Isometric Standard

The Isometric Registry records Verified Credits that represent Removals of atmospheric CO₂ which satisfy the latest Version of the Isometric Standard. The Isometric Standard, detailed in this document, lists the requirements that ensure Delivered tonnes have measurable climate impact. In summary, tonnes must be Durable, Additional, and calculated using the latest scientific techniques. These tonnes must also include a scientifically robust Uncertainty quantification meeting at minimum with the requirements outlined in the Standard.

As outlined in this Isometric Standard, Isometric coordinates data curation, quantification and Verification necessary to Issue Credits on the Isometric Registry. All data, calculations and evidence associated with Credits are publicly available. The Isometric Registry is designed for voluntary Buyers focused on high durability Removals, not offsets or Emission Reductions.

This Isometric Standard sets out the duties and obligations of stakeholders in relation to the Isometric Registry. Its purpose is also to provide for a consistent and predictable experience for all parties engaging with the Isometric Registry.

This Standard and the rules contained herein were designed and developed by Isometric HQ Limited.

The Isometric Crediting Program is guided by the Isometric Standard, and exists to:

• provide guidance, transparent infrastructure and to set a high scientific caliber that fosters high quality climate action in the form of Durable Removals of CO₂ from the atmosphere; and

• Issue Verified Credits that can be used as an evidentiary statement of their ownership for Removal claims and reporting purposes.

The Isometric Crediting Program adheres to the following principles:

Collaboration

• Isometric engages with relevant governmental and Non-Governmental Organizations (NGOs) to facilitate equitable representation of stakeholders in a predominantly private industry and advance the creation of high quality industry standards.

• Isometric engages the scientific community and collaborates with experts in areas such as sensor development, physical inspection, auditing, earth-system modeling and data analysis to Verify Deliveries.

• Where appropriate and practicable, Isometric Systems may be integrated with similar tracking systems to help ensure full and accurate information for Buyers of Removals and minimize the potential for Double Counting.

Incentive Alignment

• Isometric does not sell or broker the sale of credits.

• Isometric charges Buyers – not Project Proponents – a single flat fee per Offtake or purchase which is based on effort required for monitoring, reporting, and verification of a specific pathway/process. This price structure is independent from the number of Credits issued and thus reduces incentives for overcrediting.

• Isometric collects fees from Buyers on a payment schedule decoupled from the credit delivery schedule. This mechanism eliminates incentives for early crediting.

• Isometric does not receive payments from Project Proponents to Verify the delivery of tonnes and adherence to Certified Protocols.

• Isometric undertakes the cost of Protocol development and third-party Verification to ensure neither Buyers nor Project Proponents can have undue influence over this process.

• Isometric independently and impartially chooses third-party Validation and Verification Bodies (VVBs) for Projects.

Scientific Rigor

• Isometric uses the latest science to quantify net negativity, durability, uncertainty and Additionality across a variety of heterogeneous Removal Pathways.

• Isometric will review and update Protocols without a penalty on previously Issued Credits in order to incentivize continued investigation of underlying scientific questions – through which Removal estimates can be further constrained.

• Isometric quantifies all Carbon Fluxes related to the Removal activity taken by the Project Proponent in a Conservative manner that incorporates uncertainty – including second order effects on leakage.

Transparency

• Isometric provides Buyers and Beneficiaries with access to full traceability of Carbon Fluxes involved in the quantification of Removals, alongside the evidence gathered for the Validation and Verification Process.

• Protocols and quantification Models are transparently versioned, allowing for public tracking of changes, and public consultation after major updates.

• Each Credit Issued by Isometric is publicly accessible – allowing for inspection of the information used to quantify Removals.

Isometric works with Projects conforming to a Protocol which has undergone or will undergo the Isometric Certification Process.

Isometric works with Projects worldwide. Isometric works in English. Additional languages may be considered given translation by a trusted source.

In some instances, Modules within Protocols may be tailored for Projects which have geographical specificities. In this circumstance, geography-specific alterations to utilized Modules will be made clear in order to maintain transparency amongst Project Proponents.

Isometric Issues Credits for the net Removal of atmospheric CO₂ only. In evaluating the comprehensive greenhouse gas (GHG) emissions of a Project, all GHGs are considered. Isometric uses the United States Environmental Protection Agency definition of GHGs¹, which includes: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and fluorinated gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆), and nitrogen trifluoride (NF₃).

Projects partaking solely in any of the following will not meet Isometric Protocol Requirements.

• Carbon Removal Projects with <1,000 year durability that have not been otherwise approved by Isometric on a case-by-case basis

• Ecosystem restoration, maintenance and management

• Emissions reduction and offsetting

• Point source fossil fuel emission carbon capture and storage

• Reducing Emissions from Deforestation and Degradation (REDD+)²

Projects partaking in activities leading to Enhanced Hydrocarbon Recovery (EHR) will also not meet Isometric Protocol Requirements.

This is version 1.0.0 of the Isometric Standard, first published 4th October 2023.

The document will be updated on an ongoing basis to reflect changes in the operation, governance and/or rules that apply to either Projects on, or activity described by, the Registry.

Any proposed material changes to the Standard will be put forward for review by the independent Science Network. Following any amendments resulting from that process, the draft changes will be put out for public comment. After having incorporated any further amendments, the final changes will be published in an updated version of the Standard, alongside a clear explanation of the stakeholder input received and how this informed the final changes that were made.

Version numbers are updated according to standard Semantic Versioning³ practice, where three positive integers A.B.C denote the version of the Protocol.

• Major (Integer A) - Updated when the Standard has undergone a significant change that may have impacts on Project eligibility, Verification practices or Credit issuance

• Minor (Integer B) - Updated when non-critical information has been added to, or removed from, the Standard – for example optional guidance

• Patch (Integer C) - Updated when minor changes have been made – for example phrasing or reference changes

A full change-log, along with all previously published versions and their dates of publication, is publicly available on Isometric’s website.

The latest version is always the current version.

The appropriate citation for the document is the Isometric Standard (2023), version 1.0.0.

This section outlines the requirements for all Isometric Certified Protocols including Isometric Certified Modules.

All Projects must be Validated against, and Removals Verified against, an Isometric Certified Protocol.

An Isometric Certified Protocol is either:

• a Protocol developed by Isometric that has undergone Public Consultation; or

• a Protocol developed by external authors that has been reviewed by Isometric and undergone Public Consultation and which finally has been approved by Isometric for use on the Isometric Registry.

Externally-assembled protocols, once authorized by Isometric, may utilize the Isometric Modular Framework – in which Isometric Certified Modules are incorporated into a Project Proponent's Protocol where Isometric is represented as a lead author. All Modules will undergo rigorous Isometric review, with external Consultation deemed necessary on externally-assembled protocols which substantially modify Isometric Certified Modules. Upon completion of the protocol development and/or assembly process and final approval by Isometric, the Protocol will be listed as Certified and can be used by Projects.

Isometric will not list multiple Protocols or Modules as Certified where they pertain to the same or essentially the same underlying carbon removal activities.

The external Consultation process will be as follows:

1. Expert review through the Isometric Science Network

2. Public Consultation

Expert review will be conducted through the Isometric Science Network. Expert review is the process in which the internal Isometric Science Team invites individuals with deep subject matter expertise to submit feedback on a Protocol. Isometric generously compensates experts for their detailed review with a flat hourly fee paid upon feedback submission.

