Logged to Protected Forest

This Module provides the requirements and procedures for the calculation of net carbon dioxide equivalent (CO₂e) removal from the atmosphere through improved forest management (IFM) practices that protect forests from planned logging operations. This Module addresses scenarios where forests with active timber concessions or legal harvest allocations would undergo logging under baseline conditions but are instead maintained as intact, protected forests under the Project.

Commercial timber harvest encompasses a range of silvicultural systems employed globally to extract merchantable wood products from forests. Harvest practices include selective logging, clear-cutting, keyhole rotation, shelterwood systems, seed tree systems, group selection, and various hybrid approaches adapted to site-specific conditions, market demands, and regulatory frameworks^{1, 2}.

While timber harvest systems vary substantially in their ecological outcomes, all forms of commercial harvest result in short-term carbon stock reductions relative to undisturbed forest conditions. Clear-cutting operations remove nearly all aboveground biomass from harvest areas, creating temporary non-forest conditions before regeneration³ on rotation cycles of 25-120 years⁴. Selective logging, while it maintains continuous forest cover through rotation cycles⁵, generates carbon emissions through direct extraction of merchantable timber, collateral damage to residual stands^6,7, the establishment of forestry infrastructure (e.g., roads, skid trails, landing areas), and altered forest structure that impacts the regeneration dynamics and future carbon accumulation rates of the forest^8,9. Shelterwood and seed tree systems cumulatively remove the majority of original stand biomass while managing for specific regeneration outcomes¹⁰, often requiring additional maintenance which increases GHG emissions^10,11.

Forest protection from commercial timber harvest — regardless of the specific silvicultural practice(s) employed — delivers multiple climate, community, and ecological benefits. Protected forests maintain their capacity for continued carbon sequestration and storage, maintain soil carbon pools otherwise degraded by harvest operations, and sustain the forest structural integrity and biodiversity that enhance ecosystem resilience to climate change^12,3,8,9. Research demonstrates that forest-based natural climate solutions can provide over two-thirds of the 11.3 gigatons CO₂e per year of cost-effective mitigation needed by 2030 to stabilize warming below 2°C, with forest conservation and improved management representing pathways with additional co-benefits^13,14.

However, forest protection projects have traditionally faced substantial methodological challenges in credibly quantifying carbon benefits. Legacy standards and methodologies have relied on static baselines of projected harvest schedules over multi-decadal time periods, introducing considerable uncertainty around harvest timing and intensity, operational efficiency, and collateral impacts. These uncertainties have led to systematic concerns about baseline accuracy and over-crediting in past improved forest management carbon projects^15,16.

This Module addresses these methodological challenges by taking a scientifically rigorous approach that combines legal and operational validation of baseline harvest scenarios with a dynamic baseline approach that compares project forests to similar reference forests within the same region undergoing commercial timber harvest operations, accounting for variations in forest type, forest structure, species composition, operational accessibility, regulatory environment, economic context, management history, and site conditions. The Module employs advanced remote sensing technology, including LiDAR-enhanced forest inventories, to monitor carbon accumulation with high precision across The Project while maintaining rigorous standards for measurement, reporting, and verification. This Module thus ensures accurate quantification of additional carbon benefits and reduced field-based verification costs while easing the technical burden on Project Proponents through continuous change detection owned jointly by Isometric and The Project Proponent.

To ensure high ecological fidelity, project crediting durations are established based on the expected maturity of the specific forest types, with a required ongoing monitoring period to ensure meaningful carbon storage duration.

This Module accounts for the quantification of the gross amount of CO₂e removed via enhanced carbon storage in forest biomass, as well as all cradle-to-grave life-cycle Greenhouse Gas (GHG) emissions associated with the implementation process. This Module is developed to adhere to the requirements of ISO 14064-2: 2019 – Greenhouse Gasses – Part 2: Specification with guidance at the Project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements.

The Module ensures:

• Consistent, accurate procedures are used to measure and monitor forest carbon accumulation through standardized methodologies appropriate for commercial-scale implementation;

• All net CO₂e removal claims are verified through robust field work and/or LiDAR-enhanced monitoring systems and third-party validation;

• Forest management practices maintain ecological integrity through conservation measures;

• Removals are additional through the use of dynamic assessments of the counterfactual that account for regional management practices and other guardrails set forth in the Isometric Standard;

• Comprehensive leakage accounting through Global Timber Model implementation addresses both activity-shifting and market-mediated leakage with a minimum 10% deduction;

• Comprehensive risk management through buffer pools and optional insurance mechanisms protects against potential reversals while ensuring transparent Credit delivery;

• Economic viability for landowners through guaranteed revenue sharing and appropriate contract terms; and

• Technology-enabled monitoring reduces transaction costs while maintaining high standards for carbon accounting and environmental integrity.

Throughout this Module, the use of "must" indicates a requirement, whereas "should" indicates a recommendation.

This Module relies on and is intended to be compliant with the following standards and protocols:

• The Isometric Standard

• Improved Forest Management v1.0, Isometric

• ISO 14064-2: 2019 - Greenhouse Gases - Part 2: Specification with guidance at the project level for quantification, monitoring, and reporting of greenhouse gas emission reductions or removal enhancements

Additional reference standards that inform the requirements and overall practices incorporated in this Module include:

• ISO 14064-3: 2019 - Greenhouse Gases - Part 3: Specification with Guidance for the verification and validation of greenhouse gas statements

• ISO 14040: 2006 - Environmental Management - Lifecycle Assessment - Principles & Framework

• ISO 14044: 2006 - Environmental Management - Lifecycle Assessment - Requirements & Guidelines

Additional principles that were considered in the development of this Module and aligned with, where feasible, include:

• The Core Carbon Principles of The Integrity Council for the Voluntary Carbon Market, v1.1, ICVCM, 2024

• Criteria for High-Quality Carbon Dioxide Removal, Carbon Direct & Microsoft, 2025

This Module was developed based on the current state of the art, publicly available science regarding IFM activities and long-term monitoring of forest carbon projects. This Module aims to be scientifically stringent and robust. We recognize that some requirements may exceed the status quo in the market and that there are numerous opportunities to improve the rigor of this Module as new approaches and techniques enter the Voluntary Carbon Market.

Additionally, this Module will be reviewed when there is an update to published scientific literature, government policies, or legal requirements which would affect net CO₂e removal quantification or the monitoring guidelines outlined in this Module, or at a minimum of every 2 years.

In addition to the requirements outlined in Section 4 of the Improved Forest Management Protocol, Projects are subject to the following applicability requirements, which must be demonstrated in the Project Design Document (PDD).

In order to maintain ecological integrity and ecosystem function, demonstrate additionality, and ensure trust and transparency, it is incumbent upon Projects to adhere to the requirements below, which must be demonstrated and reported in the Project Design Document.

To ensure accurate carbon sequestration claims and facilitate Validation and Verification, Projects registered under this Module must register a singular or grouped Site(s) — sets of parcels subject to similar bioclimatic, regulatory, and geographic conditions.

• For grouping multiple Sites under one Project, all Sites must be within the same RESOLVE Biome and country.

• Sites must consist of enrolled land parcels — discrete commercially-harvestable stands.

• Contiguous parcels and/or parcels on the same harvest rotation within 10-kilometers of each other should be grouped into a single Site. Discontinuous parcels beyond 10-kilometers and/or those on different harvest rotations must be enrolled as separate Sites.

• Each Site — and every constituent parcel — within a Project must independently meet all applicable eligibility criteria within this Module, which must be evidenced in the PDD.

• Carbon quantification will be calculated at the Site level (see Section 9).

The Project Proponent(s) must adhere to the following additional requirements for parcel and Site enrollment:

• All Sites must be greater than 10 hectares.

• All parcels must have road or navigable waterway access.

  • Exceptions to this rule apply under extenuating circumstances — such as the presence of an easement or prior commercial harvest history — and can only be claimed after consultation with Isometric, and must be justified in the Project Design Document.

To ensure the credibility of the climate impact of project activities, non-additional areas of The Project must be excluded, as set out by various requirements in Section 4.1 of the Improved Forest Management Protocol and Section 4.1.2 of this Module.

It is vital to the integrity of The Project that no other areas within each parcel may be excluded from project activities. Project Proponents must enroll all eligible areas of a parcel. This requirement prevents the selective enrollment of areas that are less desirable for harvest. Land can only be excluded for reasons stated within this Module or the Improved Forest Management Protocol, and these excluded areas must be documented and mapped within the PDD in accordance with and to fulfill the cumulative impact assessment requirements of the IFM Protocol (see Section 4.1.2) — with sufficient justification of the legal, financial, or operational restrictions on harvest.

Project activities must demonstrate additionality by accounting for Site-specific constraints that limit harvesting feasibility under baseline conditions. If ecological and Site conditions would render harvesting unlikely under baseline conditions, these areas within the Project Boundary cannot be claimed as additional and must be excluded from the Project Boundary. Soil saturation, permanent water bodies, slope gradients, and proximity to dwellings and other structures create natural and regulatory limitations on harvesting activities that must be evaluated when determining eligible project areas.

Project Proponents must identify and exclude from Crediting (see Section 4.1.1.1) any areas within the Project Boundary where economic, physical or regulatory constraints make harvesting highly unlikely under baseline management scenarios based on the guidance and requirements below.

Historically, harvesting operations in waterlogged soils occurred primarily during periods of prolonged freezing temperatures, which provided ground stability for heavy timber equipment. Climate change has reduced the predictability and duration of these freezing periods, particularly in temperate and polar regions, making winter harvesting increasingly unreliable. Consequently, harvest avoidance in these soil types does not constitute additional management activity beyond what would occur under baseline conditions.

Project Proponents must identify and exclude from Crediting any areas within the Project Boundary with soils classified as "very poorly drained" or "inundated" according to the U.S. Soil Taxonomy classification system, or similarly classified soils in equivalent authoritative sources if a Project occurs outside of the United States of America.

