If you have visited coral reefs over the years you cannot help but notice the deterioration. I have my doubts about the relative vulnerability of reefs to slight temperature or acidity variations. I suspect the combination of nitrogen runoff pollution that creates algae carpets to grow over the reefs and overfishing of the species that normally keep algae at bay is the major factor. Coral reefs need nutrient-poor seas or they get outcompeted by algae. We need to stop dumping fertilizer into the oceans.
Some of us Freepers have saltwater aquariums with coral in our homes. We know how difficult it can be to provide the right conditions for their health and growth.
Algae is the one thing that almost destroyed my corals and it has been a constant battle. Keeping a nutrient-poor environment for the corals is rather difficult, when you are also trying to maintain a healthy fish population.
Salt is a chemical buffer, so minor variations of acidity is not possible with seawater.
Increased pH makes calcification more difficult for calcareous organisms.
You are right in my opinion. If you read the whole article he mentions climate change MAY reduce coral reefs by 40%, but overfishing and folks grabbing coral products to sell is what has so far caused the much larger problem. That is how I read the article anyway. Of course, that is not how the headline reads.