The first IUCN Red List of Ecosystems assessment of the world’s photic coral reefs finds that almost all ecoregions face a high risk of collapse over the next 50 years, driven mainly by projected marine heatwaves.

The Global Red List of Coral Reef Ecosystems assesses the Photic Coral Reefs of the world assessed 127 ecoregions in more than 80 countries and territories, grouped into ten regions. It was coordinated by IUCN, the University of Melbourne and CORDIO East Africa with the regional nodes of the Global Coral Reef Monitoring Network (GCRMN), and involved more than 250 experts.

Results

122 ecoregions (96%) are Critically Endangered. One, the Western Galápagos Islands, is Collapsed, following the 1982–83 El Niño. Four are Data Deficient: three in Brazil and the Northern Monsoon Current in the Western Indian Ocean. 

Observed change versus projections: Based on the past 50 years alone (criteria A1, B, C1 and D1), 118 ecoregions (93%) are threatened and 30 (24%) are already Critically Endangered. The jump to 122 is driven by criterion C2: projected heat stress under IPCC scenario SSP2-4.5 (2026–2075) places 121 ecoregions in the Critically Endangered category. Critically Endangered means a high risk of collapse, not collapse itself, and most reefs still support living coral.

Drivers

Marine heatwaves are the most consistent driver: heat stress over the past 50 years (C1) threatens 98 ecoregions (77%). Disruption of the balance between corals, algae and fish (D1) threatens 80 (63%), and overfishing of parrotfish and groupers is a major pressure in several regions. Restricted distribution (B) affects 57 ecoregions (45%) and reduction in distribution (A1) 32 (25%).

Using the results

The Red List of Ecosystems is a headline indicator (A.1) of the Kunming-Montreal Global Biodiversity Framework. This assessment gives countries a baseline for reporting and a starting point for national assessments. It also points to priorities: protecting reefs that are coping best, such as the thermally tolerant Northern Red Sea; rebuilding fish populations; reducing local pressures; and filling data gaps, for example in the Gulf of Aden, the Western Arabian Sea and parts of northern Brazil. Local measures cannot stop marine heatwaves, so rapid emissions cuts remain essential.

Acknowledgements

Funded by the MSC Foundation, with regional contributions from partners including the DELTA Environmental and Educational Foundation, and Global Affairs Canada. Many other regional partners also provided in-kind support that made the ten regional assessments possible. We also thank the more than 250 experts, monitoring programmes and local communities who collected and shared the data on which this assessment rests.

Explore de results

• IUCN full story
  IUCN Press release
  From Risk to Application: What Critically Endangered means for the world's coral reefs
• Companion Red List of Threatened Species assessment of reef-building corals
• RLE Guidelines v2.0