It seems impossible to acidify the oceans, given how salty they are. How could CO2 overcome all that salt?
When acids and bases neutralize each other in a laboratory experiment, salt and water form. But in the ocean, the major ions that make seawater “salty” (like sodium, chloride, and magnesium) have come from rock weathering, which provides a balanced amount of positive and negative ions to the seas over many millennia. Variations in ocean pH on shorter time scales of decades to centuries are controlled by weak acids and bases, like bicarbonate or borate. Of these weak acids and bases, the dissolved forms of CO2, known as carbonic acid, bicarbonate, and carbonate, have the largest impact on global ocean pH variations because their concentrations are changing quickly relative to other ions in the ocean. — Christopher L.
