CO₂e (carbon dioxide equivalent)

CO₂e is a single unit that expresses the warming effect of all greenhouse gases as the amount of carbon dioxide that would cause the same warming.

Products cause several greenhouse gases, not just carbon dioxide: methane from farming and landfills, nitrous oxide from fertilisers, and fluorinated gases from some industrial processes. Each traps a different amount of heat over time.

To add them up, each gas is multiplied by its global warming potential, a factor published by the Intergovernmental Panel on Climate Change (IPCC) that compares its effect over 100 years with carbon dioxide. The result is given in kilograms of CO₂e, which is the unit every product carbon footprint uses.