• Exceptions to this rule can be made if the Project Proponent demonstrates all requirements in Section 4.1.2.1.1.

Project Proponents may include areas with soils classified as "very poorly drained" or "inundated" within the Project Boundary where evidence demonstrates that baseline harvesting operations remain economically viable despite soil drainage limitations.

Areas with waterlogged soils may be included when the Project Proponent demonstrates:

• Baseline harvesting activities in the region commonly occur during predictable seasonal windows when soil conditions permit equipment access, as evidenced by regional timber market data, harvesting permits, or forestry operation records covering a minimum of the prior 10 years;

• Specialized harvesting equipment or techniques (such as winter harvesting, low ground-pressure machinery, or helicopter logging) are established practice in the region for similar soil conditions, demonstrated through equipment rental availability, contractor specialization, or documented use in comparable forest stands; and

• The proposed IFM activities constitute a measurable departure from baseline management that would otherwise occur despite drainage constraints.

To include these areas, The Project must also demonstrate additionality of these waterlogged soils through financial analysis showing that baseline harvesting remains economically feasible despite drainage-related operational constraints, and that the carbon revenue represents a necessary incentive for the proposed management changes.

Project Proponents must identify and exclude from the Project any areas within the Project Boundary that fall within management buffers around permanent water bodies as defined by applicable governmental regulations or voluntary Best Management Practices, i.e., BMPs (see Appendix B of the Improved Forest Management Protocol).

• Project Proponents must provide documentation of applicable governmental regulations and BMPs governing management buffers around water bodies, along with mapping of permanent water bodies and associated buffer zones within the Project Boundary.

Project Proponents must provide evidence of common harvesting practices and equipment availability within the relevant wood basket to demonstrate whether steep-slope operations are feasible under baseline management scenarios. Changes in carbon stocks in areas that are too steep to reasonably harvest would not be considered Additional.

• Project Proponents must include a spatially-explicit topographic analysis of slope gradients within the Project Boundary.

• Project Proponents must include a regional assessment of harvesting capabilities on steep terrain, collated from industry, government, or NGO reports and/or scientific literature.

• Project Proponents must document the selection of the relevant wood basket.

  • Project Proponents should ascertain the relevant wood basket by: (1) examining scientific literature; (2) evaluating governmental, regulatory, NGO, and industry databases; and/or (3) identifying the regional catchment of the timber product(s) of their harvests. In the absence of this information, Project Proponents should generate wood baskets as the Thiessen polygons of mills which intersect with the project boundary.

• Project Proponents must exclude from crediting calculations areas with sustained slopes exceeding 30% over 30 meters in regions where specialized steep-slope harvesting equipment is not commonly deployed¹⁷.

  • The U.S. Forest Service has found that harvest equipment encounters significant limitations on slopes of 25% to 35%, with severe constraints on slopes exceeding 35%¹⁸. Areas with sustained slopes above these thresholds represent natural barriers to conventional harvesting operations.

Regulations or BMPs may prohibit harvesting within a certain proximity of built structures.

Project Proponents must exclude from crediting calculations any areas within 15 meters of permanent structures, or within larger buffers if required by applicable regulations or BMPs (see Appendix B of the Improved Forest Management Protocol).

• Project Proponents must document any applicable governmental or BMP buffer requirements which would prohibit harvesting around dwellings and structures.

• Project Proponents must include a spatially-explicit vector-based map of all permanent structures within and adjacent to the Project Boundary.

Project Proponents must demonstrate that each Site contains sufficient merchantable stocking in a market where harvests would be economically viable in the baseline scenario. This merchantable stocking determination will establish which areas of The Project contain timber that would be economically attractive for harvest under common practice, thereby demonstrating the additionality achieved through placing the forest into protection.

Project Proponents must exclude all areas from the Project which do not meet the requirements in Sections 4.1.2.5.1 and 4.1.2.5.2.

For each Site, the Project Proponent(s) must demonstrate economic viability through a Site-specific financial analysis accounting for all revenues and costs associated with timber harvest operations under baseline management scenarios.

• Site-level financial analysis should include gross timber revenues calculated using: (a) stumpage values taken from regional market pricing and/or forest-type pricing from Isometric's implementation of the Global Timber Model (GTM); and (b) merchantable volumes by, if feasible, product class at the time of enrollment into The Project.

• Project Proponents should include — to best approximation — cost enumeration taken from Isometric's implementation of the GTM (Section 8.2or developed from estimates of: (a) logging and processing; (b) access infrastructure; (c) transportation from the parcel to a processing facility; (d) equipment mobilization; (e) post-harvest obligations; (f) administrative and regulatory costs; and (g) property carrying costs during harvest operations.

• Project Proponents must apply discount rates appropriate to landowner classification accordingly:

  • Commercial Orientation (6%)

  • Smallholder - Commercial Orientation (5%)

  • Smallholder - Subsistence/Mixed Objectives (4.5%)

  • Community Forest (4%)

  • Indigenous Land(s) (3%) The selected rate will be assigned by Isometric upon parcel enrollment based on documented ownership characteristics, management objectives, and regional economic conditions — with higher rates indicative of greater commercial orientation.

• For each Site, the Project Proponent must report the: (a) merchantable volumes, ideally by species and product class; (b) revenue calculations with price sources and dates and/or revenue estimates generated by Isometric's implementation of the GTM (Section 8.2); (c) complete cost enumeration with supporting data and/or cost estimates generated by Isometric's implementation of the GTM; (d) NPV or IRR worksheets showing discount rate application; and (e) sensitivity analysis demonstrating impacts of ±20% parameter variations on viability.

• A Site shall be classified as economically viable for harvest in the baseline scenario if:

  • The Net Present Value (NPV) is greater than zero at the applicable discount rate, or

  • The Internal Rate of Return (IRR) is greater than or equal to the minimum acceptable rate for the ownership class and net stumpage value ≥ 0.

• Sites which fail to meet one of these thresholds must be excluded from The Project.

• Economic viability must be re-evaluated at re-enrollment of the Site(s). When triggered, the Project Proponent must update economic parameters, recalculate parcel viability, and adjust classifications as warranted. This re-evaluation is prospective, with changes affecting current and future baseline projections without retroactive adjustment to historical Credit issuance.

In addition to Site-level economic analysis, Project Proponents must evaluate whether sufficient regional market capacity exists to absorb timber volumes from enrolled Sites under baseline harvest scenarios.

• For each Site classified as economically viable, the Project Proponent must identify and/or confirm:

  • All processing sites (e.g., sawmills, pulp mills, biomass facilities, and specialty processors) within economic hauling distance; and

  • The road and/or waterway distance from the parcel to each facility, with maximum hauling distances established by regional standards.

• For each Site classified as economically viable, the Project Proponent should identify and/or confirm:

  • The current annual processing capacity by product type within the identified scope, using mill surveys, published reports, or direct facility operator communication; and

  • That facilities accept the Site’s species composition and actively procure these species for timber products; or, for roundwood products,

  • The economic viability and costs associated with roundwood export, the anticipated market for roundwood export, and the historic export pricing and transportation costs of roundwood.

• The Project Proponent must assess whether aggregate baseline harvest volumes from all economically viable project Sites would exceed regional processing capacity by:

  • Summing the projected annual harvest volumes across all project Sites within the applicable region; and

  • Comparing aggregate volumes by product class to total facility capacity within economic hauling distance; or for roundwood,

  • Summing the projected annual harvest volumes across all enrolled parcels within the applicable region; and

  • Comparing aggregate roundwood volumes to average regional export levels.

• Project Proponents must account for existing non-Project timber supply as part of this analysis.

• Where appropriate, Project Proponents may consider temporal market dynamics to justify the additionality of the Project, such as:

  • Historical timber price trends for species over the previous 5-10 years to ascertain any significant fluctuations;

  • Processing facilities that have opened, closed, or changed capacity in the past five years and likelihood of similar changes during the Crediting Period; and

  • Whether competing timber supply sources may affect market capacity or pricing.

• Where significant market changes are documented or reasonably anticipated, the Project Proponent should adjust merchantability classifications or apply appropriate discount factors to baseline projections.

• When market capacity is exceeded by The Project, Project Proponents must remove some Site(s) until the aggregate baseline harvest volumes from all economically viable project Sites is less than the regional processing capacity.

• Market capacity determinations must be re-evaluated upon re-enrollment of the Site(s). During re-evaluation, the Project Proponent must update market capacity assessments, recalculate regional absorption capacity, and adjust Site merchantability classifications as warranted. This re-evaluation is prospective, with changes affecting current and future baseline projections without retroactive adjustment to historical Credit issuance.

In order to prevent manipulation of the dynamic baseline and ensure additionality, it is incumbent upon Projects to demonstrate that harvest intensity by the Project Proponent and/or prior landowner did not increase above historical rates after consideration of enrollment into a carbon project (under Isometric or another Standard).

Projects must demonstrate for each Site that carbon stocks at the most recent harvest have not differed from historical averages.

• For each Site, Projects must identify all known harvest events. Acceptable forms of evidence include:

  • Commercial harvest records (e.g. Cut and Sold reports)

  • Using remote sensing data indicative of historical disturbance history (e.g., Hansen Global Forest Change Product)

• For each harvest event, Projects must provide an estimate of the total biomass removed. Acceptable forms of evidence include:

  • Commercial harvest records (e.g. Cut and Sold reports)

  • Forest growth curves calculated using peer-reviewed data and methods such as national or sub-national forest inventory plots, chronosequence sampling, and/or regionally-calibrated growth and yield models (e.g., FVS, ORGANON)

    • Project Proponents must provide the data and code used to generate the growth curve(s), along with justification for the selected approach (e.g. FVS, Chapman-Richards, etc.)

Any Sites where the total biomass removed during the most recent harvest event was greater than the historical average by more than one standard deviation are ineligible for inclusion in this Module.

