Harmonisation of ISO and GHG-P standards must raise the quality bar

By Thea Lyngseth

By Benja Faecks

Today, Tuesday 9 September 2025, the International Organisation for Standardisation (ISO) and the Greenhouse Gas Protocol (GHG-P) announced a new strategic partnership to align and merge parts of their respective greenhouse gas accounting frameworks. In the announcement, the collaboration is described as “a significant milestone in the harmonization of greenhouse gas (GHG) accounting standards” and aims to deliver a unified global framework for emissions quantification and reporting.

Matching footprints

At the heart of the agreement is the harmonisation of three core areas: the corporate footprint standard, the product footprint standard, and the project level GHG accounting standard. These standards matter for corporate financial disclosure, energy efficiency, and carbon crediting projects and supply chain GHG disclosure. An implementation guide will be published later, although not much detail of the process has been made publicly available.

The new partnership will combine each organisation’s leading standards into co-branded, harmonised international standards. This includes standards from the ISO 1406X family (a series of standards for climate change mitigation and navigating to a zero carbon economy) alongside the GHG-P’s Corporate Accounting and Reporting Standard, its scope 2 and scope 3 guidances, and the Product Life Cycle standard. The ambition is to provide a common approach and a shared portfolio covering corporate, product, and project accounting, while creating a platform for future co-development. The GHG-P Land Sector and Removals Guidance (forthcoming) does not fall into the scope of the collaboration.

Harmonisation can’t cost the climate

We welcome the provision of a single reference point, since it opens the door for more coherence in an ecosystem that is currently fragmented and where this fragmentation is often used as an excuse for corporate inaction. The alignment of standards would also support the comparability across jurisdictions and reduce the reporting burden for companies operating internationally. However, harmonisation must not involve the dilution of standards or the lowering of ambition.

Any unified standard will only be effective if it maintains or enhances the depth, robustness, and ambition required to enable genuine emission reductions and other measures needed to halt temperature increases. In particular, no vital elements should be dropped in the process. For example, carbon credits must remain complements to, and never substitutes for, companies’ own emission reductions. The risk of misinterpretation here is real, and a unified standard must speak clearly: carbon credits cannot replace the obligation to reduce emissions at source. For scope 3 accounting, market-based instruments are another field in which ambition cannot be dropped in the process. Allowing flexibility to artificially lower scope 3 emissions with certificate trading would undermine the credibility of the forthcoming joint standards.

Standard bearers

In addition, the two organisations have different governance structures and stances regarding crucial aspects like transparency and democratic decision making. If the merger is to be successful, the highest standard (pun intended) needs to be adopted. More on that below.

The GHG-P and ISO frameworks complement each other but have distinct features. GHG-P standards are widely recognised for their detailed guidance and explanatory depth, while ISO standards carry more formal recognition in legal and regulatory frameworks, where the 1406X series has been transposed into legal frameworks for assessing and verifying GHG emissions in trading schemes. ISO’s texts tend to be more concise, while GHG-P standards can be more prescriptive, offering more practical detail to users. Merging the two could provide both clarity and authority. But only if managed well.

Inclusive process needed

Of equal importance to the technical content is how the standards are developed. Governance will determine legitimacy. GHG-P has typically emphasised and facilitated balanced stakeholder representation by directly appointing experts and providing public access to working group minutes, though its technical working groups do not always have the final word. ISO, by contrast, allows participation of any interested party via their national standard bodies and external organisations that may join as liaisons. This process can be more inclusive in theory, but the composition of ISO working groups often overrepresents larger companies’ interests because they have the necessary capacity and resources to engage. In addition,  liaison organisations have limited rights within the process.

Both approaches bring advantages, but neither is perfect. ISO is often more respected in regulation, while GHG-P offers transparency and breadth of perspective. For this merger to succeed, it is critical that the governance of the harmonised standards draws from the best of both systems. A balanced representation of stakeholder views, most importantly from those without conflicts of interest, must be guaranteed, and the process must be transparent and open. Standards of such global relevance cannot be left to closed rooms or a narrow group of well-resourced stakeholders.

Looking ahead

The announcement sets an important tone: cooperation, and alignment, with the ambition to provide clarity to the growing field of GHG accounting. But the process has only just begun, and the real test will be the implementation. Details about how the harmonisation will be managed, potentially differing per set of standards, remain open questions.

As the standard development unfolds, it is vital that ambition is not diluted and that the resulting frameworks empower, rather than weaken, climate action.