An assessment by United Nations nature advisers has determined that approximately 96% of the planet’s shallow-water coral reefs across more than 80 countries face a high risk of ecosystem collapse before 2075 when the projected impacts of global heating are factored in. Currently, about 24% of reefs are already classified as critically endangered, but this figure rises dramatically when future warming scenarios are included in the analysis.
Coral reefs support an estimated quarter of all known marine species and provide food, coastal protection, and tourism revenue for hundreds of millions of people worldwide. The ecosystems have already experienced significant declines over the past 50 years due to overfishing, pollution, coastal development, and global heating, measured through the loss of live coral and changes in fish populations. The assessment evaluated 127 coral reef regions and was coordinated by the International Union for Conservation of Nature, which advises the United Nations.
The analysis assumed greenhouse gas emissions would follow a middle-of-the-road pathway, resulting in approximately 2.7 degrees Celsius of global heating by the end of the century compared to pre-industrial temperatures. The assessment did not fully account for a recent global mass bleaching event occurring from early 2023 to mid-2025, described as the most widespread on record. Marine heatwaves cause corals to separate from symbiotic algae, weakening them and increasing susceptibility to disease.
Scientists leading the assessment characterized the findings as a critical wake-up call rather than a cause for complete despair. They emphasized that coral reefs could survive with rapid reductions in fossil fuel consumption and strong local conservation efforts. In Australia specifically, all 17 reef regions, including the Great Barrier Reef, were classified as critically endangered when climate change impacts were included in the analysis, though only four held that designation based on current conditions alone.
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