Coral reefs face severe risk of collapse by 2075, IUCN report warns

Nearly all of the world's shallow-water coral reefs are at severe risk of collapse by 2075 as rising ocean temperatures continue to fuel destructive bleaching events, according to a global assessment released by the International Union for Conservation of Nature.

In its first comprehensive worldwide review of its kind, the conservation body classified 96 percent of marine coral reef systems as critically endangered, the highest category on its scale. Rising heat driven by human-induced climate change was identified as the primary threat destabilising these marine habitats globally.

The assessment evaluated 127 tropical and subtropical reef systems encompassing 188,362 square kilometres. Among the areas designated as critically endangered are major marine environments, including Australia's Great Barrier Reef, the Coral Triangle across southeast Asia and the western Pacific, the Mesoamerican Barrier Reef in the Caribbean, and reef networks in the Red Sea.

An ecosystem collapse occurs when hard corals, which build the physical foundation of the reef, vanish and are overtaken by algae, rubble and sponges. Researchers based their projections on a scenario from the United Nations climate panel in which global temperatures increase by 2.7 degrees Celsius above pre-industrial levels by the end of the century. The assessment follows a recent UN warning that existing worldwide carbon reduction pledges place the planet on track for approximately 2.6 degrees Celsius of warming.

Beyond heat stress, other pressures are compounding the destruction. The report noted that overfishing disrupts reef balance by removing species like parrotfish and groupers that feed on algae. The excessive harvesting of these herbivorous and predatory fish threatens 63 percent of reef ecosystems. Coastal infrastructure work, runoff, tourist activity and worsening storms also contribute to reef deterioration.

The findings were presented in Yerevan, Armenia, during the UN COP17 biodiversity summit, where negotiators face pressure to meet targets to halt biodiversity decline by 2030.

IUCN officials emphasised that despite the grim outlook, complete ruin is not yet inevitable. When researchers examined only historical data from the past 50 years without future climate projections, the share of reefs considered critically endangered stood at 24 percent rather than 96 percent.

Mishal Gudka, scientific lead for the assessment and research director at CORDIO East Africa, stated that while the danger is mounting, reefs have demonstrated an ability to recover after severe bleaching, framing the report as an urgent call for action rather than despair. IUCN Director General Grethel Aguilar similarly urged governments to enact immediate greenhouse gas curbs, broaden marine protections and back community-level resilience initiatives to give reefs an opportunity to survive.