As Coral Bleaching Becomes More Frequent, Reefs Have Less Time to Recover

Coral reefs are being hit by bleaching so often that they are losing the time needed to recover between events, according to the 2025 Status of Coral Reefs of the World report.

The share of reef surfaces covered by living coral fell from an average of 30.2% between 1980 and 2009 to 27.3% from 2020 to 2024. It dropped to 25.8% in 2024. The Global Coral Reef Monitoring Network attributed the decline mainly to marine heatwaves and large-scale bleaching linked to climate change.

Bleaching occurs when corals expel the symbiotic algae that supply them with energy, turning white and potentially dying. The phenomenon can occur naturally, but rising seawater temperatures have made it more frequent and severe. Global bleaching events have occurred four times, in 1998, 2010, 2014-2017 and 2023-2025. Coral cover fell by 6.5%, 9.9%, 6.6% and 8.9% during those periods, respectively.

Coral reefs cover less than 0.2% of the ocean floor but support more than a quarter of marine species. Their ecosystem services are valued at $9.9 trillion a year, and about 1 billion people depend on reefs for livelihoods, food and cultural identity. Reefs can also reduce wave energy by as much as 97%, protecting coastal areas from erosion and storms. Meanwhile, the coastal population living within 5 kilometers of reefs rose 46% from 2000 to 2020, reaching about 104 million.

The report said recovery remains possible. Global coral cover increased by about 6% from 2017 to 2019 after the third bleaching event, showing that reefs can rebound partly when pressures decline. Results varied by region: cover fell 43.4% in the Caribbean, 18.3% in the Pacific and 10.9% in Australia, while it rose 43.0% in the western Indian Ocean and 16.2% in South Asia. The report urged countries to limit warming to 1.5 degrees Celsius, reduce overfishing and pollution, and strengthen reef protection and long-term monitoring.