How to approach consensus on climate tipping points and why it is important

Thomas Stocker Oeschger Centre for Climate Change Research University of Bern, Switzerland Moving Beyond Uncertainty: Rethinking Climate Models and Tipping Points 5November 2024 How to approach consensus on climate tipping points and why it is important high level of attention by public and policymakers often (ab-)used to express urgency for climate action potential to divide the climate science community Tipping Points —Surprises —High Impact Low Likelihood events Tipping points and surprises: Assisting decision making IPCC, 2024, P60, Inf.6 Scientific assessment would facilitate consensus and accelerate understanding Proposal to IPCC AR7 for a Special Report was unsuccessful Highly policy-relevant topic to be assessed across the three IPCC Working Groups The IPCC considers an Expert Meeting in 2025 on High-Impact Events and Tipping Points AR7 Scoping: December 9-13, 2024 Tipping points and surprises: Assisting decision making The IPCC considers … ??? Boers, Ghil, Stocker, 2022 Many elements are proposed for tipping and surprises Atlantic Meridional Overturning Circulation: CMIP6 models IPCC 2023, WGI Fig. 4.6 Romanou et al., 2023 AMOC: Models and Observations IPCC 2023, WGI Fig. 4.6 Volkov et al., 2024 Zhang et al., 2023 Western boundary currents Subtropical upwelling zones Southern Ocean CMIP6 SST Bias Tipping Points: Systematic model shortcomings Tipping Points: Systematic model shortcomings 50 km 2 km Schär et al., 2024Hewitt et al., 2022