From Risk to Application: What Critically Endangered means for the world's coral reefs

Mishal Gudka, David Keith, David Obura, Ena Suarez, Marcos Valderrabano, Emily Nicholson

The first global risk assessment of coral reef ecosystems has found all fully assessed, shallow-water (photic) coral reef ecosystems are at an extremely high risk of ecological collapse in the next 50 years. This Critically Endangered risk assignment under the Red List of Ecosystems (RLE) applies to 122 of the 127 coral reef ecosystems (ecoregions) and was assessed by regional expert teams, combining global datasets with local monitoring data and knowledge. The primary driver of risk is the frequency of marine heatwaves, projected to exceed tolerable limits within 50 years, even under a moderate climate scenario (IPCC SSP2-4.5). Even ecoregions that have shown resilience to warming and retained a relatively intact balance of corals, algae, and fish are at extremely high risk due to the elevated frequency of projected marine heatwaves.

The outlook is alarming, yet much of the risk stems from projected changes that have yet to fully materialise, providing a critical window to scale up conservation and climate efforts. A Critically Endangered outcome is an early warning that calls for an urgent response. This assessment provides an evidence base for policy on coral reef ecosystems. It identifies the need for clear and urgent actions that stakeholders can take to reduce risks to reefs and support their recovery at global, national, and local scales. The data and results can be used to strengthen legal protection for threatened ecosystems, reporting under the Kunming-Montreal Global Biodiversity Framework, and building climate resilience in dependent coastal communities. Importantly, this assessment highlights the urgent need for drastic emissions reduction. If coral reef ecosystems are to persist as we know them, strong local management and restoration must be underpinned by efforts to contain global warming as close as possible to 1.5°C.