There are reasons to assume that marine life will not be overly affected by an increase in ocean acidity due to atmospheric carbon dioxide:
That is probably why the Ocean remains alkaline, not acidic.
Al Black

I agree with your points. Nicely laid out btw.

But people like the OP, with legit credentials, say otherwise. If they are right there must be a forcing that is overwhelming the natural ocean buffer system. Have we run out of calcium or other metal molecules that bond with excess CO2? I don’t see how that could be possible.

Neither can I think of another reason that an ocean’s pH buffer system would be inactived by excess CO2.