Climate, scientists sound the alarm about points of no return

The climate crisis is being felt in Europe with the heat waves and mega-fires that devastated northern countries in June and southern countries in August. In this context, a growing group of scientists is focusing on the ongoing dynamics that could bring some ecosystems essential for climate stability, from the Amazon to Greenland, to a point of no return, which until now have been underestimated.

"Policy makers need to think more about the consequences of tipping points and how societies need to prepare for them," argued Tim Lenton, world expert on tipping points and professor of Earth System Science at the University of Exeter, where the second world conference on the subject was held in July 2025. No government, with the possible exception of the Nordic countries, is considering scenarios such as ice cap collapse as seriously as other high-impact hazards such as pandemics, Lenton argued.

The organisers of the conference (in addition to the Global Systems Institute in Exeter, also the Potsdam Institute for Climate Impact Research and the Max Planck Institute of Geoanthropology) appealed to the scientific community, policy-makers and companies to make them aware of the importance of tipping points and to accelerate action against them. In addition to scientists, emergency services, insurance companies and pension funds are also showing increasing interest in tipping points. The same goes for the Brazilian organisers of Cop30, who will devote much attention to the topic, not least because the summit will be held in November in Belém, the gateway to the Amazon.

The basic problem is that no one knows the exact level of warming required to trigger a specific tipping point. The Earth's climate is governed by many interconnected processes, some of which - such as the dynamics governing ice sheet melting or the potential effects of forest fires - are poorly understood. To complicate matters further, one point of no return can trigger another, in a domino effect. The fresh water released into the oceans by melting Greenland ice, for example, may lead to the slowing of the Atlantic Meridional Overturning Circulation (Amoc, less known but more important than the Gulf Stream), further reducing precipitation over the Amazon, which risks turning into a savannah and releasing tens of billions of tonnes of carbon dioxide into the atmosphere, further warming the planet.

Lenton argues that since the last tipping point conference in 2022, global temperatures have risen, pushing many ecosystems towards a point of no return, i.e. towards a collapse caused by 'amplified feedbacks', in a system becoming self-propulsive: these processes are 'very difficult to reverse and could be quite abrupt'. The points of no return of greatest concern include the West Antarctic Ice Sheet, where the losses are now self-perpetuating, with the risk of ocean levels rising by about 1.2 metres. There is also the Greenland ice sheet, which is losing mass at an accelerated rate. Then there is the permafrost, parts of which have already passed localised points of no return, with huge methane losses into the atmosphere. And there is the unprecedented bleaching of coral reefs, on which hundreds of millions of people depend for their livelihoods. Other ecosystems close to a point of no return are the Amoc, which in turn could trigger monsoonal points of no return in India, and the degradation of the Amazon rainforest due to a combination of climate change and man-made fires.