The UNFCCC Secretariat has released a concept note on carbon dioxide removal (CDR) activities under the Article 6.4 Mechanism (the Concept Note), published as an annex to the annotated agenda of the first meeting of the Article 6.4 Supervisory Body (SB) taking place beginning today in Bonn, Germany. This bulletin provides a brief summary of the Concept Note.

Alongside the Concept Note, the UNFCCC Secretariat also released draft rules of procedure for the SB and concept notes on SB work in 2022-2023, its support structure, share of proceeds, and guidelines on baselines and additionality.

Overview. The Concept Note is the first step in the SB’s work to develop recommendations for CDR and includes analysis of possible CDR activities under the Article 6.4 Mechanism, including CDR monitoring, reporting, accounting, crediting periods and issues relating to addressing reversals, avoidance of leakage, and avoidance of other negative environmental and social impacts. We anticipate that CDR will be given particular attention at COP 27 set to take place in Sharm El-Sheikh, Egypt this November and note that the SB is due to make recommendations on CDR in advance of the COP.

Key issues and analysis. The Concept Note provides analysis on the following key issues:

  1. Types of CDR activities. The Concept Note defines CDR as “anthropogenic activities that remove carbon dioxide (CO2) from the atmosphere and ensure its long-term storage in terrestrial, geological, or ocean reservoirs, or in long-lasting products” and acknowledges that CDR cannot serve as a substitute for deep emissions reductions, but can fulfil multiple complementary roles (including near-term reductions, addressing residual emissions from ‘hard-to-transition’ sectors, and achieving and sustaining net-negative in the long-term). The Concept Note breaks CDR out into the following categories:
                • Afforestation and reforestation (A/R) and revegetation;
                • Sustainable forest management; 
                • Wetlands restoration and re-wetting; 
                • Agroforestry;
                • Urban forestry;
                • Soil organic carbon enhancement in croplands and grasslands;
                • Direct air carbon dioxide capture and storage (DACCS);
                • Enhanced rock weathering and ocean alkalinization; and
                • Ocean fertilization.
  2. Enabling sustained removal through long-term storage of removed carbon. The Concept Note identifies long-term storage of sequestered carbon as necessary to overcoming the limits of bio-sequestration-based CDR, which can be limited by saturation. The following activities are highlighted as enabling sustained long-term storage of carbon and keeping bio-sequestration sinks working:
                • Timber in construction; 
                • Long-lasting bio-based products;
                • Biochar applications to soils; and
                • Bioenergy with carbon capture and storage/use (BECCS).
  3. Eligibility of CDR activities in existing carbon market mechanisms. CDR activities are limited to A/R under the Clean Development Mechanism (CDM) and joint implementation (JI) of the Kyoto Protocol. The range of CDR activities eligible under voluntary sector carbon market mechanisms is broad by contrast and includes — in addition to A/R — improved forest management (IFM), conservation of wetlands, and activities enhancing carbon sequestration in agricultural soils. Table 1 on pages 10 and 11 of the Concept Note summarizes the types of CDR activities eligible under key carbon market mechanisms (including the CDM, JI, CAR, ACR, VCS, Gold Standard, and California Compliance Offset Program).
  4. Methodological issues in CDR activities. Finally, the Concept Note addresses methodological issues that arise when CDR activities are used to generate carbon credits, including baseline setting, additionality demonstration, monitoring, verification, crediting periods, reversals, leakage, addressing negative environmental and social impacts, and co-benefits (including contributions to sustainable development). Table 2 on pages 15 and 16 provides options for addressing each of the issues in the context of A/R, revegetation and IFM; wetland restoration; agroforestry and urban forestry; and soil organic carbon enhancement. It appears that further work will be required on methodological issues relating to technology-based CDR activities, including DACCS, BECCS, and ocean alkalinization. 

For further information or to discuss the contents of this bulletin, please contact Lisa DeMarco at


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