A phenomenon of exceptional importance such as global change and its multiple effects has been discussed in several Mètode monographs. In recent years, public concern about what we already perceive to be the greatest threat to humanity has not stopped growing; at the same time, the United Nations have proclaimed the period 2021-2030 as the Decade of Ocean Sciences for Sustainable Development, recognising the close relationship between the oceans, climate, and social welfare. The sea is a climate regulator and a reservoir of biodiversity, a source of food and other resources, a transport route, a cultural asset, and the driving force behind the tourism industry; it is also a natural hazard and, unfortunately, a dumping ground for waste and refuse.