Article 6 of the Paris Agreement, explained

Paris Agreement

The 2015 treaty under the UNFCCC in which countries committed to holding global warming well below 2°C above pre-industrial levels while pursuing efforts to limit it to 1.5°C. Article 6 is one of its provisions.

Nationally Determined Contribution

NDC

A country's self-defined climate pledge under the Paris Agreement, submitted and updated on a five-year cycle. Article 6 provides frameworks through which Parties can cooperate in implementing their NDCs, with the aim of enabling higher ambition and promoting sustainable development and environmental integrity.

Conference of the Parties serving as the meeting of the Parties to the Paris Agreement

CMA

The supreme decision-making body for the Paris Agreement, and the forum in which Article 6 rules are adopted. Decisions are cited in the form "2/CMA.3": decision 2 of the third session.

Mitigation outcome

A quantified result of mitigation, such as a reduction in greenhouse gas emissions or a removal from the atmosphere. It can be expressed in tonnes of carbon dioxide equivalent or, under Article 6.2, another metric.

Tonne of carbon dioxide equivalent

tCO₂e

The standard unit of account, converting different greenhouse gases into a common measure based on their warming effect. A6.4ERs each represent one tCO₂e. Article 6.2 ITMOs may use this metric or another metric permitted by the rules.

Corresponding adjustment

CA

An adjustment to the emissions balance or other indicator used to track an NDC. The first-transferring Party accounts for outcomes first transferred, while a Party using ITMOs toward its NDC accounts for those it uses. The adjustment does not change either Party's national greenhouse gas inventory.

Double counting

The umbrella term for a single mitigation outcome being counted or used more than once: by two Parties (double claiming), through two issuances (double issuance), or in more than one transaction (double use). Preventing it is the central accounting problem of Article 6.

Host Party

The Party in which a mitigation activity takes place. It approves Article 6.4 activities and decides whether their A6.4ERs are authorised. Under Article 6.2, the host Party is often also the first-transferring Party and must account for outcomes first transferred.

Acquiring Party

A Party that receives ITMOs. It may hold or further transfer them and, if it uses them toward its NDC, must account for that use.

Registry

The electronic system that records the issuance, holding, transfer, use and cancellation of units. Countries may operate their own or use the UNFCCC international registry; Article 6.4 has its own registry.

Vintage

The year in which the mitigation occurred, as distinct from the year a unit was issued or transferred. Vintages matter because NDC periods are time-bound.

Cooperative approach

The arrangement between participating Parties through which mitigation outcomes may be authorised and first transferred, thereby becoming ITMOs. Subsequent negotiations have not provided a more precise definition of it, giving countries broad latitude over design.

Internationally Transferred Mitigation Outcome

ITMO

A mitigation outcome that has been authorised and first transferred under a cooperative approach. Under the Article 6.2 guidance, the underlying mitigation outcomes must be real, verified and additional, represent mitigation from 2021 onward, and be authorised for an Article 6 use. It can be measured in tCO₂e or another metric permitted by the Article 6.2 rules.

Authorisation

The formal act by which a participating Party permits specified mitigation outcomes to be used toward another Party's NDC, for other international mitigation purposes, or for other purposes. An authorised outcome becomes an ITMO when first transfer occurs. Authorisation determines whether units may be internationally transferred as authorised Article 6 units. This differs from approval, which permits an activity to participate in PACM.

Letter of Authorisation

LoA

A common name for a document or statement that records an authorisation. COP29 specified the information an authorisation must contain, but use of the UNFCCC's standard template is voluntary.

Other International Mitigation Purposes

OIMP

Uses of authorised mitigation outcomes other than a Party's NDC, most prominently CORSIA, the international aviation offsetting scheme. The first-transferring Party must apply a corresponding adjustment when the specified first-transfer event occurs.

First transfer

The event that turns an authorised mitigation outcome into an ITMO and triggers accounting by the first-transferring Party. For NDC use it is the first international transfer. For other international mitigation purposes, the Party may define it as authorisation, issuance, use or cancellation.

Initial report

A Party's first submission on its participation in cooperative approaches. It covers participation requirements, NDC accounting and each approach's design and environmental integrity. It is due no later than authorisation or, where the Party considers this practical, with its next Biennial Transparency Report, and before or with its first annual information.

Annual information

The yearly data each participating Party submits on ITMO authorisations and actions, including first transfer, transfer, acquisition, holdings, cancellation and use. It is submitted in the agreed electronic format.

Agreed Electronic Format

AEF

The standardised tables in which Parties report Article 6.2 information, designed to make submissions comparable and machine-readable.

Structured summary

The section of a Party's Biennial Transparency Report that sets out its use of cooperative approaches and its emissions balance after corresponding adjustments.

Centralized Accounting and Reporting Platform

CARP

The UNFCCC platform through which Article 6.2 initial reports, annual information and related documentation are published. The main public window onto cooperative approaches.

