As CO2 Increases, Carbonic Acid Build Up in Oceans

[Zoaelite]

From what I understand of basic chemistry:
Carbon dioxide dissolved in water is in equilibrium with carbonic acid:
CO2 + H2O ⇌ H2CO3

Although Carbonic acid is only a weak acid as soon as it hits sea water it dissociates a small amount. I just find it unfeasable that if anythings going to kill our reefs its a weak acid, I could be wrong though.
Levi