From shipping to oil drilling, sounds from human activities spread across the oceans. This noise causes much trouble to ocean creatures. However, according to a new study, climate change might influence how sound travels through the water.
Human-caused climate change impacts the ocean in many ways, such as changing its temperature, salt levels, and acidity(酸度). When the water becomes more acidic, it also can't absorb certain sounds. So those sounds travel further, adding to the noise in some areas. However, this effect is not as big as other changes. Changes like temperature and salt level can affect how the ocean's different layers(层) mix. That, in turn, affects how sound travels.
"We were surprised to see that actually there was a big change in the North Atlantic," says Luca Possenti, who studies sound in the ocean at the Royal Netherlands Institute. Researchers used computers to model how those factors influence noise levels across the world's oceans. They compared the models of the world now to models of the world in about70 years if climate change continues. In the North Atlantic, they saw an increase in sound levels in the upper 125 meters of the ocean.
This was caused mostly by ice melting from Greenland, forming a cold layer of water near the ocean's surface. When sound travels through water, it turns toward the coldest area. This made sound waves get stuck in the cold top layer and spread further out across the water instead of traveling deeper. As a result, the sound became louder at this specific depth in the North Atlantic.
The rising noise levels in the Atlantic Ocean is concerning as it could stress out animals reliant on sound for communication, hunting, and navigation. Marine mammals already avoid loud harbors, but with noise levels increasing everywhere, we don't know what will happen.
