DUBAI, United Arab Emirates (AP) — The world is in danger of hitting the point of no return for five of Earth’s natural systems because of human-caused climate change, a team of 200 scientists said on Wednesday on the sidelines of the United Nations’ climate summit.

The report on so-called “tipping points” — moments when the Earth has warmed so much that certain side effects become irreversible — looks at 26 different systems and points to five of them — the melting of the Greenland and West Antarctic ice sheets, the dying off of warm-water coral reefs, the thawing of permafrost and impacts to a North Atlantic ocean current — as close to triggering.

“These tipping points pose threats of a magnitude that has never been faced before by humanity,” said Tim Lenton, the report’s lead author and Earth systems scientist and the University of Exeter in the U.K.

The warnings come as negotiators discuss how best to slash emissions from the burning of coal, oil and gas at the United Nations’ COP28 climate summit. This year is set to be the hottest on record, and activists and officials alike have been ramping up their warnings that governments need to do more to curb global warming.

And those in vulnerable regions are already seeing the start of these effects.

In the Himalayas for example, glaciers are melting at such a rate that landslides, floods and other erratic weather has become common, said Izabella Koziell, from the International Centre for Integrated Mountain Development. Coral bleaching — which happens when the water is too hot — is blighting oceans from Australia to Florida. And some ice sheets near Earth’s poles are disappearing at an alarming rate.

Tipping points “can trigger devastating domino effects, including the loss of whole ecosystems,” Lenton said.

C. R. Babu of the Centre for Environmental Management of Degraded Ecosystems at University of Delhi, agreed that Earth warming past 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial times may mean “the extinction of natural systems.”

Abhilash S from Cochin University of Science and Technology said it was almost certain that “some natural systems will be permanently damaged.”

“Protecting them is beyond our control,” he warned. “We have already lost that chance.”

But the report’s bleak outlook is tempered with a message of hope, as researchers say there are positive tipping points that can be reached too, particularly in the transition from planet-warming fossil fuels to renewable energy, people changing to plant-based diets and social movements.

“Human history is full of examples of abrupt social and technological change,” said University of Exeter’s Steve Smith. “Many areas of society have the potential to be ‘tipped’ in this way.”

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EDITOR’S NOTE: This article is part of a series produced under the India Climate Journalism Program, a collaboration between The Associated Press, the Stanley Center for Peace and Security and the Press Trust of India.

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