IUCN reassessment classifies 44% of assessed reef corals as threatened

Researchers reassessed the IUCN Red List status of 892 reef-building coral species, most of which were first assessed in 2008. Sufficient data were available for 774 species. Because species-level population trends are unavailable for most corals, the team inferred population reductions using global coral-cover trends and projected annual severe bleaching under the SSP2-4.5 climate scenario over three decades, adjusted for species vulnerability traits.

Of the 774 species assessed, 340 (44%) were classified as threatened: 33 as Critically Endangered, 251 as Endangered and 56 as Vulnerable. Most classifications reflected the risk of population decline associated with projected thermal stress.

The authors note that these findings predate the three hottest years on record and the fourth global coral bleaching event, which occurred in 2023–2025. IUCN categories indicate relative extinction risk; they do not predict whether or when a species will become extinct. The assessment is also limited by sparse species-level population data and under-surveyed ranges. The authors say future assessments would benefit from population, thermal-stress and recovery data that better represent species’ ranges.