More corals bleached

More than 90% of Great Barrier Reef coral surveyed this yearwas bleached, in the fourth such mass event in seven years in the world’s largest coral reef ecosystem, Australian government scientists say. Bleaching is a heat stress response to globalwarming, but this was the reef’s first bleaching event during a La Nina weather pattern, which is associated with cooler Pacific Ocean temperatures. The Great Barrier Reef Marine Authority said in its annual report that 91% of the areas surveyed were affected. Bleaching in 2016, 2017 and 2020 damaged two-thirds of the reef’s coral. Scientists hoped that most of the coral would recover from the current event, said the authority’s chief scientist, Davidwachenfeld. In July last year, Australia deferred an attempt by the United Nations’ cultural organisation Unesco to downgrade the reef’sworld Heritage status because of the damage caused by climate change. But the question will be back on the World Heritage Committee’s agenda at its annualmeeting next month.