As the voluntary carbon market matures, the integrity of individual project types is under increasing scrutiny, and biochar is no exception. This framework sets out Residual's approach to evaluating ARR carbon credit quality across five primary considerations (Additionality, Carbon Accounting, Permanence, Environmental and Social Safeguards, and Delivery Risk) and two secondary ones (Co-Benefits and Scalability). Rather than a points-based scorecard, it is a qualitative tool designed to surface the questions that matter most before projects are mature and credits are issued. Whether you are a buyer, investor, or developer, this framework offers a principled lens for understanding where biochar credit quality is made or lost.
Afforestation, reforestation, and revegetation (ARR) carbon credit quality, like any project type in the voluntary carbon market, is assessed across two dimensions: the credibility of the tonnes claimed, and the broader strategic value of supporting the project. Residual organises the first into five main considerations (Additionality, Carbon Accounting, Permanence, Environmental and Social Safeguards, and Delivery Risk) and the second into two secondary considerations (Co-Benefits and Scalability). The relevant details within each consideration and its subsections vary by project type, and this framework outlines Residual's focus when evaluating and designing ARR projects specifically.
The five main considerations assess whether the carbon credit represents a credible, durable, and responsibly delivered climate claim. Additionality asks whether the project and land-use pathway would have occurred without carbon finance. Carbon Accounting assesses whether the quantification of removals is complete, conservative, and supported by a defensible baseline-to-project comparison, including leakage, project emissions, and MRV integrity. Permanence evaluates whether the carbon stored in trees and soil is likely to remain out of the atmosphere over the claimed durability period, based on species selection, site conditions, and risk management. Environmental and Social Safeguards assess whether the removal is delivered without material environmental or social harm, including biodiversity degradation, water competition, or adverse impacts on Indigenous Peoples and local communities. Delivery Risk evaluates whether the project can realistically be financed, planted, operated, and monitored at the volumes committed.
Residual also considers two secondary considerations: Co-Benefits and Scalability. These do not determine whether a credit removes the tonnes of carbon dioxide equivalent claimed, but they shape the broader value of supporting a project. Co-benefits can strengthen the project narrative and increase its relevance to buyers, communities, and other stakeholders, while scalability can create future access to larger credit volumes, potential cost efficiencies, and a credible role for investors in helping scale high-quality carbon removal.
This framework covers the major voluntary carbon standards applicable to ARR - Verra VCS (and its VM0047 methodology), Gold Standard, Plan Vivo, and ACR - and applies primarily at the ex-ante stage, where many of the most important questions about project quality can already be assessed if the right evidence is available. This is particularly relevant to Residual, as we co-design and implement projects from early stages rather than assessing mature projects that are already issuing credits. The framework is also intended to help buyers, investors, and project developers identify where quality risks typically arise, what evidence should be requested, and how ARR projects can be designed to meet a higher standard of carbon credit integrity.
The framework serves three roles simultaneously. As a first-pass filter, it surfaces projects missing defensible substantiation on any pillar before deeper diligence begins. As a diligence tool, it gives the assessor a consistent structure for each dimension: the questions to ask and the features that indicate quality. As a public benchmark, it is an articulation of what we believe is required of high-quality ARR credits, against which project developers can hold their own work. The framework is qualitative by design. It is not a points-based scorecard and does not resolve into a composite score; integrity is assessed by whether the evidence on each pillar stands up to informed scrutiny.
Mathematical relationships used to estimate tree biomass (and hence carbon content) from measurable variables such as diameter at breast height (DBH), height, and wood density. Locally validated equations are preferred; pantropical defaults (e.g., Chave et al. 2014) are acceptable where local equations are unavailable.
A pool of non-tradeable carbon credits set aside to compensate for unforeseen reversals. Under Verra VCS, this is a centralised Pooled Buffer Account; under Gold Standard and ACR, it is a project-level reserve. Typical ARR buffer contributions range from 10–25% of issued credits.
The window over which a project can issue carbon credits, typically 20–30 years for ARR projects, renewable once or twice depending on the applicable standard.
A standard forestry measurement taken at 1.3 m above ground. DBH is the primary input variable for most allometric equations used to estimate aboveground biomass.
A key feature of Verra's VM0047 methodology. Rather than a static historical baseline, the PB is derived ex-post from matched control plots in the same landscape at each verification event. The project earns credits only for carbon accumulation that exceeds what the control plots achieved, integrating additionality and baseline-setting into a single dynamic step.
A principle drawn from international human rights law (ILO Convention 169, UNDRIP) requiring that Indigenous Peoples and local communities give documented, voluntary, and informed consent before a project proceeds on or near their territories. FPIC is a mandatory requirement under all major voluntary carbon standards where IPLCs are present.
A term used across the voluntary carbon market to refer collectively to groups with customary or legal relationships to project land. IPLC rights — including land tenure, consent, and benefit-sharing — are a central safeguard requirement in all major ARR methodologies.
