The frequency, intensity and magnitude of marine heat waves that cause this bleaching are increasing, the study says.
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Corals are increasingly threatened. Bleaching has affected 98% of Australia’s Great Barrier Reef since 1998, sparing a small part of the world’s largest coral reef, according to a study released Thursday, November 4. The frequency, intensity and magnitude of the marine heat waves that cause this bleaching are on the rise, says lead author Terry Hughes of the Australian Research Council (ARC) Center of Excellence.
According to the article in the journal Current Biology, only 2% of this immense underwater ecosystem has escaped the phenomenon since the first major bleaching episode in 1998, the hottest year in history. This record has since been broken several times.
“Five episodes of massive bleaching since 1998 have transformed the Great Barrier Reef into a checkerboard of reefs with very different recent histories, ranging from 2% of reefs that have completely escaped bleaching, to 80% that have now significantly bleached at least one. times since 2016 “, did he declare.
Bleaching is a wasting phenomenon which results in discoloration. It is due to the increase in the temperature of the water, which causes the expulsion of the symbiotic algae which gives the coral its color and its nutrients. Listed as World Heritage by Unesco in 1981, the Great Barrier suffered three unprecedented episodes of bleaching during the heatwaves of 2016, 2017 and 2020.