Isometric reserves the right to audit submitted harvest data via earth observation remote sensing systems, and compare these results against the submitted harvest claims.

As the purpose of this Module is to transition commercially logged forests into mature forests which store carbon, it is vital that Projects ensure the sequestration of carbon through means of enforceable protection. The term “protection” constitutes different meanings across different countries and regulatory landscapes. For the purposes of this Module, the IUCN definition of a protected area is used:

“A clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values”.¹⁹

Projects must demonstrate an intent to protect the project area.

If formal agreements to place the project area into protection by the end of the Crediting Period are not in place at Validation, Project Proponents must describe in their PDD how they intend to protect the forest after Crediting. At each Verification without a formal agreement in place, Project Proponents must contribute an additional 5% to the buffer pool (see IFM Protocol Section 10).

Governance of protected areas may be private, governmental, and/or by indigenous peoples and local communities. Examples of what is considered an eligible protected area include but are not limited to:

• Wildlife management areas

• Forest reserves

• Conservation easements

• Community conservancies

To avoid potential conflicts of regulatory additionality, formal protection must not begin until the end of the Crediting Period (see IFM Protocol Section 7.7.2).

In the transition from historical logging to forest protection, the planting of new trees cannot be the primary method to achieve forest cover. Project Proponents must limit new planting only to facilitate regeneration of healthier stands through planting of understory species²⁰, fill in gaps in existing patches of degraded forests, and/or to regenerate small areas — less than 1 hectare — of otherwise forested land.

• The Project Proponent must disclose this planting, as well as the justification for it, within the PDD for initial Validation and follow all biodiversity requirements as set forth in the IFM Protocol (see IFM Protocol Section 6.4).

• Any new planting after Validation must be reported to Isometric before the next verification event.

The timeline for Projects crediting under this Module is described by a Project Commitment Period. The Project Commitment Period encompasses two distinct periods, the Crediting Period plus a minimum 40-year Ongoing Monitoring Period which commences after the end of the Crediting Period.

For grouped Projects or Projects where there is a mixture of initial stand ages within the project area such that there is variation in the timing of individual Crediting Periods and Ongoing Monitoring Periods, the overall Project Commitment Period must reflect the collective start and end dates for all areas within The Project (i.e., the start of the first Crediting Period through the end of the last Ongoing Monitoring Period).

The length of the Crediting Period under this Module must reflect the anticipated time to forest maturity within the project area. The underlying data and/or modeling for these estimates must be provided in the PDD and demonstrate that they are informed by harvesting history/stand age, forest growth factors, and tree biology within the project area.

For project areas where there is a mixture of initial stand ages (e.g., as a result of staggered harvesting history), this may result in distinct Crediting Period durations across the project area. In this scenario, the PDD must report how the project area will be divided into areas with distinct Crediting Periods and provide evidence for the length for each individual area.

The Project must then set the overall Crediting Period length for The Project to the maximum of these Site-specific Crediting Periods.

The Crediting Period consists of subsequent Reporting Periods (see IFM Protocol Section 5.2). Under the IFM Protocol, the minimum length of a Reporting Period is 1 year and the maximum length is 5 years. 

The Ongoing Monitoring Period commences at the end of the Crediting Period. The Ongoing Monitoring period must be a minimum of 40 years and a maximum of 100 years. The durability of Credits are determined by the duration of the Ongoing Monitoring Period. Throughout the Ongoing Monitoring Period, Isometric will conduct monitoring for Reversals. If a Reversal is detected, the Project Proponent is responsible for conducting Reversal Reporting (see IFM Protocol Section 10.5.2). Reversals during the Ongoing Monitoring Period are compensated by the Buffer Pool (see IFM Protocol Section 10.4). 

A project has a Project Commitment Period of 100 years composed of a 40 year Crediting Period followed by 60 year Ongoing Monitoring Period. Credits issued have a 60+ year durability. Monitoring for quantification is conducted by the Project Proponent through the Crediting Period, and the reported activities are verified by a Validation and Verification Body (VVB) for each Reporting Period. At the end of the Crediting Period, maintenance of carbon stocks and monitoring for Reversals occurs for the remaining 60 years of the Project Commitment Period.

Project Proponents must develop and report a forest management plan (FMP) for each Site.

• The FMP(s) should be developed in consultation with an expert forester

Additionally, certain forest management activities must also be disclosed by the Project Proponent, such as Stand Improvement Activities, subject to the requirements set forth by Isometric in this Module, the IFM Protocol (Section 6.5), and the Isometric Standard.

Project Proponents may engage in Isometric-approved stand-improving activities. These activities must be approved in consultation with Isometric to ensure that the volume of harvested wood does not exceed the volume of issued Credits.

The Project Proponent must disclose all planned stand-improvement activities in the Project Design Document prior to Validation and at each subsequent Verification, and must inform Isometric of any changes to these plans immediately and report these changes prior to the next Verification.

• Only stand-improvement activities defined by the USDA NRCS guidance are permitted.

• All stand-improvement activities must comply with applicable environmental and social safeguards set out in the IFM Protocol (seeIFM Protocol Section 6).

Credits will not be issued until the forest biomass within the Site recovers above the Site’s most recent pre-stand-improving-activity carbon stock baseline.

Project emissions associated with stand improvement activities must be reported according to the requirements in the IFM Protocol (see IFM Protocol Section 9.5).

Project Proponents must disclose all pre-existing forest management or traditional stewardship plans for any enrolled Site(s).

• Plans which expire during the Crediting Period but after Validation fulfill this requirement.

• For Indigenous landowners practicing traditional forest stewardship: Where principles of traditional land use are not documented in a formal plan, demonstration may include oral histories, cultural practices documentation, or traditional ecological knowledge (TEK) assessments that evidence ongoing forest engagement and resource use patterns informed by traditional practices.

These plans must specify likely or planned harvest(s), or traditional forest stewardship activity, during the Crediting Period.

Given the inherent economic nature of forest management activities, the impacts of The Project extend beyond landowner(s) to local economies. Giving these stakeholders early notice of planned changes in timber harvest enables market adaptation and prevents job losses in any local timber-based economy.

In addition to stakeholder engagement requirements specified in the IFM Protocol (see IFM Protocol Section 6.6.1) the Project Proponent must notify local authorities and loggers, mills, or other parties with existing formal or informal offtake agreements of the contracted change in harvest volume and/or schedule of timber upon enrollment into The Project.

• Project Proponents should also provide similar information to any and all requesting entities/individuals — e.g., municipal authorities, research groups, or reporters.

Given the relationship between forests and local communities, it can be anticipated that some logging activities provide direct benefits or subsidies to local communities. For the purposes of this Module, any local communities who had received direct benefits or subsidies from logging activity are defined as community beneficiaries.

• Project Proponents must disclose in the PDD any historical disbursement of direct benefits or subsidies to local communities from the timber operations now ceased by The Project.

  • Project Proponents must report disbursements for each identified community beneficiary.

In addition to the requirements set forth in the IFM Protocol (see IFM Protocol Section 6.6.2), the Project Proponent must disburse to community beneficiaries revenues generated from Credits issued to The Project, which match or exceed historical direct benefits or subsidies. Eligible forms of revenue sharing include:

• Direct payments

• Equipment and/or infrastructure

Projects with community beneficiaries must provide details of the systems which will be used for the disbursement of revenue and how the disbursement will be tracked (e.g., digital payment records, other documentation in absence of formal financial systems).

• These systems must include a mechanism for community beneficiaries to report any grievances or disputes related to revenue sharing, and for the tracking of the response and resolution of these issues.

• Any non-monetary, in-kind compensation must involve a transfer of ownership to community beneficiaries.

Revenue sharing percentages should also be made public, including percent revenue or Credits divided among each party (e.g., Project Proponent, community beneficiaries, insurance provider(s), and other documented parties listed in the PDD).

Project Proponents must provide an anticipated timeline of revenue sharing disbursement over the duration of each contract.

• At every Verification, Project Proponents must provide evidence demonstrating progress against this plan, including proof of revenue disbursement, and report any grievances raised by community beneficiaries, and the subsequent responses and resolution by the Project Proponents.

  • Projects which fail to report or provide sufficient evidence may be required to undergo an audit by an independent certified financial auditor.

  • If at any Verification the cumulative revenue disbursement has fallen >20% below the original projected level for that timepoint, the Project Proponent must submit an updated revenue disbursement plan and timeline to demonstrate how The Project will meet the revenue sharing requirement of this Module.

    • This new plan will be used for benchmarking at any future Verification(s).

In addition to the eligibility and applicability requirements set out in Section 4, Projects must meet the following requirements to ensure all claimed environmental impacts demonstrate the four pillars of additionality described in the Isometric Standard (Section 2.5.3).

In order to ensure additionality, Projects must demonstrate a pre-existing intent to harvest trees within the Project Boundary and prove a demonstrable history of commercial harvesting and/or traditional forest stewardship within enrolled Site(s). These requirements must be robustly evidenced by data of the following types:

• A written attestation that the Project Proponent or previous landowner(s) intended to harvest, would accept harvest offers, and/or conduct traditional stewardship activities during the Crediting Period.

• If applicable, this attestation must include reference to the pre-existing forest management plans disclosed in Section 6.1.2.

• Historical satellite imagery that clearly shows evidence of commercial harvesting and/or indicators of traditional forest stewardship activities during the Project Proponent’s and/or previous landowner’s tenure.

  • For traditional forest stewardship, indicators include, but are not limited to, patterns of selection harvesting for cultural or subsistence purposes, traditional fire management practices, or other sustainable use consistent with established Indigenous land management practices.

• This evidence should prioritize high-resolution historical imagery with clear sourcing information and acquisition dates. Preferred sources include: the USDA’s NAIP, the USGS's NHAP programs, and/or private data providers (e.g., Planet).

