Coral reefs around the world are experiencing a fourth year of global bleaching, leading reef experts said Monday, the result of warming ocean waters under human-caused climate change.
Coral reef bleaching in at least 53 countries, territories or local economies has been confirmed between February 2023 and today, scientists from the National Oceanic and Atmospheric Administration (NOAA) and the agency said. International Coral Reef Initiative. This happens when stressed corals expel the algae that are their food Source and give them their color. If bleaching is severe and prolonged, the coral may die.
Coral reefs are important ecosystems that support underwater life, protect biodiversity and slow erosion. They also support local economies through tourism.
Bleaching has been occurring for some time in various regions. In the world’s largest coral reef ecosystem, Australia’s Great Barrier Reef, bleaching affected 90% of corals assessed in 2022. Florida’s coral reef, the third largest, experienced significant bleaching last year. last year.
But for the phenomenon to be declared on a global scale, significant bleaching had to be documented in each of the major ocean basins, including the Atlantic, Pacific and Indian Oceans, in the Northern and Southern Hemispheres.
Monday’s news marks the second global bleaching event in the last 10 years. The last one ended in May 2017: caused by a powerful “El Nino” climate phenomenon that warmed the planet’s oceans, it lasted three years and was judged worse than the two previous bleaching events, in 2010 and 1998.
This year’s whiteout follows the declaration that 2023 was the hottest year on record.
“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and more severe,” Derek Manzello, NOAA’s coral reef coordinator, said in a statement.
Biologist Selina Stead, chief executive of the Australian Institute of Marine Science, called climate change “the biggest threat to the world’s coral reefs.” She said scientists were working to learn more about how corals respond to heat and identify naturally heat-tolerant corals, but said it was “essential that the world strives to reduce carbon emissions.
One reef fared better than others last year: the Flower Garden Banks National Marine Sanctuary, which enjoyed some protection thanks to its location in the deeper waters of the Gulf of Mexico, about 100 miles from the Texas coast.
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