When the International Organization for Standardization (ISO) and the Greenhouse Gas Protocol (GHG‑P) announced in September 2025 that they would integrate their greenhouse‑gas accounting standards, they did more than streamline a niche set of reporting rules. The plan is to merge the ISO 1406X series with the GHG Protocol corporate, scope 2, scope 3 and product life‑cycle standards.
This harmonisation aims to provide a single reference point for emissions measurement across industries, covering corporate inventories, product footprints and project-level accounting. A unified framework could finally end the fragmentation that has forced companies to juggle multiple methodologies, leaving stakeholders comparing apples with oranges.
Why Harmonisation Matters
For years, companies have had to choose between two approaches or struggle to translate between them. ISO 14064 emphasises high-level principles and requires mandatory third-party verification. It even allows companies to incorporate carbon removals directly into their balance sheets. The GHG Protocol, by contrast, provides detailed calculation methods and sector-specific guidance. It treats removals separately as “additional information”.
This divergence has led to comparable businesses reporting very different numbers due to varying treatments of removals and offsets, optional verification, and inconsistent terminology. Regulators have added to the confusion. The European Sustainability Reporting Standards (ESRS) ask companies to “consider” the GHG Protocol but permit the use of ISO methods. Countries like Australia and South Africa require ISO 14064 for mandatory reporting, while financial standards such as IFRS S2 and disclosure frameworks like CDP point to the GHG Protocol.
The result was a patchwork that imposes extra cost on multinationals and undermines comparability. The inclusion of a product carbon footprint standard is particularly relevant for aviation, where emissions per passenger-kilometre or per freight ton are key metrics for procurement and marketing.
Harmonisation offers a pathway to a single, coherent language. The alignment of standards will also support comparability across jurisdictions and reduce the reporting burden for companies operating internationally
These problems are amplified in aviation because the sector depends on complex supply chains, cross-border operations and high capital intensity. Investors, regulators and customers are increasingly demanding high‑quality carbon data, not only at the corporate level but for individual flights and even products. Without a unified accounting language, airlines and airports face higher audit costs and inconsistent metrics that can erode stakeholder trust.
Anchoring Decarbonisation in Data
Better measurement alone will not cut emissions. It enables a more precise focus on what is achievable, but does not ensure achieving the climate targets. Carbon Market Watch even underscores that today’s fragmented system is often used as an excuse for corporate inaction. The harmonized standard should raise the quality bar rather than water down ambition. The unified standard should maintain depth and robustness, making it clear that carbon credits are important complements, not substitutes, for emission reductions.
Measurement is only the first step. To translate aligned data into real reductions, companies need operational changes. Many industries already utilise machine-learning algorithms and real-time data to reduce fuel use and energy consumption (which is only part of the carbon footprint). Digital solutions can bridge the gap between reporting and action.
Key Takeaways?
- Embrace the unified standard early. Early adoption will simplify compliance with diverse regulations and make your data comparable across markets.
- Understand the differences. Recognise why the merger matters: ISO’s focus on principles and mandatory verification contrasts with the GHG Protocol’s prescriptive methodologies and separate treatment of removals.
- Invest in data infrastructure. Accurate, granular data is the foundation of credible decarbonisation. Upgrade measurement and reporting systems to capture emissions across operations, supply chains and product life cycles.
- Translate numbers into action. Use digital optimisation tools to turn data into operational improvements. Machine‑learning‑based scheduling, real‑time weather and energy‑management platforms help reduce fuel and energy use.
- Collaborate across the value chain. The forthcoming product‑level standard will require shared data from suppliers and customers. Work with partners to collect high-quality information and explore low-carbon materials, renewable energy and circular design.
- Maintain ambition. Ensure decarbonisation plans prioritise absolute emission reductions and treat carbon credits as a complement, not a substitute.
A Positive Outlook
The real value of aligned numbers lies in how businesses use them. Transparent, harmonised data should direct investment towards low-carbon technologies and operational efficiency. Digital tools and innovative practices across various industries demonstrate that translating information into action is not only possible but also already happening. By embracing harmonisation and coupling it with ambition and innovation, companies can move beyond reporting and make climate action central to their strategy.
Article by Veronika Doubner, Global Sustainability & CSR Manager at SITA
Veronika Doubner
For more sustainability stories: https://essmag.co.uk/category/sustainable-solutions/
