What is CO2e?
CO2e is an abbreviation of 'carbon dioxide equivalent' and is the internationally recognised measure of greenhouse emissions.
There are many types of greenhouse gases. Six such gases are controlled by the Kyoto protocol. These include:
and a range of synthetic (industrial) gases including
Each of these gases has a different capacity to heat the atmosphere. This is referred to as their global warming potential (GWP).
CO2 is the standard bearer for GWP - it has been assigned a GWP = 1. Other GWPs include:
Clearly, CO2 is not a potent greenhouse gas compared to the others. However, because CO2 is produced in such huge quantities, its effect dwarfs all the other greenhouse gasses combined.
For the sake of ease, when an organisation calculates its greenhouse emissions these are reported as though they were equivalent to a given volume of CO2. This is the CO2e.
For example, greenhouse emissions from a landfill of 100 tons of methane are recorded as 2,100 tons CO2e.
Using CO2e as a measure of greenhouse emissions allows for comparing the greenhouse impact of a variety of greenhouse emissions sources.
your own CO2e
Emissions Trading Association
Convention on Climate Change