  • In cases where high-resolution imagery is unavailable, Sentinel-2 or Landsat imagery may be used as an alternative, which must be accompanied by spectral analysis showing patterns consistent with harvest activities and a detailed explanation for why high-resolution imagery could not be obtained.

The carbon pool within the scope of this Module is aboveground woody biomass, as this is the main additional carbon pool affected by converting logged areas to protected areas. Soil carbon is also conservatively excluded CO₂e_Stored,RP. Belowground biomass is also excluded as a conservative measure since evidence indicates that the removal of carbon through the growth of new belowground biomass does not exceed the degradation of pre-logged belowground biomass^{21, 22}. For the remainder of the Module, the use of AGB refers to only the living aboveground woody biomass, unless otherwise noted.

This Module requires Projects to account for leakage through the Global Timber Model (GTM), which captures both direct landowner behavioral responses (activity-shifting) and broader market-mediated effects (market leakage) within a unified economic modeling approach. This integration reflects the reality that in improved forest management, activity-shifting behaviors are often driven by the same market signals and economic incentives that drive broader market leakage in response to timber supply restrictions. In this Module, leakage is calculated for distinct species groups for each regional wood basket, which vary by geographic location and forest composition.

• Projects may elect to apply an alternative leakage deduction to calculate CO₂e_Leakage,RP provided that the Project Proponent meets all requirements in Section 8.3.

Recent scientific literature has highlighted significant challenges in accurately quantifying leakage from forest carbon projects. Studies by Badgley et al. (2021)²³, Haya et al. (2023)²⁴, and others have found systematic over-crediting in forest carbon offset programs, largely due to inadequate accounting for leakage impacts²⁵. This research indicates that traditional approaches to leakage assessment for forest carbon offset programs often underestimate both the magnitude and geographic scope of displacement effects.

The complexity of global timber markets means that reduced harvest in one location can trigger responses across multiple regions and through various economic pathways. Market-mediated leakage can occur through price signals that incentivize increased harvesting in distant locations, while activity-shifting often occurs through landowner responses that extend to other land owned by the Project Proponent or enrolled landowners, but not included in The Project.

This methodology adopts a modeling approach with a minimum 10% leakage deduction, using the Global Timber Model (GTM) to prevent well-documented over-crediting that has resulted from other improved forest management methodologies.

The Project Proponent or previous landowner(s) who own or manage forested land outside of the enrolled Site(s) of The Project are prohibited from altering forest management on these lands outside of regular harvests and stand improvement activities such as pre-commercial thinnings. The Project Proponent must provide an attestation that they will not alter forest management on this land outside of the enrolled Site(s) as a result of project activities.

• The Project Proponent or previously enrolled landowner(s) should provide documentation of their annual harvest volume(s) for all non-enrolled lands for every year that The Project issues Credits to Isometric prior to each Verification.

• Isometric reserves the right to audit future harvests on non-enrolled land(s), including via earth observation remote sensing systems, and compare these harvests against the submitted attestation.

The Global Timber Model (GTM) was conceptualized by Sohngen et al. (1999)²⁶, and it seeks to re-balance supply and demand in response to market shocks over decadal time periods for forest-type regions.

The GTM has been adopted for carbon projects through an update led by the University of Maine, in collaboration with The Nature Conservancy and the Global Forest Lab at The Ohio State University, as discussed in Daigneault et al. (2025)²⁷. This updated GTM estimates how forest carbon projects in aggregate change trade balances regionally and globally, as a result of both direct and indirect leakage.

Isometric will quantify the leakage deduction for each Reporting Period for Projects based on global runs of leakage rates (Equation 1) for the forest-type using the Global Timber Model (GTM), annualized and weighted by The Project’s basal area. As changes to timber harvest through project activities directly and indirectly impact the balance of supply and demand for decades, and the GTM initiates this predicted response within the same decadal time period as the start of the Crediting Period, the leakage deduction schedule for the percent deduction of a Reporting Period, L_project,RP, will be set at project initiation, and updated as needed by Isometric with the inclusion of any new site(s).

Further information on how Isometric implements the GTM and determines leakage is set forth in Appendix D, which contains additional information on the technical requirements of model implementation and the data sources used for modeling.

The average leakage rate, $LR$, for each forest type-region (see Appendix D3) in 10-year time periods is calculated as:

$$LR_{f,r,t} = \rho \left[ \frac{(PCS_{Project,f,r,t} - PCS_{Counterfactual,f,r,t}) - (GCS_{Project,f,r,t} - GCS_{Counterfactual,f,r,t})}{(PCS_{Project,f,r,t} - PCS_{Counterfactual,f,r,t})} \right]$$

(Equation 1)

Where:

• $LR_{f,r,t}$ is the average leakage rate per given decade in a forest type-region

• $PCS$ indicates the carbon stock within the Project Boundaries, in tonnes of C

• $GCS$ indicates global forest carbon stock, in tonnes of C

• $f$ is the forest type

• $r$ is the region

• $t$ is the time period (in decades)

• $⍴$ is the discount rate, set at 5%

The Project’s leakage for each Reporting Period, CO₂e_Leakage,RP is then calculated using the following equation:

$$L_{Project,t} = \frac{\sum B_{f,r,t} * LR_{f,r,t}}{B_{Project,t}}$$

(Equation 2)

Where:

• $L_{Project,t}$ is the project leakage for a given decade

• $LR_{f,r,t}$ is the average leakage rate per given decade in a forest type-region

• $B_{f,r,t}$ is the basal area in each forest type-region in the project area

• $B_{Project,t}$ is the basal area in the project area

• $f$ is the forest type

• $r$ is the region

• $t$ is the time period (in decades)

And, $B_{Project,t}$ must equal $B_{f,r,t}$

As the GTM outputs leakage estimates on decadal timesteps, Isometric will then annualize the project leakage, applying a linear interpolation between decadal estimates to derive the leakage deduction for each year within a decade:

$$L_{Project,RP} = L_{Project,0} + \frac{t}{10} \left( L_{10} - L_0 \right)$$

(Equation 3)

Where:

• $L_{Project,RP}$ is the project leakage rate for a given Reporting Period, RP

• $L_{Project,0}$ is the project leakage rate for the first year within a decadal time-step

• $L_0$ is the project leakage rate for the first year within a decadal time-step

• $L_{10}$ is the project leakage rate for the last year within a decadal time-step

• $t$ is the year into the decadal time step for the Reporting Period, $RP$

The final leakage deduction for each Reporting Period, CO₂e_Leakage,RP can then be calculated as a percentage of the sequestered carbon in a Reporting Period, CO₂e_Stored,RP (see Section 9.1).

$$CO_2e_{Leakage,RP} = L_{Project,RP} * CO_2e_{Stored,RP}$$

(Equation 4)

If the leakage rate, $L_{Project,RP}$, is <10%, the minimum annual leakage deduction of 10% will be applied by Isometric. When positive leakage is predicted by a negative leakage rate ($L_{Project,RP}$ < 0%), it will be subject to the minimum annual leakage deduction of 10%. Positive leakage indicates a model which predicts that restricting supply in the region could increase timber prices, and incentivize more considered forest management or land to be converted to forest.

Projects may elect to apply an alternative leakage deduction to calculate CO₂e_Leakage,RP provided that the Project Proponent demonstrates all of the following:

• The alternative CO₂e_Leakage,RP is more conservative than the GTM output in Section 8.2;

• The alternative approach is a supply-chain-specific analysis that quantifies leakage based on the actual wood products, supply chains, and substitution dynamics relevant to the project concession, as described in Section 8.3.1; and

• All activity-shifting monitoring and attestation requirements in Section 8.1.2 are independently satisfied, regardless of whether the alternative approach is applied.

Where a Project Proponent elects to apply an alternative leakage deduction, the assessment must meet all of the following requirements. The alternative approach does not replace the GTM calculation in Section 8.2, which must still be calculated and reported for each Reporting Period. The alternative deduction may only be applied where it yields a higher (more conservative) leakage deduction than the GTM output.

Project Proponents must develop and report in the PDD, for approval by Isometric and the VVB, an alternative approach assessment that demonstrates the following:

• The assessment must assume that 100% of the volume of wood products that would have been produced under the baseline scenario is displaced to international or domestic markets.

  • No reduction in demand or market absorption may be assumed.

• The assessment must identify the most probable supply of substitute wood product based on documented trade flows, regional supply chains, and species-specific product markets relevant to The Project’s historical output.

• The assessment must compare the carbon intensity — expressed as carbon stock per unit volume of wood product — between The Project’s merchantable species and operations, and those of the identified substitute supply.

• Where the substitute supply sources have lower carbon stock per unit volume than The Project, the leakage deduction must reflect the full substitution volume adjusted by the ratio of substitute to Project carbon intensity.

  • Where substitute sources have equal or higher carbon stock per unit volume, no reduction from the 100% displacement assumption is permitted.

The Project Proponent must provide the following for each Reporting Period in which the alternative deduction is applied:

• Concession-specific data on the species composition, wood density, and carbon content of the harvested wood products produced under baseline operations;

• Identification of the most probable substitute supply, supported by at least two of the following: (a) trade flow data or export/import records; (b) documented procurement relationships or offtake agreements; (c) published market analyses of the relevant wood product sector; or (d) industry or government reports on regional supply dynamics;

• Published or peer-reviewed data on the wood density and carbon content of the substitute species, with preference for region-specific values over global defaults; and

• A transparent model and calculation showing the derivation of the alternative leakage deduction from the above inputs.

  • All modeling must meet requirements in Section 9.5

The alternative leakage deduction applied for each Reporting Period must be the higher of:

• The leakage rate derived from the supply-chain assessment in this Section; or

• The leakage rate derived from the GTM implementation in Section 8.2.

If the supply-chain assessment yields a lower leakage deduction than the GTM for any Reporting Period, the GTM-derived deduction must be applied for that Reporting Period.

