Why carbon estimates won’t cut it any longer: The Scope 3 Reckoning

GHG Protocol is rewriting the rules on Scope 3 data

For the first time since 2011, the GHG Protocol is overhauling how companies report Scope 3 emissions, tightening the line between real supplier data and rough estimates. ISO is moving in step, consulting on a new standard for what counts as a credible net zero claim. Neither is final, but the direction is clear: the bar for credible carbon reporting is rising, and it won’t stay contained to one industry.

Granular Scope 1, 2 and 3 data remains a challenge across sectors with fragmented, subcontracted supply chains. The coming changes don’t demand everyone be ready now; they set a direction. Businesses that build good data habits today will be in a fundamentally different position in two to three years than those who wait for a deadline or a client to force it.

The way forward needn’t be complicated or expensive. Our approach breaks it into four stages, prepare, validate, calculate, communicate:

1. Start with Scope 1 and 2. A verified footprint of your direct emissions and purchased energy is the foundation everything else builds on.
2. Map your supply chain. Identify your highest-spend suppliers, household goods shipping, temporary housing, flights, and start asking them basic questions about their data.
3. Move from estimates to real data, category by category. Prioritise your highest-spend or highest-risk Scope 3 categories first rather than covering everything at once. That’s where real supplier data matters most, and where rough estimates carry the greatest exposure.

Now is the time to start collecting real supplier data, while you can still do it on your own terms.

That is where we come in. Our JustOne Planet Certification “LEAD” service is built for exactly this. We work directly with your suppliers to collect and verify their data, educate them on what good looks like and why it matters, and give them a free platform to record it, so the numbers coming back are real, consistent and defensible rather than estimated. It turns the hardest part of Scope 3, getting reliable data out of a fragmented supply chain, into something your suppliers are equipped and supported to deliver.

For more information, say hello@justone.uk