Great Barrier Reef: JCU professor warns of ‘catastrophic damage’ from global warming

Immediate global action on “ambitious climate and reduced emissions targets” are now needed to halt “catastrophic damage” to the Great Barrier Reef.

Michael Kingsford, a Distinguished Professor of Marine Biology at Townsville-based James Cook University, and scientists from the University of Sydney say the latest study of the effects of a heatwave on a part of the Great Barrier Reef shows ‘catastrophic’ damage, with global warming no longer a projection but an immediate reality and urgent action necessary. Picture: Evan Morgan

Immediate global action on “ambitious climate and reduced emissions targets” are now needed to halt “catastrophic damage” to Australia’s Great Barrier Reef.

That’s the stark warning from Michael Kingsford, a Distinguished Professor of Marine Biology at Townsville-based James Cook University and scientists from the University of Sydney.

He said on Tuesday that the latest study of the effects of a heatwave on a southern section of the GBR around One Tree Island about 500 kilometres north of Brisbane showed irreversible damage – “with global warming no longer a projection but an immediate reality and urgent action necessary”.

“Catastrophic conditions and dire ecosystem changes are no longer a threat on a distant horizon: It’s happening now,” he said.

“Our findings reinforce the need for urgent global action, immediately, on ambitious climate and reduced emissions targets.”

Extensive coral bleaching has been recorded across the entire Great Barrier Reef in 2024. Photo: Supplied

The scientists tracked the health of 462 coral colonies near One Tree Island during a heatwave.

“The 2023- 2024 marine heatwave was extreme in triggering coral bleaching and high mortality,” Professor Kingsford said.

“We tracked the colonies over 161 days in 2024 from the heatwave peak through autumn and winter cooling.”

He said in February 66 per cent of the colonies were bleached, rising to 80 per cent by April.

“By May, 44 per cent of the bleached colonies were dead and 53 per cent in July.

“Across that month, 31 per cent of colonies remained bleached and 16 per cent recovered.”

A green turtle swimming at Lizard Island 270 kilometres north of Cairns in 2024. Picture: David Gray-AFP

Professor Kingsford said the 2024 event was the seventh mass bleaching on the reef since 1998 and the fifth since 2016.

He said it brought severe conditions and rapid coral health decline “not previously seen in the southern GBR region”.

“As corals can recover from mild bleaching when water cools, there is a perception that while bleaching is bad, it’s not necessarily catastrophic,” he said.

“What we saw at One Tree Reef was catastrophic: Rapid high mortality left no opportunity for these corals to recover, some coral even turned to rubble.”

Professor Kingsford said despite heavy protections for five decades, there was no defence against global warming.

“While protection from disturbances caused by humans can enhance prospects for coral survival during heatwaves, the protected status and offshore location did not guard One Tree Reef from bleaching and mortality,” he said.

He said mass coral bleaching was “a global phenomenon and is now starting to be seen every two years on the GBR”.

Originally published as Great Barrier Reef: JCU professor warns of ‘catastrophic damage’ from global warming