A phenomenon caused by climate change is underway in one of Australia's jewels: a "mass bleaching" of Australia's Great Barrier Reef is underway.
The world's largest coral reef, stretching more than 2,300 kilometers along Australia's northeast coast, is home to some 1,500 species of fish and 4,000 types of molluscs.
“We know that the greatest threat to the world's coral reefs is climate change. The Great Barrier Reef is no exception,
Environment Minister Tanya Plibersek said in a statement.
We must act against climate change.
We must protect our exceptional sites and the plants and animals that inhabit them.”
This new episode of mass bleaching, the seventh since 1998, was confirmed by scientists working for the government following aerial surveys carried out on 300 shallow reefs.
Further studies need to be carried out to assess the severity and extent of bleaching, according to the Australian Coral Reef Authority.
This phenomenon of dieback, which results in discoloration, is caused by an increase of one degree in the water temperature which leads to the expulsion of the symbiotic algae giving the coral its bright color.
“Extreme temperatures”
It occurs when underwater temperatures exceed the long-term average by more than one degree.
Ocean temperatures along the Great Barrier Reef have reached record highs in recent weeks, official data shows.
According to the head of oceans for WWF Australia, Richard Leck, many corals risk dying if ocean temperatures do not drop quickly in the coming weeks:
“This bleaching episode is occurring in an area where corals do not have never been exposed to these extreme temperatures,”
he said before specifying that climate change was causing
“considerable pressure”
on the Great Barrier Reef.
Similar diebacks occurred last year in the northern hemisphere, leading to
“dramatic”
coral losses in Florida and the Caribbean.
They
“bear less well”
Some corals can recover if weather conditions improve, with the exception of those that have significantly bleached or are experiencing repeated heatwaves.
But Terry Hughes, one of Australia's leading coral reef scientists, said bleaching events are now so frequent that reefs are struggling to recover.
“The reef is no longer capable of regaining the mix of coral species and the size of corals that existed 20 years ago
,” he analyzed to AFP.
The irony is that the corals that predominate today in most areas of the Great Barrier Reef grow quickly and quickly regain ground, but they are sensitive to heat and will be less resistant to the inevitable next episodes of bleaching
.
According to him, heat stress has increased in recent days and is expected to worsen over the next two weeks.
The future of the reef has been a source of tension between the Australian government and UNESCO, which in 2021 threatened to put it on a list of
“in danger”
world heritage sites .
Such a listing would have been a snub for Australia, dealing a serious blow to the tourist attractiveness of this coral complex which generates $4.8 billion in revenue.
Behind-the-scenes diplomatic negotiations and fierce lobbying by Australia have so far prevented the reef from being included on this list.
Prior to this event, the Great Barrier Reef experienced massive coral bleaching in 1998, 2002, 2016, 2017, 2020 and 2022.