Ocean warming is the long-term rise in the temperature of seawater, driven mainly by excess heat trapped by greenhouse gases. It can disrupt marine ecosystems by shifting species’ ranges, changing ocean conditions, and increasing stress on organisms such as corals.
For coral reefs, unusually warm water can trigger bleaching, in which corals lose the algae that provide much of their energy. Prolonged or repeated heat stress can cause severe damage or death. Researchers monitor ocean temperatures and study restoration methods, but recovery efforts do not remove the underlying heat stress; their effectiveness depends on conditions and must be tested over time.