Great Barrier Reef’s third mass bleaching in five years the most widespread yet

The government’s top Great Barrier Reef scientist says a third mass bleaching event in five years is a clear signal the marine wonder is “calling for urgent help” on climate change.

One quarter of the Great Barrier Reef suffered severe bleaching this summer in the most widespread outbreak ever witnessed, according to analysis of aerial surveys of more than 1,000 individual reefs released on Tuesday.

Dr David Wachenfeld, chief scientist at the Great Barrier Reef Marine Park Authority, told Guardian Australia: “My greatest fear is that people will lose hope for the reef. Without hope there’s no action.

“People need to see these [bleaching] events not as depressing bits of news that adds to other depressing bits of news. They are clear signals the Great Barrier Reef is calling for urgent help and for us to do everything we can.”

Prof Terry Hughes, director of the Centre of Excellence for Coral Reef Studies at James Cook University, surveyed 1,036 reefs from a plane over nine days in late March. The marine park authority also had an observer on the flights.

Hughes has released maps showing severe levels of bleaching occurred in 2020 in all three sections of the reef – northern, central and southern – the first time this has happened since mass bleaching was first seen in 1998.