Technical Expert Review

TER

The independent expert review of a Party's Article 6.2 reporting, checking consistency with the rules and identifying inconsistencies for the Party to address. It is not UNFCCC approval or certification of a cooperative approach or individual ITMOs.

International Registry

The UNFCCC-operated registry for Parties that choose to use it rather than their own domestic registry. It was mandated at COP26 and later supplemented by optional additional registry services. It tracks ITMOs, while connections with Party registries continue to be developed.

Paris Agreement Crediting Mechanism

PACM

The operating name of the Article 6.4 mechanism: a UN-supervised crediting system that issues units from activities reducing or removing emissions while supporting sustainable development.

Article 6.4 Supervisory Body

SBM

The body that supervises PACM: it sets standards, approves methodologies, accredits DOEs, registers activities and oversees the registry, operating under CMA guidance. See the current members.

Article 6.4 Emission Reduction

A6.4ER

A unit issued by PACM, each representing one tCO₂e reduced or removed. If the host Party authorises it, it is identified as an AER and becomes an ITMO at first transfer; otherwise it is an MCU.

Mitigation Contribution Unit

MCU

An A6.4ER that the host Party has not authorised for international use. It contributes to mitigation in the host Party and may support results-based finance or domestic programmes. It cannot be used by another Party toward its NDC unless it is later authorised and converted to an AER.

Designated Operational Entity

DOE

An independent body accredited by the Supervisory Body to validate proposed activities and verify reported reductions and removals. DOEs are the mechanism's auditors.

Activity cycle

The regulated sequence every PACM activity follows: design, validation, registration, monitoring, verification and issuance.

Methodology

The approved set of rules for a given activity type, specifying how the baseline is set, how reductions are quantified, what must be monitored and how leakage is treated.

Clean Development Mechanism

CDM

The Kyoto Protocol's crediting mechanism and PACM's predecessor. Concerns about additionality and over-crediting in parts of its portfolio inform scrutiny of Article 6.4's integrity rules.

CDM transition

The process by which eligible CDM projects and programmes of activities migrate into PACM. Thousands of activities have applied, making transition rules a major determinant of early credit quality.

Overall Mitigation in Global Emissions

OMGE

The requirement that at least 2% of issued A6.4ERs are transferred to a cancellation account rather than used, so the mechanism delivers a net reduction rather than a pure transfer.

Share of Proceeds

SOP

The transfer of 5% of issued A6.4ERs to an account held for the Adaptation Fund, which supports adaptation in developing countries. Activities in least developed countries and small island developing States are exempt, although those countries may choose not to use the exemption.

Sustainable Development Tool

The mandatory assessment through which an activity must demonstrate its sustainable development contribution and its compliance with the mechanism's environmental and social safeguards. The current tool is under review as of September 2026.

Non-market approaches

NMA

Cooperation between countries that delivers mitigation and adaptation without transferring mitigation outcomes. It can include finance, capacity building, technology transfer and policy coordination. No corresponding adjustments arise.

Glasgow Committee on Non-market Approaches

GCNMA

The body established at COP26 to implement the Article 6.8 framework and run its work programme.

Non-market approaches platform

The matching platform under Article 6.8 through which countries record needs for support and potential providers identify where they can contribute. Access the platform.

Environmental integrity

The broad principle that mitigation outcomes should not overstate the mitigation achieved. It includes conservative quantification, avoiding double counting and, where relevant, managing reversal risk.

Baseline

The reference scenario describing what emissions would have been without the activity. Reductions are measured against it, so a baseline set too high generates credits that do not reflect real mitigation.

Additionality

The test of whether the mitigation would have happened anyway. An activity that was going ahead regardless is not additional, and crediting it inflates the global emissions budget.

Leakage

Emissions displaced outside an activity's boundary as a result of the activity. One example is logging shifting to a neighbouring forest. Unaccounted leakage overstates the net reduction.

Removals

Activities that take greenhouse gases out of the atmosphere and store them, rather than avoiding or reducing an emission. They raise distinct questions about measurement, permanence and reversal risk. Under Article 6.4, they are governed by the removals standard.

Permanence and reversal

Whether stored carbon stays stored. A fire, harvest or policy change can reverse a removal and release carbon that has already been credited. Removals therefore require monitoring and risk management well beyond issuance.

Emission avoidance

A contested term for preventing emissions from a source that does not yet exist, sometimes also used for conserving carbon stocks. Parties have not consistently defined its scope or eligibility under Article 6.4.

Safeguards

The environmental and social requirements an activity must meet, including consultation with affected communities and respect for the rights of Indigenous Peoples and local communities.

Grievance mechanism

The Article 6.4 process through which people affected by an activity can raise concerns and seek redress (see the procedure). The CDM had no equivalent process.

Confidentiality

The provision allowing Parties to designate some Article 6.2 information as confidential. Technical reviewers can access it on a need-to-know basis, but it is not made public. How widely this is used affects independent scrutiny.