Ocean acidification refers to the process by which the pH level of the ocean decreases due to the absorption of excess atmospheric carbon dioxide (CO2). When CO2 is absorbed by seawater, it reacts with water to form carbonic acid, which can dissociate into bicarbonate and hydrogen ions. The increase in hydrogen ions leads to a decrease in pH, resulting in more acidic ocean conditions.
Typically, the average pH of ocean surface waters has been around 8.2, but since the beginning of the Industrial Revolution, it has dropped significantly, with estimates indicating a decrease of about 0.1 to 0.2 units, which corresponds to a 30% increase in acidity. Projections suggest that if CO2 emissions continue at current rates, ocean pH could decrease further by the end of the century, possibly dropping to as low as 7.8 or lower.
The impacts of ocean acidification on marine life and ecosystems are significant, particularly for calcifying organisms like corals, mollusks, and some plankton species, which struggle to maintain their calcium carbonate structures in more acidic waters. This has broader implications for marine food webs, biodiversity, and fisheries.