What is the main cause of ocean acidification?

Ocean acidification primarily results from the increased absorption of carbon dioxide (CO2) from the atmosphere. When CO2 is released into the atmosphere—largely due to human activities such as burning fossil fuels and deforestation—much of it gets absorbed by the oceans. This process leads to a chemical reaction that forms carbonic acid, which in turn lowers the pH of ocean water, making it more acidic.

This change in acidity can have significant impacts on marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons, such as corals and some shellfish. As ocean acidity increases, it becomes harder for these organisms to form and maintain their structures, which can disrupt marine ecosystems and food webs.

The other options, while they may affect marine environments in various ways, do not directly cause ocean acidification. Increased ocean temperature can influence marine species and ecosystems, a decrease in biodiversity can alter ecosystem dynamics, and excessive overfishing can lead to imbalances in marine life. However, none of these directly relate to the chemical processes that lead to acidification as CO2 absorption does.