A new report has warned that coral reefs around the world are at risk of an irreversible decline as rising ocean temperatures, pollution and other environmental pressures continue to damage marine ecosystems.
Scientists say increasingly frequent marine heatwaves are causing widespread coral bleaching, a process in which corals lose the algae that provide them with food and their characteristic colours. Severe or prolonged bleaching can eventually lead to coral death.
Coral reefs support around a quarter of marine species and provide food, coastal protection and livelihoods for hundreds of millions of people worldwide. Their continued deterioration could therefore have serious consequences for both marine biodiversity and coastal communities.
The report calls for stronger action to reduce greenhouse-gas emissions, improve water quality and protect areas where coral reefs remain healthy. Researchers say limiting global warming is essential if the world's remaining reefs are to have a chance of recovering.
Experts warn that without urgent action, some coral reef ecosystems could pass ecological tipping points from which recovery would become extremely difficult or impossible.