The Paris Agreement calls for net-zero greenhouse gas emissions in the second half of this century (UNFCCC 2015). Without large-scale implementations of carbon dioxide removal (CDR), we will not be able to reach such a net-zero goal. Accordingly, in recent years, along with urgent greenhouse gas emissions reduction, CDR continues attracting attention as a necessary part of climate mitigation. CDR implementation has the potential to serve three systemic functions in ambitious mitigation pathways: 1) to accelerate the reduction of net emissions, 2) to compensate for remaining (residual) GHGs emissions, enabling us to reach net-zero goals, and 3) to potentially reach net-negative emissions with the aim to reverse global mean temperature (IPCC AR6 WG3, Cross-Chapter Box 8). 

Carbon dioxide removal describes anthropogenic activities that aim at removing CO₂ from the atmosphere and store it in terrestrial, marine or geological carbon reservoirs. The most prominent options currently considered in ambitious climate change scenarios are: Bioenergy combined with geological carbon capture and storage, direct air carbon capture combined with geological storage, reforestation and afforestation. In pilot studies further CDR options considered include ocean alkalinity enhancement, soil carbon enhancement through e.g. biochar or agricultural practices, or the enhancement of coastal vegetated ecosystems. 

In preparation for the seventh phase of the Coupled Model Intercomparison Project (CMIP7; Dunne et al. 2025) that will provide future climate projections to the seventh Assessment Report (AR7) of the Intergovernmental Panel on Climate Change (IPCC), the international climate modelling community has shown growing interest in exploring CDR in ambitious climate mitigation pathways. As the global community explores the feasibility of meeting and sustaining net-zero and net-negative emissions targets (Baatz et al. 2025, Förster et al. 2022), a more accurate understanding of CDR efficiency, both in general terms and method-specific, as well as potential side effects has become more critical than ever.