Which of the following is a major contributor to ocean acidification?

The major contributor to ocean acidification is increased carbon dioxide in the atmosphere. When carbon dioxide is released into the atmosphere from various human activities such as fossil fuel combustion, a significant portion of it is absorbed by the oceans. This absorption leads to chemical reactions in seawater, resulting in the formation of carbonic acid. As carbonic acid dissociates, it releases hydrogen ions, which lead to a decrease in the pH of ocean water, making it more acidic.

This process can have profound effects on marine ecosystems, particularly on organisms that rely on calcium carbonate to build their shells and skeletons, such as corals, mollusks, and some plankton species. Ocean acidification disrupts the availability of carbonate ions necessary for these organisms to maintain their structures, threatening biodiversity and the overall health of marine environments.

While excessive nitrogen from fertilizers contributes to nutrient pollution and can lead to issues such as algal blooms, it is not a direct factor in ocean acidification. Similarly, overfishing and destruction of coral reefs can have significant ecological impacts, but they do not directly cause changes in ocean acidity levels.