Multiple climate ‘tipping points’ are likely to be triggered if global policies stay on their current course, scientists assessing the risk of triggering 16 different parts of the Earth system, ranging from the collapse of major ice sheets to the dieback of tropical coral reefs and vast forests, have warned.

Based on current policies and the resulting global warming, their most conservative estimate is a 62% risk of triggering these tipping points on average.

The study (led by the Universities of Exeter and Hamburg) has been keen to point out, however, that more sustainable pathways – with lower greenhouse gas emissions – significantly reduce the risk of tipping points. 

The research has also found that carbon released by certain tipping points (Amazon rainforest dieback and permafrost thaw) is unlikely to cause enough warming to trigger other tipping points.

The good news of the study is that the power to prevent climate tipping points “is still very much in our hands” and that – according to the paper’s lead author, Jakob Deutloff “by moving towards a more sustainable future with lower emissions, the risk of triggering these tipping points is significantly reduced.”

“And it appears that breaching tipping points in the Amazon and the permafrost region should not necessarily trigger others,” he said. 

A ‘tipping point’ occurs when a small change tips a system into a new state, causing significant and long-term transformation. The study assessed tipping point probabilities in five different scenarios, known as ‘shared socioeconomic pathways’ (SSPs).

Increasing numbers of Earth system components have been identified which could possibly exhibit tipping behaviour, with 15 candidates being shortlisted in the latest IPCC report. These Earth system components are referred to as ‘tipping elements’ and occur within the biosphere, cryosphere, and oceanic or atmospheric circulation.

The global mean surface temperature relative to pre-industrial levels is used as a common metric to describe the forcing of the ‘tipping elements’ (Earth system components). There has been growing concern over just how close Earth systems are moving towards climate tipping points as threshold temperatures have been revised to lower levels, leaving some of those tipping elements at risk of being triggered. 

Crossing those thresholds could, according to professor Tim Lenton from Exeter’s Global Systems Institute, “have devastating consequences for humanity.” 

“It is clear that we are currently on a dangerous trajectory, with tipping points likely to be triggered unless we change course rapidly,” he said. “We need urgent global action – including the triggering of ‘positive tipping points’ in our societies and economies – to reach a safe and sustainable future.”

The study concludes that rapid action is needed to reduce greenhouse gas emissions, adding that ‘since climate tipping points are already close, it will be decided in the coming decades if they will be crossed or not.’

The paper – published in the journal Earth System Dynamics is entitled ‘High probability of triggering climate tipping points under current policies modestly amplified by Amazon dieback and permafrost thaw.’

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