The world’s oceans are a natural sink for carbon dioxide, both organically and inorganically.
Organically, primary producers such as phytoplankton present in the oceans absorb carbon from the atmosphere, fixating it in their bodies as they grow and reproduce, and relegating it to the bottom of the ocean once they die. Inorganically, carbon dioxide from the atmosphere is absorbed into oceanic waters, given that carbon dioxide is soluble in water.
Whenever carbon dioxide is dissolved directly into water, it creates carbonic acid (H2CO3), which makes the ocean less alkaline (ocean water is naturally slightly alkaline, with current pH of about 8.1, and a pH of 7 being neutral on the logarithmic scale). Thus, the more anthropogenic carbon dioxide increases in the atmosphere, the more carbon dioxide is absorbed into the ocean, and the more acidic the oceans become. This process of ocean acidification has many consequences for marine ecosystems, especially shellfish and coral reefs, whose exoskeletons are made of calcium carbonate (CaCO3), a substance that dissolves in acidic conditions.
SciencePoles, 4 March 2010. Full article.