The processes by which a project tracks its emissions and removals (monitoring), documents them (reporting), and has them independently checked (verification). MRV integrity is central to whether a credit can be trusted.
Fixed, GPS-registered plots within the project area that are remeasured at each monitoring event to track changes in carbon stocks over time. PSPs are the primary ground-truthing tool for carbon stock measurement and remote sensing calibration.
The organic carbon stored in mineral soils and litter. SOC changes can be significant in ARR projects converting degraded grassland to forest, but are associated with high measurement uncertainty (±30–50% by IPCC standards) and are frequently omitted from project accounting unless material.
A remote sensing-derived metric used in Verra's VM0047 area-based approach as a proxy for aboveground biomass. The SI is generated by vetted Data Service Providers (DSPs) from satellite imagery and is correlated to AGB through field-based calibration.
A 1-to-9 scale describing the maturity of a technology. Most ARR activities rely on well-established silvicultural practices (TRL 8–9), though novel agroforestry designs or remote sensing monitoring methods may sit at lower TRL levels.
Verra's Methodology for Afforestation, Reforestation, and Revegetation, version 1.1. VM0047 is the dominant voluntary methodology for ARR globally and the first ARR methodology to receive ICVCM Core Carbon Principles (CCP) approval. It offers two quantification approaches: an area-based approach using a remote sensing-derived Stocking Index and Dynamic Performance Benchmark, and a census-based approach for dispersed or non-forest planting contexts.
An accredited third-party auditor that independently reviews a project's design (validation) and performance (verification) against the applicable methodology. VVB capacity is a practical bottleneck in the ARR market; validation queues of 12–24 months are common.
Additionality is the foundational claim of any carbon project: that the carbon removal from the project activity would not have occurred in the absence of carbon finance. For ARR projects, this claim operates across three dimensions. Financial additionality establishes that the project economics depend on carbon revenue rather than on revenue from harvesting or forest products. Regulatory additionality establishes that the restoration activity is not legally mandated. Alternative scenario analysis demonstrates that the chosen land-use pathway is preferable to realistic counterfactuals. Together, these three dimensions constitute the additionality argument. The table below considers the aspects of additionality and the details required to prove integrity.
Financial additionality risk in ARR projects is primarily associated with the possibility that the land-use change would have occurred under existing incentives without the intervention of carbon revenue. In many geographies, government reforestation programmes, timber market conditions, or non-timber forest product revenues can make tree-planting financially attractive without carbon finance. The main uncertainty, therefore, lies in whether carbon finance is truly decisive in overcoming the project's capital costs - particularly site preparation, seedling production, and aftercare - or whether it merely improves returns for an activity that would have proceeded regardless. This risk is typically highest where government reforestation subsidies are substantial, where timber revenues are significant, or where the project is integrated into an existing commercial forestry operation. In contrast, projects in regions with weak existing incentives for forest cover, thin timber markets, and high upfront establishment costs are generally more likely to depend on carbon finance as a genuine enabling condition.
Regulatory additionality in the ARR sector is primarily affected by whether the planting activity goes beyond existing legal obligations or government-mandated reforestation programs. Risk arises where land clearing permits require revegetation, where watershed protection laws mandate riparian buffer restoration, or where reforestation is prescribed as part of environmental impact mitigation for an adjacent development. The central assessment is whether carbon finance supports a genuinely voluntary action that exceeds baseline legal requirements, rather than simply monetizing an activity already mandated by the jurisdiction.
Alternative scenario analysis in the ARR sector depends on whether the project has considered plausible, locally relevant counterfactual land uses and provided credible evidence for rejecting them. The main risk is that an alternative pathway like natural regeneration, low-intensity pasture, or continued degraded grassland would have delivered some carbon removal without the project, reducing net additionality. Where natural regeneration is a plausible baseline, the project must demonstrate either that natural regeneration would not have occurred (due to seed source absence, invasive species, grazing pressure) or that the project significantly accelerates the rate and scale of carbon accumulation relative to the counterfactual. Dynamic baselines mitigate these risks by accounting for alternative scenarios implicitly.
Carbon accounting assesses the integrity of the quantification and measurement system that underpins every credit a project issues. A project can have a strong additionality case and deliver genuine climate benefit but still issue low-quality credits if its monitoring, quantification, and verification systems are weak. The table below considers the aspects of carbon accounting and the details required to prove integrity.