The minimum annual leakage deduction of 10% specified in Section 8.2 applies regardless of the method used.

The supply-chain assessment must be updated and resubmitted at each Verification. Updated assessments must incorporate any material changes to substitute supply markets, trade flows, or carbon intensity data that have occurred since the prior assessment. Where region-specific data for substitute species become available that were not available at the prior assessment, these must be incorporated.

Isometric reserves the right to require the Project Proponent to revert to the GTM-derived leakage deduction if the supply-chain assessment is found to rely on incomplete, outdated, or insufficiently conservative data.

Project Proponents applying an alternative leakage deduction must satisfy all attestation, documentation, and monitoring requirements for activity-shifting leakage in Section 8.1.2.

Under this Module, the difference in storage between the project scenario and the counterfactual scenario are assessed cumulatively over the course of The Project. For a given Reporting Period, the incremental change is assessed by via the difference between the total additional carbon storage at the end of the current Reporting Period and the same value at the end of the prior Reporting Period. As such, change in the net difference between the project and counterfactual storage over a Reporting Period is calculated as a net storage term (CO₂e_{net, storage,RP}):

$$CO_2e_{net,storage,RP} = CO_2e_{stored,RP} - CO_2e_{counterfactual,RP} = (CO_2e_{stored,total} - CO_2e_{counterfactual,total}) - CO_2e_{net,storage,RP-1}$$

(Equation 5)

Where:

• $CO_2e_{stored,total}$ is the total CO₂ removed from the atmosphere and stored as carbon in living trees at the end of the current Reporting Period, in tonnes of CO₂e

• $CO_2e_{counterfactual,total}$ is the total CO₂ removed from the atmosphere and stored as carbon in the counterfactual scenario at the end of the current Reporting Period, in tonnes of CO₂e

• $CO_2e_{net,storage,RP-1}$ is the net storage term for the prior Reporting Period, in tonnes of CO₂e; If this is the first Reporting Period this term is set to 0

This net storage for the Reporting Period can then be used for the difference between $CO_2e_{stored,RP}$ and $CO_2e_{counterfactual,RP}$ for the calculation of net removals using Equation 1 in the IFM Protocol.

Under this Module, the primary storage pool is aboveground woody biomass. In formerly logged areas, evidence indicates that the removal of carbon through the growth of new belowground biomass (BGB) does not exceed the degradation of pre-logged belowground biomass^{28, 29}. This indicates that there is limited net removal of carbon through belowground biomass and, as a conservative measure, Projects must set CO₂e_BGB to 0.

With this, the stored carbon in the project area at time t can be described by the following equation:

$$CO_2e_{stored}(t)=CO_2e_{AGB}(t)$$

(Equation 6)

Where:

• $CO_2e_{stored}$ is the total CO₂ removed from the atmosphere and stored as carbon in living trees at time $t$, in tonnes of CO₂e

• $CO_2e_{AGB}$ is the total carbon stored in living aboveground woody biomass (AGB) at time $t$, in tonnes of CO₂e

The total carbon stored in The Project up to the end of the current Reporting Period can be calculated as:

$$CO_2e_{stored,total} = CO_2e_{stored,t=RP} - CO_2e_{stored,t=0}$$

(Equation 7)

Where:

• $CO_2e_{stored,t=RP}$ and $CO_2e_{stored,t=0}$ are the total CO₂ removed from the atmosphere and stored as carbon in living trees at the end of the current Reporting Period and project initiation, respectively, in tonnes of CO₂e

Isometric encourages Project Proponents to quantify the total above-ground biomass, M_AGB, in the project area through one of the Capture & Conversion Modules listed in the IFM Protocol (see IFM Protocol Section 9.3.3).

• If either LiDAR or Earth Observation methods are selected, benchmarking these methods with field plots must occur, at minimum, every ten years following the procedures within the corresponding Module. This benchmarking may use field data from national or sub-national forest inventory plots, as long as it can be demonstrated that these plots are representative of the project area in species composition and range of biomass density, and the data are otherwise adherent to the requirements for the benchmarking procedure.

Alternatively, subject to meeting all the requirements set forth in Section 9.2.1, Projects may elect to quantify M_AGB through an alternative growth-disturbance model. Projects electing to use a growth-disturbance model must obtain approval from Isometric at Validation based on a comprehensive evaluation of the methodology in accordance with the requirements in Sections 9.2.1.1 and 9.5.

The total aboveground woody biomass at time t, M_AGB(t), can be derived via modeling of the change in biomass due to growth and disturbance (loss) since the most recent direct measurement of biomass within the project area (Figure 1). The model must be developed using national or sub-national forest inventory (NFI), or other publicly-available inventory (e.g., research, industry) plot data from the region, which may be derived from field plot measurements, LiDAR measurements, or some combination thereof. Hereafter these will be collectively referred to as NFI data for simplicity, but eligible datasets are broader as noted.

Figure 1. Visualization of growth-disturbance model for no-disturbance (left) and disturbance (right) scenarios. In the disturbance scenario, the biomass credited (green) is derived by imputing the loss from a disturbance event (grey) from the measured biomass.

To apply the model across the project area, the project area should be subdivided in a manner that corresponds to the NFI dataset which is being used for model development. For example, if rasterized NFI data are being used, the project area should be divided into pixels of equivalent or greater (up to 100%) size. If NFI field plots are being used, sampled field plots of equivalent size should be used within the project area as the basis for assessment.

Under this approach, The Project’s total aboveground woody biomass, M_AGB, at the current time point, t, can be calculated as:

$$M_{AGB,i}(t) = M_{AGB,i}(t_m) + \int_{t_m}^{t} G_i \, dt + \int_{t_m}^{t} D_i \, dt$$

(Equation 8)

Where:

• $M_{AGB,i}(t)$ is the total aboveground woody biomass at timepoint $t$ in project area sub-unit $i$ (e.g., pixel or plot), removed from the atmosphere and stored as carbon in living tree trees, in tonnes of C.

• $M_{AGB,i}(t_m)$ is the carbon stock of sub-unit $i$ at year $t_m$, where $t_m$ is the time of the most recent assessment of pixel-level carbon using field surveys or LiDAR (see Section 9.2.1.4)

• $t$ is the current year

• $G_i$ is the rate of carbon accumulation in sub-unit $i$, derived from the modeling approach, in tonnes C yr^-1

• $D_i$ is the rate of carbon loss associated with disturbance in sub-unit $i$, derived from the modeling approach, in tonnes C yr^-1

To determine the project-level aboveground biomass, the mean across the project area sub-units should be used:

$$M_{AGB}(t) = \frac{\sum_{i=1}^{n} M_{AGB,i}(t)}{n}$$

(Equation 9)

Where:

• $M_{AGB}(t)$ is the project-level mean total aboveground woody biomass at timepoint $t$ in tonnes of C

• $n$ is the total number of project area sub-units (e.g., pixels or plots) over which the model was applied.

To apply the growth-disturbance model described in Equation 8, Projects must meet all of the applicability requirements in Sections 9.2.1.2 and 9.2.1.3 for the respective model components.

Project Proponents must demonstrate that the growth-disturbance model development and performance meets the following requirements:

• Model performance must be assessed using out-of-sample data not involved in model training (e.g., using the model to predict biomass in NFI plots withheld from model development, and comparing modeled biomass to actual measured biomass in these plots).

• The validation dataset must cover a range of biomass values that encompasses those within the project area, be from the same ecoregion, be at least 30% the size of the project area dataset, and include a disturbance magnitude.frequency which is relevant for the project area.

• Based on assessment against the validation dataset, the model must achieve a minimum R² of 0.6.

• The characterized model uncertainty impacts on overall Removal estimates must be propagated in accordance with the Isometric Standard (see Section 2.5.7).

Growth in the project area can be assessed through the development of models which estimate growth based on observed growth measured in NFI data for similar areas.

Project Proponents must meet all of the following requirements for the development and application of such growth model(s):

• The model(s) must be developed using NFI plots with repeat measurements spanning at most 10 years;

• Sub-area i must be matched to the three most similar NFI plots using k-nearest neighbors and compared to the average growth rate of these matched plots; and,

• Current sub-area growth in i must be matched to a historical NFI or publicly available inventory plot, with plot re-measurement occurring over a period of time equal to or greater than the number of imputation years.

If using NFI data with spatially disjoint sub-plots, Project Proponents should aggregate these sub-plots according to the guidance and design of the NFI dataset.

Absolute change is then imputed on an annual basis for each sub-area plot based on the matches, and those annualized growth estimates are added to the latest direct measurement-derived estimate of the pixel (Equation 8).

Disturbance models may be used to estimate forest carbon loss stocks since the last field survey or LiDAR acquisition. Disturbance models both detect the occurrence of a loss within the project area, and estimate the carbon stock changes associated with the loss. The loss model is developed based on relevant observations of post-disturbance biomass change from NFI data or other publicly available datasets.

Project Proponents must meet all of the following requirements for model development and performance to use any disturbance model(s):

• The model(s) must directly forecast absolute or relative decreases in carbon stock following a disturbance;

• The model(s) must be parameterized with NFI data or repeat LiDAR acquisitions which capture a sufficiently large sample of disturbance events;

• The model(s) must have a minimum recall of 0.85 for detecting disturbances within the harvested class; and

• The model(s) must be able to detect partial harvests equivalent to ≤ 30% removal of carbon stocks.

Project Proponents are encouraged to leverage commercial high-resolution imagery, spaceborne multi-spectral imagery (e.g., Sentinel-2), and/or synthetic-aperture radar (SAR - e.g., ALOS or NISAR) in the development of their disturbance model(s).

In the event of a disturbance, the corresponding carbon stock must then be subtracted from the sub-unit biomass and sub-unit plot matches must be remapped for subsequent years (Equation 8).

