The distinction between voluntary carbon market (VCM) credits and Article 6 credits under the Paris Agreement is becoming increasingly relevant as scrutiny on credit quality intensifies. While Article 6 introduces UN-backed governance, accounting, and methodological rigor, credit integrity ultimately remains a project-level issue. As frameworks converge, the boundary between voluntary and compliance markets is likely to narrow.
Article 6 of the Paris Agreement was established as a UN-negotiated market mechanism designed to facilitate international cooperation on climate mitigation. Its core objective is to enable developed countries, equipped with financial resources and technological capacity, to support emissions reduction projects in developing countries. In return, the resulting emissions reductions can be counted toward the investing country’s decarbonization targets, while host countries benefit from finance, technology transfer, and sustainable development outcomes.
In parallel, the voluntary carbon market (VCM) has evolved as a decentralized ecosystem where carbon credits are issued under independent standards. The most widely used standards include Verra’s Verified Carbon Standard (VCS), Gold Standard, the American Carbon Registry (ACR), and the Climate Action Reserve (CAR), alongside legacy credits from the Clean Development Mechanism (CDM) established under the Kyoto Protocol. These credits are generated across a wide range of project types, including REDD+ (avoided deforestation), afforestation, reforestation and revegetation (ARR), clean cookstoves, and renewable energy, among others.
In recent years, particularly since 2023, the integrity of certain VCM credits has come under increasing scrutiny. Concerns have focused on whether credits genuinely represent one ton of CO2 reduced or removed from the atmosphere on a durable basis. Key issues include additionality (whether the emissions reduction would have occurred without carbon finance) and permanence (whether carbon remains stored over the long term).
Beyond carbon accounting, scrutiny has also extended to broader environmental and social impacts, including unintended consequences for local communities and native biodiversity. Commercial afforestation projects are often cited as a typical example: financial additionality may be weak due to expected timber revenues, carbon storage may be temporary rather than permanent, and land-use change can negatively affect local ecosystems.
In response, a range of initiatives has emerged to strengthen integrity in carbon markets by identifying shortcomings and establishing clearer principles and guidance. Frameworks such as the Core Carbon Principles (CCPs), the Science Based Targets initiative (SBTi), the Voluntary Carbon Market Integrity Initiative (VCMI), and the Oxford Offsetting Principles aim to guide both supply and demand toward higher-quality outcomes.
Within this broader push for integrity, Article 6 plays a central role. It comprises two main components: Article 6.2, a decentralized framework enabling countries or authorized entities to exchange Internationally Transferred Mitigation Outcomes (ITMOs), and Article 6.4, also known as the Paris Agreement Crediting Mechanism (PACM). The latter is a centralized mechanism under the UNFCCC that establishes methodologies and standards for generating carbon credits. These credits can either be authorized for international transfer as ITMOs or issued as Article 6.4 Emission Reductions for mitigation contribution purposes (often referred to as MCUs), which resemble traditional VCM credits but benefit from UN oversight.
VCM credits are not inherently inferior to Article 6 credits; quality ultimately depends on the specific project and methodology. However, the UNFCCC framework provides an additional layer of institutional credibility that the VCM has, at times, struggled to maintain. For credits intended for use toward national climate targets (NDCs) or compliance schemes such as CORSIA, Article 6 introduces robust accounting rules based on corresponding adjustments, ensuring environmental integrity and avoiding double counting, as explained on a previous blog.
Furthermore, methodologies developed under the PACM are expected to adopt more conservative baseline assumptions. This was illustrated in February 2026 with the first issuance of PACM credits from a clean cookstove project in Myanmar, where the volume of credits issued was approximately 40% lower than it would have been under the CDM. This outcome signals a more stringent and conservative approach to crediting under the Paris Agreement framework.
Voluntary carbon credits cannot be categorized as inherently “good” or “bad”; their quality depends heavily on the underlying methodology and the project developer’s approach, whether prioritizing financial returns or maximizing climate, social, and biodiversity co-benefits.
That said, credits generated under Article 6, whether through the PACM or bilateral cooperation under Article 6.2, are expected to demonstrate higher average integrity due to the backing of the UNFCCC, standardized methodologies, and internationally coordinated accounting systems.
Looking ahead, the distinction between voluntary and internationally regulated carbon markets is likely to become increasingly blurred. This trend is already evident as traditional VCM standards begin issuing credits eligible for use in compliance frameworks such as CORSIA, Singapore’s carbon tax, and many other national schemes. Similarly, the use of internationally transferred credits with corresponding adjustments may play a role in meeting future decarbonization targets, including those under the European Union for 2040.
If you want to go deeper on the Article 6 landscape, we've just published our latest policy report, The Article 6 Market: Scale, Value and Pipeline, covering everything from the host party authorization gap to PACM pipeline dynamics and what it all means for buyers, developers and governments.
You can access the report here.