What is Article 6?
Article 6 of the Paris Agreement establishes the rules for international carbon market cooperation between countries. It replaced the Kyoto Protocol’s Clean Development Mechanism with a two-track system: Article 6.2, which governs bilateral government-to-government trading of Internationally Transferred Mitigation Outcomes (ITMOs); and Article 6.4, which establishes the Paris Agreement Crediting Mechanism (PACM), a centralised, UN-supervised mechanism for crediting emission reductions and removals from project activities.
The stakes for forests are significant. In 2019, agriculture, forestry, and other land use accounted for 22 percent of total net anthropogenic greenhouse gas emissions; which is more than either global transport or buildings, and is second only to energy supply (IPCC AR6). Natural climate solution pathways could provide around 37 percent of the cost-effective mitigation needed by 2030 to hold warming below 2°C, at a cost of under $100 per tonne (Griscom et al., 2017). Article 6 is the framework that should make that potential financeable at compliance-market scale. Whether it does depends almost entirely on how the rules on removal activities, particularly permanence, get operationalised.
Of the two main market mechanisms, Article 6.2 is the flexible bilateral route: it allows direct trades between two countries and is less prescriptive, faster to market, and where most trading currently happens, though quality concerns are rising. Article 6.4 is more rigorous and centralised, it intends to issue the highest-integrity compliance-grade credits. The tension for forests is that 6.4’s draft permanence rules may be unworkable for nature-based projects, pushing developers toward 6.2 and risking a two-tier market.
Open as full pageITMOs, corresponding adjustments, and what they mean in practice
When a country sells an ITMO, whether under 6.2 or 6.4, it applies a corresponding adjustment: it adds those emissions back to its own national inventory, so the reduction counts once, for the buyer. This is the mechanism that prevents double counting at the international level.
For forest projects, corresponding adjustments create a structural question about who holds what. A forest carbon project hosted in a country with a nationally determined contribution (NDC) that covers the land sector means the host country’s NDC absorbs the emissions. Selling ITMOs from that sector requires the host to correspondingly adjust, that is, giving up the credit toward its own climate targets. Countries with ambitious NDCs have limited appetite to do this, which constrains supply. Countries with less ambitious NDCs may have more headroom, but face reputational and political pressures of their own. The mechanics of how ITMOs interact with NDC ambition cycles is one of the less-discussed constraints on forest carbon supply under Article 6.
The Paris Agreement Crediting Mechanism (PACM) was operationalised at COP30 in Belém, but methodology progress has been slow: as of mid-2026 just one methodology is approved (landfill-gas flaring) and no nature-based methodology exists. CDM afforestation/reforestation transition has largely stalled on host-country sign-off. Existing voluntary methodologies like Verra’s VM0047 could also serve as viable near-term bridges, but would need to be submitted for review.
Open as full pageThe 6.4 permanence standard sets a 100-year monitoring commitment, with the “negligible risk” threshold still unresolved. Critics warn the proposed thresholds are functionally unachievable for biological systems, and stacking project-by-project remediation on top of buffer pools risks a de facto exclusion of nature. The fix belian backs: assess risk at project level, manage remediation at portfolio level, which is the logic of the ICVCM Permanence Trust.
Open as full pageREDD and large-scale crediting: the pathway under development
Reduced Emissions from Avoided Deforestation and Degradation (REDD+) has no clear home in Article 6.4 as currently structured. A concept note on large-scale crediting is under development, and jurisdictional REDD (JREDD) is expected to fit within that framework, likely initially through Programmes of Activities architecture. REDD faces the additional complication of how to treat ‘downward adjustment’ of baselines, which requires a different crediting logic than afforestation and reforestation. Dynamic baselines may help bring REDD into the mechanism, though they are more straightforward to implement for afforestation and reforestation. International leakage, where protecting one forest displaces deforestation elsewhere, must also be addressed explicitly in any REDD methodology under 6.4. A number of hurdles remain before a clear pathway for jurisdictional REDD emerges in 6.4.
The rules governing forests under Article 6.4 were not designed to exclude them. But the effect is the same. A 100-year monitoring commitment, an unattainable negligible-risk threshold no forest can meet, project-by-project remediation requirements still to be fully specified: this is not a framework anyone can finance against today.
The flexibility provisions built into the adopted standard are useful, containing multiple exit pathways, methodology-set monitoring periods, and potential for trust-based liability transfer. The question is whether the implementation tools will honour that flexibility or progressively constrain it.
On methodology, the immediate priority is transition, which requires finalising the afforestation and reforestation methodology assessment. But this will only matter if the permanence framework is workable enough for developers to proceed.
Belian’s work on independent reference area selection and dynamic baselines will provide exactly what these methodologies need for high quality implementation. The integrity of any afforestation and reforestation or REDD methodology under 6.4 depends on the quality of the counterfactual: what would have happened without the project. Getting that right, at the level of rigour that compliance markets now require, is the foundational technical problem. It is also the one that has been consistently the most contentious.
Related reading
Where the belian.earth team has written on the questions this page raises.
Who's Afraid of the Big, Bad Forest?
by Chloé Naomi Swickard
Permanence has been a sticking point for Nature-Based Solutions since the Kyoto debates. The ICVCM Permanence Trust may finally unlock long-term durability. Even then, the deeper question of how nature gets financed will remain.
Read articlePolicyPermanence
Permanence is the question of whether the carbon a forest project stores will still be stored when the world needs it to be. Buffer pools, the Non-Permanence Risk Assessment, the ICVCM Permanence Trust, and the live debate over what counts as durable.
Read moreOpinionVM0047's brave call is your ARR project's defining moment
by belian.earth
VM0047 locks the developer's matched reference areas at validation and keeps them fixed for the full crediting period. That single choice defines your ARR project's baseline for decades.
Read articleStay in the loop
Stay up to date with developments in independent reference area selection and carbon market baselining.