I was recently in the Caribbean on vacation and went diving. The guide stated that the die-off of coral has nothing to do with water temperature change or acidity. Both have not changed at all over the past 30 years when he had been a dive guide. He stated that the die-off of coral is directly associated with pollution, and in some local situations severe hurricanes. He further stated that anyone who says differently doesn't know what the heck they are talking about. Maybe you need to go on a dive trip and hear it for yourself.