What are scope 1, 2 and 3 emissions?
A classification of an organisation's greenhouse gas emissions by where they occur relative to the organisation, established by the Greenhouse Gas Protocol and now the standard framework for corporate reporting.
Scope 1 — direct emissions. From sources the organisation owns or controls: fuel burned in its own boilers, furnaces and vehicles, and process emissions from its own operations. Also fugitive emissions such as refrigerant leaks.
Scope 2 — indirect emissions from purchased energy. Principally electricity, plus purchased heat, steam and cooling. The emissions occur at the power station, not on the organisation's site, but are attributed to it because it caused the demand.
Scope 2 is reported two ways, which matters: location-based, using the average grid intensity where the electricity was consumed, and market-based, reflecting contractual instruments such as renewable energy certificates. A company can report near-zero market-based Scope 2 while consuming ordinary grid electricity, which is the source of most scepticism about renewable claims.
Scope 3 — all other indirect emissions across the value chain, both upstream and downstream. Fifteen defined categories including purchased goods and services, capital goods, business travel, employee commuting, transport and distribution, waste, investments, and use of sold products.
Why Scope 3 dominates. For most organisations it is the overwhelming majority of total emissions — frequently the large majority, and for some sectors far more. An oil company's Scope 3 includes the fuel its customers burn; a bank's includes what it finances, which dwarfs everything else it does.
Why it is also the hardest:
It depends on other organisations' data, which is frequently unavailable or estimated.
Double counting is inherent — one company's Scope 3 is another's Scope 1, by design. This is intentional and means Scope 3 figures cannot be summed across companies.
Methodological choices change results substantially, and spend-based estimation is crude.
Boundary decisions determine what is included.
Why it matters for claims. A net zero or reduction target excluding Scope 3 omits most of the footprint — which is why the scope covered is the first thing to check in any corporate climate claim.
Reporting requirements increasingly mandate Scope 3 disclosure.