Scope 3 data still depends on suppliers, and most suppliers are not ready to provide it

Scope 3 emissions typically account for the largest share of a company's total carbon footprint, but the data that underpins those calculations sits with suppliers who, in most cases, have not built the systems, processes, or expertise to produce it. This is not a new finding, but it remains the central unresolved problem in corporate carbon accounting as CSRD reporting obligations expand the number of European companies required to disclose Scope 3 data under ESRS E1. The gap between what buyers need and what suppliers can deliver is widening, not closing.

NEST, the UK pension fund, offered a parallel illustration of the data quality problem this week. The fund's head of sustainability flagged that public markets lag real assets when it comes to asset level location data for physical climate risk, describing the gap as a material challenge. While the context is investment rather than supply chain, the underlying dynamic is the same: the granular, asset level information that rigorous climate accounting requires is simply not being produced at scale by the entities that hold it.

For procurement leads and in house ESG managers, the supplier readiness gap creates a direct compliance risk. ESRS E1 requires companies to disclose Scope 3 emissions across all material categories, and auditors are expected to scrutinise the methodology and data sources behind those figures. Where suppliers cannot provide primary data, companies must rely on spend based estimates or industry averages, both of which carry higher uncertainty and may draw more scrutiny from assurance providers. Automated supplier engagement tools, where platforms like SOMA's AI agent handle the collection workflow, can cut the time needed to gather and validate supplier data from weeks to hours, but they cannot create data that suppliers have not generated.

The structural problem is that smaller suppliers, who often sit in the most emissions intensive tiers of a supply chain, face the steepest cost and complexity barriers to implementing carbon measurement. Expecting those suppliers to self report without support, standardised templates, or financial incentive has not worked at scale. Some larger buyers are beginning to offer supplier capacity building programmes, but adoption remains uneven and coverage across global supply chains is thin.

Compliance teams preparing their first CSRD filings should treat supplier data readiness as a priority workstream rather than a reporting exercise. The quality of Scope 3 disclosures under ESRS E1 will ultimately reflect the quality of supplier engagement programmes built over the next twelve to eighteen months. Companies that start that engagement now, document their methodology, and build systematic audit trails will be better positioned when assurance requirements tighten in subsequent reporting years.