GHG Accounting: The Practice Uptil Now

For years, organizations globally have relied on two major frameworks for greenhouse gas (GHG) accounting and reporting: the GHG Protocol and the ISO standards (notably the ISO 14064/1406X family). So why choose one over the other? Each standard has strong adoption and differing strengths.

The GHG Protocol, managed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), has become nearly ubiquitous in voluntary corporate disclosures. It provides detailed guidance on measuring emissions across Scope 1, 2, and 3, covering value chains and upstream/downstream emissions. Its tools, sector guidance, and calculation methodologies are widely used by companies, investors, and sustainability reporting initiatives. Even the IFRS S2 Standards requires companies to measure their greenhouse gas emissions in accordance with GHG Protocol.

On the other hand, the ISO standards have traditionally held more weight in formal assurance, verification, regulation, and procedures. ISO 14064-1, 2, and 3 set out steps for quantification, reporting, and verification (including third-party verification) for measuring and reporting GHG emissions. Other ISO standards, like ISO 14067, address product carbon footprints. In many countries, including Brazil, Germany and Belgium, regulators or legislation refer to or require ISO standards for official or regulated reporting, while GHG Protocol standards are more common in voluntary or investor-driven reporting.

Because both frameworks are robust and credible, many organizations have used one or both: for example, using GHG Protocol for internal or voluntary reporting and switching to or referencing ISO standards when verification or regulatory compliance is needed. But this dual usage has often led to overlaps, differing terminology, inconsistencies in verification rigor, and extra burdens for companies trying to align with multiple frameworks.

Moving Towards Standardization: The Partnership and Its Outcome

On 9 September 2025, the ISO and the GHG Protocol announced a strategic partnership aimed at harmonizing their existing portfolios of GHG standards and jointly developing new ones. The goal is not merely alignment but co-creation of a unified set of standards, co-branded, to cover corporate accounting, Scope 2 and Scope 3 emissions, as well as a product carbon footprint (PCF) standard. This harmonized portfolio is intended to merge ISO’s 1406X family with the GHG Protocol’s corporate, scope-2 and scope-3 suites, bringing together technical rigor, policy relevance, and practical usability. The collaboration aims to produce a common global language for emissions accounting; simplifying practices for companies, increasing consistency for policymakers, and reducing reporting burdens for all users.

While the partnership promises much, some details remain to be worked out. For example, existing standards will continue in force until the new ones are developed. The announcement indicates that the work will require an integrated technical process, stakeholder engagement, and wide consultation. Some external commentary estimates that development, drafting, consultation, and publication of the unified standards could take at least 18 to 24 months.

Why Is This Step Significant?

The ISO-GHG Protocol partnership addresses several longstanding challenges in the carbon accounting and reporting landscape. First, it reduces fragmentation. With many different standards, guidance documents, verification approaches, and terminology, companies operating across jurisdictions often face confusion, duplication, and inefficiency. Standardizing terminology, measurement, scope definitions and verification practices will help streamline reporting, reduce compliance costs, and make data more comparable.

Second, this harmonization will enhance credibility and trust. A unified standard backed by two major institutions can strengthen assurance and verification. It can also assure investors, regulators, auditors, and other stakeholders that disclosures are consistent, transparent, and robust.

Third, in the context of growing regulatory demands, such as climate disclosure mandates, this partnership could provide a solid baseline for regulation. Where regulators have asked companies to follow GHG Protocol or ISO standards (or both), the unified standard may reduce conflicts or inconsistencies in regulatory obligations.

Finally, from a climate action perspective, more consistent and accurate data means better measurement of progress toward net-zero goals. It can reduce risk of double counting, increase clarity over Scope 3 emissions, and provide more granularity for product-level emissions, enabling better strategies for reductions.

What to Expect Next?

Over the coming months and years, several developments are likely:

  • Draft standards and public consultations: ISO and GHG Protocol will prepare drafts of the unified standards and possibly new ones, then seek feedback from businesses, auditors, civil society, governments, and other stakeholders.
  • Timeline estimates likely to settle: While 18-24 months is an early estimate, it will be important to confirm when the co-branded unified standards will finally be released, and when companies should expect them to become usable or required in different jurisdictions.
  • Transition and implementation challenges: Companies will need to assess how to transition from existing standards to unified ones i.e. updating internal systems, possibly changing verification partners, retraining staff, adjusting for new methodologies (especially around Scope 3 and product footprinting).
  • Ongoing oversight and governance: A successful unified standard will need strong and transparent governance, inclusive stakeholder engagement, clear rules for verification, and accessibility. Issues like cost of standards, open access, regional differences, and sector-specific needs will need careful attention.