MRV integrity depends on whether the project has a complete, consistent, and reproducible system for tracking carbon stocks across the full project area and over time. Three risks recur in ARR projects: system boundaries defined inconsistently across documentation; omitted material emission sources, including land preparation emissions, nursery operations, and non-CO2 gases from burning; and monitoring procedures too weak to support the claimed credit volumes. High-integrity MRV practice therefore includes a clearly documented monitoring plan, permanent sample plots that meet statistical power requirements, use of validated allometric equations, and where relevant, a remote sensing approach tied to a vetted DSP. The monitoring plan should cover all carbon pools, define data gap treatment, and specify QA/QC procedures that an independent reviewer can follow. Where measurement uncertainty exceeds the methodology's threshold, a conservative uncertainty deduction should be applied so that credited volumes are not overstated.
Leakage risk is primarily associated with the possibility that displacing pre-project land uses causes emissions to shift outside the project boundary. Activity-shifting leakage arises where smallholders, livestock herders, or charcoal producers are displaced from the project area and continue their activities elsewhere. Market leakage arises where timber or biomass products from the project substitute for supply from other sources, affecting harvesting pressure in adjacent forests. Ecological leakage can arise where over-extraction of existing vegetation for site preparation alters surrounding biomass dynamics or nutrient flows. Leakage assessment in this sector therefore depends on identifying plausible offsite effects, quantifying them conservatively where material, and applying appropriate deductions so that credited removals are not overstated.
Baseline and project scenario risk is primarily associated with whether the credited comparison is built on a realistic, evidence-based counterfactual and a complete accounting of project emissions. The baseline should reflect current practice in the project region, supported by documentary evidence. For VM0047 area-based projects, the quality of the Dynamic Performance Benchmark depends critically on the quality of matched control plot selection; if control plots are systematically different from project plots in soil type, water access, or management history, the PB may understate the counterfactual and inflate credits. On the project side, risk arises where direct or indirect emissions are omitted — particularly from land preparation activities such as burning, mechanical clearing, or drainage modification — or where allometric equations are applied outside their validated size class or species range.
In the ARR sector, permanence risk is primarily associated with three uncertainties: whether the established trees will survive and grow over the full crediting period given climate change projections; whether the land will remain under forest management against economic, political, and social pressures; and whether the project's monitoring system is robust enough to detect and account for reversals when they occur. ARR projects face a category of permanence risk absent from engineered removal approaches; biological and climatic forces operate over the entire crediting period and cannot be managed out of the system. This makes species selection, site-climate matching, diversification of planting design, and the quality of the buffer pool mechanism particularly critical.
Biological and climate risk is a unique challenge for ARR compared to other carbon removal approaches. Unlike engineered removals, trees are living systems subject to fire, drought, pest outbreaks, and the ongoing effects of climate change, none of which can be fully engineered out. Risk is lowest where planting designs are species-diverse and use climate-adapted native species; where fire management plans are in place and enforced; where the project is in a climate zone that is expected to remain suitable for the target species across the crediting period; and where the monitoring system can detect mortality events quickly. Risk is highest for large-scale monocultures of exotic species in climate zones facing increasing drought or fire probability, or in regions with a history of pest or disease outbreaks in the same species.
Human and political risk is the second major permanence challenge for ARR projects. Unlike biological risk, which is managed primarily through planting design and monitoring, political and tenure risk is managed primarily through legal documentation, community relationships, and financial instruments. Projects in jurisdictions with strong rule of law, secure property rights, and stable government policy have materially lower political permanence risk than those in fragile or conflict-affected states. Community benefit-sharing is not only a social safeguard requirement but also a permanence tool — communities with a direct economic stake in the standing forest have a demonstrated track record of defending it against encroachment and clearing pressure.
Reversal detection depends on whether the project's monitoring system is frequent and spatially comprehensive enough to identify and quantify carbon losses between verification events. Annual remote sensing change detection, supplemented by community monitoring is best practice. Projects should demonstrate that their buffer contributions — typically calibrated using the applicable non-permanence risk tool, whether a shared buffer pool or a form of insurance — are conservative relative to the risk profile, and that the monitoring system is designed to detect reversals at the scale that would exhaust the buffer.
The Environmental and Social Safeguards assessment covers the environmental and social context within which the carbon removal activity takes place. A project can have strong carbon accounting and a credible additionality case but still carry material risks through its environmental footprint, community relationships, and non-carbon outcomes. This section does not assess carbon quality directly, but it does assess the conditions that determine whether a project is sustainable, insurable, and attractive to the range of buyers who increasingly evaluate carbon credits on a wider set of criteria than additionality and permanence alone. The table below considers the aspects of non-GHG performance and the details required to prove integrity.
Environmental performance depends on whether the project can demonstrate that planting design, site preparation, and long-term management do not create material harm to biodiversity, water, or soil. Risk arises where monocultures of exotic species replace biodiverse grasslands or shrublands; where fast-growing plantations in water-limited catchments reduce dry-season streamflow; where deep tillage or burning for site preparation causes soil erosion or SOC loss; or where invasive species introduced via planted seedlings escape into adjacent natural ecosystems. A further concern arises where the project lacks a biodiversity monitoring plan capable of detecting harmful impacts after planting. Environmental performance assessment in this sector therefore depends on thorough pre-project assessment, appropriate species selection and planting design, and a long-term monitoring plan that tracks non-carbon environmental outcomes alongside carbon stocks.
