Sound propagation: the new frontier of the impact of climate change in the oceans

Climate change will significantly alter the way sound propagates underwater, affecting the ecosystem and potentially accentuating human-generated noise.

In warmer waters, sound waves propagate faster and persist longer, and a study published in the American Geophysical Union's (AGU) scientific journal Earth's Future has identified acoustic hotspots in the ocean that could have a significant impact on the life of aquatic organisms.

According to the projections of the research, in which OGS was involved, there are two key areas, in the Greenland Sea and in the northwestern Atlantic Ocean east of Newfoundland, where the greatest change could take place which, in the article, is analyzed at a depth of 50 and 500 meters. In the “non-mitigation” scenario of greenhouse gas emissions, the data from climate models shows a general increase in the average speed of sound by the end of the century on a global scale. In particular, in the two areas, the increase will be over 1.5%, or about 25 meters per second both in surface waters and at a depth of 500 meters.

In the collective imagination, marine ecosystem is silent and quait, but in reality, the waters of seas and oceans are quite noisy and, due to the sounds produced by marine organisms that use them to move and communicate with each other, as well as natural phenomena such as breaking waves and ice. Another cause, increasingly relevant, is man-made noise, such as ship traffic and mining.

The one published in the journal of the American Geophysical Union - AGU is the first estimate on a global scale of the speed of ocean sound linked to the future climate. The next step will be to extend the study to other areas of the global ocean by comparing the projections of variation in the speed of sound with other anthropogenic impacts to identify new areas at risk and develop any monitoring projects.