The study presents an analysis of natural climate solutions (NCS) for mitigating climate change, focusing on 20 pathways, including reforestation, avoided forest conversion, natural forest management, improved plantations, and others. It estimates the maximum mitigation potential by 2030, considering safeguards for food and fiber security and biodiversity conservation. The study also evaluates the cost-effectiveness of these solutions in keeping global warming below 2°C, and identifies the proportion of maximum potential needed for this goal. It further assesses the cost barriers for each pathway. The maximum mitigation potential is calculated based on the potential extent and flux intensity of each pathway. For example, reforestation has the highest potential for sequestration, while avoided forest conversion has the highest potential for avoided emissions. The study also considers uncertainties in these estimates, using expert elicitation and empirical methods. It finds that the maximum mitigation potential for reforestation is around 1.2 PgC yr⁻¹, and for avoided forest conversion around 158 TgCO₂e. The study also evaluates the co-benefits of these pathways, such as biodiversity, water, soil, and air benefits. It finds that many of these pathways provide multiple co-benefits, such as improved air quality from avoided forest conversion and reforestation, and enhanced water regulation from wetland restoration. The study projects the contribution of NCS to climate mitigation through 2100, assuming a linear ramp-up period for mitigation levels and a gradual saturation of pathways. It also considers the proportion of NCS mitigation that can be achieved at low cost, with a marginal cost threshold of around $10 MgCO₂e⁻¹. The study concludes that NCS have the potential to significantly contribute to climate mitigation, with reforestation and avoided forest conversion being the most promising pathways. However, the study also highlights the need for further research and data to improve the accuracy of these estimates and to better understand the complex and geographically variable costs and benefits associated with these pathways.The study presents an analysis of natural climate solutions (NCS) for mitigating climate change, focusing on 20 pathways, including reforestation, avoided forest conversion, natural forest management, improved plantations, and others. It estimates the maximum mitigation potential by 2030, considering safeguards for food and fiber security and biodiversity conservation. The study also evaluates the cost-effectiveness of these solutions in keeping global warming below 2°C, and identifies the proportion of maximum potential needed for this goal. It further assesses the cost barriers for each pathway. The maximum mitigation potential is calculated based on the potential extent and flux intensity of each pathway. For example, reforestation has the highest potential for sequestration, while avoided forest conversion has the highest potential for avoided emissions. The study also considers uncertainties in these estimates, using expert elicitation and empirical methods. It finds that the maximum mitigation potential for reforestation is around 1.2 PgC yr⁻¹, and for avoided forest conversion around 158 TgCO₂e. The study also evaluates the co-benefits of these pathways, such as biodiversity, water, soil, and air benefits. It finds that many of these pathways provide multiple co-benefits, such as improved air quality from avoided forest conversion and reforestation, and enhanced water regulation from wetland restoration. The study projects the contribution of NCS to climate mitigation through 2100, assuming a linear ramp-up period for mitigation levels and a gradual saturation of pathways. It also considers the proportion of NCS mitigation that can be achieved at low cost, with a marginal cost threshold of around $10 MgCO₂e⁻¹. The study concludes that NCS have the potential to significantly contribute to climate mitigation, with reforestation and avoided forest conversion being the most promising pathways. However, the study also highlights the need for further research and data to improve the accuracy of these estimates and to better understand the complex and geographically variable costs and benefits associated with these pathways.