A devastating coral bleaching event, the most widespread and severe ever recorded, has now affected 84% of the world’s coral reefs, according to a report released Wednesday by the International Coral Reef Initiative (ICRI).
This marks the fourth global bleaching crisis since 1998, and it has now surpassed the previous record from 2014–2017, which impacted about two-thirds of reefs. The current event, which began in 2023, is fueled by rising ocean temperatures, and experts are unsure when it will end.
Mark Eakin, executive secretary of the International Coral Reef Society and former NOAA coral monitoring chief, warned that ocean temperatures may never fall below the level that causes global bleaching again. “This is reshaping our planet and threatening the oceans’ ability to support life and human livelihoods,” Eakin said.
2023 was the hottest year on record for Earth, with much of that heat absorbed by oceans. Sea surface temperatures in non-polar regions reached an average of 20.87°C (69.57°F), a dangerous level for coral survival.
Coral reefs, often called the “rainforests of the sea,” are vital to marine biodiversity, supporting around 25% of all marine life. They also play a key role in food supply, tourism, and protecting coastlines.
Bleaching occurs when high temperatures stress corals, causing them to expel the algae that give them color and nutrients. This leaves behind a white skeleton, leaving the coral vulnerable and often leading to death.
The bleaching has become so extreme that NOAA’s Coral Reef Watch had to expand its alert system to track the increasing threat to coral survival.
Restoration efforts are underway. In the Netherlands, researchers are growing coral fragments in labs, including samples from the Seychelles, to eventually help restore wild reefs. In Florida, similar projects aim to rehabilitate heat-stressed coral and return them to the sea.
However, scientists stress that these efforts alone are not enough. The primary solution, they say, is to cut greenhouse gas emissions—mainly carbon dioxide and methane—from burning fossil fuels.
“The only real way to protect coral reefs is to tackle climate change directly,” Eakin emphasized. “Otherwise, everything else is just a temporary fix.”
Melanie McField, co-chair of the Caribbean Steering Committee for the Global Coral Reef Monitoring Network, added that public awareness and action are crucial. “Doing nothing is a death sentence for coral reefs,” she warned.
The report comes amid controversial policy shifts in the U.S., where President Donald Trump’s administration has pushed to expand fossil fuel use and scale back clean energy initiatives. Eakin criticized these moves, saying, “Rolling back environmental protections will have catastrophic effects on ecosystems like coral reefs.”