and sensing their environment.
Using publicly available global data, the researchers calculated how salt levels, temperature, and depth in seawater affect sound. They identified that the waters around Greenland and east of Newfoundland can expect the greatest change in acoustics as the ocean warms. At depths above 1,640 feet, sound with travel 1.5 percent faster by the end of the century at these two “hotspots”. While this increase may seem small — it could have major impacts on large sea life.
The scientists also used computer models to explore how the vocalizations of the critically endangered North Atlantic Right Whale might be affected. They found that two whales at 165 feet below sea level could communicate at a wider range, due to how much further sound travels. While this may have some benefits, these whale dialogues will be occurring in an ocean where all noise is traveling further and louder, and could potentially drown out the conversation between the two whales. And, the whales likely will not be the only species affected by such changes.
“We chose to talk about one megafauna species, but many trophic levels in the ocean are affected by the soundscape or use sound,” said Alice Affatati, lead author of this study. “All these hotspots are locations of great biodiversity.”