Increased carbon dioxide emissions from human activities, particularly fossil fuel burning, are the primary cause of ocean acidification.

Ocean acidification occurs when excess carbon dioxide (CO2) in the atmosphere is absorbed by seawater, lowering its PH. This process reduces the availability of calcium carbonate, a vital substance for marine organisms like corals, shellfish, and plankton. The main driver of this is the rising levels of CO2 due to human activities such as burning fossil fuels, deforestation, and industrial processes. While pollution, overfishing, and habitat loss also impact coastal ecosystems, ocean acidification is primarily caused by the increase in CO2 emissions.