Great Barrier Reef Hit by Sixth Mass Bleaching Event

Australia’s Great Barrier Reef is suffering another mass bleaching due to high ocean temperatures.

The news of widespread and severe coral bleaching arrives just as a United Nations delegation is scheduled once again to assess whether the reef’s UNESCO World Heritage listing “should be downgraded due to the ravages of climate change,” reports the Associated Press.

This is the sixth mass bleaching event since 1998, with such marine heat stress occurring in 1998, 2002, 2016, 2017 and most recently in 2020. The last three mass bleachings damaged two-thirds of the reef, writes AP.

Last summer, the Scott Morrison government lobbied hard and deferred UNESCO’s efforts to protectively downgrade the reef’s status to “endangered,” a decision that would require Canberra to take more aggressive steps to protect the ecosystem.

With a spring election looming, Morrison recently announced that should his government retain power, it would spend AU$1 billion on reef conservation, with the bulk of the money going to fight marine pollution, one of the biggest threats to marine heritage sites, according to UNESCO.

But now, a “flood of reports from the field” points to a sixth mass bleaching event under way all along the Queensland coast, Queensland coral scientist Terry Hughes told the Guardian a few days before the Great Barrier Reef Marine Park Authority (GBRMPA) released its report.

Concern for the well-being of the reef began months ahead of what has become the normal, the Guardian writes. “the amount of heat stress over the reef tends to peak in early to mid-March each year, but scientists began to worry as early as December after water temperatures rose to record levels for that month.”

And while the reef seemed to rebound as the New Year turned, regaining healthy colour in January and February, recent ocean temperatures as high as 2°C above average have hammered the corals again.

“In the last three weeks there have been reports of moderate to strong bleaching all along the reef,” Hughes said.

Citing a November study led by Hughes, the Guardian writes that only 2% of the corals on the Great Barrier Reef have been able to escape bleaching, adding that reefs can recover from mild bleaching but will die “if heat stress is too severe.”

Environmental groups are urging that provisions be made for the visiting UN scientists to see the Great Barrier Reef with their own eyes. But as yet, “no details have been released either by UNESCO or the Australian government about where the mission will go or who it will meet,” the Guardian says.

The delegation’s report is expected in early May, with a World Heritage Committee meeting scheduled for June.