Why supplier data quality is still the Scope 3 blocker in 2026

Your Category 1 number is probably an industry average applied to spend, and nobody can act on it. Verdantix research points to the cause: poor supplier data. This post covers where that barrier sits and a way past it that does not start with a survey.

What does Verdantix say is the main barrier to Scope 3 progress?

In its blog From Supplier Data To Product Footprints: Three Innovation Trends Reshaping Supply Chain And Product Carbon Management, Verdantix draws on its 2026 benchmark of 14 software providers, Smart Innovators: Supply Chain And Product Carbon Management. It reports that more than 80% of supply chain and product sustainability leaders see a lack of high-quality supplier data as a major barrier to improving sustainability performance.

"The market's biggest challenge is still obtaining reliable data from suppliers." Alessandra Leggieri, Senior Analyst, Verdantix

Verdantix adds that supplier engagement, data collection and product-level emissions analysis are being pulled into the same platforms, because buyers want more granular carbon data across their products and value chains.

Why do spend-based estimates stop being useful?

Spend is an input, not the problem. The GHG Protocol defines its spend-based method as spend multiplied by secondary data, meaning industry averages. A sector average applied to spend moves only when procurement spends less. The same spend multiplied by an organisation's own emission factor, taken from its own published inventory, is primary data, and it moves when that supplier reports a reduction.

The four ways to calculate a line do not cost the same:

The line is calculated onWhat it costs youDoes the number move when the supplier cuts emissions?A sector average applied to spendA spend fileNoThe organisation's own factor applied to spendThe same spend fileYesActivity dataReal work to gather consumption dataYes, and it separates two suppliersA published product carbon footprintAllocating spend to named products, item by itemYes, at item level

The second row is the one most teams do not know is available. The third and fourth are better still, and they take real effort from you and often from the supplier, so they belong on the lines carrying the emissions rather than across the whole tail.

What supplier data already exists before you ask anyone?

More than most teams expect. Primary emissions data already exists for many organisations on a typical Category 1 list: their reported GHG inventories, their published service and product-level carbon footprints, and activity and product data that suppliers have already provided for other clients and chosen to share. Sharing is always the supplier's decision, and a disclosure made privately for one client is never shared with anyone else.

That is the layer DitchCarbon builds on: verified emissions data for over 2 million organisations, built on primary emissions data wherever it exists. The organisation reports its own inventory. The allocation to your spend is ours, and every figure carries its source and change history. In a recent deployment, about 60% of a large supplier base was reached within 2 weeks.

What do you do about suppliers who have not published anything?

Ask them, and make the ask small. Requests go out from the platform prepopulated with what the supplier has already published, so the supplier confirms and corrects rather than compiling an answer from scratch. That gets a higher response rate than a cold survey.

A four-step maturity ladder sorts suppliers by embodied emissions, which decides who is worth asking first. Hotspotting sets where the conversations start. It does not limit how far they reach, because every reply type (a corrected figure, an uploaded report, a product carbon footprint) is read into the same record.

Any model that has to ask every supplier before it knows anything adds to the queue of forms a small sustainability team is already working through, whoever is running it. Where nothing comes back, a generic emission factor closes the inventory and the gap is shown rather than hidden.

DitchCarbon works in that order: coverage first, targeted requests second, and the remaining gap in plain view.