Scaling Carbon Dioxide Removal in Germany: Insights from the CDRterra Framework and Scenario

To achieve the goals of the Paris Agreement, the European Union and Germany have committed to achieving net-zero greenhouse gas emissions by 2050 and 2045, respectively. This requires not only drastically reducing emissions but also scaling up Carbon Dioxide Removal (CDR) deployment and infrastructure. Large-scale implementation of CDR involves challenges related to feasibility (technological viability, resource availability, legal compliance, political feasibility) and fairness (inclusive decision-making, transparent communication), while the CDR deployment impacts individuals, society, the environment, and the ratio and distribution of these impacts. To enable legitimate, fair, and widely supported decision-making on the scaling-up process, a comprehensive framework is needed that compares CDR measures and additionally evaluates their trade-offs with other sustainability goals, necessitating transparent assessments of both, implementation processes and outcomes.

Existing assessments of CDR either analyze CDR methods or portfolios without considering the socio-economic context or focus on future scenarios that only cover a small set of CDR methods due to missing method implementation in the models. To address these gaps, we developed the CDRterra assessment framework (AF) and an ambitious, plausible future CDR scenario for Germany to which the AF is applied to. All works are part of the interdisciplinary CDRterra research program involving around 100 researchers who contributed to workshops, including stakeholder groups and colleagues from the partner program CDRmare to design the scenario and develop the AF.

The scenario is based on the SSP2 aligned with Germany's climate policies and combines cost-optimization and agent-based models, ex-post assumptions, and bottom-up calculations. It considers land, biomass, energy, and CO₂ transport and storage capacities in Germany to derive consistent deployment targets for nine CDR methods: afforestation/reforestation and forest management, agroforestry, cover cropping, BECCS, DACCS, PyCCS, enhanced rock weathering, artificial photosynthesis, and CO₂-negative building materials. Results indicate potential annual removal of 1-40 MtCO₂ per method by 2045.

We applied the CDRterra AF to the CDR measures of this scenario for the years 2030, 2045, and 2060, and evaluate both, the process and impact of such a large-scale CDR implementation which is embedded in a future socio-economic context, described by e.g., energy and biomass demand and supply, economic growth, and societal behavior. The data to fill the AF was generated by the research process within CDRterra. The structure of the AF itself builds on existing frameworks (esp. IPCC and German-specific assessment frameworks) but introduces key innovations: a clear distinction between feasibility and desirability, and between descriptive information and its normative assessment. The descriptive level is based on a data base of 120 variables, informing 90 indicators. The indicators are evaluated according to the 18 assessment criteria linked to societal norms, policy goals, and ethical considerations.

By applying the CDRterra AF to the German CDRterra scenario, we evaluated large-scale CDR implementation and identified key risks, benefits, barriers, and leverage points for each CDR method. This analysis provides a transparent knowledge base to inform societal debates and support evidence-based climate policy decisions on CDR deployment.