Almost every shallow-water coral reef on the planet faces ecosystem collapse by 2075, UN advisors say

An assessment by the International Union for Conservation of Nature (IUCN) has found that 96% of the planet’s coral reefs are critically endangered. The report, which advises the United Nations, warns that almost every shallow-water reef, including the Great Barrier Reef, faces a high risk of ecosystem collapse before 2075.

The assessment analysed the current status and future threat levels of 127 coral reef regions across more than 80 countries. It concluded that 24% of reefs are already critically endangered, a figure that rises to 96% when the expected impacts of global heating are factored in.

Coral reefs as vital ecosystems

Coral reefs are often described as the rainforests of the sea. They support hundreds of millions of people by providing food and protecting shorelines, while a quarter of all known marine species are found in and around them.

The assessment notes that overfishing, pollution, coastal development, and global heating have already caused significant declines in reef ecosystems over the past 50 years, measured by the loss of live coral and changes in fish populations.

Climate projections and the outlook

The assessment assumed greenhouse gas emissions would follow a “middle-of-the-road” pathway, causing about 2.7°C of global heating by the end of the century. Current climate policies are projected to cause about 2.6°C of warming, which would likely push the share of critically endangered coral eco-regions even higher.

The IUCN considers a coral reef ecosystem to have collapsed if it can no longer maintain itself due to a near or complete loss of living reef-building corals. Four regions did not have enough data to be assessed, and the coral reefs of the western Galápagos had already collapsed.

The assessment did not fully account for the impacts of the fourth global mass bleaching event from early 2023 to mid-2025, which was the most widespread on record. This event was bookended by the worst mass bleaching event on record for reefs in Western Australia, where a heatwave killed corals across 1,500 kilometres.

A call for decisive action

Dr Mishal Gudka, the scientific lead for the assessment, said the results were a “wake-up call” and were “alarming, but certainly not hopeless.” She stated that the findings should be seen as a call to action and an early warning sign before the worst outcomes eventuate.

Dr Grethel Aguilar, the director general of the IUCN, emphasized that it is not too late to give coral reefs a chance to recover. She said decisive action is required to tackle climate change and halt further ocean warming.

For Australia, the assessment found that four of its 17 reef regions were critically endangered, five were endangered, and five were vulnerable. However, all 17 regions, including the Great Barrier Reef, were critically endangered once the expected impacts of climate change were accounted for.

Dr Ben Fitzpatrick of the University of Western Australia Oceans Institute led the Australian assessment. He said even after accounting for the ability of some corals to adapt to warmer water, the rising heat “overwhelmed everything.”