IFRS.Report
Scope 3 GHG Accounting under IFRS S2
A source-verified guide to value-chain greenhouse gas disclosure, boundaries, categories, and assurance-ready evidence.
The world's largest carbon emitter is not a country. It is not a company. It is a supply chain that no one has ever been required to put on a balance sheet: the combined Scope 3 emissions of the S&P 500. These are the emissions that occur upstream and downstream of a company's own operations — in the factories of its suppliers, the logistics networks that move its products, the use of its products by customers, the disposal of its products at end of life. For most companies, Scope 3 represents 70 to 90 percent of their total carbon footprint. And until IFRS S2, most companies did not have to report it.
IFRS S2 §29 changes that. Companies must disclose Scope 3 emissions using the GHG Protocol's fifteen categories. They must explain their boundary-setting methodology, their data sources, and their assumptions. They must disclose which categories are relevant and which are not — and justify the exclusions. The standard provides transition relief (§C4–C5) for companies that need time to build data systems, but the relief is temporary. The disclosure requirement is permanent.
The challenge is not measurement — it is ownership. Scope 3 emissions belong to no single company. They are shared across value chains, buried in supplier invoices, embedded in logistics contracts, distributed across customer use patterns. IFRS S2 §B32–B57 provides application guidance: use spend-based methods when primary data is unavailable, prioritize categories that are material, document assumptions transparently. The goal is not perfection. It is progress — a disclosure that improves each reporting period, with a clear trail from estimate to evidence.
Scope 3 is the disclosure that measures what companies do not own but still cause — the emissions embedded in every supplier, shipment, and customer interaction.
In Plain Language
Scope 3 emissions represent the largest share of most companies' carbon footprint — and the hardest to measure. IFRS S2 §29 and §C4–C5 provide transition relief for the first reporting year, but companies must disclose the categories included, the data sources used, and the basis for measurement. These four requirements map the pathway from Scope 3 screening through to assurance-ready evidence.
- Scope 3 is the disclosure that measures what companies do not own but still cause — the emissions embedded in every supplier, shipment, and customer interaction.
- The GHG Protocol's fifteen categories are the measurement framework; IFRS S2 §29 makes them a disclosure requirement with explicit boundary-setting methodology and transition relief provisions.
- The practical test is whether a Scope 3 disclosure separates the categories that are material from those that are excluded — with justified reasoning for each boundary decision.
Technical Requirements
- Scope 3 category screening — IFRS S2 §29 and §C4–C5: Companies must screen their 15 Scope 3 categories, disclose which are included in the inventory, and explain the basis for inclusion or exclusion.
- Boundary setting and data hierarchy — GHG Protocol Corporate Value Chain Standard: Companies must set organisational boundaries, apply a data hierarchy (primary data preferred, secondary data when primary is unavailable), and disclose the approach.
- Financed emissions — IFRS S2 §27–36: Financial institutions must disclose the greenhouse gas emissions associated with their lending and investment portfolios using the PCAF methodology.
- Assurance-ready evidence packs — ISAE 3000 / ISSA 5000: Scope 3 disclosures must be supported by evidence — category screening rationales, data source identities, and calculation methodologies — that an assurance provider can verify.