Carbon Dioxide Removal Pathways in Climate Overshoots Are Decisive for Tipping Risks in an Earth System Model-Based Tipping Dynamics Emulator

As the aim of limiting global warming to 1.5°C above preindustrial levels is getting out of reach, the world enters a risk zone for climate tipping points. For several crucial tipping elements, such as the polar ice sheets and the Atlantic Meridional Overturning Circulation (AMOC), a tipping threshold below 2°C cannot be ruled out. We develop an emulator for tipping elements to assess the risks of continental and regional tipping points with severe impacts on global conditions for human life, namely the Greenland and West Antarctic ice sheets, the Amazon rainforest, the AMOC and permafrost. Given the most recent advances in model capabilities for simulating coupled components of the Earth system, we directly parameterize the dynamic behaviour of our modelled tipping elements and their interactions according to a range of current process-based Earth system model experiments for the first time. With this empirically calibrated emulator, we assess tipping risks under overshoot scenarios and investigate the impact of several properties of temperature trajectories like peak temperatures, overshoot timescales and temperature reduction pathways, including carbon dioxide removal. Our results imply a crucial role for both emission mitigation and carbon dioxide removal (CDR) for tipping risks until 2200. We find that under current policies and actions, substantial deployment of CDR methods would have to take place well within this century to limit tipping risks in the next centuries to 10%. On millennial timescales, the return to a safe operating space w.r.t. tipping points is decided by the mitigation efforts of the next decades and the global storage capacity for carbon removal.