84% of World’s Coral Reefs Struck by Worst Bleaching Event in History

Washington: A staggering 84 percent of the world's coral reefs have been affected by the most severe bleaching event ever recorded, according to a grim announcement by the International Coral Reef Initiative (ICRI) on Wednesday. This marks the fourth global bleaching event since 1998 and has already surpassed the devastation caused by the 2014–2017 event, which impacted around two-thirds of coral reefs.
The ongoing crisis, which began in 2023, is being driven by persistently warming ocean temperatures. Experts warn that there’s no clear end in sight.
“We may never see the heat stress that causes bleaching dropping below the threshold that triggers a global event,” said Mark Eakin, Executive Secretary for the International Coral Reef Society and former coral monitoring chief for the U.S. National Oceanic and Atmospheric Administration (NOAA).
2023 was the hottest year ever recorded on Earth, with much of the excess heat absorbed by oceans. The average annual sea surface temperature away from the poles reached a record 20.87°C — a deadly level for coral ecosystems.

Coral reefs, often dubbed the “rainforests of the sea,” support about 25 per cent of all marine species and are vital for seafood production, tourism, and coastal protection. Coral bleaching occurs when prolonged heat stress causes symbiotic algae — which give corals their vibrant colours and supply them with food — to release toxic compounds. The corals then eject the algae, leaving behind their pale skeletons and making them highly vulnerable to death.
The current bleaching event is so extreme that NOAA’s Coral Reef Watch has had to add new levels to its bleaching alert scale to reflect the escalating risk of coral mortality.
Global restoration efforts are underway, including coral propagation in controlled environments like Dutch labs using fragments from the Seychelles, and recovery programs off Florida’s coast aimed at nursing heat-damaged corals back to health for reintroduction to the wild.
However, scientists stress that addressing the root cause — climate change driven by greenhouse gas emissions — is crucial. “The best way to protect coral reefs is to address the root cause of climate change. And that means reducing the human emissions that are mostly from burning of fossil fuels — everything else is looking more like a Band-Aid rather than a solution,” said Eakin.

Melanie McField, co-chair of the Caribbean Steering Committee for the Global Coral Reef Monitoring Network, added a stark warning: “I think people really need to recognise what they're doing — inaction is the kiss of death for coral reefs.”
The timing of the update is politically charged, as it coincides with US President Donald Trump’s second-term moves to aggressively boost fossil fuel production and dismantle clean energy initiatives. “We’ve got a government right now that is working very hard to destroy all of these ecosystems,” said Eakin. “Removing these protections is going to have devastating consequences.”
As ocean temperatures continue to rise, scientists and conservationists alike fear that coral reefs — vital lifelines for both marine biodiversity and human livelihoods — may be pushed beyond the brink unless global action is taken immediately.