Article 6 of the 2015 Paris Agreement sets out how countries (âÂÂPartiesâÂÂ) may cooperate voluntarily to implement their nationally determined contributions (NDCs). It is intended to allow higher ambition in mitigation and adaptation while promoting sustainable development, and it conditions cooperation on environmental integrity, transparency and robust accounting, especially to avoid double counting of the same mitigation outcome across countriesâ NDCs.
The article establishes three cooperation pathways. Under Article 6.2, Parties may use âÂÂcooperative approachesâ to transfer and use internationally transferred mitigation outcomes (ITMOs) through bilateral or multilateral arrangements, subject to guidance adopted by the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (CMA). Article 6.4 creates a UNFCCC-supervised crediting mechanismâÂÂreferred to by the UNFCCC as the Paris Agreement Crediting Mechanism (PACM)âÂÂthat registers mitigation activities and issues units (A6.4ERs), including provisions such as a share of proceeds for the Adaptation Fund and cancellation of a portion of units to deliver an overall mitigation in global emissions (OMGE). Article 6.8 establishes a framework and work programme for âÂÂnon-market approachesâÂÂ, which support cooperation without international transfers of mitigation outcomes.
Implementation depends on cross-cutting accounting and transparency arrangements that link Article 6 reporting to the Paris AgreementâÂÂs transparency system (Article 13), including tracking through registries and, where required, âÂÂcorresponding adjustmentsâ to ensure that an internationally used mitigation outcome is reflected in only one PartyâÂÂs NDC accounting. Parties adopted the core âÂÂArticle 6 rulebookâ at COP26, and later CMA decisions have continued to operationalize technical standards and reporting infrastructure. The impacts of Article 6 remain debated, particularly around environmental integrity, governance capacity and the risk of over-crediting.
Article 6.1 of the Paris Agreement recognizes that some Parties may choose to pursue voluntary cooperation in implementing their nationally determined contributions (NDCs) âÂÂto allow for higher ambitionâ in mitigation and adaptation actions, while promoting sustainable development and ensuring environmental integrity.
Article 6 frames cooperative approaches as voluntary tools that may be used in implementing NDCs to support higher ambition. The mechanism established under Article 6.4 is also intended to âÂÂdeliver an overall mitigation in global emissionsâÂÂ, in addition to enabling the transfer of mitigation outcomes between Parties. Article 6 also links cooperation to sustainable development: cooperative approaches under Article 6.2 are to promote sustainable development, and the Article 6.4 mechanism is intended to contribute to mitigation while fostering sustainable development.
For cooperative approaches under Article 6.2, the Paris Agreement requires Parties to ensure environmental integrity and transparency (including in governance) and to apply robust accounting âÂÂto ensure, inter alia, the avoidance of double countingâÂÂ, consistent with guidance adopted by the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (CMA). The CMA guidance adopted at COP26 (CMA.3) includes requirements on âÂÂcorresponding adjustmentsâ and reporting intended to apply these accounting and integrity principles in practice.
Article 6 summaries often use specialized accounting and carbon-market terminology; later sections explain these concepts in more detail.
The Paris Agreement offers three ways in which Parties may cooperate on a voluntary basis.
Article 6.2 provides for âÂÂcooperative approachesâ in which Parties may voluntarily transfer and use internationally transferred mitigation outcomes (ITMOs) without relying on the centralized crediting mechanism established under Article 6.4. Participating Parties are to promote sustainable development, ensure environmental integrity and transparency (including in governance), and apply robust accounting consistent with guidance adopted by the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (CMA), including measures intended to avoid double counting.
In practice, ITMOs can represent quantified emission reductions or removals and may be expressed in greenhouse-gas metrics (such as tCO<sub>2</sub>e) or, where Parties determine, in other metrics. Cooperative approaches can be implemented through a variety of bilateral or multilateral arrangements, including crediting-based transfers and policy-based cooperation such as linked emissions trading systems, provided Parties authorize the use of outcomes and apply the agreed accounting framework.
CMA guidance links key accounting steps to authorization and âÂÂfirst transferâÂÂ. Where an ITMO is authorized for use toward another PartyâÂÂs NDC (or other international purposes), Parties apply corresponding adjustments and disclose relevant information through Article 6 reporting under the Paris AgreementâÂÂs transparency framework (Article 13).
