The International Union for Conservation of Nature has released the first global Red List assessment of coral reef ecosystems, classifying 96% of the planet's shallow-water reef systems as critically endangered once future climate impacts are included — its highest risk category, meaning an extremely high risk of ecosystem collapse before 2075.

The analysis covered 127 tropical and subtropical reef regions across more than 80 countries, spanning roughly 188,362 square kilometres.

When only the past 50 years of impacts are considered, 24% of reef ecosystems are critically endangered, a figure that jumps to 96% when projected warming is added.

The findings were presented at the UN's COP17 biodiversity summit in Yerevan, where governments face pressure on a pact to halt biodiversity loss by 2030.

The surprise is not that reefs are struggling — it is the scale.

Even the world's largest and most biodiverse systems, including Australia's Great Barrier Reef, the Coral Triangle, the Mesoamerican Barrier Reef and Red Sea reefs, fall into the critically endangered category once climate projections are counted.

The Peninsula Qatar reports that overexploitation of parrotfish and groupers threatens 63% of reef ecosystems, with heat stress from climate change named the single most consistent threat driving decline worldwide.

The IUCN assumed a 'middle-of-the-road' emissions pathway with about 2.7C of heating by 2100, close to the 2.6C current policies are likely to deliver. A reef is considered collapsed when its living reef-building corals are nearly or completely lost and replaced by algae, rubble and sponges.

According to The Guardian, the assessment did not fully account for the fourth global mass bleaching event from early 2023 to mid-2025, the most widespread on record, and the western Galápagos reefs have already collapsed.

The Peninsula Qatar notes a Nature study last week found nearly half of coral species were at elevated risk of extinction by 2020.

Despite the dire outlook, scientific leads stress the findings are 'alarming, but certainly not hopeless.' According to The Guardian, Dr Mishal Gudka of CORDIO East Africa called the results a wake-up call and an early warning sign before the worst outcomes eventuate.

IUCN director general Grethel Aguilar said it is not too late to give reefs a chance to recover, requiring ambitious emissions cuts, stronger protection and restoration, and sustained investment in resilient coastal ecosystems.

The Peninsula Qatar reports a 'super' El Niño emerged this year, adding fresh risk — and that the next few years of action will determine whether reefs persist or transform into ecosystems worth less to nature and people.