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IUCN's first global reef assessment rates 96% of coral reefs Critically Endangered, citing climate-driven thermal stress.
The International Union for Conservation of Nature (IUCN) has published its first global reef assessment, which classifies 96% of coral reefs as Critically Endangered. The assessment covers 127 tropical and subtropical reef ecosystems spanning 188,362 km².
Coral reefs support about a quarter of all marine species. The assessment finds that nearly all shallow-water coral reefs face an extremely high risk of disappearance by 2075. Climate-driven thermal stress is identified as the most persistent cause of global reef decline.
The projections use the IPCC intermediate scenario, which anticipates 2.7°C of warming by 2100. Current national emissions commitments place the world on track for 2.6°C of warming this century, a figure that differs from the scenario used in the assessment. A strong 'super' El Niño emerged in 2026, posing an added risk to corals.
A separate study published in Nature found that nearly half of coral species were at high relative extinction risk in 2020. The Great Barrier Reef, Coral Triangle, Mesoamerican Reef and Red Sea reefs are among the most threatened areas.
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Projections point to nearly all shallow reefs at risk by 2075
The assessment's projections extend through 2075 and 2100. It uses the IPCC intermediate scenario, which projects 2.7°C of warming by 2100. Current national emissions commitments place the world on track for 2.6°C this century, a lower figure than that scenario, though the assessment still projects severe risk to shallow-water reefs.
Coral reefs support a quarter of marine species under threat
Coral reefs support about a quarter of all marine species, so their decline affects a large share of ocean life. The Great Barrier Reef, Coral Triangle, Mesoamerican Reef and Red Sea reefs rank among the most threatened. A Nature study found nearly half of coral species at high relative extinction risk in 2020.