negativeemissions

Negative emissions refer to processes or activities that remove carbon dioxide or other greenhouse gases from the atmosphere on a net basis, reducing atmospheric GHG concentrations. They are distinct from emissions reductions and are often described as a means to offset residual emissions or to help meet temperature targets in models and policy.

Methods are typically grouped into nature-based and engineered approaches. Nature-based solutions include afforestation and reforestation, forest restoration and improved forest management, and soil carbon sequestration through practices such as reduced tillage, cover crops, and compost additions. Biochar—the carbon-rich product of biomass pyrolysis—can also contribute to long-term soil carbon storage. These approaches depend on land availability, climate, and ongoing stewardship to maintain stored carbon.

Engineered and technologically driven methods include direct air capture and storage (DACCS), which uses chemical processes to remove CO2 from ambient air and store it underground. Be Leaned on energy and infrastructure, BECCS combines bioenergy production with carbon capture and storage. Other concepts involve mineralization or enhanced weathering, and limited ocean-based approaches, though many are in early research or pilot stages and face scientific, regulatory, and ecological uncertainties.

Measurement and accounting are critical, addressing additionality, permanence, leakage, and verification. Permanence can be threatened by disturbances such as fires or drought for natural methods, or by technology failures and policy changes for engineered methods.

Policy relevance remains debated: many climate scenarios rely on negative emissions to achieve late-21st-century targets, highlighting both potential value and feasibility constraints for scaling up these solutions.