Introduction

The Policy and Action Standard, developed by the GHG Protocol, provides a framework to estimate and report the greenhouse gas (GHG) effects of policies and actions. It applies to ex-ante and ex-post assessments and is designed for use by governments, institutions, and other stakeholders aiming to understand GHG impacts with consistency and transparency.

Objectives of estimating the GHG effects of policies and actions

The standard is intended to inform policy design, improve effectiveness, support reporting, and ensure accountability. It may be used to evaluate mitigation and non-mitigation policies. Users are expected to specify the purpose and intended audience of the assessment, which may include policymakers, NGOs, funders, and the public. GHG effects must be assessed with appropriate accuracy and completeness relative to the assessment’s objectives.

Overview of steps, key concepts, and requirements

The standard outlines a sequence of steps: define the policy or action, identify effects, estimate impacts, optionally verify results, and report findings. Users may assess individual or grouped policies/actions, and the same general approach applies across contexts. GHG effects refer to changes in emissions or removals, while non-GHG effects refer to broader environmental, social, or economic outcomes.

Accounting and reporting principles

The standard is guided by five principles: relevance, completeness, consistency, transparency, and accuracy. These principles support credible GHG assessments and inform the selection of methods, boundary definitions, and data collection strategies.

Defining the policy or action

Users must define the policy or action clearly, including its objectives, implementation context, and type (e.g. regulation, incentive). This includes specifying whether the assessment will be ex-ante (forecasting) or ex-post (evaluating actual outcomes).

Identifying effects and mapping the causal chain

All potential GHG effects must be listed and linked to specific source/sink categories and gases. The causal chain helps map out how the policy/action leads to changes in emissions.

Defining the GHG assessment boundary

The boundary defines which effects, sources, sinks, and gases are included. Exclusions must be justified. A significance assessment helps prioritise which effects to include.

Estimating baseline emissions

The baseline scenario represents what would occur without the policy. This includes annual and cumulative emissions over the assessment period. Key assumptions and data sources must be documented, and the method (e.g. scenario-based or comparison group) justified.

Estimating GHG effects ex-ante

For ex-ante assessments, users must define the policy scenario and estimate expected emissions. The same methods used for the baseline must be applied. Emission factors, global warming potential (GWP) values, and assumptions must be consistent. The GHG effect is calculated by subtracting baseline emissions from policy scenario emissions.

Monitoring performance over time

Monitoring supports both implementation tracking and future ex-post assessments. Key performance indicators (KPIs) should be selected to reflect inputs, activities, and outcomes. A monitoring plan should be developed during policy design to ensure relevant data is collected.

Estimating GHG effects ex-post

Ex-post assessments rely on observed data. The method must mirror the ex-ante structure to allow for accurate comparisons. Normalised results, top-down vs. bottom-up discrepancies, and any unestimated effects must be disclosed.

Assessing uncertainty

Uncertainty must be addressed qualitatively or quantitatively. Sensitivity analyses identify key parameters that most affect outcomes. A range of potential outcomes may be reported when uncertainty is high.

Verification

Verification is optional but encouraged. If undertaken, it must disclose the type (e.g. third-party), the verifier’s competence, and the assurance level. This adds credibility to the reported results.

Reporting

Users must report key details, including the policy description, methodology, assumptions, results, interactions with other policies, and any unquantified effects. Optional data include disaggregated effects by gas or likelihood, and probability-adjusted estimates.

This standard aims to provide a robust foundation for transparent and comparable assessments of the GHG impacts of diverse policies and actions.