In brief
The latest global study identified 340 threatened coral species and classified 122 of 127 shallow‑water ecosystems as Critically Endangered. Rising ocean temperatures are driving more frequent bleaching, leaving reefs no chance to recover. Scientists say urgent action on emissions and local pressures like overfishing and pollution is needed to prevent irreversible collapse.
A recent global assessment released by the International Union for Conservation of Nature (IUCN) warns that rising ocean temperatures are threatening coral species and reef ecosystems across the world.
Out of 892 reef‑building species studied, 340 are now considered threatened with extinction, according to a paper published in Nature in October 2023.
The same report notes that 122 of 127 shallow‑water coral reef ecosystems—about 96 %—have been classified as Critically Endangered when projected climate change is included.
IUCN officials said, "There is still time to act, but the window is closing."
Marine ecologist Francoise Cabada‑Blanco, co‑chair of the IUCN SSC Coral Specialist Group, explained that bleaching is moving towards a near‑annual frequency, leaving reefs no recovery window at all.
We are now moving towards near‑annual bleaching, which leaves no recovery window at all.
The assessment projects that, under an Intergovernmental Panel on Climate Change scenario, marine heatwaves will become so common over the next 50 years that reefs will not recover between events.
Cabada‑Blanco noted that the data set ended in 2020, before the large bleaching event that spanned 2023‑2025, and that conditions have likely worsened since.
Even though most reefs still function, the loss of coral cover threatens a system that covers less than 1 % of the ocean floor but supports about 25 % of marine fish species, and provides food, tourism and coastal protection.
To avoid irreversible reef collapse, scientists urge reducing emissions and addressing local stresses such as overfishing and pollution.
