That is horrible for the ocean. Acidification will be killing off whole ecosystems and lead to drastically lower carbon sequestration by our oceans. As well as other horrible problems for us humans, who are still quite dependent on functional living oceans.
I've read in several places that 50% of carbon in the atmosphere is absorbed by the ocean within 20-200 years.
I'm guessing that's bad for the ocean, and maybe there's a limit, and the rate probably isn't constant. It's not a half-life at all.