A new report from the Australian government highlights a concerning decline in coral health in the Great Barrier Reef, attributed primarily to climate change-induced heat stress. This study, conducted by the Australian Institute of Marine Science (AIMS), reveals that the reef experienced its most extensive coral bleaching on record, marking a significant environmental challenge.
Between August 2024 and May 2025, the AIMS assessed the state of the reefs and found that coral cover in the southernmost third of the reef has dropped by nearly one-third, now sitting at just 26.9 percent. This decline is notable as it represents the steepest year-on-year drop recorded since monitoring began almost four decades ago.
The Great Barrier Reef, recognized as the world’s largest living structure, spans over 2,300 kilometers and supports a remarkable diversity of marine life, including approximately 400 types of coral and thousands of fish, mollusks, and bird species. AIMS CEO Professor Selina Stead commented on the escalating frequency and intensity of mass bleaching events, emphasizing that robust reductions in greenhouse gas emissions are crucial for the future of coral reefs.
UNESCO, which designates the Great Barrier Reef as a World Heritage Site, supports the view that the reef should be labeled as “in danger.” However, the Australian government has been lobbying against this designation, concerned that it may threaten the lucrative tourism industry that relies on the health of the reef.
Despite these concerns, the Climate Change Authority of Australia proposes several avenues to protect the reef. It suggests that fossil-fuel exporting nations adopt low- and zero-emission alternatives while taking stronger actions to reduce significant climate pollutants. It has been noted that a staggering 93 percent of excess atmospheric heat has been absorbed by the oceans, with 2024 seeing record-breaking ocean temperatures.
The continued health of the Great Barrier Reef is instrumental not only for the ecosystem but also for the economy and for ongoing research into climate change impacts. There remains hope that through concerted global efforts and local management practices, the reef can be supported in adapting to the ongoing climate crisis.