Carbon footprint is a measure of the amount of carbon dioxide or CO2 emitted through the combustion of fossil fuels; in the case of an organization, business or enterprise, as part of their everyday operations; in the case of an individual or household, as part of their daily lives; or a product or commodity in reaching market. In materials, is essentially a measure of embodied energy, the result of life cycle analysis.
A carbon footprint is often expressed as tons of carbon dioxide or tons of carbon emitted, usually on a yearly basis. There are many versions of calculators available for carbon footprinting.
This is directly related to the amount of natural resources consumed, increasingly used or referred to as a measure of environmental impact. Carbon dioxide is recognized as a greenhouse gas, of which increasing levels in the atmosphere are linked to global warming and climate change.
The Clean Development Mechanism (CDM) under the Kyoto Protocol sets forth a methodology by which voluntary emission reduction can be monetized in the form of a carbon project. These standards involve the use of an environmental proof called additionality.
A carbon label - which shows the carbon footprint embodied in a product in bringing it to the shelf was introduced in the UK in March 2007 by the Carbon Trust. Examples of products featuring their carbon footprint are Walkers Crisps, Innocent Smoothies and Boots shampoos. This has caused significant debate in a number of industries, with claims that there is no way to accurately measure a carbon footprint, and these labels are merely PR tools.