Public Consultation will be announced on the Isometric Science Platform and to the Isometric Science Network. Protocols are open for public commenting for a minimum of 30 days. All relevant stakeholder comments are considered and responded to by the internal Isometric Science Team via the Science Platform, and the results of the Consultation will be published on the Science Platform. All anonymized comments and reviews will be made available upon request.

Typically, at least 5-10 scientific experts are engaged for a given Module or Protocol via the combination of the above processes.

The Consultation process will be conducted in compliance with the Isometric Stakeholder Input Process for Projects.

A Protocol can reference or incorporate an existing Isometric Certified Module. Protocols which incorporate these Modules are subject to the same Protocol requirements as entirely externally-developed Protocols. Modules are developed by Isometric and will be Certified either through an Isometric-developed Protocol or individually as stand-alone items through the same Certification process.

Individual Isometric Certified Modules which are incorporated into a Protocol will not be subject to individual Consultation unless changes are made in accordance with Isometric's Updates to Protocols policy. Protocols which incorporate Modules will still require Consultation, with input and revisions only occurring to additional (non-Modular) parts of the Protocol and to assess the suitability of the incorporation of appropriate Modules.

All Protocols will include the same Modules for accounting for transport emissions, energy emissions and embodied emissions, in order to create a consistent accounting framework across all Projects.

Isometric will review individual Modules annually and be responsible for version changes in accordance with our Updates to Protocols policy.

The internal Isometric Science Team will review a Protocol or Module if Isometric deems it necessary due to material changes in realms such as scientific knowledge, technology and/or regulatory frameworks. This review must be completed within a period of 6 months from the date an issue is raised. If the review results in substantial changes to a Protocol or Module such that a new version is required, these changes must adhere to the full Certification process.

In addition to the triggers for review outlined above, each Protocol will be reviewed at the sooner of the following criteria:

• after 2 years have passed since the original Certification; or

• whenever the number of Credits Issued under a Protocol passes the following milestones: 100,000 Credits Issued; 500,000 Credits Issued; 1,000,000 Credits Issued; 5,000,000 Credits Issued.

All changes will be documented on the Isometric Science Platform and published with the results of a public commenting period of a minimum duration of 30 days. All versions of Protocols and Modules will be documented, archived and made publicly available. Revisions and updates to Protocols will be done in accordance with our standard Versioning policy.

If a Module is updated, all existing Protocols which make use of this Module will be automatically updated. Existing Projects Validated against the previous Protocol version will remain unchanged until Project re-Validation unless otherwise specified with justification in the updated Protocol.

Isometric reserves the right to suspend and/or withdraw a Protocol if deemed necessary due to credible, evidence-based concerns that carbon removal activities are being overestimated or that additionality may not be ensured. In such exceptional cases, Isometric may take immediate action to suspend and/or withdraw a Protocol. The Protocol may then be re-introduced following the usual period of public consultation in the case of any material change.

All Projects must have a defined temporal and geographical boundary as specified by the relevant Protocol. This must include at a minimum all GHG sources, sinks, and Reservoirs from:

• the construction or manufacturing of each physical site and associated equipment;

• the closure and disposal of each site and associated equipment; and

• the operation of each process.

Protocols require a Cradle-to-Grave GHG Assessment of all emissions associated with a Project's Removal process. The GHG emissions that result from the Project's activities within the defined boundary combined with any Leakages should together encompass the entire impact of a Project on GHG emissions.

All Projects must be assessed against a Baseline of their activities not having taken place. The method for Baseline assessment will differ between Project types and will be specified in the Protocols specific to certain processes. Baselines will be calculated using Conservative assumptions as outlined in relevant Protocols. Any Removals accounted for will need to include quantification of GHG emissions associated with diversion from the Baseline in the Project activities.

Projects will only be Credited for Removals above and beyond what Isometric has assessed to have likely occurred in a Counterfactual scenario. Projects will not be Credited for emissions reductions or avoidance.

If Projects cause additional non-Durable (<1,000 years) CO₂ storage through their processes, this is not able to count positively towards the end number of Credits, but this can be used to offset losses in non-Durable Counterfactual storage as outlined in the relevant Certified Protocol.

Projects must reassess Baselines whenever a Crediting Period extension is requested, unless otherwise specified in the relevant Certified Protocol, and must be validated as part of Project Validation.

The Project Proponent must be able to demonstrate three pillars of Additionality (Financial, Environmental and Regulatory), in order to show that the claimed environmental impact would not have otherwise occurred in the Counterfactual Scenario.

A Project can be considered Additional when all of the following criteria are met.

• Financial:
  • The Project can be considered to demonstrate Financial Additionality if Removals are the main purpose and only source of revenue of the Project.
  • Otherwise, the Project must demonstrate that economic barriers would prevent Project implementation in the absence of Carbon Finance, as outlined in the Financial Additionality Considerations section below.
• Environmental:
  • The Project can be considered to demonstrate Environmental Additionality if the climate impact of the Project is net negative when compared to the Counterfactual scenario, using a Cradle-to-Grave GHG Assessment, in accordance with the assessment framework defined in the relevant Protocol.
• Regulatory:
  • The Project can be considered to demonstrate Regulatory Additionality if the Project is not required by any regulatory, policy or other legal requirement.
  • Otherwise, the Project must be able to demonstrate that it exceeds the minimum regulatory requirements, as outlined in the Regulatory Additionality Considerations section below.

Evidence of Financial Additionality must be provided via full Project financials.

Proof of Financial Additionality requires, at minimum, the calculation of the return on investment via calculation of the Internal Rate of Return (IRR) for the Project. The IRR determination may be completed in accordance with generally-accepted accounting practices. The analysis should be completed for a 10-year period, with non-depreciated residual values of any equipment or assets included as positive cash flows in year 10. Existing government subsidies or tax incentives must be taken into account as a revenue stream.

The Project Proponent must determine the IRR for the Project without Carbon Finance revenues. For new Projects, The Project must ultimately demonstrate:

• a zero or negative IRR; or
• an IRR of less than the cost of capital (required rate of return) or return on equity for the Project.

A Project may justify a higher IRR as additional if the Project Proponents can demonstrate that the Project requires such an IRR to enable financing for higher risk Projects, which may require higher interest rate loans, high interest rate venture or equity investment, or similar.

The IRR analysis should also include a scenario analysis that demonstrates the ability to meet the above Additionality criteria for cases where values in the analysis change. Scenario analyses should include:

• variation of initial investment costs, if greater than 20% of total Project costs;
• variation of projected revenues to consider market changes for products or fees charged;
• evaluation of any assumption, value, or projection that accounts for greater than 20% of Project costs or Project revenues, or any value that impacts less than 20% of costs or revenues but which the Project Proponent determines can have significant impact (>10%) on IRR.

At a minimum, the IRR analysis should include variation of the factors above by ±20% or by a more appropriate value based on historical data or literature.

For pre-existing Projects:

• Projects must provide a historical Counterfactual Baseline in the absence of Carbon Finance.
• Removals only in excess of this Counterfactual Baseline may be considered Financially Additional.

Project Proponents must demonstrate that the Project is not required by existing laws, regulations, policies, or other binding obligations. If the activity is required by such legal requirements, the Project is not considered Additional. Legal requirements that should be considered include, but are not limited to:

• any national, state, municipality or other local law or regulation; and
• any policy, such as a procurement practice that requires the specific Project activity.