Social performance depends on whether the project identifies affected stakeholders early, engages them through a structured and accessible process, respects IPLC land and tenure rights, protects worker health and safety, and shares benefits fairly with the communities connected to the project land. Risk arises where consultation is limited or poorly documented; where FPIC processes are procedurally compliant but substantively inadequate; where community members are displaced from land they depended on; where grievance mechanisms are inaccessible or unresponsive; or where economic benefits are captured mainly by commercial investors rather than shared with local workers, smallholders, or nearby communities. Social performance assessment in this sector therefore depends on credible, documented FPIC, appropriate labour and safety protections, and a clear benefits framework that demonstrates the project is socially responsible as well as operationally viable.
This section assesses whether the project has the foundations to do what it says it will do over the crediting period: issue credits, establish and maintain forest cover, and sustain operations. A project that cannot secure its land tenure, establish its nursery supply chain, or attract the financial backing it needs is at high risk of not delivering at all, making it a low-quality ex-ante credit.
Ex-ante financial viability risk in ARR projects is primarily associated with whether the project proponent has the financial standing, delivery track record, and committed backing needed to reach first verification and sustain operations through the crediting period. ARR projects have a distinctive cash flow profile: high upfront establishment costs - site preparation, seedling production, planting, and aftercare in years one to three - with carbon revenues deferred until first verification, typically three to five years after planting. Risk is lower where capital expenditure and initial operating costs are covered by credible committed finance, where backers have relevant experience, and where the proponent can show a track record of bringing comparable projects to verification. Revenue visibility also matters: forward offtake agreements and commercial arrangements for agroforestry products can materially reduce price and delivery risk.
Seedling supply and security is analogous to feedstock security in engineered removal projects, and is a significant operational risk in large-scale ARR programmes. Risk arises where nursery capacity is insufficient, where seed provenance is poorly documented (reducing survival and growth rates), where planting windows are missed due to seedling production delays, or where a single species monoculture approach creates catastrophic supply chain vulnerability if that species faces outbreak, drought mortality, or regulatory restriction. Best practice involves multiple nursery sources, locally adapted seed provenance, contingency gap-filling budgets, and planting designs that diversify across multiple species and stocking densities to buffer against supply disruption.
Operational capacity assesses whether the project team has the species expertise, equipment, and management capability to establish and maintain forest cover at forecast throughput over the crediting period. ARR at commercial scale is operationally demanding: site preparation quality directly affects survival rates, weed competition management in years one to three is critical to achieving stocking targets, and PSP remeasurement requires trained and quality-controlled field teams. Sensible operational conservatism in planting survival assumptions, combined with a credible aftercare and gap-filling strategy, is the mark of a well-prepared project.
Secondary considerations assess features of a carbon project that sit outside the core question of credit integrity but still matter to buyers, investors, and other market participants. Whereas the primary quality pillars determine whether a credit credibly represents a real tonne of CO2 removed, secondary considerations examine whether supporting the project creates wider strategic value. This includes the extent to which the project delivers meaningful environmental or social co-benefits beyond its greenhouse gas impact, and whether it has the potential to scale in a way that increases climate impact, lowers delivery costs, or improves market accessibility over time. These factors do not by themselves make a low-integrity credit high quality, but they can strengthen the overall attractiveness of a high-integrity project by showing that it offers broader positive impact and longer-term growth potential.
ARR projects have particularly strong co-benefit potential compared to most other carbon removal approaches, because forest restoration delivers a well-established package of ecosystem services alongside carbon sequestration. The most important co-benefits including biodiversity habitat, watershed protection, soil health improvement, and rural livelihoods, are strongly correlated with the design decisions that also improve permanence: native species planting, multi-strata designs, IPLC benefit-sharing, and active community stewardship. Projects that invest in co-benefit documentation and certification (CCBS, Gold Standard SDG Impact Statements, Plan Vivo) command market premiums that reflect the genuine additional value these outcomes deliver.
Scalability assesses whether supporting an ARR carbon project is likely to help expand the future supply of high-quality credits, reduce their cost, or both. ARR is one of the most land-abundant removal pathways globally, with estimates of 1–2 billion hectares of degraded land potentially suitable for restoration. However, high-quality land that is ecologically appropriate, tenure-secure, non-food-competing, and accessible to community benefit-sharing is significantly scarcer than gross area estimates suggest. A highly scalable ARR project is therefore one where capital today contributes not only to current credit delivery but also to developing the nursery capacity, community relationships, monitoring infrastructure, and silvicultural knowledge base that enables future projects to be deployed more efficiently and at lower cost.
