Carbon footprint
The greenhouse gas emissions associated with an activity, product, person or entity across a defined boundary.
Example
A footprint may include direct fuel use and emissions from purchased goods.
The catch
Results are only comparable when boundaries, periods and methods align.
In more depth
Carbon footprint, explained.
A carbon footprint is most useful as a map of where emissions sit, because it shows which activities to tackle first. Organisations usually build one with the GHG Protocol, sorting sources into scopes, while products are assessed through life-cycle assessment from raw materials to disposal. Despite the name, a footprint normally covers all greenhouse gases, expressed in CO₂e.
Treat the precision with care. Most footprints are estimates built from activity data and average emission factors, so a figure quoted to the last kilogram carries more confidence than its inputs justify. For a company, the largest share often sits in Scope 3 emissions, the part it controls least and measures worst.