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(noun) A threshold that once crossed can trigger dramatic and irreversible changes in large natural systems
Scientists have warned for years that the more the world warms, the greater the risk of hitting multiple climate tipping points and setting off self-propelling shifts in everything from the Amazon rainforest to vital ocean currents and polar ice sheets.
These alerts have intensified in 2025, which began with scientists confirming 2024 was the first calendar year during which the average global temperature exceeded 1.5C above pre-industrial levels.
Later, researchers found that the world was reaching the first tipping point following record levels of bleaching of the warm-water coral reefs on which millions of people depend. Meanwhile, scientists said the level of warming that would trigger widespread Amazon rainforest dieback was lower than previously thought.
There are also signs that another climate-regulating system is weakening: the Atlantic Meridional Overturning Circulation, one of the chief current systems in the world’s oceans. Researchers say its collapse would disrupt weather patterns and undermine food production.
It is unclear precisely when such tipping points may be reached but it is feared that many are interconnected, so crossing one makes another more likely. Hundreds of scientists wrote an open letter this year urging governments to cut emissions faster because “if we wait, it will be too late”.
They also want more focus on so-called positive tipping points, or thresholds in the rollout of solar panels, batteries and other green technologies.
Finding ways to identify and trigger such shifts, along with those in social attitudes to climate action, may offer the best chance of avoiding the tipping points from which there is no return.