What is Article 6.4 of the Paris Agreement?

Since its adoption in 2015, the Paris Agreement has become the global standard for international cooperation on climate change. One of the major negotiations within the framework has been focused on Article 6.4 – a new international carbon market mechanism intended to help countries accelerate their climate action and finance to developing countries.

To operationalize Article 6.4, the UNFCCC created the Paris Agreement Crediting Mechanism, whose key rules were adopted at COP29 in Baku in 2024.

Read on to learn what is Article 6.4 of the Paris Agreement, how does it work, and what is the role of validation and verification under the framework.

Article 6 of the Paris Agreement sets out how countries can pursue voluntary cooperation to reach their climate targets. It enables international cooperation to tackle climate change and unlock financial support for developing countries.

Article 6.4 creates a new UNFCCC-operated international carbon market known as the Paris Agreement Crediting Mechanism (PACM). Under Article 6.4, countries are able to transfer carbon credits from the reduction or removal of greenhouse gas emissions to help one or more countries meet their climate targets (known as Nationally Determined Contributions, NDCs). The PACM is a market-based instrument that countries can voluntarily use to complement their climate strategies.

The PACM replaces the Clean Development Mechanism (CDM), which was created under the Kyoto Protocol. The UNFCCC estimates that the PACM can reduce the costs of implementing NDCs by $250 billion, expecting a substantial growth to the size of existing voluntary carbon markets.

The PACM credits are called Article 6.4 Emission Reductions (A6.4ERs). They can be created with both emission reductions and carbon removals. Project host countries can choose to count the credits toward their own NDCs, or transfer them to the buying country. In the former case, the credits are accounted as mitigation contribution A6.4ERs. On the other hand, if the buyer country accounts for the A6.4ERs toward its NDC, the host country needs to apply “corresponding adjustments” to avoid double counting the emission reductions and removals. As all signatory countries have NDCs under the Paris Agreement, host countries need to make sure that they can still meet their own targets even when transferring A6.4ERs to another country.

The PACM is governed by the Article 6.4 Supervisory Body, which makes decisions regarding guidance, procedures, approving methodologies, registering projects, and issuing credits. Methodologies may be created by project owners, host countries and other stakeholders, in addition to being created by the Supervisory Body.

As with the voluntary carbon market, the PACM mandates projects to be validated and verified by independent third-parties, known under the framework as Designated Operational Entities (DOEs). This ensures the credibility and reliability of emission reductions and removals carried out under the framework. The first group of DOEs, including SustainCERT, have been accredited in 2025.

DOEs play two important roles:

• Validating and seeking registration for new activities or renewing existing ones under the Article 6.4 mechanism;
• Verifying and certifying emissions reductions of registered activities.

The Supervisory Body is still working to establish some rules under PACM before projects start to issue credits. The first methodologies for Article 6.4 carbon projects are expected in the fall of 2025, with eligible credits from the CDM transitioned to PACM. Entirely new methodologies developed for PACM will follow in 2026.

As an accredited DOE under Article 6.4, SustainCERT is authorized to provide validation and verification activities for projects under the framework. For further details or to discuss your project, please get in touch.