It is the fourth time since 2016 that such a devastating event has been found, Australia says.
Australia's Great Barrier Reef is being devastated by another mass bleaching event, officials have confirmed.
It is the fourth time in six years that such severe and widespread damage - caused by warm sea temperatures - has been detected.Scientists say urgent action on climate change is needed if the world's largest reef system is to survive. There are particular concerns that this bleaching event has occurred in the same year as a La Niña weather phenomenon. Typically in Australia, a La Niña brings cooler temperatures.The declaration was madeRecently it warned that water temperatures in parts of the reef had been up to 4C above the March average.The first mass bleaching event was seen in 1998. It was again observed in 2002, 2016, 2017 and 2020.