In a report released today, October 13, 2025, international climate researchers conclude that the death of numerous tropical coral reefs caused by rising ocean temperatures can now only be prevented with the utmost effort. Parts of the polar ice sheets may have already passed their tipping points. Their continued melting could lead to an irreversible sea level rise of several meters.
Among the lead authors of the Global Tipping Points Report 2025 (GTPR 2025) is Nico Wunderling, Professor of Computational Earth System Sciences at Goethe University's Center for Critical Computational Studies | C3S and researcher at the Senckenberg Research Institute Frankfurt, who, together with other lead authors, headed the chapter on "Earth System Tipping Points and Risks." Wunderling says: "The devastating consequences that arise when climate tipping points are crossed pose a massive threat to our societies. There is even a risk of the tipping of one climate system potentially triggering or accelerating the tipping of others. This risk increases significantly once the 1.5°C threshold is exceeded."
Some two dozen subsystems of the climate system are known to have tipping points. According to the report, the first of these - that of tropical coral reefs - has now been reached. The study further assumes that the global average temperature will increase by 1.5°C above pre-industrial levels within the next few years. This means the world is entering a phase in which the crossing of further climate tipping points is at risk, potentially leading to far-reaching consequences such as sea level rise from melting ice sheets or global temperature changes in the event of a collapse of the Atlantic Ocean circulation. The report also proposes measures to counter further temperature increases.
Coordinating lead author of the GTPR 2025 is Tim Lenton, Professor at the University of Exeter's (UK) Global Systems Institute. More than 100 scientists from over 20 countries contributed to the report, published just in time for the 30th World Climate Conference, which begins on November 10, 2025, in Belém, Brazil. The Global Tipping Points Report, first published in 2023 and already widely noted at the time, is regarded as an authoritative publication in the field of assessing both the risks and opportunities of negative and positive tipping points in the Earth system and in human societies.
Climate tipping points have started receiving greater attention within climate sciences for only about 20 years. The authors of the report define a climate-induced tipping point in Earth systems - such as coral reefs, the Amazon rainforest, or large-scale ocean currents - as the level of warming beyond which these systems undergo self-reinforcing and often irreversible changes. For example, many tropical coral reefs would die off after exceeding their tipping point, even if humanity were to limit further global warming. The scientists predict that it is quite possible that additional tipping points will be crossed in the coming decades, especially as some may already lie at around 1.5°C of global warming - including those of the Amazon rainforest (leading to savannization), the ice sheets of Greenland and West Antarctica (causing several meters of sea level rise), and the Atlantic Ocean circulation (causing a sharp cooling of the European continent).
The GTPR also features a series of case studies on various tipping elements of the climate system, including the following:
- Coral Reefs: Worldwide, coral reefs in tropical regions are suffering unprecedented mortality due to repeated mass bleaching events. The current global warming of about 1.4°C already exceeds their thermal tipping point, which scientists estimate at about 1.2°C. Even in the unrealistic case that warming could be stabilized at 1.5°C, there is a very high probability that the reefs will tip. Many will be permanently lost unless global temperatures drop again to 1°C above pre-industrial levels or less. The longer and the further this threshold is exceeded, the less likely recovery becomes.
- Amazon Rainforest: Climate warming combined with partial deforestation is already exposing the Amazon rainforest to the risk of large-scale savannization at 1.5-2°C of global warming. This in turn could further amplify climate change.
- AMOC (Atlantic Meridional Overturning Circulation): The collapse of the AMOC, which includes the Gulf Stream, could already occur at less than 2°C of global warming. This would lead to much colder winters in northwestern Europe, disrupt global monsoon systems, and reduce agricultural yields in large parts of the world.
The GTPR's authors emphasize that, alongside these negative tipping points in the climate system, there also exist positive tipping points in our societies. Crossing these can trigger rapid transformations toward more climate-friendly behavior. Some examples:
- Renewable energies are already cheaper than fossil fuels in most parts of the world, and electric vehicles are replacing gasoline and diesel cars on the roads. This trend could prove to be both irreversible and self-reinforcing.
- The gradual introduction and promotion of climate-friendly technologies by policymakers can accelerate the emergence of positive tipping points, including in the adoption of sustainable heating systems or in freight transport.
- "Social contagion" mechanisms can cause a majority of people to adopt behavioral changes initiated by a minority - such as reducing meat consumption or altering mobility habits.
Global Tipping Points Report: https://global-tipping-points.org/
