This underwater photo taken on April 5, 2024, shows bleached and dead coral around Lizard Island on the Great Barrier Reef, located 270 kilometers north of the city of Cairns. Australia's famed Great Barrier Reef is teetering on the brink, suffering one of the most severe coral bleaching events on record -- the fifth in eight years -- and leaving scientists unsure about its survival.
Bleaching occurs when stress from heat breaks down the symbiotic relationship that transfers nutrients from algae to coral. Over the past year, about 54 percent of the global ocean area that is home to coral reefs experienced heat stress at levels that cause bleaching, according to NOAA’s Global Bleaching Event Index. The index peaked at 56 percent between 2014 and 2017.
“Just in terms of the sheer magnitude of the heat in the Atlantic is very shocking, and the other thing is, a lot of places like Florida and Bahamas, it started five to six weeks earlier than, you know, the ‘normal’ sort of bleaching season,” Manzello said, adding that bleaching events are now more severe and frequent than in the 1980s.of global warming is occurring in the world’s oceans, which cover 70 percent of the planet’s surface.
Britta Schaffelke, the manager of international partnerships at the Australian Institute for Marine Science, said more long-term data on the health of coral reefs is needed to put the global bleaching event in context for conservationists exploring potential human interventions.