The Greenhouse Gas Protocol (GHGP) and the International Organization for Standardization (ISO) yesterday announced that they will combine their corporate carbon accounting standards into a single, harmonized global accounting standard. GHGP noted that the new standard will “help reduce duplication, improve consistency, simplify reporting and support more effective decision-making by companies, investors, policymakers and other stakeholders”. The announcement builds on the strategic partnership established between GHGP and ISO last year and the COP30 Presidency mandate in November 2025 that GHGP and ISO jointly lead the harmonization of global GHG accounting standards within the Action Agenda. The combined standard aims to create a common global language for emissions accounting, supporting governments, investors and regulators.   Overview. The combined standard will integrate and consolidate GHGP’s existing entity-level standards (Corporate Standard, Scope 2 Guidance, Scope 3 Standard) and outputs from the GHGP’s Actions and Market Instruments workstream with ISO’s 14064-1 standard (Part 1: Specification with guidance at the organization level for quantification and reporting of greenhouse gas emissions and removals) to produce a single standard with multiple parts: Part 1: General Requirements and Physical GHG Inventory Part 2: Actions and Market Instruments.  GHGP indicated that the combined standard will seek to “reduce fragmentation, increase interoperability, and provide organizations with a single trusted foundation for climate reporting and decision-making” with additional guidance documents provided to assist users with implementation.    Next steps. GHGP also published a new “Corporate Standard – Standard Development Plan” which provides key details, processes, and timelines for developing the consolidated corporate standard. GHGP noted that to achieve harmonization under its partnership with the ISO, each of their respective governance bodies approved a new timeline which includes a consolidated public consultation in Q2 2027 and publication of the consolidated joint corporate standard in Q4 2028.   For further information or to discuss the contents of this bulletin, please contact Lisa DeMarco at lisa@resilientllp.com.