The essentials
IUCN finds 96% of assessed coral reefs Critically Endangered, with nearly all shallow-water reefs at extremely high risk by 2075.
An IUCN assessment covers 127 tropical and subtropical reef ecosystems totaling 188,362 square kilometers. It classifies 96% of assessed coral reefs as Critically Endangered on the IUCN Red List and finds that nearly all shallow-water reefs face an extremely high risk of disappearing by 2075.
The assessment uses the IPCC intermediate scenario, which projects 2.7°C of warming by 2100. IUCN identifies climate-driven thermal stress as the most persistent cause of global coral reef decline. The Great Barrier Reef, Coral Triangle, Mesoamerican Reef, and Red Sea reefs are among the most threatened areas named.
Separately, the UN projects 2.6°C of global warming this century under current national emissions pledges. The two projections rest on different scenarios and are not directly comparable.
A Nature study found that nearly half of coral species had high relative extinction risk in 2020. IUCN describes a 50-year window for conservation action, and some coral reefs have shown capacity to recover from severe bleaching events.
The assessment was released during COP17 biodiversity talks in Yerevan, Armenia, where governments are discussing implementation of the 2022 target to protect 30% of land and seas by 2030.
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Assessment Sets a 50-Year Window for Reef Conservation Action
IUCN describes a 50-year window for coral reef conservation action, and the assessment was released during COP17 talks in Yerevan. Governments there are discussing the 2022 target to protect 30% of land and seas by 2030. Reef recovery after severe bleaching events has been observed in some locations, which the assessment places alongside the broader risk findings.
Warming Scenarios Shape Projected Future of Shallow-Water Reefs
The IUCN assessment relies on the IPCC intermediate scenario of 2.7°C warming by 2100, while the UN projects 2.6°C under current national pledges. Thermal stress is identified as the most persistent driver of decline. Both projections place the outlook for reefs within a warming trajectory that remains a central variable in the assessment's findings.