Scopes 1, 2 and 3
Scopes 1, 2 and 3 are the three categories of greenhouse gas emissions defined by the GHG Protocol. Scope 1 is direct emissions, scope 2 is indirect emissions from purchased energy, and scope 3 is all other indirect emissions in the value chain.
Scope 1 covers emissions from sources the company owns or controls: fuel burned in boilers and vehicles, industrial processes, refrigerant leaks. Scope 2 covers emissions from the electricity, heat, steam and cooling the company buys. It is reported two ways: location-based (average grid factor) and market-based (reflecting the company's energy contracts).
Scope 3 covers the 15 categories upstream and downstream: purchased goods and services, transport, business travel, employee commuting, use and end-of-life of sold products, and more. For many companies it is the largest part of the footprint and the hardest to measure, because the data sits with suppliers and customers.