If the Project is legally required as described above, but the Project provides Removals that exceed the legal requirement, the Removals in excess of the legal requirement may be considered additional if the other Additionality requirements are also met.

Projects should demonstrate a robust assessment of potential increases in GHG emissions outside the defined project boundary that occurs as a result of the Project activity. Where the potential for such Leakage is identified, it must be quantified and deducted from the CO₂ Removals in accordance with the relevant Protocol.

Where appropriate, Leakage includes, but is not limited to:

• upstream considerations (such as Feedstock sourcing or energy procurement) as laid out in the relevant Protocol; and

• downstream storage considerations beyond a Project's direct activities.

Protocols can use Default Emission Factors, Standards, Proxies and Models to quantify Removals, demonstrate Additionality and/or establish Baselines. In metered systems, the preference is for direct measurement of required variables where possible.

Proxies and Models will only be permitted for use under circumstances which are justifiable, such as for reasons of practicality, reliability, and for gap filling in variable un-metered systems. This justification must be outlined in the Protocol. Proxy measurements are secondarily preferred, and models may be used when neither Proxy or direct measurements are viable. When used, Models and Proxy measurements must apply Conservative Uncertainty factors and make Conservative assumptions. Assumptions and estimations must be disclosed and justified. When Models and Proxy measurements are used, Uncertainty must be assessed and clearly outlined in the Protocol.

Further requirements and guidance for the use of Default Emission Factors, Standards, Proxies and Models in Protocols are outlined below.

The Protocol must appropriately cite and describe the source of any third-party Default Emission Factor, Standard, Model or Proxy. Third-party Default Emission Factors and Standards must be either internationally recognized or derived from a Reputable Source.

Where a newly established Default Emission Factor is used in a Protocol, the reasoning behind this choice and documentation of Default Emission Factor calculations must be clearly outlined and will be subject to review in accordance with the Consultation Requirements.

Protocols must identify Default Emission Factors that are likely subject to future changes. Default Emission Factors can be subject to updates and revisions given the Isometric Updates to Protocols policy.

Proxies must be shown to be well-correlated with the variable of interest, preferably through established calibration studies from Reputable Sources. The Proxy data, empirical fits, correlation data, and sources must be provided to Isometric.

Models must be from a Reputable Source and/or shown to be reliable via peer-review, testing or correlation with empirical data. The source of models, any modifications, input parameters, data used and validation results must be clearly outlined to Isometric.

All calculations should use consistent, standardized factors, including the following:

Global Warming Potential (GWP): Calculations should use the 100-yr GWP for the GHG of interest, based on the most recent volume of the IPCC Assessment Report, currently the Sixth Assessment Report⁴. Current 100-yr GWPs are: CO₂ = 1; CH₄= 27.9; N₂O = 273.

Uncertainty is due to factors such as inability to precisely measure certain physical phenomena and/or assumptions in Models or GHG Assessments. Protocols must set up frameworks that allow for the reduction of uncertainties with time as measurements, models, and scientific understanding improves.

Protocols must report a list of all parameters that are used in the Removal calculations. A sensitivity analysis that demonstrates the impact of each input parameter’s uncertainty on the final net CO₂e uncertainty must be provided. Details of the sensitivity analysis method must be provided so that the results can be re-created. Parameters may be omitted from a full uncertainty analysis if a Sensitivity Analysis can demonstrate that the parameter contributes to <1% change in Removal. For all other parameters, information about Uncertainty must be specified.

Uncertainty information will vary depending on the data, but may include the type of distribution and parameters needed to describe uncertainty and/or shape of the data when plotted. Appendix A provides additional guidelines for assessing different types of uncertainties.

Furthermore, the source for information relevant to Uncertainty calculation and/or justification is required for each input parameter. The Uncertainty information may be obtained from instrument calibrations, measurement variability, published literature, Proxies, expert judgment, and/or other Reputable Sources.

Protocols must include a procedure for incorporating Uncertainties into a Conservative estimate of Removal. The following approaches are acceptable, and other methods may be considered after an internal Isometric review.

A. Conservative estimate of input parameters

B. Variance propagation

C. Monte Carlo Simulations

Option A is suitable for Projects where it is difficult to obtain detailed information on input parameter distributions. Using conservative estimates of input parameters will lead to a Conservative Removal estimate.

Option B can be used when parameters follow normal distributions and errors are linear (i.e., errors increase linearly as parameter values increase) and independent (i.e., changing one variable has no effect on another variable).

Option C provides a more comprehensive representation of Uncertainties and may result in more Credits Issued. This approach is suitable for Projects where sufficient information is available for all input variables so that Monte Carlo Simulations can be conducted.

As Removal quantifications become better-constrained and more data is gathered, Protocols may progress from using Option A to Option B to Option C.

For Option A, a uniform distribution is assumed for all parameters, unless it can be demonstrated otherwise. Isometric recommends that the value used in the Removal calculation be either ≤16^th or ≥84^th percentile, depending on which one yields a more Conservative estimate of Removal. There may be instances where a parameter might only have a few reported values, and it does not make sense to assume a continuous distribution. In these cases, it would be more appropriate to use the minimum or maximum value as the Conservative estimate. See Appendix A for some examples.

For Option B, the variance must be defined for all input parameters. Variance propagation should be conducted following uncertainty propagation rules⁵, where the outcome is the variance in the Removal. Isometric recommends that the Conservative Removal estimate be at least 1 standard deviation (square-root of the variance) below the mean, equivalent to ≤16^th percentile.

For Option C, the input distributions must be specified for all input parameters. The final distribution for the Removal is determined by randomly sampling from input distributions many times (e.g., n = 1,000).⁶ The Conservative estimate of Removal will be ≤16^th percentile for consistency between Option B and C in the case of normal distributions.

Parameter Uncertainties that are based on expert judgment and which contribute the most significantly to the final Removal calculation (based on a Sensitivity Analysis) will be subject to expert review by Isometric and/or selected Science Network experts.

Uncertainty assessment should initially be revisited as part of every Verification, with updates incorporated as appropriate. The frequency of assessments may be amended on a Protocol-by-Protocol basis as Uncertainties reduce over time.

Project Proponents must demonstrate a Durability of at least 1,000 years to ensure meaningful long-term climate action. Projects with <1,000 year durability will need to be reviewed on a case-by-case basis.

Justification of Durability can be established in two possible ways:

• via containment mechanisms, where the Conservatively-estimated engineering and/or scientific methods for containment exceed 1,000 years – possibly supported by secondary containment; or

• via scientifically falsifiable hypotheses that can be used to show there is no alternative destination for carbon storage other than the Reservoir in question.

A full risk assessment must be undertaken to identify all possible mechanisms that will lead to Reversals and subsequent decreases in Durability. There must be a monitoring plan in place to quantify the amount of potential Reversal that may occur via each identified Reversal mechanism.

The duration of storage monitoring required is process and location specific and requirements will be specified in the relevant Protocol.

Monitoring requirements must include:

• adherence to the monitoring program of the Protocol that the individual Project is following;

• the frequency of measurement and reporting, which should be specified in the relevant Protocol, reflect the relative Uncertainties of a technology at the start of a program and be reviewed on an annual basis;

• consideration of Baselines and incorporating provisions for reevaluation at the end of a Project's Crediting Period or at set timescales as defined within the Protocol;

• the methodology for detecting all potential Reversal mechanisms;

• provisions for reporting Reversals to the VVB and Isometric, as adequate deductions to net Removals may be required;

• identification of (and actionable plan for remediation of) emissions of CO₂e during a Project's operational and post-cessation life cycle; and

• monitoring reports that are made publicly available to the Registry.

