[pfdietz]

It also can make sense to add limestone (or other carbonates) to the ocean. As long as you don't make the ocean too alkaline, you get the following net reaction:

CaCO3 + CO2 + H2O --> Ca(+2) + 2 HCO3(-1)

[ianburrell]

Seeing as climate change is making the ocean acidic, making it alkaline would be a good thing.