Scope 3

All other indirect emissions across the value chain — purchased goods, transport, use of sold products, end of life.

Scope 3 is everything you cause but do not control, split across fifteen categories. For most manufacturers it is the large majority of the total, and purchased goods and services usually dominates it.

It is also the least reliable part of most inventories, because the standard fallback is spend-based estimation: money spent multiplied by an industry-average factor. That produces a number, but one that barely moves when your actual suppliers or processes change — which makes it nearly useless for reduction.

Replacing estimates with supplier-specific data is the only route to a Scope 3 figure that responds to reality. It is a data-collection problem across organisations, which is why it is hard.

Scope 1 Direct emissions from sources a company owns or controls — its own combustion, its own vehicles, its own process emissions.
Scope 2 Indirect emissions from the electricity, heat and steam a company buys.
Primary data Data measured at its source — your meter, your supplier's actual production — as opposed to an industry average.
Precursor An input that already carries embedded emissions of its own — the steel in a bolt, the clinker in cement.