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…