Reactions like this tend to buffer changes in atmospheric . Since the right side of the reaction produces an acidic compound, adding on the left side decreases the pH of seawater, a process which has been termed ocean acidification (pH of the ocean becomes more acidic although the pH value remains in the alkaline range). Reactions between and non-carbonate rocks also add bicarbonate to the seas. This can later undergo the reverse of the above reaction to form carbonate rocks, releasing half of the bicarbonate as . Over hundreds of millions of years, this has produced huge quantities of carbonate rocks.