WWF says the global coral bleaching event, announced by the U.S. National Oceanic and Atmospheric Administration (NOAA), will have severe negative consequences for coastal communities and ocean health.
The global coral bleaching event means wide swathes of tropical reefs in the three largest ocean basins – the Atlantic, Pacific, and Indian – are experiencing extreme stress. Sufficiently severe or prolonged stress can cause coral mortality. This event – the second in 10 years and fourth overall – was triggered by record-shattering ocean temperatures that began last year. The ocean absorbs 90% of the excess heat caused by burning fossil fuels.
“If we need a specific, visual, contemporary case of what’s at stake with every fraction of a degree warming, this is it. The scale and severity of the mass coral bleaching are clear evidence of the harm climate change is having right now. We must act urgently to stop burning fossil fuels or we will lose coral reefs worldwide, with devastating consequences for coastal communities and marine wildlife,” says Pepe Clarke, WWF Oceans Practice Leader.
Roughly 850 million people worldwide rely on coral reefs for food, jobs, and coastal protection from storms. They also provide habitat for more than 25% of all marine species. Half of all tropical reefs have disappeared in the last century; the world is on course to lose up to 90% by 2050 and all coral reefs by the end of the century.
A bleached coral reef is not dead but is severely stressed. When exposed to prolonged heat – sometimes a difference of just a few degrees – corals expel the beneficial algae they host. This deprives them of their color and nutrients. Bleached corals can recover, but it requires reducing other sources of stress, such as overfishing and polluted run-off from land.
Most importantly, reefs need ocean temperatures to drop. “The coral crisis is a climate crisis, and the most important way to address marine heatwaves is to stop burning fossil fuels,” says Clarke.
Many coastal communities have done little to contribute to climate change, but are vulnerable to the effects.
“We’ve experienced mass coral bleaching in 2010, then 2016, and this year. This year felt worse, as bleached coral not only occurs in its ecosystems, but also in our restoration structures. Restoration structures are one of our active conservation efforts to revive coral reefs, providing a house for reef fish, and tourism attraction related to our local income. I really hope bleaching does not make coral die, if so our active conservation efforts like restoration could be in vain,” says Nyoman Sugiarta, head of the community monitoring group for Bondalem’s Locally Managed Marine Area and dive instructor in Bondalem village, Bali, Indonesia.
“In light of this global coral bleaching event, it is more important than ever to protect specific reefs that have exhibited resilience to marine heatwaves and can help in the future to re-seed damaged coral reefs. We must focus on limiting pressures from overexploitation, pollution, and over-development on these resilient reefs to enable their survival in a changing climate,” says Carol Phua, Coral Reef Rescue Initiative Lead.
Australia’s world-famous, UNESCO-listed Great Barrier Reef is also among the sites affected. It is experiencing the fifth mass coral bleaching event since 2016.
“The coral bleaching happening now on the Great Barrier Reef is a result of the global underwater heatwave that began last year in the Northern Hemisphere. Coral reefs in Florida and the Caribbean were decimated as a result of bleaching in 2023. The fate of corals in the Great Barrier Reef is on a knife edge – a significant cooling of water temperature is needed to avoid a similar outcome as the Northern Hemisphere. This event drives home that no reef anywhere is safe from the impacts of climate change,” says Richard Leck, WWF-Australia Head of Oceans.
WWF calls on countries to get serious about climate mitigation. This means stepping up efforts to reduce greenhouse gas emissions, putting in place added protections around affected reefs while they recover (such as limiting or halting fishing), and reducing land-based pollution sources that may run off onto reefs.