Structuring the International Carbon Market: The Article 6.2 and 6.4 Mechanisms Explained

On November 13, 2021, negotiators at the COP26 summit in Glasgow finalized the rulebook for Article 6 of the Paris Agreement, establishing the structural framework for a global carbon market. The decision ended six years of deadlock over how countries could trade greenhouse gas emission reductions to meet their national targets.[1]

The framework divides the international carbon trade into two distinct tracks. Article 6.2 governs bilateral agreements between sovereign states, allowing one country to overachieve its climate target and sell the excess to another. Article 6.4 creates a centralized, multilateral market accessible to both public and private entities, replacing the Kyoto Protocol's Clean Development Mechanism.[2][4]

The primary function of both mechanisms is to lower the global cost of reducing emissions by directing capital to where mitigation is cheapest. The World Bank estimates that trading under Article 6 could reduce the total cost of implementing national climate plans by $250 billion per year by 2030.[2]

Under Article 6.2, countries trade Internationally Transferred Mitigation Outcomes (ITMOs). When a seller country transfers an ITMO, it must apply a corresponding adjustment to its own greenhouse gas inventory, adding the sold emissions back to its ledger to ensure the buyer country is the only entity claiming the reduction.[3]

This accounting mechanism is designed to eliminate double-counting, a structural flaw that plagued earlier carbon markets. "A host Party shall apply a corresponding adjustment for all internationally transferred mitigation outcomes," mandates the UNFCCC rulebook adopted at Glasgow.[1]

The bilateral nature of Article 6.2 allows countries to set their own terms, provided they meet the United Nations Framework Convention on Climate Change (UNFCCC) reporting requirements. In July 2025, Ghana and a European buyer executed an Africa-first carbon offset deal under this framework, trading credits generated by distributing clean cookstoves to rural communities.[6]

The Ghana transaction demonstrated how Article 6.2 can function in practice. The project reduced reliance on wood fuel, generating verifiable emissions reductions that the European buyer purchased to meet its own compliance obligations, while Ghana received direct foreign investment.[6]

In contrast, Article 6.4 operates as a centralized hub overseen by a UN-appointed Supervisory Body. This mechanism allows project developers—such as a renewable energy company building a wind farm—to generate credits that can be bought by countries, corporations, or individuals.

The Article 6.4 rules mandate that a mandatory 5% share of proceeds from all traded credits be transferred to the Adaptation Fund, which finances climate resilience projects in developing nations.[1]

Additionally, the 6.4 mechanism requires a 2% cancellation of all generated credits. This Overall Mitigation in Global Emissions (OMGE) rule ensures that the market does not merely shift emissions from one ledger to another, but actively reduces the total volume of greenhouse gases in the atmosphere.[3]

The transition from the Kyoto Protocol to the Paris Agreement framework involved significant compromises regarding older carbon credits. Negotiators agreed to allow credits generated under the Clean Development Mechanism between 2013 and 2020 to be used toward first-generation national climate targets, a concession that introduced millions of older credits into the new system.[5]

Chatham House analysts warned that this influx of legacy credits could dilute the environmental integrity of the new market. Because these older projects are already operating, buying their credits does not necessarily finance new emissions reductions.[5]

Corporate buyers face distinct rules when interacting with the Article 6.4 market. If a company purchases a credit to claim carbon neutrality, the host country must authorize the transfer and apply a corresponding adjustment. If the host country does not authorize the transfer, the credit can only be used for domestic corporate claims, not international offsetting.[4]

The distinction between authorized and unauthorized credits creates a two-tiered market. Authorized credits, backed by sovereign accounting adjustments, command a premium price due to their compliance-grade status, while unauthorized credits serve the voluntary corporate market.[4]

Enforcement relies entirely on transparency and peer review. The UNFCCC does not possess a policing mechanism to punish countries that fail to apply corresponding adjustments; instead, it relies on a centralized registry and an expert review process to flag accounting discrepancies.[1]

The operationalization of these markets shifts the focus from negotiation to implementation. The volume of capital moving through these mechanisms will depend on the stringency of the methodologies approved by the Supervisory Body and the willingness of buyer nations to pay a premium for highly verified reductions.

As the Factlen Editorial Team notes in its synthesis of the framework, the success of Article 6 depends on whether its accounting rules can withstand the financial incentives for both buyers and sellers to overstate the climate impact of their trades.[7]

The next phase of market development requires the Supervisory Body to finalize the specific methodologies for carbon removal projects, including direct air capture and afforestation. Until those technical standards are published, the Article 6.4 mechanism remains a framework waiting for its operational code.