The article discusses the need for sustainability limits in carbon dioxide removal (CDR) to ensure that climate mitigation efforts do not cause additional environmental and social harm. Current climate strategies rely heavily on large-scale CDR, such as bioenergy with carbon capture and storage (BECCS) and afforestation/reforestation (A/R), to achieve net-zero and net-negative emissions. However, these methods pose significant risks to biodiversity, food security, and planetary boundaries. The study highlights that the IPCC's estimates of CDR potential are primarily based on technical and economic factors, but do not account for sustainability risks. The research assesses the sustainability limits of BECCS and A/R, finding that high-risk levels for these methods start well below the IPCC's technical potential. For BECCS, the upper bound of low risk is 0.7 GtCO₂/year, and medium risk is 1.3 GtCO₂/year. For A/R, the upper bound of medium risk is 5.1 GtCO₂/year. These thresholds are far below the IPCC's technical potential and even below the economic potential. The study emphasizes that sustainability issues such as biodiversity loss, water availability, and food security should guide CDR deployment rather than technical and economic potentials. The article also discusses the sustainability of "nature-based" CDR, which includes ecosystem restoration. These methods are considered more sustainable and have fewer feasibility challenges compared to afforestation. The study recommends that research on a sustainable and realistic CDR budget be prioritized, considering ecological, social, and economic factors. It also calls for a CDR hierarchy to allocate limited sustainable supply to the most legitimate uses, such as counterbalancing residual emissions. The study highlights the need for reframing CDR governance to ensure that CDR supplements rather than substitutes for deep emission cuts. It emphasizes the importance of setting high integrity standards for CDR providers and purchasers, and calls for transparency in CDR land footprints. The article concludes that there is an urgent need for analyses that make CDR land footprint and resource use transparent, and that governments and the IPCC should support research to clarify the land footprint of mitigation pathways and define pathways that do not overstep sustainable CDR thresholds.The article discusses the need for sustainability limits in carbon dioxide removal (CDR) to ensure that climate mitigation efforts do not cause additional environmental and social harm. Current climate strategies rely heavily on large-scale CDR, such as bioenergy with carbon capture and storage (BECCS) and afforestation/reforestation (A/R), to achieve net-zero and net-negative emissions. However, these methods pose significant risks to biodiversity, food security, and planetary boundaries. The study highlights that the IPCC's estimates of CDR potential are primarily based on technical and economic factors, but do not account for sustainability risks. The research assesses the sustainability limits of BECCS and A/R, finding that high-risk levels for these methods start well below the IPCC's technical potential. For BECCS, the upper bound of low risk is 0.7 GtCO₂/year, and medium risk is 1.3 GtCO₂/year. For A/R, the upper bound of medium risk is 5.1 GtCO₂/year. These thresholds are far below the IPCC's technical potential and even below the economic potential. The study emphasizes that sustainability issues such as biodiversity loss, water availability, and food security should guide CDR deployment rather than technical and economic potentials. The article also discusses the sustainability of "nature-based" CDR, which includes ecosystem restoration. These methods are considered more sustainable and have fewer feasibility challenges compared to afforestation. The study recommends that research on a sustainable and realistic CDR budget be prioritized, considering ecological, social, and economic factors. It also calls for a CDR hierarchy to allocate limited sustainable supply to the most legitimate uses, such as counterbalancing residual emissions. The study highlights the need for reframing CDR governance to ensure that CDR supplements rather than substitutes for deep emission cuts. It emphasizes the importance of setting high integrity standards for CDR providers and purchasers, and calls for transparency in CDR land footprints. The article concludes that there is an urgent need for analyses that make CDR land footprint and resource use transparent, and that governments and the IPCC should support research to clarify the land footprint of mitigation pathways and define pathways that do not overstep sustainable CDR thresholds.