This event, one of six since 1979, really should be a wake-up call to policymakers. It was caused by the combination of calm conditions and the baseline of steadily rising sea-surface temperatures in the tropics. While the Pacific was largely spared, other areas were devastated. Reefs in the Persian Gulf were all but annihilated, and Kenya and Tanzania saw their reefs reduced by 90 percent. Southeast Asia was similarly hard hit, with localized losses of 60-90 percent in Vietnam, the Philippines and Indonesia.
Climate change affects corals on many levels.
The first is heat stress. Given the pace of global warming, scientists expect sea surface temperatures to rise between 1-3 degrees Centigrade over the next 20 years. Since most corals are already living at their upper tolerance limit for warm water, any further increases are likely to result in widespread bleaching and death. Several studies presented in Bali illuminated more subtle effects. Warmer temperatures dampen primary productivity and reduce a coral's ability to withstand other types of stress.