Of the CO2 released into the atmosphere by humans, around 30-40% of it dissolves in the oceans, while the rest remains in the atmosphere or is absorbed by living things on land. This has caused oceans, which are alkaline, to become more acidic over time. The overall pH of seawater has fallen from 8.2 to 8.1 from the start of the industrial era to
The chemical reactions associated with ocean acidification also drive a reduction in the availability of calcium carbonate – a compound that hard corals use to build their tough outer shell. With less calcium carbonate available, hard corals find it more difficult to repair or grow their skeletons.
Music credit: Into Infinity artists Unrecognisable Now, Naohito Uchiyama, Languis (CC BY-NC 3.0 US).