As the world sees rising ocean temperatures, it will also see more cases of coral bleaching. When corals bleach, they become more vulnerable to other stressors such as water pollution. However, many reefs harbor corals that persist despite warming oceans. Unraveling the complex issue of coral bleaching and its impact on their survival or death may be key to conserving coral reefs— ecosystems that more than half a billion people around the world rely on for food, jobs, recreation and coastline protection.