Ocean acidification
Ocean acidification from increasing level of atmospheric CO2 represents a major global threat to coral reefs, and in many regions acidification is exacerbated by local smaller-scale disturbances such as overfishing. Studies have shown that severe acidification and warming alone can lower reef resilience even under high grazing intensity and low nutrients. Furthermore, the threshold at which herbivore overfishing (reduced grazing) leads to a coral-algal phase shift was lowered by acidification and warming. Also, increasing temperature and ocean acidification are predicted to have a synergistic effect; ocean warming will further magnify ocean acidification changes.