[evan_au (OP)]

I was interested in this story, which claims that you can reduce ocean acidification by converting Carbonic Acid into Sodium Bicarbonate (often used as an antacid).
- Carbonic acid comes from increased levels of CO₂ dissolved in seawater. It breaks down corals and had-shelled creatures, and they need to exert more energy to protect themselves.
 
An enzyme used by animals to control pH in the blood might be used to control pH in the ocean, if it could be scaled up.
- Sodium Bicarbonate is a salt, with a more neutral pH
See transcript or listen (11 minutes) at: http://www.abc.net.au/radionational/programs/scienceshow/new-approach-buries-carbon-dioxide-safely-in-sea-water/9556660

[Bored chemist]

To properly overcome the effect of carbon dioxide in the water you need a fairly strong base- a stronger base than carbonate. The only practical ones are  hydroxide and oxide.
We could dump massive amounts of calcium oxide into the sea.
However, producing that calcium oxide would require roasting  massive amounts of limestone  to decompose the carbonate and make the oxide.
 And the carbon dioxide produced would (if we didn't trap it somehow) end up in the air, and then in the ocean undoing all the work we tried to do.

There are other options but fundamentally most suffer from the same problem.
There's a few plausible ones
http://www.innovationconcepts.eu/res/literatuurSchuiling/olivineagainstclimatechange23.pdf