At the start of the Crediting Period, and at a minimum frequency of every 10 years thereafter throughout the Crediting Period, the Project Proponent will collect field-based or LiDAR-derived estimates of carbon stock across the project area to establish M_AGB,i(t_m). Further, if the modelled losses over the entire project area are greater than 60% of the modeled growth over the entire project area for a given Reporting Period, direct measurements must be made for that Reporting Period. Project Proponents must quantify this carbon stock through one of the following two approved Capture & Conversion Modules:

The following section outlines the workflow that Isometric will take for the calculation of CO₂e_{counterfactual,RP} via a dynamic baseline approach; the Project Proponent is not responsible for carrying out the steps in this section. Project Proponents may suggest areas that could constitute suitable control pixels or features for matching based on their expert knowledge of their unique system. However, the ultimate determination of control pixels will be done by Isometric following the procedure and criteria below.

At Validation, the control plot zone must meet the following eligibility criteria:

• Located in the same country and ecoregion as the project area;

• Does not lie within protected areas, or within other carbon projects;

• Be subject to commercial harvesting activities;

• Be subject to the same relevant regulations, government incentives, and programs as the project area; and

• Biomass, e.g., carbon stock values and productivity values must be within 10% of those of the project plots.

Where possible, other features should also be matched between the control plot zone and project area to the best extent possible following the matching procedure in Section 9.3.3. Examples, and potential data sources, are presented in Table 1.

Table 1. Potential variables and data sources for informing the matching procedure between project and control areas.

Initially, the zone for eligible control plots should be limited to the same state or province, or a 100 km band around the project area — whichever is smaller. However, if suitable matches (see Section 9.3.3) are not found in this zone, additional step-outs in 10 km increments may occur to find appropriate control plots, assuming they meet the criteria above. The final area determined for suitable control plots is hereafter referred to as the Donor Zone.

If after, including geographic expansion of the boundary up, the Donor Zone is less than ten times the size of the project area, the donor pool may be further expanded by using the Time for Space Substitution procedure described in Section 9.3.1.1.

In some scenarios, constraining the zone for eligible control pixels based on the criteria above may severely limit the size of the Donor Zone. Although further control pixels can be selected by expanding the potential Donor Zone area in 10-kilometer increments, doing so may only marginally increase the area of the Donor Zone or improve the performance benchmark accuracy.

Environmental criteria such as bioclimatic variables, productivity, and biogeography used for control pixel matching tend to exhibit spatial autocorrelation — especially in areas of high topographic relief. Therefore, control pixels selected even short distances from the project area can have fundamentally different ecological conditions that can lead to biased control pixel selection and forest carbon stocks and/or proxies. Land use history can similarly constrain the Donor Zone. To ensure accurate matching, the Donor Zone should account for legacy effects—such as prior management regimes, levels of degradation, and priority effects—that influence long-term carbon storage capacity. However, controlling for land use history does further limit eligible Donor Zone pixels due to the asynchronous timing of land-use changes across the landscape. In any given year, areas with similar land use may vary in the time elapsed since active management (e.g., harvesting, cultivation, grazing, or disturbance), potentially biasing control pixel selection and forest carbon stocks and/or proxies.

One consequence of a small Donor Zone is small control pixel sample sizes, which can reduce performance benchmark accuracy through sampling bias. If the eligible Donor Zone after masking for the initial set of variables (see Section 9.3.1) is less than five times the size of the project area, Isometric may temporally expand the pool of potential control pixels using a time-for-space substitution (TFSS) sampling strategy. TFSS relaxes the requirement to match the Donor Zone and project area from identical calendar years, thereby expanding the n-dimensional area available for valid control pixel selection. Instead of aligning control pixel and project forest carbon stocks and/or proxies by the same calendar year, TFSS compares changes in forest carbon stocks and/or proxies relative to the time elapsed since pre-project conditions, enabling more robust estimates of additionality.

In this approach, historical data for control pixels can be matched to current data for the Project. The same criteria as listed above must apply across the time points (i.e., current regulations which apply to the Project must have also been applicable at the historical time point for the control pixel). If TFSS is required based on the initial Donor Zone size, Isometric will include the justification for the approach as well as the specific methodological approach and data included in the TFSS in its documentation of the baseline procedure.

When the TFSS is used, the temporal range considered for eligible control pixels will be expanded in 5-year increments, up to 15 years maximum. In addition to the features and criteria above, eligibility for the use of time substituted control pixels also includes:

• Historical data must be collected using the same methodology and be of equivalent quality and resolution as current data, ensuring consistent data fidelity across all years included;

• Datasets must be temporally harmonized to ensure that observed trends reflect actual changes in vegetation dynamics rather than inconsistencies in data sources or collection methods;

• Climate conditions must be similar between historical and current time windows; and,

• There must be no meaningful differences in the occurrence of disturbance events.

  • Sampling must avoid years with atypical socioeconomic or ecological conditions (e.g., government-mandated harvesting or severe droughts) within the TFSS temporal window that could introduce biased sampling or artificially inflate estimates of additionality by suppressing control pixel growth.

When temporal substitution is used for control pixels, their eligibility will be re-evaluated at each Reporting Period according to the guidance set out in Section 9.3.4.

Once the boundaries of the Donor Zone are determined, Isometric will generate high-resolution (≤30 m) pixel maps representing forest carbon stocks or a suitable proxy for forest carbon stocks. These layers must cover the entire project area and Donor Zone at the same resolution for at least five historical time points relative to the start of The Project. Each historical time point must be separated by at least 1 year.

Isometric will select a suitable proxy that meets the following criteria:

• The proxy must be correlated with AGB throughout the Crediting Period.

• If the proxy saturates in the project area or Donor Zone during the Crediting Period and becomes insensitive to further carbon gain (e.g., as is the case for many simple optical indices), it will be excluded³¹. Proxies such as canopy height from models which use datasets from multiple types of earth observation (particularly 2D satellite imagery, LiDAR and SAR) are preferred³².

• The proxy map product should exclude cloud occlusion, saturation, and other contamination. This may lead to seasonal composite images.

• The proxy should be insensitive to seasonal variability, which may be addressed through taking an annual average to remove the seasonal cycle.

• The proxy should be stable, so that in the absence of carbon change, the proxy value stays the same.

Project and control plot pixels will be matched by Isometric at Validation, and these matches will be retained and tracked over the Crediting Period. In this procedure a representative random sample of project pixels are matched to control plot pixels based on a mix of current and historical time series of environmental, socioeconomic, management, and forest structure data — including the selected forest carbon proxy, C_proxy, of each pixel — using k-nearest neighbors without replacement, or an alternative justified algorithm.

This matching will use, at a minimum, five historical time points of C_proxy capturing at least the five years prior to project initiation. Isometric shall use, where possible and relevant, additional datasets from Table 1 for matching. Other than the historical time series of C_proxy, all dynamic remotely sensed variables must be captured within the past 18 months. Each selected project pixel must be matched to a minimum of 5 different control pixels, and the mean of each dataset over the group of control pixels is used — with the mean forest carbon proxy over the group of control pixels derived from the map product created using the procedure described in Section 9.3.2.

To evaluate the carbon stored in the counterfactual scenario, the change in the stocking index in the project pixels is compared to the change in the control pixels. Specifically, linear regressions are fit through both the project and control pixels proxy values, and the relative ratio is then used to calculate the counterfactual storage:

$$CO_2e_{Counterfactual,Total} = CO_2e_{Stored,total} \left( \frac{Control_{proxy,slope}}{Project_{proxy,slope}} \right)$$

(Equation 10)

Where:

• $CO_2e_{Counterfactual,Total}$ is the total counterfactual CO₂ removed from the atmosphere and stored in the absence of project activities over the course of The Project up to the end of the current Reporting Period, in tonnes of CO₂e

• $Control_{proxy,slope}$ and $Project_{proxy,slope}$ are the slopes for the linear regressions fit through the proxy values for the control and slope pixels, respectively

To meet the additionality condition, the change in proxy value in the project area represented by the slope of the project pixels, must be statistically greater ($p$ < 0.05, inclusive of uncertainty) than that of the matched control pixels. If the slope of the proxy change in the control pixels is negative such that the resulting product of Equation 10 is negative, the counterfactual carbon storage, $CO_2e_{counterfactual}$, will be assumed to be 0 in order to ensure the accounting of carbon storage is limited to removals above the harvest counterfactual.

At each Verification, the control pixels are reviewed to determine continued eligibility around similar regulatory regimes within control plots as outlined in Section 9.3.1. In the event that control pixel matches are no longer suitable, replacements will be selected for the impacted project pixels. For example, a change in regulations around IFM projects which leads to variance in the legality of such projects between control and project pixels would lead to rematching of control and project pixels.

The counterfactual will be calculated using Equation 10 for each Reporting Period, unless:

• Within a single Reporting Period, the mean proxy value of the controls decreases by 20% or more, which is indicative of harvest having occurred in the counterfactual; or

• The slope of the control regression is $\leq$ 20% of the slope of the project regression for the prior five year period (excluding years prior to project initiation), which is indicative of harvesting keeping biomass levels far below what is being observed in the no-harvest project scenario.