Protocols must categorize the Risk of Reversal for determining the appropriate Buffer Pool Size in the event of a Reversal. Isometric has provided a risk questionnaire (see Appendix B) that can serve as guidance on how Risk of Reversal is determined. The answers to the risk questionnaire are used to support the Risk of Reversal and Buffer Pool Size.

The Risk of Reversal and the corresponding Buffer Pool Size are meant to insure against Reversals that may be observed as a result of monitoring. The Buffer Pool is not meant to insure against risks in cases in which carbon is stored in an open system (e.g., the ocean) and direct observation would not be possible. In open systems, storage risks should be assessed as part of the Uncertainty assessment and accounted for in the Conservative estimate of Removal.

All Projects must follow GHG accounting guidelines as set out by the relevant Protocol. This includes guidelines for conducting transport emission accounting, energy use accounting and embodied emission accounting as well as specific Protocol requirements such as Default Emission Factors.

Protocols Certified by Isometric should use Consequential Analysis to determine carbon emissions. Protocols must address:

• byproduct accounting;

• accounting regime (consequential); and

• considerations relating to the temporal aspects of emissions and possible effects on quantification.

Attributional Analysis may be permitted on a case by case basis by Isometric, if appropriately justified (e.g. on grounds of accuracy and feasibility).

When submitting Claimed Removals, the Project's emissions, Removals and Leakages must be presented together in net metric tonnes of CO₂e as part of a GHG Statement.

Removals are conducted and Verified as part of specific Projects. This section describes the requirements for Projects to be compliant with the Isometric Standard.

Projects must demonstrate that they have legal ownership over the rights to all Removals that will be claimed from the Project, including at minimum making a representation to Isometric to this effect.

When there are multiple parties involved in the Removal process, and to avoid Double Counting, a single Project Proponent must be specified as the sole owner of the Removals.

Ownership must be defined in contracts between the Project Proponent and other Project participants, which may include, for example, suppliers of Feedstocks, transportation and logistics companies, and/or storage site owners and operators.

Contracts must:

• relinquish ownership of all Removals to the Project Proponent;

• clearly indicate that other companies or operators participating in the Project cannot claim Credits, Emissions Reductions or offsets as a result of participation in the Project;

• provide mechanisms for the Project Proponent to obtain required information to fully calculate the Removals from aspects of the Project relevant to the company; and

• stipulate that unless these third parties are the end owners of the generated Credits that they will not advertise that they are producing a “low emission product or practice,” in connection with or benefitting from the Removals carried out by the Project.

For a Project to be evaluated for the Isometric Registry, the Project Proponent must document Project characteristics in a Project Design Document (PDD). The document will form the basis for Project Validation and evaluation in accordance with the relevant Certified Protocol. The PDD should be consistent with ISO 14064-2:2019⁷, and should include:

• Project title, purpose(s) and objective(s);

• type of Project, including descriptions of how the Project will achieve Removal based on the emission calculation requirements laid out in the relevant Protocol;

• Project location, including organizational, geographic and physical location information, allowing for the unique identification and delineation of the specific extent of the Project;

• conditions prior to Project initiation to support identification of the Counterfactual emissions;

• Project technologies, products and services;

• anticipated aggregated net Removals in tonnes of CO₂e likely to occur from the Project;

• anticipated Uncertainty determination approach;

• identification of risks that could substantially affect the Project's Removals and, if applicable, any measures to manage those risks;

• roles and responsibilities, including contact information of the Project Proponent and other Project participants;

• a summary environmental impact assessment;

• description of stakeholder, community, or other interested party Consultations and mechanisms for ongoing communication, and outcomes of any such discussions;

• a chronological plan or actual dates and justification for the following:

  • Project Start Date;

  • GHG Baseline time period;

  • Project Crediting Period; and

  • frequency of monitoring and reporting and the Project period, including relevant Project activities in each step of the Project cycle, as applicable; and

• Project Risk of Reversal.

  • Note that project Risk of Reversal must be greater than or equal to the Risk of Reversal outlined in the relevant Protocol. The Risk of Reversal can be increased to account for site-specific considerations that may make a Reversal more likely (e.g., increased risk of a natural disaster). Any increase in Risk of Reversal must be documented, along with its justification, in the PDD.

Isometric will not publicly disclose sensitive business information inherent to data included in the PDD or otherwise provided by the Project Proponent. Information will be labeled as sensitive by the Project Proponent, and Isometric will communicate to the Project Proponent whether any information deemed sensitive is necessary to be shared in order to accurately reflect Removal GHG calculations. Sensitive business information may include, but is not limited to:

• locations,
• names,
• proprietary processes,
• non-public acquisitions/partnership plans, etc.

Projects are only eligible to claim Credits for activities that are exclusively registered with the Isometric Registry. Projects are only eligible to receive Credits on the Isometric Registry using an Isometric Certified Protocol.

At time of Project application and Validation, Projects must use the latest available version of a Certified Protocol, unless a grace period has been explicitly specified by Isometric, whereby a former version of a Protocol may continue to be used for a defined time period.

Projects which have already been Validated may continue to apply the version of the protocol they were Validated under, until the next Crediting Period renewal, unless otherwise specified in the updated Certified Protocol.

Projects should conform to all relevant laws and regulations in the jurisdiction in which they operate.

Projects must be Additional, according to the guidance described in the Isometric Standard Additionality approach.

Projects must use the Isometric approved Default Emission Factors as laid out in relevant Protocols. If Projects believe there is reason for them to deviate from these values they may contact Isometric with supporting information.

The Project Proponent is responsible for notifying Isometric of any changes to operations that could change the eligibility of their process.

Projects are eligible to begin submitting Claimed Removals to Isometric following Project Validation which, once Verified, may be used to issue Credits. See Section 6 for more information on Crediting.

Projects are eligible to Issue Credits for the duration of the Crediting Period specified in the Project's PDD. If a Project Proponent wishes to renew the Crediting Period of a Project, an updated PDD must be provided and the Project must be re-Validated. There is no limit on the number of times a project can be renewed providing it is still in compliance with the relevant Certified Protocol. In general, the maximum Crediting Period is 5 years, unless otherwise specified by the relevant Certified Protocol. The minimum monitoring frequency to ensure projects still remain active should be at maximum the length of the Crediting Period.

Isometric does not Issue Ex-ante Credits.

Relevant stakeholders must be informed of the Project's proposed and current activities by the Project Proponent. All stakeholders should be equitably represented, involved and able to contribute freely. This includes but is not limited to Indigenous Peoples and Local Communities (IPLCs), stakeholders with land-tenure rights, local policymakers. Additional stakeholders may include regional or national government officials, local NGOs, or other groups likely to be affected by the project.

Consultation with stakeholders and rights-holders should be conducted and evidence of these meetings should be submitted to Isometric. Consultations should meet the requirements below.

• Iterative:

  • The first consultation meeting should occur prior to Project development, such that any input and concerns can be incorporated into the Project's design, and meeting and correspondence should be operational throughout the Project's life cycle.

• Accessible:

  • Stakeholders and rights-holders should be invited to consultation meetings with a minimum notice of 14 days.

