The article reviews the role of negative emission technologies (NETs) in limiting global warming to 2°C and 1.5°C, as outlined in the IPCC's Fifth Assessment Report. It highlights the importance of NETs, particularly bioenergy with carbon capture and storage (BECCS), in achieving these temperature goals. The review focuses on seven specific NETs: BECCS, afforestation and reforestation, direct air carbon capture and storage (DACCs), enhanced weathering, ocean fertilization, biochar, and soil carbon sequestration. The authors present estimates of their costs, potentials, and side effects, emphasizing the need for a systematic and transparent literature assessment. They find that the sustainable global NET potentials in 2050 range from 0.5 to 3.6 GtCO₂ yr⁻¹ for afforestation and reforestation, 0.5 to 5 GtCO₂ yr⁻¹ for BECCS, 0.5 to 2 GtCO₂ yr⁻¹ for biochar, 2 to 4 GtCO₂ yr⁻¹ for enhanced weathering, 0.5 to 5 GtCO₂ yr⁻¹ for DACCs, and up to 5 GtCO₂ yr⁻¹ for soil carbon sequestration. The costs and permanency of these technologies vary widely, and a single NET is unlikely to sustainably meet the required carbon uptake rates. The article also discusses the ethical and policy considerations surrounding the deployment of NETs, emphasizing the need for a comprehensive and transparent assessment of their potential impacts.The article reviews the role of negative emission technologies (NETs) in limiting global warming to 2°C and 1.5°C, as outlined in the IPCC's Fifth Assessment Report. It highlights the importance of NETs, particularly bioenergy with carbon capture and storage (BECCS), in achieving these temperature goals. The review focuses on seven specific NETs: BECCS, afforestation and reforestation, direct air carbon capture and storage (DACCs), enhanced weathering, ocean fertilization, biochar, and soil carbon sequestration. The authors present estimates of their costs, potentials, and side effects, emphasizing the need for a systematic and transparent literature assessment. They find that the sustainable global NET potentials in 2050 range from 0.5 to 3.6 GtCO₂ yr⁻¹ for afforestation and reforestation, 0.5 to 5 GtCO₂ yr⁻¹ for BECCS, 0.5 to 2 GtCO₂ yr⁻¹ for biochar, 2 to 4 GtCO₂ yr⁻¹ for enhanced weathering, 0.5 to 5 GtCO₂ yr⁻¹ for DACCs, and up to 5 GtCO₂ yr⁻¹ for soil carbon sequestration. The costs and permanency of these technologies vary widely, and a single NET is unlikely to sustainably meet the required carbon uptake rates. The article also discusses the ethical and policy considerations surrounding the deployment of NETs, emphasizing the need for a comprehensive and transparent assessment of their potential impacts.