Scientists sound alarm over climate ‘tipping points’ ahead of COP30

Over the past three years marine heatwaves have impacted over 80% of the world’s coral reef area and mass coral bleaching has been documented in at least 83 countries and territories. Napat Wesshasartar / Reuters

With the widespread, irreversible die-off of tropical coral reefs, the Earth has reached its first climate tipping point. Scientists warn that others may soon follow, from melting ice sheets to rainforest collapse. As delegates prepare for the COP30 climate summit in Belém, Brazil, attention is turning to these “points of no return” and how to mitigate further damage.

What are climate tipping points?

The term “climate tipping point” has gained prominence over the past two decades. The Intergovernmental Panel on Climate Change (IPCC) definesExternal link it as a “critical threshold” that, once reached, triggers abrupt and potentially irreversible changes in the climate system with serious consequences for humanityExternal link.

Researchers have long warned that exceeding 1.5° degrees Celsius (2.7° degrees Fahrenheit) of warming above pre-industrial levels would sharply raise the risk of crossing multiple tipping pointsExternal link. The current five-year global average temperature rise is already estimatedExternal link at between 1.3°C and 1.4°C.

Scientists focus onExternal link nine global “tipping elements” and several regional ones, including the Greenland and Antarctic ice sheets, the Amazon rainforest, boreal forest permafrost, mountain glaciers such as those in Switzerland and the Atlantic Meridional Overturning Circulation (AMOC) – a vital system of ocean currents that shapes weather worldwide.

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To better understand and detect early-warning signals in these areas, researchers use a combination of satellite technology, improved climate models, and direct observations to track changes.

Coral reefs: first threshold crossed

Coral ecosystems sustain up to one-third of all known marine biodiversityExternal link and provide food and livelihoods to nearly a billion people. In the last two years—the warmest on recordExternal link— marine heatwaves affected 84% of the world’s reefsExternal link, and researchers believe tropical coral reefs have now passed their tipping point. The second “Global Tipping Points” reportExternal link, coordinated by the University of Exeter and the World Wildlife Foundation (WWF) and involving 160 scientists from 23 countries, concluded last month that reefs are collapsing at around 1.2°C of warming. Even if heating stabilises at 1.5°C, the probability of collapse exceeds 99%.

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Thomas FröhlicherExternal link, a leading climate scientist at the University of Bern, said the report’s coral reef finding was “serious, but not unexpected”.

“We have known for some time that the critical temperature for many coral reefs is around 1.2°C to 1.5°C of warming compared to pre-industrial levels. The report now confirms that this limit of 1.2°C has already been exceeded,” he told Swissinfo.

Some experts, however, question the report’s claims about the fate of coral reefs, with one sayingExternal link that while reefs are in decline, there is evidence they could remain viable at higher temperatures than suggested.

The Amazon region is increasingly exposed to unprecedented stress from warming temperatures, extreme droughts, deforestation and fires, even in central and remote parts of the system. Raphael Alves / Keystone

The Amazon rainforest approaches collapse

The Amazon rainforest – already strained by the climate crisis and deforestation – is also closer than previously thought to its tipping point, the report’s authors say. The region experienced record drought in 2023–24, and the report warns that widespread dieback of plant and animal species could begin at just 1.5–2°C of warming.

Droughts and wildfires are increasing, killing trees and releasing carbon, creating a feedback loop that makes the forest hotter and drier. Collapse would disrupt rainfall across South America and trigger global climate fluctuations.

Ocean currents weakening

The AMOC, a “conveyor belt” that drives ocean circulation and stabilises Europe’s climate, could collapse if warming exceeds 2°C, according to the report. Such a breakdown could cause harsh winters in northwest Europe, disrupt African and Asian monsoons, and reduce crop yields.

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In recent years, the impact of the warming planet on the AMOC and Gulf Stream system has given rise to numerous scientific publications warning of its weakening – or even possible collapse. Not all scientists agree that an AMOCExternal link or rain forest collapseExternal link is close, however. A Swiss-US study published this year concludedExternal link that the current had been stable over the past 60 years.

A view of Russell Glacier in the Qeqqata municipality in central-western Greenland. Sebastian Steude / Keystone

Ice sheets at risk

Scientists are also closely monitoring ice sheets in Greenland and the West Antarctic, which are melting at accelerating rates, causing sea levels to rise. The report warns that the sheets are “looking perilously close” to their tipping point.

Claudia R. Binder,External link an environmental researcher at the Swiss Federal Institute of Technology Lausanne (EPFL) and co-author of the “tipping points” report, says the planet faces “drastic changes”.

“We are convinced the Greenland and West Antarctic ice caps are on the verge of irreversible collapse,” she toldExternal link Swiss public radio RTS. “Antarctica could have a strong tipping point in the future. The same goes for the Amazon rainforest if we continue at 1.5 degrees or more.”

The University of Bern’s Fröhlicher agreed that risks were increasing but cautioned that “there is great uncertainty about the exact level of warming at which these tipping points are located”.

“It is crucial to further improve the monitoring and understanding of these systems,” said the Swiss scientist, who will be a lead author of a chapter on tipping points in the IPCC AR7 Working Group 1 report to be published in 2028.

China’s installed solar photovoltaic capacity has now surpassed 1,000 GW for the first time, equivalent to half of the world’s total installed solar capacity. Yuan Hongyan / Getty Images

Signs of hope: positive tipping points

The Global Tipping Points report also offers some hope amid its alarming findings. It also outlines “positive tipping points”: large-scale, self-reinforcing social or technological shifts that can speed up the transition to a cleaner, more stable world.

Tim LentonExternal link, chair in climate change and Earth system science at the University of Exeter and lead author of the “tipping points” report, has identified breakthroughs in solar and wind power, electric vehicles, battery storage and heat pumps as examples of transitions that have become self-sustaining and are accelerating worldwide. Nations like Norway and China have seen rapid electric car adoption, Denmark leads in offshore wind, and the UK has phased out coal power. In 2025, renewables generated more electricity than coal for the first time, according to energy think tank Ember.

Indigenous people from the Brazilian Amazon and activists take part in a climate protest ahead of COP30 in Brasilia, Brazil, on October 14, 2025. Andre Borges / Keystone

A call to action at COP30

To avert the negative cascading climate dynamics and seize the positive opportunities, urgent, coordinated action is needed from world leaders at the upcoming UN climate conference (COP30) to cut emissions faster and reduce the time temperatures spent above 1.5°C, says Lenton.

Researchers involved in the report have been working with Brazil’s COP30 organisers to ensure that tipping points and climate change solutions are firmly on the agenda in Belem and are given time and consideration.

“We are in discussion with the COP30 presidency team … to see how the positive tipping points framework can be helpful designing the COP30 “Action Agenda”,” Steve SmithExternal link, an environmental scientist from Exeter, told Swissinfo.

The “Action AgendaExternal link” aims to be a core element of the summit conference that bring together and accelerate nations’ climate transition plansExternal link and voluntary climate solutions from around the world to trigger change across different sectors – from agriculture to energy and from forests to cities.

Ultimately, change depends on everyone coming together to make a difference — government, industry, researchers, and consumers — Binder says.

“That’s a crucial point to remember when we place so much hope in COP30, because the government can only do so much. Real change will only happen if we, as individuals, do our part too,” she added.

Edited by Gabe Bullard/vdv