ESG Reporting and Supply Chain: What You Need to Disclose

Until recently, most corporate sustainability reporting focused on what a company does within its own four walls — the emissions from its facilities and vehicles, the energy it consumes, the waste it generates. That scope is no longer sufficient. Regulators, institutional investors, and major customers are increasingly demanding disclosure of the environmental and social performance of the entire value chain, including suppliers, logistics providers, and in some frameworks, the downstream use of sold products. For most companies, this extended scope reveals that the operations they directly control represent a minority of their total environmental footprint. Scope 3 emissions — the indirect emissions in a company's value chain — account for 70 to 90 per cent of the total greenhouse gas footprint for a typical manufacturer or retailer. Disclosing those emissions, and demonstrating a credible plan to reduce them, is rapidly becoming a baseline expectation in global capital markets.

The major ESG reporting frameworks and what they require

1. GRI Standards. The Global Reporting Initiative Standards are the most widely used voluntary ESG reporting framework globally. The GRI supply chain standards require disclosure of the percentage of significant suppliers assessed for social and environmental impacts, the types of impacts identified, and actions taken to address them. GRI 308 (Supplier Environmental Assessment) and GRI 414 (Supplier Social Assessment) are the specific standards that govern supply chain disclosure. GRI reporting is topic-based and modular — organisations select the topics material to their context rather than reporting against the full standard.

2. SASB Standards. The Sustainability Accounting Standards Board Standards are sector-specific: they identify the sustainability topics most likely to be financially material for companies in each industry. Supply chain disclosures in SASB are calibrated to industry context — what matters for a food and beverage company (agricultural supply chain, water use, deforestation) is different from what matters for a technology hardware company (conflict minerals, labour practices in contract manufacturing). The sector specificity makes SASB particularly useful for investor-facing reporting, where the relevance of each metric to financial performance is more important than comprehensiveness.

3. CDP. The Carbon Disclosure Project runs the most widely used voluntary carbon disclosure programme globally. CDP's supply chain programme specifically requests Scope 3 data and asks companies to report on supplier engagement — the percentage of suppliers by emissions that have set science-based targets, provided CDP disclosures themselves, or been assessed for climate risks. CDP scores are used by major institutional investors and increasingly by large corporate buyers as a condition of supply chain participation. A number of large companies now require their key suppliers to complete CDP disclosure as a procurement requirement.

4. TCFD and ISSB (IFRS S1 and S2). The Task Force on Climate-related Financial Disclosures framework established the four-pillar structure — governance, strategy, risk management, and metrics and targets — that now underpins most mandatory climate disclosure regimes globally. The International Sustainability Standards Board, established under the IFRS Foundation, has issued IFRS S1 (general sustainability disclosures) and IFRS S2 (climate-related disclosures) that are built on TCFD recommendations and are expected to become the global baseline for mandatory sustainability reporting in most major jurisdictions. Both require disclosure of climate-related risks and opportunities across the value chain, including Scope 3 emissions where they are material.

What supply chain ESG data is required

Across the major frameworks, supply chain ESG disclosure converges on five categories of data. Supplier emissions — the greenhouse gas emissions attributable to suppliers' operations and the production of goods and services purchased — are at the centre of Scope 3 Category 1 (purchased goods and services) disclosure, which is typically the largest single Scope 3 category. Water use in the supply chain is material for companies in water-intensive industries or sourcing from water-stressed geographies. Labour practices — working hours, wages, freedom of association, child labour prohibitions, safe working conditions — are required across GRI, SASB, and mandatory due diligence frameworks in Canada, the European Union, and Germany. Conflict minerals — tin, tantalum, tungsten, and gold — require specific supply chain traceability under the Dodd-Frank Act in the US and equivalent requirements in the EU. Forced labour risk has become a distinct disclosure category following the Canadian Fighting Against Forced Labour and Child Labour in Supply Chains Act and similar legislation in other jurisdictions.

The data collection challenge

The practical challenge of supply chain ESG reporting is that most of the required data sits with suppliers, not with the reporting company. Collecting emissions data from hundreds or thousands of suppliers, many of whom have not measured their emissions and lack the capacity to do so accurately, is the fundamental difficulty that most organisations face. Spend-based estimation — using average emissions factors applied to procurement spend by category — is the starting point for Scope 3 Category 1 reporting and is acceptable under most frameworks as a first-year approach. But spend-based estimates can be wildly inaccurate for companies with concentrated supply chains or suppliers with emissions profiles significantly above or below their sector averages. Moving from spend-based to supplier-specific data requires supplier engagement that most organisations have not previously invested in for sustainability purposes.

Building a supply chain ESG programme incrementally

The most pragmatic approach to supply chain ESG compliance is to tier suppliers by materiality and invest data collection effort proportionately. A spend-based emissions estimate for the full supply base identifies the categories and suppliers that account for the majority of estimated Scope 3 emissions. Focused supplier engagement — questionnaires, assessments, and where needed, site audits — can then prioritise those high-materiality suppliers for the shift to supplier-specific data. Contractual requirements for ESG data provision, built into supplier agreements at the next renewal, create the structural foundation for sustained data collection rather than one-time survey responses. The programme does not need to be complete before reporting begins — disclosing what you know, describing the methodology honestly, and committing to improvement over time is the approach most frameworks explicitly support.

If your organisation is navigating ESG reporting requirements for your supply chain — establishing your Scope 3 baseline, building supplier engagement programmes, or selecting the right frameworks for your disclosure obligations — XNM's procurement, sourcing, and contract management practice works with organisations to build supply chain ESG programmes that meet regulatory and investor requirements while creating the supplier relationships that make improvement over time achievable.