The Great Barrier Reef faces a severe threat of widespread coral bleaching and potential ecosystem collapse as this year’s El Niño climate event intensifies, marine scientists have warned. The reef, located along the Queensland coast and recognized as the world’s largest coral reef system, has recently avoided being listed as a World Heritage Site in danger by Unesco, but experts say the situation remains critical.

Morgan Pratchett, a marine ecologist at James Cook University in Queensland, highlighted the unprecedented strength of the ongoing El Niño, which is expected to bring significant increases in sea surface temperatures in the central and eastern tropical Pacific. These temperature rises trigger global changes in wind patterns, atmospheric pressure, and rainfall, all of which can exacerbate stress on coral ecosystems.

Between 2024 and 2025, hard coral cover on the Great Barrier Reef declined sharply due to sustained above-average water temperatures, marking the reef’s sixth major mass bleaching event since 2016. Scientists are raising concerns that the current El Niño episode could intensify these effects, potentially driving localized species extinctions and systemic collapse of the reef’s complex ecological network.

Pratchett emphasized the high probability of large-scale and severe bleaching events occurring in the near term. The ongoing monitoring by Unesco, which began annually in 2021 amid worries that the reef might be placed on the List of World Heritage Sites in danger, underscores the precarious condition of this natural landmark.

As the El Niño event advances, researchers continue to track the reef’s health closely, warning that mitigating global warming and reducing marine stressors are urgent priorities to help preserve the reef’s biodiversity and ecological functions.