  • Stakeholders and rights-holders should be invited to consultation meetings via methods including but not limited to the post, email, or notices in newspapers and public places.

  • Consultation meetings should be scheduled to maximize attendance, taking note of cultural or religious holidays and heritage.

  • Meetings, documentation and correspondence should be:

    • in the local language(s), or have a translator where necessary to facilitate communication;

    • respectful of local knowledge; and

    • accessible to a non-technical audience.

• Transparent:

  • The intention of each consultation meeting should be communicated to all stakeholders prior to the meeting.

  • All stakeholder or Project Proponent conflicts of interests should be declared.

• Free from external manipulation.

• Where applicable, ensure free, prior and informed consent (FPIC) processes with IPLCs.

• Include a system for stakeholders to voice, process, and resolve grievances:

  • Project Proponent contact information must be made available to all stakeholders.

  • Grievances must be acknowledged no later than 14 days after receipt by the Project Proponent.

  • Grievances must be resolved or escalated no later than 60 days after receipt.

• Systematically documented and made public or accessible upon reasonable request.

Projects must assert with the PDD the method(s) for compliance with regulations for all jurisdictions to which the Project is beholden.

Projects must comply with national and local laws and regulations and, where relevant, international conventions and standards.

Projects must consider the material environmental and social impacts that could potentially arise as a result of their activities, both within and beyond its boundary, and at minimum must do no net environmental or social harm. Remediation of any unintentional harm, caused directly or indirectly by a project, must be carried out by a Project Proponent. Failure to adequately remediate any harm caused may lead to a project being subject to Credit cessation and cancellation. The consideration of these impacts should be ongoing throughout a Project's lifespan and assessments updated when necessary, and should include provisions for Project closure and post-closure.

For each aspect of the environmental and social impacts assessment, the Project must demonstrate how these risks have been assessed and, if applicable, what mitigation plan is in place to prevent them. If risks are not applicable to the project this finding must be reported to Isometric, and environmental regulators where applicable, and justified within the PDD.

A full Environmental and/or Social Impact Assessment (EIA and/or SIA) conducted by a third party is suggested for all Projects but is only required if impacts are considered significant and/or if required by the host jurisdiction. It is the responsibility of the Project to ensure that any EIA or SIA undertaken meets all local, regional and national and international regulations and laws.

Assessments undertaken to evaluate the potential for environmental harm by a Project may be undertaken with varying formats, names and costs, depending on the location of a Project. These assessments are commonly named environmental impact assessments (EIA) and are often required under specific environmental laws or regulations. Within some countries, such as the U.S., multiple levels or types of EIA may exist. Within the U.S. EIA’s exist as Environmental Impact Statements (EIS) and Environmental Assessments (EA), with requirements for each type of assessment varying on a federal and state by state basis. It is the responsibility of the Project Proponent to identify specific requirements for EIA’s within the location and type of a Project. Within this Standard all such assessments are referred to as Environmental Impact Assessments (EIA).

A Project must demonstrate that it creates no net environmental harm. These assessments and mitigation strategies should consider, where applicable, the potential negative environmental risks from a Project’s implementation. This should include, but is not limited to, the following, as outlined in the ICVCM Core Carbon Principles⁸:

1. Resource efficiency and pollution prevention, including:
   1. Pollutant emissions to air.
   2. Pollutant discharges to water, noise and vibration.
   3. Generation of waste and release of hazardous materials, chemical pesticides and fertilizers.
2. Biodiversity conservation and sustainable management of living natural resources:
   1. Avoid, or where this is not feasible, minimize negative impacts on terrestrial and marine biodiversity and ecosystems.
   2. Protect the habitats of rare, threatened, and endangered species, including areas needed for habitat connectivity.
   3. Do not convert natural forests, grasslands, wetlands, or high conservation value habitats.
   4. Minimize soil degradation and soil erosion.
   5. Minimize water consumption and water stress in any necessary mitigation activities.

A Project must demonstrate that it creates no net social harm. These assessments and mitigation strategies should consider, where applicable, any risk of a negative social impact. This should include, but not be limited to, the following, as outlined in the ICVCM Core Carbon Principles⁸:

1. Labor rights and working conditions including:
   1. Providing safe and healthy working conditions for employees. Health and Safety risk assessments and mitigation strategies in accordance with local, national and international laws and guidelines are required by every Project for each stage of their operations and must ensure the nature of the work being undertaken is captured.
   2. Providing fair treatment and equal opportunities to all employees, regardless of age, gender, race, ethnicity, religion, disability, sexual orientation, sexual identity, education, national origin, or any other distinguishing characteristic or trait.
   3. Prohibiting the use of forced labor, child labor or labor by trafficked persons.
   4. Protecting third party contracted personnel.
2. Land acquisition and involuntary resettlement, including:
   1. Actively avoiding physical or economic displacement.
   2. Where not possible, minimizing the amount and the impact.
3. Impacts on Indigenous People (IP), Local Communities (LC) and cultural heritage; The project must:
   1. Identify any direct or indirect impacts on IPLCs, including customary rights.
   2. Recognise, respect and promote the protection of the IPLCs rights in line with applicable international human rights laws and UN Declarations, including the United Nations Declaration on the Rights of Indigenous Peoples⁹.
   3. Preserve and protect cultural heritage and ancestral knowledge aligned with IPLCs and any UNESCO Cultural Heritage Conventions.
   4. Not force eviction or physical or economic displacement.
   5. If there are any potential negative impacts or displacement is required, the Project must not proceed without the free and prior and informed consent (FPIC)¹⁰ of the relevant IPLCs.
4. Respect for human rights and stakeholder engagement, including:
   1. A Stakeholder Input Process is in place and aligns with the guidance outlined in Section 3.5 of the Isometric Standard.
   2. Avoiding discrimination arising as a result of the Project.
   3. Identifying, avoiding, mitigating and remediating any human rights impacts as defined by international treaties, organizations, and conventions including the United Nations International Bill of Human Rights¹¹.

Projects must demonstrate, where relevant and feasible, how their carbon removal activities are consistent with relevant Sustainable Development Goals (SDG) objectives of all jurisdictions in which they operate. The SDGs are a set of 17 global and interconnected goals established by the United Nations in 2015 to address a wide range of social, economic, and environmental issues.

Such an explanation should be included in the Project Design Document. If applicable, a qualitative assessment should be included for any positive impacts identified in relation to SDGs other than SDG13. Project Proponents should provide information on any standardized assessment tools and methods used as part of this explanation.

All evidence and data related to the underlying quantification of Removals will be available to the public through Isometric's platform for any Verified Credit. This includes:

• Project Design Document
• Measurements taken
• Emission factors used
• Scientific literature used

The Project Proponent may request for confidential information to be restricted, whereby it will only be available to authorized Buyers, Isometric and designated VVBs (during Validation or Verification). However, numerical data produced or used as part of the quantification of CO₂e removed may not be restricted in this way.

This section defines the requirements for Validation and Verification of Projects on the Isometric Registry. Accredited VVBs Validate Projects and Verify Removals in line with this Isometric Standard and a Certified Protocol.

All VVBs are approved by Isometric independently and impartially based on alignment with Conflict of Interest policies, rotation of VVB policies, oversight on quality, and the following requirements:

• VVBs must be able to demonstrate accreditation from:

  • an International Accreditation Forum¹² member against ISO 14065 or other relevant ISO standard, including but not limited to ISO 14034, ISO 17020, ISO 17029; or

  • a relevant governmental or intergovernmental regulatory body.

