I find it a bit strange that the happy people are predicting the end to coral reefs, but I'm not going to argue with them. Clearly, injecting huge amounts of carbon dioxide into the atmosphere will have some nasty effects.
But there have been many injections in the geological past, and yet the coral survives. What happens to them during a CO2 episode? Do they just give up on the reef building and float around? Would evolution be friendly to such an arrangement? Do they shift to other areas of the world? I find this interesting.