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

Assessment finds global heating is endangering 96% of coral reefs across 80 countries – a figure scientists say should serve as a ‘wake-up call’

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Almost every shallow-water coral reef on the planet, including Australia’s Great Barrier Reef, faces a high risk of ecosystem collapse before 2075 because of global heating, according to an assessment by United Nations nature advisers.

About 24% of the planet’s reefs across more than 80 countries are already critically endangered, the assessment said, but when the expected impacts of global heating were added this rose to 96%.

Coral reefs are known as the rainforests of the sea. A quarter of all known marine species are found in and around them and they support hundreds of millions of people with food, as well as protecting shorelines and supporting tourism.

Overfishing, pollution, coastal development and global heating have already caused declines in the ecosystems over the past 50 years, measured by the loss of live coral as well as changes in fish populations, the assessment said.

But the scientists said while the prognosis was dire, the findings should serve as a “wake-up call” because reefs could survive with rapid cuts to fossil fuel use and strong conservation action at local levels.

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“The risk is real and very concerning,” said Dr Mishal Gudka, research director at CORDIO (Coral Reef Degradation in the Indian Ocean) East Africa and the scientific lead for the assessment.

“We stand to lose one of the most valuable ecosystems we have – the impacts of which will affect millions of people around the world.”

The assessment analysed the current status and future threat levels of 127 coral reef regions and was coordinated by the International Union for Conservation of Nature (IUCN), an international group that advises the United Nations.

The assessment assumed greenhouse gas emissions – mainly from burning fossil fuels – would follow a “middle-of-the-road” pathway, causing about 2.7C of global heating by the end of the century when compared with temperatures before the Industrial Revolution.

Current climate policies and targets adopted by countries around the world are likely to cause about 2.6C of global heating, one assessment finds.

The share of coral eco-regions considered critically endangered would likely be even higher, the IUCN said, but four regions did not have enough data to assess them and the coral reefs of the western Galápagos had already collapsed.

The critically endangered classification meant an “extremely high risk” of ecosystem collapse before 2075.

The group considers a coral reef ecosystem to have collapsed if the reef could not maintain itself because of a near or complete loss of living reef-building corals.