• Alternatively, on a case-by-case basis, if VVBs are able to demonstrate to Isometric that they satisfy all required Verification needs and competencies required for the relevant Protocol and follow the guidelines of ISO 19011 or other relevant standards, they may be approved.

All Projects must undergo an initial Project Validation, carried out by an independent VVB, to assess conformity with the Isometric Standard, and with the applied Certified Protocol. Once a Project has been Validated, the Project is subsequently able to submit Claimed Removals to Isometric. Isometric requires Verification of any Claimed Removal in order to Issue Credits. Validation and Verification will be carried out in line with ISO 14064-3 and ISO 14065. Additional requirements are listed below.

• Removals may be Verified annually, or more or less frequently, according to the requirements of the relevant Certified Protocol, or at the Project Proponent's request.

• Project Validation may occur at the same time as the first Verification, or before the first Verification.

• If a Project Proponent wishes to renew the Crediting Period of a Project, an updated PDD must be provided and the Project must be re-Validated.

• Unless otherwise specified in the relevant Certified Protocol, a site visit is required for Validation and the first Verification of a Project. For subsequent Verifications, the VVB must identify whether a site visit is needed, based on an independent risk assessment.

• The level of assurance for Verifications must be reasonable.

Prior to Validation/Verification, the third party should prepare a Validation/Verification plan that details the activities and schedules. The plan may be revised as necessary during the process. The plan should be communicated with the Project Proponent and should include, at minimum:

• the scope and objectives;

• identification of the Validation/Verification team and their roles;

• client/responsible party contact;

• schedule of activities;

• level of assurance;

• Verification criteria;

• Materiality; and

• schedule for site visits.

The Verifier should produce a report that documents the activities, results, findings, and conclusion of the Verification. The Verification report should contain, at a minimum¹³:

• a statement that the Project Proponent is responsible for the fair presentation of the PDD in accordance with the criteria;

• a statement that the Verifier is responsible for expressing an opinion on the PDD based on the Verification;

• a description of the Verification evidence-gathering procedures used to assess the PDD;

• the Verification opinion, which will will state the net Removal during the covered period to a reasonable Level of Assurance;

• the date of the report;

• the Verifier’s location;

• the Verifier’s signature;

• a summary of the Claimed Removals, as presented in the GHG Statement;

• reference to the Verification criteria; and

• Verification scope.

Following this process, Isometric will review the Project documents used for Validation and Verification, and either accept them, request corrections or clarifications for the Project Proponent or VVB to address, or reject them. Once Isometric has accepted a Verification Report, the corresponding Removals will be deemed Verified, and eligible for issuance of Credits. The results of the Validation and Verification process, including the Verification Report and Opinion, will be made available for each Project.

The threshold for Materiality, considering the totality of all omissions, errors and mis-statements, is 5% for all Projects. To accept a Verification Opinion, Isometric requires that discrepancies between the Removal Claimed by the Project Proponent and that estimated by the VVB for a given statement be less than the Materiality threshold.

Qualitative materiality issues may also be identified and documented, such as¹⁴:

• control issues that erode the verifier’s confidence in the reported data;
• poorly managed documented information;
• difficulty in locating requested information;
• noncompliance with regulations indirectly related to GHG emissions, removals or storage.

If an overstated Project (one which claims more Credits than it has produced) is discovered after Credits have been Issued, please see the Isometric policy on Changes to Issued Credits.

Any organization which has been involved in the development of a particular Project Proponent may not act as a VVB for Validation and/or Verification purposes for that Project. Any organization which has been paid by a particular Project to assist in developing any part of a Certified Protocol for their process may not act as a VVB for Validation and/or Verification purposes for that Project.

To minimize the risk of conflicts of interest occurring between the Project Proponent and the VVB, Isometric will select and engage VVBs for Project Validation and Verification, and VVBs must complete a conflict of interest disclosure.

Isometric requires that Projects must work with a single VVB for no longer than five consecutive years. A given VVB may conduct Verification for a Project during no more than five out of seven consecutive years.

In addition to the qualification requirements, Isometric may oversee VVB activity during the Validation and/or Verification process, and may suspend approval of a previously approved VVB. Oversight can include review of VVB documentation, including Verification and sampling plans, reports, opinions and conflict of interest disclosures, as well as review of Project Proponent documentation.

Isometric will report significant and/or repeated VVB performance concerns to the relevant accreditation body.

Isometric Credits represent one net metric tonne of verified CO₂ removal, and may be Issued, Transferred and Retired on the Isometric Registry according to the rules and requirements set out in this section.

Isometric is the sole Credit issuing body on the Isometric Registry.

Credits have only one owner at any time. A full ownership history is tracked and is publicly visible for each Credit. Each Credit is Issued Ex-post against a net Verified Removal, thereby ensuring every tonne of CO₂ removed is Credited and accounted for only once, and that any Credit can be traced back to an individual Removal.

Each Credit has a publicly available history of ownership that indicates when the Credit was first Issued, who it was first Issued to, if and when it was subsequently Delivered or Transfered, if and when it was Retired and by whom, on behalf of whom.

When first Issued, a Credit's status is Active. Upon Retirement of a Credit, its status becomes Retired. Similarly, upon Cancelation of a Credit (for example, in compensation for erroneous overissuance, or in compensation for a Reversal as outlined in Reversals and Buffer Pools), its status becomes Canceled.

Credit metadata include:

• Unique Serial Number;

• Issuance Date;

• Issuing Project;

• Issuing Project Proponent;

• Country of Removal;

• Ownership history, including the current Owner (the Owner who is retiring the Credit) and all previous Owners and Transfer Dates;

• Retirement Date;

• Retirement Beneficiary; and

• Credit Status.

Credits are Issued against a specific Removal. This process is undertaken once a Removal has been Verified. Credits are always Issued to the Project Proponent of the Removal. The Project Proponent is then able to Deliver Credits to Buyer Credit Accounts on the Registry, and can do so at a time and in an order of their own discretion.

Deliveries can be made by Project Proponents to Buyer Credit Accounts, resulting in transfer of ownership of one or more newly Issued Credits. Further Transfers can be made by Credit Account holders to other Credit Accounts, resulting in transfer of ownership of one or more Credits. For each Credit, the initial Delivery and all Transfers are logged on the Credit and made publicly available in the Credit's history.

Project Proponent Deliveries are subject to the following rules:

• Project Proponents can only Deliver Credits that have been Issued;

• Project Proponents can only Deliver Credits that they own; and

• Project Proponents can only Deliver Credits to Buyers who have an active Isometric Registry Credit Account.

Buyer Transfers are subject to the following rules:

• Buyers can only transfer Credits that they own; and

• Buyers can only transfer Credits to another organization that has a Credit Account on the Isometric Registry.

Retirement is the mechanism by which a Credit's ownership state is finalized. This ensures that once the tonne of CO₂ represented by the retired Credit is used towards an accounting activity, it can never be used again by the owner, the Beneficiary of the retirement, or any other actor.

The Beneficiary of a Retirement is the organization on behalf of whom the Credit was retired, and must be publicly identified. Beneficiaries can be the current holder of a Credit at the time of retirement, or an organization that is specified by the Credit Account holder during the Retirement procedure. The Credit Account holder can retire Credits by following the Retirement process through their Credit Account on the Registry.

