96% of shallow coral reefs rated critically endangered, IUCN warns of collapse by 2075

Nearly all shallow reefs rated at highest threat

The International Union for Conservation of Nature (IUCN) said on Thursday, 22 October 2026, that 96% of the world's shallow-water coral reefs are now rated 'critically endangered', the highest threat level it defines. The verdict is the first global assessment of its kind, covering reefs in 127 regions across more than 80 countries and territories. Those regions span 188,362 square kilometres, according to the IUCN analysis. The organisation says the reefs now face an extremely high risk of collapse by 2075. Under its definition, collapse means living hard corals are almost or entirely gone and the reef can no longer sustain itself. Four of the regions lacked enough data to be assessed.

Heat stress as the main driver

Heat stress linked to climate change is the overwhelming cause of the finding, while pollution, overfishing, coastal construction and excessive tourism add further strain. The projection rests on the IPCC's intermediate climate scenario, which foresees warming of about 2.7 degrees Celsius by the end of the century. When water grows too warm, corals expel the microalgae that live in their tissue and feed them, leaving them bleached and often dead. Parrotfish and groupers keep algae in check, and their absence would make it harder for reefs to recover from heat stress, the IUCN wrote. Once a reef collapses, hard corals almost disappear, algae and sponges spread, and the system can no longer feed fish, turtles, sharks and shellfish that once lived there. Scientists involved in the research stressed that the reefs are not yet lost, and that their fate could brighten should nations accelerate efforts to curb warming.

Shrinking time between bleaching events

The Global Coral Reef Monitoring Network (GCRMN) had warned before this report that reefs are running out of time to recover. Global hard coral cover rose by roughly six percent between 2017 and 2019, which showed that reefs can bounce back when enough time passes between bleaching events. Those recovery periods are getting shorter, and where reefs once had decades between severe bleaching, often only five to six years remain now. Manuel González Rivero, the lead author from the Australian Institute of Marine Science, described the consequence in stark terms.

This creates a downward spiral that becomes harder to reverse with each new bleaching event.

For many reefs hit by especially strong heatwaves in 2024, the recovery phase could be even shorter, according to the German report.

Governments meet as the window narrows

The publication came as governments gathered in Yerevan, Armenia, for the COP17 biodiversity conference. Negotiators there are trying to save a 2022 nature agreement that aims to protect 30% of land and seas by 2030, though its targets are getting harder to reach because governments are slow to put their commitments into practice. Grethel Aguilar, the IUCN's director general, framed the coming decades as a critical window for conservation. Aguilar argued that the reefs can still be given a chance if action comes quickly.

It is not too late to give coral reefs a chance to recover, but this requires decisive action to fight climate change and halt ocean warming.

She listed ambitious emissions cuts, stronger protection and restoration, and sustained investment in coastal ecosystems and the communities that depend on them as the steps needed. Mishal Gudka, the scientific lead for the reef assessment, called the rising risk a wake-up call rather than a reason to despair, pointing to reefs that have shown a striking ability to recover after devastating bleaching.