The GHG Protocol explained

What is the GHG Protocol?

The Greenhouse Gas Protocol began in 1998 as a partnership between the World Resources Institute, a research organisation, and the World Business Council for Sustainable Development, a business association. It writes standards, guidance and calculation tools for measuring and reporting greenhouse gas emissions, for companies, cities, products and projects. Its standards are not law, but laws and reporting standards adopt them: IFRS S2, the European Sustainability Reporting Standards and California's SB 253 all require emissions measured under the GHG Protocol, subject to limited exceptions. See sustainability reporting explained.

Which standards make up the GHG Protocol?

• Corporate Standard (2001, revised 2004): how a company sets its boundaries and measures scope 1 and 2, the foundation for everything else.
• Scope 2 Guidance (2015): the location-based and market-based methods for purchased energy.
• Corporate Value Chain (Scope 3) Standard (2011): 15 categories of value chain emissions, from purchased goods to the use of sold products.
• Product Standard: the life-cycle emissions of a single product.
• Land Sector and Removals Standard: published on 30 January 2026 and effective from 1 January 2027, for emissions and removals from land use and carbon removal technologies.

How does the GHG Protocol define the three scopes?

Scope 1 is direct emissions from sources the company owns or controls, such as fuel burned in boilers and vehicles, process emissions and refrigerant leaks. Scope 2 is indirect emissions from generating the electricity, steam, heat and cooling the company buys, reported both location-based and market-based. Scope 3 is every other indirect emission in the value chain, upstream from suppliers and downstream from customers. One company's scope 1 is another's scope 3, which is why the scopes are designed to avoid double counting within a single inventory but not across companies. See calculating scope 1 and 2 emissions and location-based and market-based scope 2. For what each part of scope 3 covers, see the 15 scope 3 categories.

GHG Protocol inventory: a manufacturer's three scopes

A manufacturer has measured scope 1 and 2 and now estimates its main scope 3 categories for the first time, in tonnes of CO2 equivalent.

Scope 3 is 58,000 tonnes, 91% of the total, which is typical for a manufacturer: most emissions sit in the materials it buys and the energy its products use. Scope 1 and 2 are measured from meters and invoices; scope 3 relies on estimates, supplier data and spend-based factors, so it is less precise and is phased in later by most rules. On a location basis, scope 2 would be 8,000 tonnes and the total 68,440. See the spend-based method.

What are boundaries, base years and the principles?

A company first sets its organisational boundary using one of three approaches, equity share, financial control or operational control, and applies it consistently across the group; the choice decides how joint ventures, leased assets and subsidiaries with minority holders are counted. It then sets its operational boundary, which scopes and categories it covers. It chooses a base year against which progress is tracked, and recalculates base year emissions when acquisitions, disposals or method changes would otherwise distort the trend; see base year recalculation. Five principles guide every judgement: relevance, completeness, consistency, transparency and accuracy. The inventory covers seven gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride and nitrogen trifluoride, each converted to CO2 equivalent using global warming potentials. See organisational boundaries. For sorting sources into scopes, see operational boundaries.

How is the GHG Protocol changing?

The GHG Protocol is revising its main standards under an Independent Standards Board, with technical working groups that ISO experts joined in 2026 as part of a move towards harmonised standards. The first consultation on scope 2, proposing that market-based claims match consumption hour by hour and come from grids the electricity can reach, ran from 20 October 2025 to 31 January 2026 and drew nearly 1,100 responses, with low support from companies for hourly matching and deliverability; in July 2026 the Independent Standards Board asked for further work on several market-based approaches. Also in July 2026, the GHG Protocol and ISO agreed to combine their corporate standards, covering scopes 1, 2 and 3 and ISO 14064-1, into a single standard, with a public consultation planned for the second quarter of 2027 and publication in the fourth quarter of 2028. Until then, the current editions apply. See the scope 2 revision.

Who requires the GHG Protocol?

IFRS S2 requires scope 1, 2 and 3 emissions measured under the 2004 Corporate Standard unless a jurisdiction requires another method, and its December 2025 amendments allow such legally required methods for the parts of a business they cover. ESRS E1 requires emissions under the GHG Protocol. California's SB 253 requires scope 1, 2 and 3 reports under it. Customers, lenders and carbon pricing schemes increasingly ask for figures on the same basis, although emissions trading schemes have their own monitoring rules for the allowances companies surrender. See IFRS S2, California SB 253 and emissions allowances.

This guide is general information. It is not tax or legal advice for your situation.