What factor contributes most significantly to ocean acidification?

The primary driver of ocean acidification is the increased absorption of carbon dioxide (CO2) from the atmosphere into the oceans. As human activities, particularly the burning of fossil fuels, release significant amounts of CO2, a portion of this gas dissolves in seawater. This results in a chemical reaction that forms carbonic acid, which subsequently dissociates into bicarbonate and hydrogen ions. The increase in hydrogen ions decreases the pH of the ocean, causing it to become more acidic.

Ocean acidification is particularly concerning because it can have detrimental effects on marine ecosystems, including the dissolution of calcium carbonate structures, which are essential for organisms such as corals and shellfish. These organisms rely on calcium carbonate to build their shells and skeletons, and as the ocean becomes more acidic, their ability to calcify is impaired.

Other factors mentioned, such as decreased salinity, overfishing, and increased sunlight exposure, do not directly cause ocean acidification in the same way that increased carbon dioxide does. Decreased salinity can affect marine life but is not a primary contributor to pH changes. Overfishing impacts marine populations and ecosystems but does not influence the acidification process. Increased sunlight exposure often affects photosynthesis in marine plants but does not