Global warming must peak below 2°C to limit tipping point risks

A tipping point defines a critical threshold beyond which a previously relatively stable subsystem of the Earth can shift into a new state. Even a small change in environmental conditions can spark a transformation of that subsystem, which can be rapid and irreversible. Subsystems at risk of tipping include tropical coral reefs, the Amazon rainforest, permafrost and major ice sheets in Greenland and Antarctica.

Up to eight tipping points could be reached below 2°C warming, according to the new study. It builds on a chapter of the 2025 Global Tipping Points Report, which was presented at the UN Climate Conference COP30 in Belém, Brazil.

“It’s concerning that, even with a small and relatively brief overshoot of the 1.5°C target, up to five Earth system tipping points could be triggered – especially as it now appears almost unavoidable that global warming will exceed 1.5°C in the late 2020s or early 2030s,” says co-lead author Nico Wunderling from PIK and Goethe University Frankfurt.

Some subsystems are particularly sensitive to overshooting the 1.5°C limit

“The tipping point for several Earth systems could therefore be crossed – at least temporarily,” says lead author Paul Ritchie, from Exeter’s Global Systems Institute. “However, tipping does not occur immediately upon crossing a tipping point. If we limit the maximum level of warming, and keep the duration of the overshoot short, tipping could still be avoided for many tipping elements of the Earth system.”

Ritchie explained that some systems – such as tropical coral reefs – respond very quickly to higher temperatures and are therefore especially vulnerable to “overshoots, even when they are short. In contrast, potential tipping points with slower response times may be less sensitive to temporary overshoot. 

Norman Steinert, co-lead author from CICERO, concluded: “Minimising the peak of an overshoot is crucial, but arguably minimising the duration is even more important. However, it’s important to note that these things are related: the higher the peak temperature, the more difficult it is to reverse temperature below critical levels and the longer it’s likely that we’ll remain in overshoot.”