Australia’s Great Barrier Reef is on the brink of irreversible damage due to countries’ persistent failure to address the root causes of climate change, a damning new report by the country's leading reef management agency has warned.
Published every five years, this latest analysis paints a grim picture of the world’s largest coral reef system, which is struggling to recover from its fifth mass bleaching event in eight years.
Despite a slight improvement in the condition of some fast-growing coral species, the reef’s overall prospects remain "very poor", the Great Barrier Reef Marine Park Authority (GBRMPA) said in its 600-page report.
"While recent recovery in some ecosystem values demonstrates that the reef is still resilient, its capacity to tolerate and recover is jeopardised by a rapidly changing climate," it said, emphasising that any recovery is fragile at best.
The assessment lays bare the worsening condition of the reef, driven by rising ocean temperatures, severe tropical cyclones and the increasing frequency of mass coral bleaching events.
Rising threats
Bleaching occurs when heat-stressed corals expel the symbiotic algae that lives within them, leading to a ghostly white appearance and, in many cases, death.
Marine scientists in June told RFI of their deep concern for the survival of corals of the Unesco heritage-listed site, given that species typically resistant to bleaching are now also struggling.
The GBRMPA report confirms their fears, showing that the recent marine heatwave, which brought sea surface temperatures to a peak of 2.5°C above average, has caused unprecedented damage across all three regions – northern, central and southern – of the Great Barrier Reef.
Earlier this year, Neal Cantin of the Australian Institute of Marine Science, who led a team of researchers conducting aerial surveys along the 2,300-kilometre length of the reef, told RFI 2024 had delivered the worst bleaching event on record.
Almost two-thirds of the reef was struck, including the southern third, an area previously thought to be more resilient due to its typically cooler waters.
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Warmest oceans
The repeated bleaching of Australia’s reef comes as the warmest ocean temperatures in history, fuelled by El Nino, drive an ongoing mass bleaching of the world's corals. Experts say more than 60 percent are suffering.
They have described bleaching events as "underwater bushfires", reflecting the catastrophic impact on coral reefs – often described as the rainforests of the sea due to their incredible biodiversity.
However, the GBRMPA said that climate change was not the only threat bearing down on the Great Barrier Reef.
Unsustainable fishing practices, pollution from coastal development, sediment runoff from agriculture and outbreaks of crown-of-thorns starfish were combined pressures found to be severely degrading water quality and further diminishing the reef’s health.
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Final neon glow
The report also sheds light on a phenomenon observed during severe bleaching events: corals sometimes emit a vibrant, final burst of colour – bright pinks, blues and greens – as they struggle to survive.
This dramatic display is a last, desperate attempt to stave off death. Despite the initial burst of brilliance, the majority of corals that experience severe bleaching do not recover.
A survey from Australia’s Lizard Island, in the northern reaches of the Great Barrier Reef, revealed that over 97 percent of the fluorescing corals had perished just three months after heavy bleaching.
Known for its vibrant marine biodiversity and typically clear waters, the island is now a barometer of the reef’s broader health crisis and the devastating impact of prolonged thermal stress.
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Call for action
The GBRMPA warns that without substantial global efforts to reduce emissions, the Great Barrier Reef will continue to deteriorate, with its window for recovery rapidly closing.
It stresses the urgent need for governments – including Australia, a major exporter of fossil fuels – to address greenhouse gas emissions, enhance conservation efforts, combat starfish outbreaks and restore damaged ecosystems.
"Future warming already locked into the climate system means that further degradation is inevitable," the report said. "This is the sobering calculus of climate change."