If either of the above conditions is met in a given Reporting Period, the counterfactual is then calculated as the temporal mean for that Reporting Period and all remaining Reporting Periods in the Crediting Period:

$$C_{counterfactual,total} = C_{stored,total} \left( \frac{Control_{proxy,mean}}{Project_{proxy,RP}} \right) x \, f_{HWP}$$

(Equation 11)

Where:

• $Control_{proxy,mean}$ is the temporal mean of the control proxy

• $Project_{proxy,RP}$ is the mean proxy value of the project pixels at the end of the current Reporting Period

• $f_{HWP}$ is the counterfactual harvested wood storage factor

The counterfactual harvested wood storage factor reflects the relative ratio of the long-term mean of harvested wood carbon relative to the long-term mean of standing carbon in counterfactual. This term is calculated based on information about historical harvesting activities and wood products within the project area:

$$f_{HWP} = 1 + \frac{\sum_{i=1}^{n} \frac{f_i}{\lambda_i}}{T(\gamma - \beta)}$$

(Equation 12)

Where:

• $f_i$ is the fraction of pre-harvest biomass in pool i of n total pools for the fate of the harvested biomass [-]

• $\lambda_i$ is the decay rate for pool i, in years^-1

• $T$ is the harvest cycle length, in years

• $\gamma$ is the harvest intensity [-]

• $\beta$ is the normalized regrowth symmetry [-]

Further details on the calculation and required evidence for these terms are provided in Section 9.3.4.1 and the full derivation is in Appendix E. The calculation of $f_{HWP}$ must be included in the uncertainty assessment for the calculation of removals. As such, uncertainty information for the parameters must be reported, or evidence that the value is a conservative estimate provided. Project Proponents must provide their assessment and corresponding evidence for the calculation of $f_{HWP}$ at Validation.

The fraction of biomass in different pools post-harvest ($f_i$) is assessed by considering how the initial pre-harvest standing AGB volume gets divided into harvest residues, mill residues, and wood products.

First, a biomass expansion factor (BEF) is used to determine how the standing pre-harvest total AGB volume (K) is partitioned into between merchantable volume of biomass (MV) which goes to the mill and harvest residues (R_H):

$$K = MV + R_H = \frac{1}{BEF}K + (1 - \frac{1}{BEF})K$$

(Equation 13)

Where available, species-specific biomass expansion factors should be used. If none is available, then default IPCC values for the region and system may be used³³.

The merchantable volume is then further partitioned as part of the milling process into the commercial volume (CV) of wood products and waste residues produced in the milling process. This partitioning is described by the efficiency of the processing of harvested wood products (W_HWP). The efficiency of the processing of harvested wood products is well documented, and the value of W_HWP must be assigned to each harvested wood product, HWP, according to the sawmill location, with the values derived from Winjum, et. al. 1998³⁴. For developed countries, this value is 0.19; for developing countries, this value is 0.24.

$$MV = CV + R_H = (1-W_{HWP})MV + W_{HWP}MV$$

(Equation 14)

Note that the above expression represents a single type of wood product and associated wastes, but the merchantable volume may be partitioned into multiple milling processes and wood products as applicable.

The above equations can then be combined and normalized by $K$ to express the fractional pools:

$$1 = f_{RH} + f_{RM} + f_{CV} = (1 - \frac{1}{BEF}) + \frac{W_{HWP}}{BEF} + \frac{1- W_{HWP}}{BEF}$$

(Equation 15)

Where:

• $f_{RH}$ is the harvest residue fraction, equivalent to the first term on the right-hand side of the equation

• $f_{RM}$ is the milling residue fraction, equivalent to the middle term on the right-hand side of the equation

• $f_{CV}$ is the commercial volume fraction that goes into wood products, equivalent to the final term on the right-hand side of the equation

The decay rate ($\lambda_i$) is derived from the half-life of the pool:

$$\lambda_i= \frac{ln(2)}{t_{1/2,i}}$$

(Equation 16)

Where:

• $t_{1/2,i}$ is the half life of pool i, in years

The half-life values applied for harvested wood products must be specific to the product type, end use, and regional practices associated with The Project and harvested wood product. Residue pools (e.g., harvest residues and milling residues) will be subject to an assessment of decay kinetics to account for biogenic carbon that would remain durably stored in the counterfactual. Half-life values must be selected from independently published sources, in the following order of preference:

1. Peer-reviewed, region- and product-specific studies that characterize the service life of wood products in the geographic context of The Project (e.g., Skog, 2008³⁵);

2. National greenhouse gas inventories or government reports that provide country-specific half-life values for major wood product categories;

3. IPCC 2019 Refinement to the 2006 Guidelines for National Greenhouse Gas Inventories default half-life values, categorized by product type³³;

4. As a last resort, if none of the above sources are applicable, conservative assumptions must be used that reflect the longest reasonable service life for the respective product category, with justification provided based on material characteristics and market practices.

The harvest cycle length ($T$) should be derived from historical harvest data from the site. Evidence could include records from the harvesting operations or remote sensing data.

The harvest intensity ($\gamma$) describes how much of the standing biomass in the forest is subject to harvest during harvesting:

$$\gamma = \frac{B}{K}$$

(Equation 17)

Where:

• $B$ is the standing total pre-harvest biomass in the forest

• $K$ is the biomass that is harvested, inclusive of all residue pools for the harvested wood, in the same units as $B$

In scenarios of clear-cutting, $\gamma$ is equal to its minimum value of one. Where there is selection harvesting, $\gamma$ is greater than one. This should be estimated based on historical practice within the project site and can be evidenced by documentation from the harvesting operations or remote sensing. Where suitable evidence is not available, clear-cutting must be assumed as a conservative estimate of $\gamma$.

The normalized regrowth symmetry ($\beta$) describes non-linearity in the regrowth dynamics of the standing forest post-harvest (harvest occurs at t=0):

$$\beta = 1 - \int_{0}^{T} \frac{B(t) - B_{min}}{K} \, dt$$

(Equation 18)

Where:

• $B(t)$ is the standing biomass at time $t$, in the same units as $K$

• $B_{min}$ is the standing biomass post-harvest (excluding residues)

The integral term in this equation is equivalent to the temporal mean value of standing biomass over the course of a harvest cycle normalized to the harvest volume. Values of $\beta$ range from 0 to 1. A value of 0.5 represents perfectly linear regrowth in the forest. Values less than 0.5 indicate more rapid regrowth rates in early years that then decrease in latter years. Values greater than 0.5 indicate slower growth in initial years with acceleration of the growth rate in latter years.

The value of $\beta$ should be estimated from growth models which are ecologically suitable for the represented species or from historical remote sensing data of regrowth within the project area.

Isometric will account for uncertainty in the dynamic baseline to ensure a conservative estimate of CO₂e_{counterfactual,Total} in Equation 5. This will include an evaluation of at least the following sources of uncertainty:

• Uncertainty in the forest carbon proxy maps, due to the uncertainty in data and models used to generate the proxy map;

• Uncertainty in how well the forest carbon proxy represents relative changes in carbon stock between the control and project pixels;

• Variation in the ensemble of control pixel values matched to each project pixel, representing the uncertainty across the ensemble of baseline scenarios therein; and

• Uncertainty in the control pixels matched and if they adequately represent the likely Counterfactual scenario.

Situations may arise where The Project operates within an ecologically unique ecosystem, employs uncommon management techniques, or is located in a region where comparable concession-level spatial data are unavailable — thereby limiting the donor pool of spatial or temporal matches for dynamic baselining.

Under such conditions, Projects may derive the counterfactual scenario using a modeled dynamic baseline, constructed from The Project’s own historical harvesting record, supply-side operational capacity, and demand-side market conditions — subject to the constraints and dynamic evaluation requirements specified below. The modeled baseline must be conservative, evidence-based, and subject to upward-only (decreased harvest, increased counterfactual biomass) adjustment over time.

A project may apply this section only where Isometric has determined, at Validation, that the eligible Donor Zone after masking for required variables and applying the time for space substitution (see Section 9.3.1.1) is still less than five times the project area.

The determination that a limited donor zone exists must be documented by Isometric and reported in the Validation Report. Once a Project applies a modeled dynamic baseline, it must continue to use the modeled baseline approach for the remainder of the Crediting Period unless Isometric determines that a sufficient donor pool has become available, in which case The Project must transition to the standard approach on a forward-moving basis.

Project Proponents must derive modeled baseline harvest scenarios from the following inputs, which will be approved for use at Validation:

• Historical harvest rate. The baseline annual harvest area (in hectares per year) must be set equal to the historical average over a period no shorter than one-half of the rotation length and no shorter than 10 years, using the most recent pre-project data available. Years affected by exceptional circumstances (e.g., pandemic-related shutdowns, force majeure) may be excluded provided the exclusion is justified and documented. The Project must not select the historical period in a manner that inflates the baseline; where multiple defensible averaging periods exist, the most conservative value shall be used.

• Accessibility and Operability of Harvest. The baseline must be evaluated against the baseline conditions set forth in Section 4.1.2 of this Module and Section 4.1.1 of the IFM Protocol, where the initial baseline is set on the project area and carbon stock which are subject to immediate harvest demand.

• Supply-side operational capacity. The Project must document the concession’s harvesting capacity under normal operating conditions, including available equipment, workforce, and infrastructure. The baseline harvest area must not exceed demonstrated operational capacity.

• Demand-side market conditions. The Project must document the regional market demand for the relevant timber products, including identified buyers and their historical purchasing volumes. The baseline harvest area must not exceed the volume supportable by demonstrated market demand.

  • Projects must evaluate the demand in accordance with the principles outlined in Section 4.1.2.5.

• Regulatory and concession constraints. The baseline must incorporate all applicable legal and regulatory constraints on harvesting, including concession license terms, allowable annual cut provisions, and any restrictions arising from forest management plans or regulatory authorities.

• Carbon recovery curve. The Project must specify the carbon recovery curve used to translate the baseline harvest schedule into carbon stock changes over time. The curve must be derived from field data within the project area or from ecologically suitable growth models for the represented species and ecosystem. Uncertainty in the recovery curve must be quantified and reported.

  • All models used in the development of the carbon recovery curve must meet the requirements set forth in Section 9.5.

The modeled baseline harvest area shall be set to the long-term average of the historical harvest rate, demonstrated supply-side capacity, demonstrated demand-side market absorption, and the regulatory allowable harvest. This ensures the baseline is conservative across all relevant dimensions.

The model must predict the standing aboveground counterfactual biomass as a function of time (CO₂e_{counterfactual,AGB}). This should be done at a minimum of annual resolution.

