Carbon Dioxide Equivalent (CO2e)

Carbon Dioxide Equivalent (CO2e) Is the international standard used to express greenhouse gases (US EPA). Carbon dioxide (CO2) is not the only greenhouse gas. Others, like methane (CH4) have different warming properties and longevity in the atmosphere compared to CO2.  To report all the greenhouse gases in terms of one number, these gases of differing properties are converted to the amount of CO2 that would have the same warming potential.  (USDA Forest Service). As explained by The Guardian, the idea is to express the impact of each different greenhouse gas in terms of the amount of CO2 that would create the same amount of warming. That way, a carbon footprint consisting of lots of different greenhouse gases can be expressed as a single number.