Ocean acidification is a significant and harmful consequence of excess carbon dioxide in the atmosphere.
About half of anthropogenic from industrial era CO2 has been absorbed over time by the oceans. This has benefited us by slowing the climate change these emissions would have instigated if they had remained in the air.
In the past 200 years alone, ocean water has become 30 percent more acidic (lower pH)—faster than any known change in ocean chemistry in the last 50 million years.
Massive amounts of CO2 absorbed by the seas are altering water chemistry and affecting the life cycles of many marine organisms, particularly those at the lower end of the food chain.
Continued ocean acidification is causing many parts of the ocean to become undersaturated with calcium carbonate minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.