The facts
The assessment covers shallow, sunlit reefs across more than 80 countries and territories. Deeper and cold-water reefs were not included. [2]
Observed change over the previous 50 years alone puts 24% of the ecosystems in the Critically Endangered category. Adding projected heat stress under the IPCC SSP2-4.5 scenario raises the overall figure to 96%. [2][3]
IUCN, the University of Melbourne and CORDIO East Africa coordinated more than 250 experts in 10 regional teams, using monitoring data, satellite temperatures, climate projections and reef maps. [2]
The Western Galápagos ecosystem was classified as already collapsed; four other ecosystems lacked enough data for assessment. [2][3]
Relevant context
Critically Endangered is a risk category, not a finding that those reefs are already lost. IUCN says most retain living coral and recovery remains possible. [1][3]
Sources
References support the numbered facts above. Source checks: 29 Oct 2026, 06:13 UTC.
This is a catch-up report of the 22 October ecosystem assessment. Ecosystem-collapse risk is distinct from the extinction risk of individual coral species.
- Virtually all coral reef ecosystems face high risk of collapse in 50 years
International Union for Conservation of Nature · Primary source · 22 Oct 2026
- Red List of Coral Reef Ecosystems
International Union for Conservation of Nature · Primary source · 22 Oct 2026
- Nearly all the world’s coral reefs are at risk of collapse within 50 years, IUCN warns
Mongabay · Reporting · 23 Oct 2026
Independent nonprofit environmental newsroom; interviewed an IUCN scientist and an Oceana scientist outside the assessment.