Coral reefs, ice sheets and Amazon rainforest approaching a tipping point due to global heating, report says | Climate crisis

Warm-water coral reefs now face long-term decline, putting the livelihoods of hundreds of millions of people at risk, according to a new report. The world has reached its first catastrophic tipping point linked to greenhouse gas emissions.

The report by scientists and environmentalists warns that the world is also on the verge of reaching other milestones, such as the disappearance of the Amazon, the collapse of major ocean currents and the loss of ice sheets.

But some experts questioned the report’s claims about the fate of coral reefs; Although coral reefs are in decline, there is evidence they can survive in higher temperatures than recommended, an expert has said.

Tipping points are considered by scientists to be moments when a large ecosystem reaches a point where severe disruption is inevitable.

The world’s coral reefs are home to nearly a quarter of all marine species but are considered one of the systems most vulnerable to global warming.

“Unless we return to a global average surface temperature of 1.2°C (and eventually at least 1°C) as quickly as possible, we will not be able to sustain our planet’s warm water reefs on a meaningful scale,” the report says.

Reefs at tipping point

Coral reefs have been in the midst of a global bleaching event since January 2023; This is the fourth and worst incident on record; More than 80% of reefs in more than 80 countries are affected by extreme ocean temperatures. Scientists say the event has pushed the reefs into “uncharted territory.”

The Global Tipping Points report, led by the University of Exeter and funded by Amazon owner Jeff Bezos, includes contributions from 160 scientists from 87 institutions in 23 countries.

Coral reefs are predicted to reach a tipping point when global temperatures reach 1°C to 1.5°C, 1.2°C above those in the second half of the 19th century. Global warming is currently around 1.4 degrees.

The report states that unless rapid and unexpected cuts are made in greenhouse gases, the upper threshold value of 1.5 degrees will be reached within the next 10 years.

“We can no longer talk about tipping points as a future risk,” said Prof Tim Lenton, from the Global Systems Institute at the University of Exeter. “The initial rollback of a widespread return of warm-water coral reefs is already underway.”

He said this affects hundreds of millions of people who already depend on the reefs. The report highlights reefs in the Caribbean, where marine heatwaves, low diversity and disease outbreaks have pushed reefs to “collapse”.

However, Prof Peter Mumby, a leading coral reef scientist at the University of Queensland in Australia, said he accepted that reefs were declining, but there was emerging evidence that corals were adapting to global warming, with some reefs remaining alive even at 2°C.

He said coral reefs needed “aggressive” action on climate change and improved local governance, but he was concerned that some would interpret the report as coral reef habitats heading for collapse, a position he did not support.

He said he worries that society will “give up on coral reefs” if people think they can no longer be saved.

WWF-UK’s chief scientific advisor and report co-author Dr. “This shows that protecting reefs is now more critical than ever. The game has changed and this really needs urgent attention,” said Mike Barrett.

He said there are some coral reefs known as refugia (places where climate impacts are not as pronounced) and it is very important to protect these places.

“We must ensure that we have the seeds of recovery for a future world where we manage to stabilize the climate,” he said.

International Coral Reef Association vice president Dr. Tracy Ainsworth said reef ecosystems in many places were changing, either no longer dominated by corals or diversity lost.

“The future of coral reefs is about transformation, ecosystem restructuring and new challenges,” he said. “Our challenge now is to understand how all these different ecosystems reorganize and how we can ensure they continue to support diverse marine life and communities.”

The Australian Institute of Marine Science said in a statement that interpretations of global figures “must be treated with caution” for two reasons: they mask significant regional variability and global temperatures have not stabilized, “suggesting a narrow window of opportunity remains for action”.

The world is entering the ‘danger zone’

The West Antarctic ice sheet and parts of the Greenland ice sheet “appear dangerously close” to tipping point as they lose ice at an accelerating rate, Lenton said. The loss of ice currently attached to land causes sea levels to rise.

“According to current projections, we will probably exceed 1.5 degrees of global warming around 2030,” Lenton said.

“This puts the world in a greater danger zone with an increased risk of tipping points that will cause further damage.”

He said the Amazon, under pressure from the climate crisis and deforestation, was closer to reaching a turning point than previously thought.

The report offers some hope, saying there are likely “positive tipping points” in society (such as the adoption of electric vehicles) that could also have runaway effects on rapidly reducing greenhouse gas emissions.

“The race is on to highlight these positive tipping points to prevent what we are now certain will be the unmanageable consequences of further tipping points in the world system,” Lenton said.