Coral bleaching reaches unprecedented scale, hitting 84% of global reefs

A record-breaking coral bleaching event is now affecting 84% of the world’s reefs, according to the International Coral Reef Initiative (ICRI), marking the most extensive marine bleaching crisis in recorded history.

The global event, the fourth since 1998, began in 2023 and has already eclipsed the 2014–2017 bleaching period, which damaged around two-thirds of coral reefs worldwide.

The ongoing event has been fuelled by ocean warming driven by climate change.

“We may never see the heat stress levels dip below the threshold for global bleaching again,” said Mark Eakin, corresponding secretary for the International Coral Reef Society and former chief of coral monitoring at the U.S. National Oceanic and Atmospheric Administration (NOAA).

Eakin warned the crisis is fundamentally altering the planet’s ecosystems and the ocean’s ability to support human life.

Corals, which consider as rainforest of the sea, support around 25% marine species, are critical for biodiversity, food security, tourism and coastline protection.

Algae are the reason of coral bright colours and it also nurish the coral.

Due to high temperature algae release toxic compounds which is ejected by coral. Afterthat only weak white skeleton left behind and heightened the risk of coral death.

The average sea surface temperature in last year reached a record 20.87°C in non-polar regions, contributing to the mass bleaching.

NOAA’s Coral Reef Watch has even had to expand its alert system to reflect the increasing intensity of the crisis.

Conservation efforts are underway in some areas. Projects in Florida and the Seychelles are attempting to rescue, regenerate and reintroduce coral to their natural habitats.

A Dutch lab has been growing coral in captivity to help restore damaged reefs in future scenarios.

Still, scientists insist that without aggressive cuts to greenhouse gas emissions, such efforts may only offer temporary relief.
“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,” Eakin said.

Melanie McField, co-chair of the Caribbean Steering Committee for the Global Coral Reef Monitoring Network, echoed that urgency: “Inaction is the kiss of death for coral reefs.”

Their update comes as US President Donald Trump, in his second term, continues to dismantle clean energy policies in favour of fossil fuel expansion — a move Eakin says could further endanger global marine ecosystems.