When carbon dioxide (CO2) from the atmosphere dissolves in seawater, it forms carbonic acid (H2CO3), which dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-). This increase in hydrogen ions causes the pH of the water to decrease, making it more acidic.

Ocean acidification has a number of negative effects on marine life.

- Reduced calcification: Many marine organisms, such as corals, shellfish, and some types of plankton, use calcium carbonate to build their shells and skeletons. Ocean acidification makes it more difficult for these organisms to obtain calcium carbonate, which can slow their growth and make them more vulnerable to predation.

- Impaired reproduction: Some marine species, such as fish and sea urchins, have reproductive cycles that are sensitive to pH levels. Ocean acidification can disrupt these cycles, making it more difficult for these species to reproduce successfully.

- Reduced biodiversity: Ocean acidification can lead to a decline in the diversity of marine life. This is because some species are more sensitive to ocean acidification than others, and these species may be unable to survive in a more acidic ocean.

- Disrupted food webs: Ocean acidification can also disrupt food webs by altering the interactions between different species. For example, ocean acidification can make it more difficult for some predators to catch their prey, which can lead to a decline in the predator population.

Ocean acidification is a serious threat to marine life and the ecosystems that depend on it. It is important to take steps to reduce carbon emissions and slow the rate of ocean acidification.