What would happen to the annual rates of limestone (CaCO3) precipitation in the ocean if the ocean water were to become much warmer and more acidic?

CaCO3 exoskeleton dissolves in acidic water

Explanation:

The increasing CO2 level makes the ocean water acidic and hence reduces the pH. In such acidic environment, marine organism that produce calcium carbonate shells or skeletons are negatively affected. Coral reefs and coralline algae abilities to produce skeleton also reduces.

Calcium carbonate dissolves in acid. Thus, the more acidic the ocean water is the faster and easier it is to dissolve the exoskeleton and shell of marine organisms made up of calcium carbonate