Nearly All Shallow-Water Coral Reefs Face Collapse by 2075, IUCN Warns

Almost every shallow-water coral reef system on Earth faces an extremely high risk of collapse before 2075 because of global warming, according to a new assessment from the International Union for Conservation of Nature, the group that advises the United Nations on nature. Al Jazeera reported that the report was released Thursday and rates 96% of the world's reef systems as critically endangered, the highest risk category.

The finding includes the Great Barrier Reef in Australia and most of the world's other famous reef systems. The scientists behind the work stress that the outlook is serious but not hopeless.

The key numbers behind the warning

• 96%: the share of reef systems classed as critically endangered once the expected effects of climate change are included, according to The Guardian.
• 24%: the share already critically endangered across more than 80 countries before those future effects are counted, The Guardian reported.
• 127: the number of coral reef regions analyzed. Al Jazeera reported that they cover 188,362 square kilometers of tropical and subtropical reefs.
• 2.7 degrees Celsius: the global warming by the end of the century above pre-industrial levels that the assessment assumed, using a middle-of-the-road emissions pathway.
• 17 of 17: every one of Australia's reef regions, the Great Barrier Reef among them, becomes critically endangered once climate change is factored in, The Guardian reported. Without that, four of the 17 are critically endangered, five are endangered and five are vulnerable.

What is behind the risk

Reefs have already been weakened over the past 50 years by overfishing, pollution, coastal development and global warming, the assessment said, as measured by losses of live coral and changes in fish populations. Corals are sensitive to heat, and rising ocean temperatures make damaging bleaching events more frequent and more intense.

The IUCN counts a reef as collapsed when it can no longer sustain itself because nearly all of its reef-building corals have died. In a collapse, hard corals give way to algae, rubble and sponges, and the reef loses the variety of life it once supported.

The Guardian reported that the assessment did not fully account for the fourth global mass bleaching event, which ran from early 2023 to mid-2025 and which U.S. government monitoring has confirmed was the most widespread on record. The IUCN said the true share of critically endangered regions would probably be even higher. Four regions lacked enough data to be assessed, and the reefs of the western Galápagos had already collapsed.

Mishal Gudka, the scientific lead for the assessment, also said at a news conference at the U.N. biodiversity summit in Yerevan, Armenia, that this year's emergence of a strong El Nino adds risk for corals, according to Al Jazeera. A week earlier, another IUCN study in the journal Nature found that nearly 44 percent of reef-building coral species face an elevated risk of extinction because of climate change.

Why it matters for people far from the coast

Reefs shelter a quarter of all known marine species. They also supply food to hundreds of millions of people, protect shorelines from storms and erosion, and support tourism and coastal businesses, according to both outlets. Gudka said losing them would affect millions of people around the world.

Ben Fitzpatrick of the University of Western Australia Oceans Institute, who led the Australian assessment, said that even after allowing for some corals' ability to adapt to warmer water, rising heat overwhelmed everything else. He said the message is that burning of fossil fuels has to stop.

What scientists say can still be done

Gudka called the findings a “wake-up call” and an early warning rather than a final verdict. The IUCN said reefs in most parts of the world are not yet lost, and he noted that corals have shown a remarkable ability to recover from severe bleaching. Pockets of resilient reef can survive if people act.

IUCN Director General Grethel Aguilar said it is not too late to give reefs a chance to recover, but that this requires decisive action on climate change and an end to further ocean warming. She called for deep emissions cuts, stronger protection and restoration, and sustained investment in resilient coastal ecosystems and the communities that rely on them.

Around Prague, based on reporting by The Guardian, Al Jazeera