Commentators debate whether Article 6.2 transfers primarily lower costs and mobilize finance or risk undermining environmental integrity through over-crediting, unambitious baselines (âÂÂhot airâÂÂ), or weak governance; assessments emphasize that outcomes depend on ambition and the strength of accounting, transparency and review safeguards.
Under Article 6.4, Parties established a UNFCCC-supervised crediting mechanismâÂÂreferred to by the UNFCCC as the Paris Agreement Crediting Mechanism (PACM)âÂÂto register mitigation activities and issue units for verified emission reductions or removals, while supporting sustainable development and delivering an overall mitigation in global emissions.
The PACM registers eligible mitigation activities and issues units known as Article 6.4 emission reductions (A6.4ERs), which are recorded in a mechanism registry with unique identifiers to enable tracking (e.g., issuance, transfer, cancellation, and use). COP26 decisions also included a share of proceeds for the Adaptation Fund and cancellation of a portion of issued units to deliver an overall mitigation in global emissions (OMGE).
Host Parties may determine whether A6.4ERs are authorized for international use (for example, toward another PartyâÂÂs NDC or other international mitigation purposes) or retained as mitigation contribution units intended to support mitigation in the host Party. Authorized A6.4ERs interact with the broader Article 6 accounting and transparency framework intended to avoid double counting, including corresponding adjustments where applicable under CMA guidance.
The mechanism operates under the authority of the CMA and is supervised by the Article 6.4 Supervisory Body, which oversees the mechanismâÂÂs implementation framework and centralized infrastructure for registration, issuance and tracking.
Host Parties participate through domestic arrangements, including designating national authorities and providing required approvals for activities and, where relevant, authorizations when A6.4ERs are intended for international use.
In outline, an Article 6.4 activity is developed against approved requirements (including methodologies), validated and registered under the mechanism, monitored and independently verified for a crediting period, and then issued as A6.4ERs into the mechanism registry. Host Party approvals and any authorization for international use are part of this activity cycle, and the registry records whether issued units are authorized for transfer or retained as mitigation contribution units.
Article 6.8 establishes a framework for voluntary cooperation through âÂÂnon-market approachesâ (NMAs). Unlike cooperative approaches under Article 6.2 and the crediting mechanism under Article 6.4, NMAs do not involve the international transfer of mitigation outcomes between Parties. UNFCCC guidance describes NMAs as cooperation that can integrate mitigation and adaptation and may also involve finance, technology transfer, and capacity building, while contributing to sustainable development and poverty eradication.
At the COP26 meeting (CMA.3, Glasgow, 2021), Parties adopted a work programme under Article 6.8 and established the Glasgow Committee on Non-market Approaches (GCNMA) to support implementation of the framework. The work programmeâÂÂs initial focus areas include adaptation, resilience and sustainability; mitigation measures that contribute to sustainable development; and development of clean energy sources. UNFCCC materials describe work programme activities such as identifying opportunities for coordination and synergies across instruments and institutional arrangements, developing and sharing case studies and best practices, and maintaining UNFCCC web-based tools (including a platform and discussion forum) for recording and exchanging information on NMAs.
The GCNMA began its work in 2022 and holds regular meetings and workshops, alongside calls for submissions and technical papers, as part of a multi-year work programme.
Article 6 cooperation is linked to the Paris AgreementâÂÂs transparency framework (Article 13). Participating Parties are expected to report what they authorize, transfer, acquire, cancel or use, and how those actions are reflected in NDC accounting, including the corresponding adjustments used to avoid double claiming for authorized international uses.
For Article 6.2, CMA guidance sets out a reporting package that includes an initial report, annual information on transfers and authorizations, and regular information submitted through biennial transparency reporting for the relevant NDC implementation period. The UNFCCC compiles and publishes Party-submitted information through a centralized accounting and reporting platform linked to an Article 6 database.
Tracking relies on registries that record actions such as issuance, transfer, cancellation and use. Parties may use domestic registries or UNFCCC registry services for Article 6.2, while the Article 6.4 mechanism uses a UNFCCC mechanism registry for issued units. Analyses describe registry and reporting linkages as important for reconciling what Parties report and supporting environmental integrity.
