Ocean Sound Propagation in a Changing Climate: Global Sound Speed Changes and Identification of Acoustic Hotspots

Climate change is a relevant threat on a global scale, leading to impacts on ecosystems and ocean biodiversity. A considerable fraction of marine life depends on sound. Marine mammals, in particular, exploit sound in all aspects of their life, including feeding and mating. This work explores the impact of climate change in sound propagation by computing the three-dimensional global field of underwater sound speed. The computation was performed based on present conditions (2006-2016) and a "business-as-usual" future climate scenario (Representative Concentration Pathway 8.5), identifying two "acoustic hotspots" where larger sound speed variations are expected. Our results indicate that the identified acoustic hotspots will present substantial climate-change-induced sound speed variations toward the end of the century, potentially affecting the vital activities of species in the areas. Evidence is provided of the impact of such variation on underwater sound transmission. As an example of a species impacted by underwater transmission, we considered one marine mammal endangered species, the North Atlantic right whale (Eubalaena glacialis), in the northwestern Atlantic Ocean. To the best of our knowledge, this is the first global-scale data set of climate-induced sound speed changes expected under a future scenario. This study provides a starting point for policies oriented research to promote the conservation of marine ecosystems and, in particular, endangered marine mammals.