Overshooting climate targets could significantly increase risk for tipping cascades, study finds

In a new associated paper of the Earth Commission an international group of researchers show that temporarily overshooting the climate targets of 1.5-2 degrees Celsius could increase the tipping risk of several Earth system elements. This tipping risk increases even if in the longer term the global temperature would stabilize within the Paris range. Avoiding an overshoot would hence limit the risks.

Wendy Broadgate, Global Hub Director (Sweden) for Future Earth and Director of the Earth Commission says  “This work underscores that 1.5 degrees as a limit not a target, as even temporary temperature overshoots increase the risk of crossing tipping points and sensitive thresholds. We must reduce our fossil fuel emissions urgently to have a chance of staying within 1.5 degrees of warming.”

To arrive at these results, the scientists used different global warming overshoot scenarios with peak temperatures from two to four degrees and applied these to a set of four interacting tipping elements: the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic meridional overturning circulation AMOC, and the Amazon rainforest.

“Especially the Greenland and the West Antarctic ice sheet are at risk of tipping even for small overshoots, underlining that they are among the most vulnerable tipping elements. While it would take a long time for the ice loss to fully unfold, the temperature levels at which such changes are triggered could already be reached soon” says Ricarda Winkelmann, Earth Commissioner and Co-Lead of the FutureLab on Earth Resilience in the Anthropocene. “Our action in the coming years can thus decide the future trajectory of the ice sheets for centuries or even millennia to come” she adds.

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