Excerpt:
Unless global heating is reduced to 1.2C ‘as fast as possible’, warm water coral reefs will not remain ‘at any meaningful scale’, a report by 160 scientists from 23 countries warns
The earth has reached its first catastrophic tipping point linked to greenhouse gas emissions, with warm water coral reefs now facing a long-term decline and risking the livelihoods of hundreds of millions of people, according to a new report.
The report from scientists and conservationists warns the world is also “on the brink” of reaching other tipping points, including the dieback of the Amazon, the collapse of major ocean currents and the loss of ice sheets.
But some experts have questioned the report’s claims about the fate of coral reefs, with one saying while they are in decline there is evidence they could remain viable at higher temperatures than suggested.
Tipping points are recognised by scientists as moments when a major ecosystem reaches a point where severe degradation is inevitable.
The world’s coral reefs are home to about a quarter of all marine species but are considered one of the most vulnerable systems to global heating.
“Unless we return to global mean surface temperatures of 1.2C (and eventually to at least 1C) as fast as possible, we will not retain warm-water reefs on our planet at any meaningful scale,” the report says.
Reefs at tipping point
Coral reefs have been in the midst of a global bleaching event since January 2023 – the fourth and worst on record – with more than 80% of reefs in more than 80 countries affected by extreme ocean temperatures. Scientists say the event has pushed reefs into “uncharted territory”.
The Global Tipping Points report, led by the University of Exeter and financed by the fund of the Amazon owner, Jeff Bezos, includes contributions from 160 scientists from 87 institutions in 23 countries.
It estimates that coral reefs hit a tipping point when global temperatures reach between 1C and 1.5C above where they were in the latter half of the 19th century, with a central estimate of 1.2C. Global heating is now at about 1.4C.
Without rapid and unlikely cuts to greenhouse gases, the upper threshold of 1.5C would be hit in the next 10 years, the report says.
“We can no longer talk about tipping points as a future risk,” said Prof Tim Lenton at the University of Exeter’s Global Systems Institute. “The first tipping of widespread dieback of warm water coral reefs is already under way.”
He said this was already impacting hundreds of millions of people who depend on reefs. The report points to reefs in the Caribbean, where marine heatwaves, low diversity and disease outbreaks have pushed reefs “towards collapse..”
