Sydney: The Great Barrier Reef of Australia, one of the planet’s most iconic natural wonders, is suffering the most widespread coral bleaching ever recorded.
A new report by the Australian Institute of Marine Science (AIMS) has highlighted the alarming impact of climate change on the world’s largest living structure.
Surveying the reef between August 2024 and May 2025, scientists found the bleaching was ‘the most spatially extensive’ since records began in 1986. The report attributes the crisis to climate change-induced heat stress as ocean temperatures reached unprecedented levels during 2024.
Coral cover in the southernmost third of the reef, which had previously been less affected than the northern region, dropped by nearly one-third to just 26.9 percent.
The southern section also recorded its highest-ever level of heat stress, marking the most severe annual decline in coral health across the north and south in nearly four decades of monitoring.
Our latest annual report on the status of the #GreatBarrierReef has just dropped. Here’s 5 things you need to know 💡🪸 #coralcover
🧵 1/11 pic.twitter.com/Bl0TQAMwTu
— Australian Institute of Marine Science (@aims_gov_au) August 5, 2025
The Great Barrier Reef, a 2,300-kilometre stretch of coral ecosystems off Australia’s northeast coast, is home to an extraordinary range of marine biodiversity. Recognized as a UNESCO World Heritage Site, it shelters 400 coral species, 1,500 fish species, 4,000 types of molluscs, 240 species of birds, and marine life such as dugongs and large green turtles.
Professor Selina Stead, CEO of AIMS, warned that the frequency and intensity of mass bleaching events are increasing. “The future of the world’s coral reefs relies on strong greenhouse gas emissions reduction. But managing local pressures and supporting the reef’s ability to adapt and recover from the impacts of climate change are equally critical,” she said.
While scientists and global experts have urged the inclusion of the Great Barrier Reef on UNESCO’s “World Heritage in Danger” list, the Australian government continues to lobby against the move, citing fears over potential damage to the tourism industry, which generates billions of dollars annually.
Australia, however, remains one of the world’s largest fossil fuel exporters. Coal from the Adani mine continues to be transported through waters near the reef, despite environmental concerns about its impact on reef sustainability.
A separate report published last week by Australia’s Climate Change Authority warned that the opportunities to protect the reef are narrowing fast. The agency stressed the need for major fossil fuel-exporting countries to transition to low- and zero-emission alternatives.
It also highlighted the importance of reducing short-lived but potent climate pollutants like methane, which significantly contribute to near-term warming.
The Authority’s findings underscored another alarming trend that 93 percent of the excess heat trapped in the atmosphere has been absorbed by the oceans, with 2024 setting a new record for ocean temperature highs, surpassing the previous benchmark set just a year earlier in 2023.
As global temperatures rise and oceans absorb most of the excess heat, scientists warn that the Great Barrier Reef, which has experienced five mass bleaching events in the past decade, may be nearing an irreversible tipping point.
Without drastic reductions in emissions and sustainable marine management, the future of one of Earth’s most iconic natural wonders remains perilously uncertain.