Common âÂÂdouble countingâ risks and control points described in Article 6.2 guidance and secondary analyses include the following:
Article 6.2 cooperative approaches have been implemented through a range of bilateral and policy-linked arrangements. Examples include:
Article 6 cooperation is conducted between Parties under the Paris Agreement. When a mitigation outcome is authorized for international use (for example as an internationally transferred mitigation outcome under Article 6.2 or through the Article 6.4 crediting mechanism), Parties report it and apply accounting rules intended to avoid double counting, including corresponding adjustments for authorized uses toward another PartyâÂÂs NDC.
The voluntary carbon market is separate from the UNFCCC system and generally refers to organizations buying carbon credits without a legal obligation, often linked to voluntary climate claims or âÂÂbeyond value chainâ mitigation strategies. Voluntary and compliance credit markets can overlap, including when host governments authorize credits from independent programmes for use under Article 6, which can require an authorization decision and, where relevant, a corresponding adjustment so the same outcome is not claimed more than once. There are expectations that operationalizing Article 6 could influence voluntary-market demand and pricing, while voluntary credits remain governed by separate standards unless they are brought under Article 6 processes.
The Integrity Council for the Voluntary Carbon Market's CCP tagging guidance includes optional "CCP Attributes" intended to record whether a host country has authorised the use of credits for other international mitigation purposes under Article 6 of the Paris Agreement.
Following the adoption of the âÂÂArticle 6 rulebookâ at the COP26 (CMA.3, Glasgow, 2021), negotiations under Article 6 have focused largely on implementationâÂÂi.e., how the agreed rules are applied in practice through reporting, centralized infrastructure and technical standardsâÂÂrather than on whether cooperation mechanisms should exist. Further guidance and updates have been adopted through later CMA decisions, including additional Article 6 decisions in 2024 (CMA.6) and 2025 (CMA.7).
Reporting around COP29 in Baku described additional standards being approved for a UN-backed carbon market under Article 6, while noting that further operational work remained for implementation through the Supervisory Body and subsequent CMA decisions.
Scholarly and policy literature on Article 6 generally treats it as a potentially useful tool for international cooperation and finance flows, while emphasizing that outcomes depend on the ambition of participating Parties and on the strength of governance, accounting and transparency safeguards.
A recurring debate concerns environmental integrity and the risk of âÂÂhot airâÂÂ. Analysts note that international transfers can weaken climate outcomes if mitigation outcomes are overestimated (for example because baselines or accounting choices inflate outcomes), or if transfers draw on unambitious NDCs such that reductions are âÂÂexportedâ without increasing overall mitigation. Related debates focus on double counting and authorization. Reviews emphasize that avoiding double claiming between Parties and multiple uses of the same outcome depends on clear host-country authorization decisions (including intended use) and on accounting and transparency systems that allow transfers and adjustments to be reconciled across countries and time periods.
For crediting approaches, a longstanding concern is additionality and baselines: whether credited reductions would have occurred anyway and whether baselines remain credible as policies, technology costs and regulations change. Observers also note that Paris-era crediting takes place alongside NDC targets, raising questions about how crediting, authorization choices and future NDC ambition interact, including how host countries manage the relationship between exported outcomes and domestic mitigation priorities over time.
Participation can also be institutionally demanding. Commentators note that Article 6 implementation often requires legal mandates and procedures for authorization, measurement and reporting capacity, and registry and tracking infrastructure, which may be unevenly available across countries. Separate debates address sustainable development and social safeguards: while Article 6 links cooperation to sustainable development, observers differ on how consistently sustainable-development outcomes are defined, monitored and safeguarded in practice, especially for activities affecting local communities or land use. Some guidance for host-country engagement emphasizes procedural elements such as alignment with domestic law, access to information, stakeholder consultation, and monitoring of claimed co-benefits, while critics argue that uneven governance and oversight can leave gaps and that clearer safeguard expectations may be needed in practice.
Analysts debate market impacts such as price formation, liquidity and fragmentation. Some reports describe growing interest in Article 6-aligned transactions but also uncertainty about long-run demand, the availability of supply that meets authorization and accounting conditions, and the implications for pricing and market depth across different unit types and claims frameworks. Commentators also highlight the potential for fragmentation and higher transaction costs if registries and reporting systems are not interoperable, or if accounting treatments differ across mechanisms and cooperative approaches.