a measure of the total amount of greenhouse gas emissions produced directly and indirectly by a person, an organisation, an event or a product.
A carbon footprint is the total amount of greenhouse gas emissions (mainly carbon dioxide, methane, nitrous oxide, water vapor and ozone) that is produced directly and indirectly by a person, an organisation, an event or a product.
Direct emissions, also called primary footprint, come from sources directly controlled by the person(s) or activity in question, for example heating one's house. Indirect emissions or secondary footprint are emissions that are the consequence of a person(s) actions using sources owned or controlled by someone else, for example fuel that was for transport from the factory to the store for a product one has bought.
The global average carbon footprint is approximately 4 tons of CO2-equivalent per person per year [source]
Note the difference with ecological-footprint that measures the total impact (so not only greenhouse gas emissions) of a person, organisation or activity on the Earth's ecosystems.
Online carbon footprint calculators:
- Conservation International
- EPA USA - Household Carbon Footprint Calculator
- Berkeley University - CoolClimate Carbon Footprint Calculator
- Carbon Neutral Company
- WWF UK Footprint Calculator (for UK citizens)
- Nature Conservancy (for US citizens)