The modeled output must then be used in the equivalent calculations to Equations 10 and 11 to yield the counterfactual deduction. From project initiation up until any harvest is predicted by the model, the counterfactual will be calculated as:

$$CO_2e_{Counterfactual,Total} = CO_2e_{Counterfactual,AGB,t=RP}$$

(Equation 19)

Where:

• $CO_2e_{Counterfactual,AGB,t=RP}$ is the standing total counterfactual AGB at the end of the current Reporting Period in tonnes of CO₂e

Once any harvest occurs within the counterfactual, the counterfactual is calculated as:

$$CO_2e_{Counterfactual,Total} = f_{HWP} \frac{\int_{0}^{RP} CO_2e_{Counterfactual,AGB}(t) \, dt}{RP}$$

(Equation 20)

Where:

• $RP$ is the total project length at the end of the current Reporting Period, in years

Note that this equation is equivalent to Equation 11, and $f_{HWP}$ should be calculated following the parameters and procedure in Section 9.3.4.1.

At each Reporting Period, the modeled baseline assumptions must be tested against observed conditions using the Modeled Baseline Evaluation Framework (Table 2). When any category undergoes a material change in the conditions which underpin the modeled baseline, The Project must adjust the baseline harvest area and associated carbon stock projections accordingly.

Where this evaluation identifies a material change, the project must:

• Identify the specific baseline parameter(s) affected and quantify the impact on the baseline harvest area.

• Recalculate the counterfactual carbon stock projections using the adjusted harvest area for the current Reporting Period and all subsequent Reporting Periods.

• Report the adjustment, its justification, and its quantitative impact in the Monitoring Report for the current Reporting Period.

Adjustments are applied on a forward-moving basis from the start of the Reporting Period in which the change is identified. Adjustments cannot be applied retroactively to previously verified Reporting Periods. All adjustments are subject to approval by Isometric and the VVB.

Table 2. Modeled Baseline Evaluation Framework

Each Monitoring Report must include a detailed summary of the modeled baseline evaluation applied for the Reporting Period, covering all categories in Table 2 and their results. Any baseline parameters identified as requiring adjustment and the reasoning for such a determination must be clearly reported. All adjustments must be fully described, including their quantitative impact on the counterfactual carbon stock projections and the volume of Credits requested for the current Reporting Period.

The following must be reported at each Reporting Period:

• The result of each evaluation category in Table 2, including a clear statement of whether the test was passed or failed.

• For any failed test: the specific evidence relied upon, the magnitude of the adjustment to the baseline harvest area, and the recalculated counterfactual carbon stock projections.

• A comparison of the current modeled baseline harvest area with the originally validated baseline, identifying all cumulative adjustments made since Validation.

Verification of the modeled baseline evaluation must assess:

• The completeness and accuracy of the evidence supporting each evaluation category.

• The appropriateness and conservativeness of any adjustments to the baseline harvest area or carbon recovery curve.

• The correct recalculation of counterfactual carbon stock projections and their impact on credited emission reductions and removals.

Where the verifier identifies evidence of a material change in baseline conditions that The Project has not accounted for, the verifier must require The Project to apply the appropriate adjustment before Credits may be issued for the Reporting Period.

Uncertainty in the counterfactual must be characterized and propagated following to obtain a conservative estimate of C_{counterfactual}. This includes assessment of all relevant sources of uncertainty described in Section 9.3.5. Additionally, Projects using this approach must characterize and account for uncertainty in all the parameters informing the model. For parameters where uncertainty is not easily quantified, evidence must be provided to demonstrate that the value used is conservative. For all other parameters, the quantified uncertainty must be propagated through the modeled output and reported as part of the modeling procedures and results.

CO₂e_emissions,RP is the total GHG emissions associated with a given Reporting Period, RP.

Equations and emissions calculation requirements for CO₂e_emissions,RP are set out in the relevant Protocol and are not repeated in this Module.

As part of CO₂e_emissions,RP, CO₂e_Leakage,RP must be quantified for the Reporting Period. CO₂e_Leakage,RP is quantified following the approach described in Section 8.2.

Any models used under this Protocol which contribute to the quantification of net CDR must be well-validated and skillful for the purpose that they were used for. Proof of model validation can be achieved through either:

• A track record of use in science, industry, or government applications, which is demonstrated through multiple peer-reviewed papers, or proof of usage in a number of previous applications. Furthermore, the model must be relevant to the project area and tree species (e.g., covers similar ecoregions); or

• Newly developed models without a track record of usage must be validated against reputable data sources, which include quality-controlled in situ measurements and public datasets adhering to FAIR (Findable, Accessible, Interoperable and Reusable) principles³⁶). Sufficient model validation data must be provided with the PDD.

• Any models developed or used for the purpose of AGB quantification using the methodology described in Section 9.2.1 must also be evaluated and approved by Isometric as part of the required comprehensive assessment of the approach prior to use.

The storage reservoir or the CO₂ removed through the IFM interventions in this Module is live aboveground woody biomass. The durability of a CDR process refers to the length of time for which CO₂ is removed from the Earth’s atmosphere and cannot contribute to further climate change. This Section details the durability and reversal monitoring requirements for storage of removed atmospheric CO₂ as aboveground woody biomass under this Module.

The durability of a Credit is equal to the length of the Ongoing Monitoring Period as outlined in Section 5.4. The minimum duration of the Ongoing Monitoring Period, and therefore minimum durability of Credits issued under this Module, is 40 years.

The duration of the Ongoing Monitoring Period must not exceed any of the following:

• Protected status of land. If the protected status implemented at the end of the Crediting Period (see Section 4.3) has any associated duration, the Ongoing Monitoring Period must not exceed this time period.

• Forest maintenance activities. Project Proponents must continue forest management and risk mitigation practices to maintain forest carbon stocks throughout the Ongoing Monitoring Period.

For the duration of the Ongoing Monitoring Period, Isometric will conduct monitoring for Reversals in the project area following the procedures described in IFM Protocol Section 10.5. Project Proponents will be responsible for reporting and quantification in response to any detected Reversals for the duration of the Ongoing Monitoring Period.

The Risk Assessment is used to assess the overall delivery and storage risk associated with improved forest management through transition to protected status and may inform the Buffer Pool contribution during Credit delivery (see IFM Protocol Section 10.4). The assessment must first be filled in by the Project Proponent and must be validated by a VVB. During project Validation, discrepancies between the Project Proponent’s self reported score and VVB may result in monitoring or risk mitigation activities, or project ineligibility. Eligible projects must have an initial risk score ≤ 16 and initial risk category scores at or below the following thresholds:

• Project Proponent Capacity Risk ≤ 7

• Financial Viability Risk ≤ 7

• Social Governance Risk ≤ 9

• Disturbance Risk ≤ 14

All risk categories shall have a minimum score of 0, regardless of the outcome of the Risk Assessment.

If Project Proponents choose to forgo a flat 20% Buffer Pool contribution, this Risk Assessment will inform Buffer Pool contributions for The Project according to the process outlined in Appendix C for each Reporting Period and in accordance with the requirements in the IFM Protocol (see Section 10.4.1).

• After each new Risk Assessment evaluation, Isometric will update the required percentage of newly issued Credits that must be contributed to the Buffer Pool by The Project. Isometric encourages Project Proponents to continuously monitor, mitigate, and reduce risks.

Table A1. Risk Assessment for Improved Forest Management projects involving transition to protected status of previously logged lands, with the score to be filled out for each question.

The following section outlines how Isometric calculates the indicator scores for climate-related extreme weather disturbance risks to carbon permanence within a project’s region (Figure B1). Project Proponents should use Table B1 to lookup the Isometric-calculated values for their project's region and include those scores in their Risk Assessment (see Appendix A).

Extreme weather risks are assessed via two indicators: a temperature indicator (extreme heat and/or cold) and a hydrologic indicator (flooding and/or drought). Each indicator includes both historical data (1961-2015) and projected future extreme events. Historical data indicate the likelihood of extreme events based on past climate patterns, e.g., projects in regions with extended dry periods are expected to experience increased water stress as part of their typical climate. Climate model projections describe how changing climate conditions, relative to historical patterns, might present an increased risk of disturbances. Areas where there is a larger shift towards extreme conditions under future climate relative to their historical baseline have a greater disturbance risk (e.g., drier conditions relative to historical averages increases risk for drought-driven mortality).

To calculate the scores in Table B1, Isometric uses values from the Intergovernmental Panel on Climate Change AR6 report³⁷. The temperature indicator, IndicatorTemperature, is calculated using data describing the annual number of frost days (FD, minimum temperature below 0°C) and annual number of days with a maximum temperature above 40°C (TX40) to capture extreme cold and extreme heat risks, respectively. The hydrologic indicator, IndicatorHydrological, is calculated using data describing the maximum 5-day precipitation (RX5Day) and annual maximum number of consecutive dry days (CDD) to capture risks of flooding and drought, respectively. All values come from the CMIP6 climate models. Future projections use the SSP2-4.5 medium term (2041-2060) scenario and are assessed as the change in value relative to a historical baseline (1961-1990).

For each indicator subcomponent, the region’s terrestrial median value is compared with the global terrestrial distribution of the same variable (Table B2). To convert the regional value into a subscore, regional values below the global 75th percentile are considered Low Risk, regional values equal to or greater than the global 75th percentile but below the 90th percentile are Medium Risk, and any regional values equal to or greater than the global 90th percentile are High Risk. Low Risks are given a subscore of 0, Medium Risks are 0.25, and High Risks are 0.5. The overall score for each of the indicators is calculated by summing the corresponding subscores, as described below:

Projected change in the number of frost days is not included as a subcomponent since it is projected that they will decline under future climate across the globe, representing a low risk of future extreme cold events.

Figure B1. Map and lookup table for IPCC regional codes

Table B1. Regional Lookup Table of Disturbance Risk