the oceans are acidifying 3 times faster than they have the past 300 million years.Also they have been acidifying because of all the carbon dioxide in them. the carbon comes from the carbon cycle from the earth and the sun. This picture here shows how dissolved carbon dioxide CO2+water H2O= Carbonic acid H2CO3 witch latter turns into bicarbonate ions HCO3. witch also latter turn into carbonate ions witch lower the Ph of the water. A way to stop ocean acidification is by helping clean the ocean.

Ocean aciifacation