Since the beginning of the industrial revolution, about one third of the CO2 released in the atmosphere by anthropogenic activities has been absorbed by the world’s oceans, which therefore play a key role in moderating climate change. As CO2reacts with sea water, it generates dramatic changes in the carbonate chemistry, including decreases in pH and in the concentration of carbonate ions. Average surface water pH values on the total scale are in an accelerating decline: 8.3 during the last glacial maximum, 8.2 just prior to the industrial era, and 8.1 at present; surface pH may reach 7.8 by the end of this century. This pH level will probably be unprecedented in several tens of millions of years and the changes in carbonate chemistry are happening at a speed 100 times greater than has ever been seen before. The impacts of this phenomenon, known as ocean acidification, on marine ecosystems are only poorly known.As oceans continue to acidify, there is an increasing risk of loss of biodiversity and of profound ecological shifts. One of the most likely consequences is the slower growth of organisms forming calcareous skeletons or shells, such as corals and mollusks.
Gattuso J.-P. & Hansson L., 2008. EPOCA (European Project on Ocean Acidification) and other research efforts devoted to the Mediterranean Sea. In: Briand F. (Ed.), Impacts of acidification on biological, chemical and physical systems in the Mediterranean and Black Seas, pp. 31-33. Monaco: CIESM. Article.
