Many types of marine organisms such as coral, clams, and sea urchins depend on the right amounts of certain chemicals in order to form their shells. Ocean acidification changes these levels of chemicals, and could, in the future, cause these organisms to not be able to form their shells. Some organisms have more of a resistance to ocean acidification, but others that are sensitive to it could be facing extinction in the near future. However, some sea snails have proven that ocean acidification does not affect them at all because they changed their shell-making process. This could mean that other organisms can also adapt to ocean acidification.
The ocean's PH has already dropped roughly 0.1, or an approximate 30% since the 1750's. "Scientists from the Potsdam Institute for Climate Impact Research in Germany say that if we were to remove CO2 from the atmosphere at a rate of 2.5 times that of the current annual emissions, oceans would not recover to a low-emission state by 2700." -[Hannah Osborne, IBT, page 1]. However, if changes were to start now, ocean acidification could technically be reversed before it is too late, but it would take a very long time.
Ocean acidification is caused simply by CO2 emissions being absorbed by the ocean and mixed into its chemical makeup. While it is very harmful to most marine organisms, ocean acidification in itself is just basic chemistry. If scientists were to put funds, effort, and time into it, they could probably develop a way to bring the ocean's acidity back to its original state.