The owner of an unretired Credit may publicly market its ownership of said Credit, as well as the potential for the Credit to be retired by any current or future owners, but only the Beneficiary of a Retired Credit may claim the environmental benefits associated with that Credit.

Retirement is subject to the following rules:

• a Credit Account holder can only retire Credits they own, which are in their Credit Account;

• a Credit can only be Retired once; and

• any number of Credits can be retired at any given time, provided that number of Credits does not exceed the number of Credits held by the Credit Account.

Retirement Certificates serve as proof of the Retirement of one or more Credits, and are produced only on completion of a Retirement. Every Retirement Certificate relates to one or more Retired Credits. If more than one Credit is Retired at a time, the Certificate will list all Retired Credits. Retirement Certificates show the relationship between retired Credits and the Removals they derive from.

This section outlines how Reversals are handled on the Isometric Registry, through the use of Buffer Pools.

All Reversals will be reviewed by the Isometric Science Team.

Note that changes to calculations as a result of updates to Protocols are not considered Reversals, and will generally not affect previously issued Credits. However, Isometric will monitor for significant impacts due to Protocol updates to ensure overall quality and to address system level impacts (e.g. considerable evolution of scientific consensus).

Project Proponents must monitor for Reversals as prescribed by a Project's Monitoring Plan, and promptly report Reversals to Isometric if identified. At the verification following a Reversal, the Project Proponent must report relevant monitoring data for any Reversal which has occurred, to be assessed by the verifier as part of that verification. Reversal data from Projects will be made public.

When a Reversal is identified, Credits will be Canceled from the Project Proponent's Buffer Pool to compensate for the Reversal. The number of Credits to be Canceled must equal the size of the Reversal.

In the event that a Project Proponent is not able to comply with monitoring, closing or Embodied Emission allocation requirements as outlined in the relevant Protocol, the treatment of possible Reversals will be assessed on a case by case basis.

Buffer Pools are the current solution to Uncertainty in storage and are subject to re-evaluation given advancements in understanding of their effectiveness and of the risk of Reversal of Removal Projects. Isometric reserves the right to amend its Buffer Pool approach given notice and consultation with Project Propenents in line with this Standard's Updates to Protocols policy.

Isometric will maintain a Buffer Pool of Credits in accounts specific to each Project Proponent from which Credits will be Canceled in the case of a Reversal.

Whenever Credits are Issued following a Verified Removal, a percentage of these Credits will be Issued to the Project Proponent's Buffer Pool account, according to the Buffer Pool Size below.

Credits in a Buffer Pool cannot be Transferred, or used to make Deliveries during the Creding Period or after the Creding Period has ended, as they are held to accomodate for as long as there is a risk of Reversal from a Project. Exceptions may occur when Uncertainty decreases and thus Buffer Pool size is amended for a Project Proponent, in which case extra Buffer Pool Credits may be used to make Deliveries.

In the case that there are insufficient Credits in a Project Proponent's Buffer Pool to compensate for any triggered Reversals, all further Credits Issued from Removals conducted by the Project Proponent (whether from the same Project, or other Projects run by the same Project Proponent) will be assigned to their Buffer Pool and Canceled, until all such Reversals have been fully compensated. Cases where Project Proponents cease operations will be addressed on an individual basis.

The Buffer Pool Size is determined by the Risk of Reversal of a given approach, as outlined below. The Risk of Reversal is defined in the relevant Certified Protocol. Projects with a higher Risk of Reversal have a correspondingly larger Buffer Pool. Note that the Buffer Pool is applied in addition to the Conservative approach taken in the quantification of net CO₂ Removal, whereby uncertainty is factored into the Credited Removal. The following Buffer Pool sizes may be subject to change in future Standard versions based on empirical data.

Furthermore, Reversals are classed as either avoidable or unavoidable, as judged by Isometric, in consultation with selected VVB(s) and/or Science Network representatives.

Where an Avoidable Reversal has occurred, a Project Proponent must reimburse their Buffer Pool account by transferring a number of Credits equal to the size of the Reversal to the Buffer Account. While there are any outstanding Avoidable Reversals to be remedied in this way, all further Credits Issued from Removals conducted by the Project Proponent (whether from the same Project, or other Projects run by the same Project Proponent) will be assigned to their Buffer Pool, until all such Reversals have been fully remedied.

Where an Unavoidable Reversal has occurred, the Project Proponent is not required to reimburse their Buffer Pool account.

Isometric has rules and procedures in place to mitigate the risk of occurrence of Double Counting, which can occur in different ways, including double issuance, double use and double claiming.

Double issuance (occurring when more than one unique unit is Issued for the same Removal activity) is not permissible, and Isometric has checks in place to mitigate the possibility of double issuance, outlined below. Any Removal activity listed on the Isometric registry must not be listed on another program, and may not be used to make a separate carbon Removal claim elsewhere.

Isometric has mechanisms in place to enforce these requirements related to Double Issuance. Firstly, Project Proponents need to make contractual commitments to only issue Credits through Isometric for any given Project for which Isometric is acting as the Registry. Secondly, Isometric will conduct initial due diligence on Projects ahead of issuing any Credits to ensure these Projects are not being credited on another registry. Finally, Isometric conducts ongoing monitoring to ensure that Double Issuance does not take place at a later time.

Double use (occurring when an Issued credit is further transferred, used or retired after already having been retired) is mitigated through a transparent, public record of all Credits and Retirements, ensuring all Retirements used as claims towards mitigation targets can be uniquely identified, and can be traced back to the specific Removal activity the Credit was Issued against. Once a Credit has been Retired, it cannot be used further, and a unique, public Retirement Certificate is produced.

Double claiming (occurring when an Issued credit is claimed twice towards achieving mitigation targets or goals) is not permitted on the Isometric Registry. For any Credit, no separate Removal claims may be made for the underlying Removal from which the Credit was Issued. Isometric will monitor for instances of Double claiming, and Credit Account users engaging in double claiming may have their Credit Account suspended.

Calculation of Uncertainty should follow documented best practices, such as the requirements of the Joint Committee for Guides in Metrology (JCGM) JCGM100:2008 - Evaluation of measurement data — Guide to the expression of uncertainty in measurement (GUM).¹⁴ Uncertainty can be assessed using two different methods¹⁵:

• Type A Uncertainty, where Uncertainty is assessed by making repeated observations of the parameter of interest
• Type B Uncertainty, where Uncertainty is founded on a priori distributions, evaluated by scientific judgment based on all of the available information on the possible variability of the parameter of interest

Type B Uncertainties may frequently be encountered, since it is not always practical to make repeated measurements for every input parameter, and many input parameters are published values or estimated through other means.

Emission factors utilized should provide an Uncertainty value associated with the specific factor. Some databases from which emission factors are derived include and report the Uncertainty within the database¹⁶. The factor used, its source, and the value of the Uncertainty reported and used, should be documented. For emission factors for which no Uncertainty information is provided, clearly document this and refer to [11.10.5 Unknown Uncertainties].

See the GUM for details on calculation of parameter or measurement Uncertainty. For instance, measurement parameter Uncertainty estimates could be derived from manufacturers specifications or calibration records. If repeated measurements are taken, the type A uncertainty should be reported as the standard deviation. Uncertainties should be documented and reported for each measured parameter.

For laboratory analyses, Uncertainty may be reported based on laboratory quality assurance documentation, including laboratory calibration results and records which use a reference calibration standard that is traceable to a national standard.

