Multiple climate "tipping points" are likely to be triggered if global policies stay on their current course, new research shows.
Scientists assessed the risk of "tipping" in 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.
Based on current policies and the resulting global warming, their most conservative estimate is a 62% risk of triggering these tipping points on average.
However, more sustainable future pathways – with lower greenhouse gas emissions – significantly reduce the risk of tipping points.
The study, by the universities of Exeter and Hamburg, 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 from our study is that the power to prevent climate tipping points is still in our hands," said 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 within the Amazon and the permafrost region should not necessarily trigger others."
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) .
Professor Tim Lenton, from Exeter's Global Systems Institute , said: "Climate tipping points could 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.
"We need urgent global action – including the triggering of 'positive tipping points' in our societies and economies – to reach a safe and sustainable future."
During the writing phase, Jakob Deutloff was funded by the German Research Foundation. Professor Lenton's work was supported by the Bezos Earth Fund.
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."
