The phrase "carbon emissions" refers to the release of carbon dioxide (CO₂) through various natural and anthropogenic (man-caused) processes.

Natural emissions of this kind come from the metabolsim of every wild creature on earth (from ameoba to blue whale), forest fires and natural release from unground storage.

Anthropogenic carbon emissions come primarily from burning of fossil fuels in industry, homes and cars, trucks planes and trains. Certain industrial processes also release CO₂ as a bi-product such as the production of nitric acid, which is used in the production of explosives such as TNT and fertilizers.

CO₂ is a Greenhouse Gas, meaning that it contributes to trapping the sun's energy in the atmosphere, making live as we know it possible. However if the amount of these gases in the atmosphere rises it is believed that the earths temperature will begin to rise and the natural processes which contribute to the stability of this planet's climate will be disrupted, possibly irreversably.

Two other greenhouse gases included in the Kyoto agreement are methane and nitrous oxide. These gases are often expressed in "carbon dioxide equivalent", that is the amount of CO₂ that would be required for the same warming effect. Methane has around 20 times the warming potential of CO₂ and nitrous oxide has 300 times the potential of CO₂. The Food Carbon Footprint Calculator includes methane and nitrous oxide in the footprint figure.

In terms of global emissions, agriculture is believed to be responsible for 25% of CO₂, 65% of methane and 90% of nitrous oxide emitted. Modern processes such as use of machinary over man and animal power, global trading and increased use of fertilizers and other so called "agro-chemicals" has already made agriculture an energy intesive process in the developed world and is still in the process of doing the same thing in the developing world.

At present the FCF of particular foods are not widely understood or represented on food packaging. However better understanding leads to more informed choices and encourages producers to compete on the sustainability of their products, not just price.

By allowing you to calculate your own food carbon footprint, and showing you from what parts of your diet the emissions come from, the Food Carbon Footprint Calculator shows you to what extent your diet impacts global warming, and allows you to take control.