For a reported value based on multiple laboratory analyses, for which the value is reported as a mean, the type A uncertainty is calculated based on the standard deviation of the value around the mean.

When published Uncertainty information is not available and calculation via direct measurement is not feasible, estimation of Uncertainty should follow documented best practices, such as guidance from the GUM for evaluating type B Uncertainty. The specific approaches taken should be clearly documented.

Specifically regarding emission factors, the default values for basic Uncertainty from Section 10.1 of Ecoinvent’s Overview and Methodology document may be used. Ecoinvent’s protocol assumes a lognormal distribution for a value and then uses a Pedigree Matrix to assign uncertainties based on data quality.

Here are a couple of examples on how Option A (conservative estimate of input parameters) can be applied. These examples are for illustration purposes only:

Example 1: Uncertainty in Truck transportation carbon intensity

There are only a few carbon intensity factors published in a reputable emissions factor database for truck transportation. The factors range from 0.2 kg/km/t to 1.2 kg/km/t depending on different vehicle types, and the Project Proponent doesn’t know exactly what type of vehicle is used. In this case, a higher carbon intensity leads to less net CO₂ Removal, and there are only a few relevant emissions factors to choose from so a distribution is not assumed. It is recommended that the project take the conservative estimate to be the maximum value of 1.2 kg/km/t.

Example 2: Uncertainty in ocean DIC retention

For enhanced weathering in agriculture, a downstream loss term in the Removal calculation that cannot be directly measured is the percentage of bicarbonate ions from weathering that is retained as dissolved inorganic carbon (DIC) upon reaching the ocean. A Project Proponent uses a regional ocean model to determine that the DIC retention fraction follows a normal distribution, with a mean of 0.90 and a standard deviation of 0.02. A lower DIC retention fraction results in less net CO₂ Removal, so the conservative estimate is taken to be 1 standard deviation below the mean (corresponding to the 16th percentile). The conservative estimate of the DIC retention index is thus 0.88.

This questionnaire provides guidance on assessing Risk of Reversal, to be used by Protocols and Projects which need to make this assessment for use on the Isometric Registry. Please see the Reversals and Buffer Pools for more details on how Risk of Reversal is used.

Risk Score Categories

• 0: Very Low Risk Level (2% buffer)

• 1-3: Low Risk Level (5% buffer)

• 4-5: Medium Level (10% buffer)

• 6+: High Risk Level (20% buffer)

Isometric's Uncertainty and Buffer Pool policies represent two mostly non-overlapping approaches for how Isometric plans to be conservative in how credits are quantified and to potentially insure against future events that may result in a Reversal. Specifically, in removal pathways that utilize large, open-system reservoirs (e.g., the ocean) where direct observation of a reversal is not feasible, Isometric's Uncertainty policy will generally result in a larger uncertainty discount¹⁷, and Isometric's Buffer Pool policy will generally result in a smaller Buffer Pool Size. Conversely, in removal pathways that utilize closed-system reservoirs that are more straightforward to monitor, Isometric's Uncertainty policy will generally result in a smaller uncertainty discount, but the activity will be subject to a larger Buffer Pool Size. Below are two example scenarios that illustrate how and when these two policies are invoked.

Example 1: Ocean Alkalinity Enhancement

An OAE Project Proponent releases a known amount of alkalinity into the ocean. In accordance with the Protocol and PDD, the Project Proponent uses a model to estimate that the median CO₂ uptake after a certain amount of time is 100 tonnes. In accordance with Isometric's Uncertainty policy, the Project Proponent reports that the 16th percentile of CO₂ uptake outcomes is 15 tonnes below the median (resulting in a 15t uncertainty discount that is subtracted from the gross CO₂e removed). The Project Proponent follows Isometric's guidance in answering the risk questionnaire and determines they have a Risk of Reversal that corresponds to Risk Level A (resulting in a 2% Buffer Pool Size).

• Net CO₂e removed = 100t - 20t - 15t = 65t

  • Gross CO₂ removed: 100t

  • Counterfactuals and GHG emissions CO₂e: -20t

  • Uncertainty discount CO₂e: -15t

• Credits issued to Supplier: 63.7 credits (65 - 1.3)

  • Total Credits issued: 65 credits

  • Credits deposited to Buffer Pool account: 65 credits * 2% = 1.3 credits

Example 2: Bio-oil Production and Injection

A bio-oil production and injection Project Proponent produces 100 tonnes of bio-oil with a well-constrained GHG Assessment and counterfactuals (there is no uncertainty discount for the amount of CO₂e removed because conservative parameters were used in the calculation). This bio-oil is then injected into an underground reservoir that is equipped with a suite of chemical sensors that can measure CO₂ and methane. The corresponding PDD has provisions to continue monitoring for fugitive gases for 40 years after injection has concluded. The Project Proponent follows Isometric's guidance in answering the risk questionnaire and determines they have a Risk of Reversal that corresponds to Risk Level B (resulting in a 5% Buffer Pool Size).

• Net CO₂e removed = 100t - 20t - 0t = 80t

  • Gross CO₂e removed: 100t

  • Counterfactuals and GHG emissions CO₂e: -20t

• Credits issued to Supplier: 76 credits (80 - 4)

  • Total Credits Issued: 80 credits

  • Credits deposited to Buffer Pool account: 80 credits * 5% = 4 credits

1. https://www.epa.gov/ghgemissions/overview-greenhouse-gases ↑

2. https://redd.unfccc.int/ ↑

3. https://semver.org/ ↑

4. https://www.ipcc.ch/assessment-report/ar6/ ↑

5. https://www.geol.lsu.edu/jlorenzo/geophysics/uncertainties/Uncertaintiespart2.html#muldiv ↑

6. Johansen, A.M., Evers, L. and Whiteley, N., 2010. Monte Carlo methods. International Encyclopedia of Education, pp.296-303. ↑

7. https://www.iso.org/standard/66454.html ↑

8. Section 4: Assessment Framework - Core Carbon Principles 2023, The Integrity Council for the Voluntary Carbon Market ↑ ↑

9. United Nations Declaration on the Rights of Indigenous Peoples, 13 September 2007 ↑

10. UN Guiding Principles on Business and Human Rights Reporting Framework with implementation guidance (2015); International Business Leaders Forum (IBLF) and International Finance Corporation (IFC) Guide to Human Rights Impact Assessment and Management (HRIAM), September 2011 ↑

11. International Bill of Human Rights, United Nations ↑

12. https://iaf.nu/en/accreditation-bodies/ ↑

13. ISO 14064-3:2019, 6.3.3 ↑

14. https://www.iso.org/sites/JCGM/GUM/JCGM100/C045315e-html/C045315e.html?csnumber=50461 ↑ ↑

15. Ibid. ↑

16. Databases such as Ecoinvent provide uncertainty factors, often based on a lognormal probability distribution, with a 95% confidence interval. The reported uncertainty accounts for systematic error, random error, and may also use a pedigree matrix to assign additional qualitative data quality impacts as an uncertainty value. These uncertainties are reported as a combined standard uncertainty. See details and examples for ecoinvent: https://ecoinvent.org/wp-content/uploads/2020/10/dataqualityguidelineecoinvent_3_20130506.pdf ↑

17. "Uncertainty discount" is defined as the difference between the Conservative estimate of Removal, and the estimate of Removal in the absence of accounting for uncertainty ↑