What does "CO2e (CO2 equivalent)" mean ?

CO2e represents ‘carbon dioxide equivalent’. It’s a measurement of the total greenhouse gases emitted, expressed as the equivalent measurement of carbon dioxide. 

As a whole, CO₂e is a standard unit used to compare the impact different greenhouse gases (GHGs) have on the climate by expressing them as the equivalent amount of carbon dioxide (CO₂) that would produce the same warming effect over a specific time period – this time span usually refers to 100 years.

People often forget that carbon dioxide isn’t the only common greenhouse gas, but that other gases such as methane (CH₄), nitrous oxide (N₂O), and fluorinated gases actually trap heat more effectively than CO₂ itself – despite the fact that they exist in smaller quantities. Ultimately, CO₂e allows us to measure and report all these gases via one singular unit to help simplify the process of comparing and contrasting environmental impact.

CO₂e is calculated by using Global Warming Potential (GWP) factors, which describe how much heat a specific gas traps in the atmosphere compared to CO₂.

For example:

• Methane has a GWP of 28–36 over 100 years, meaning 1 tonne of CH₄ and has the same warming effect as 28–36 tonnes of CO₂.
• Nitrous oxide has a GWP of about 298, meaning 1 tonne of N₂O has the same effect as 298 tonnes of CO₂.

Converting all of these gases into one number, expressed in CO₂e, allows businesses, governments, and individuals to compare emissions and set more personalized, robust reduction targets.

FAQ

Why is CO₂e important?

CO₂e is important as it simplifies the process for climate reporting by combining all greenhouse gas emissions into one comparable metric. Think of how we use calories as a single unit to quickly compare and contrast the health of food, even if calories do not express the same picture – the same goes for CO₂e.

Does CO₂e only measure gases from fossil fuels?

No, CO₂e can include emissions from agriculture, waste, industrial processes, and more.

Is a lower CO₂e always better?

Yes, having a lower CO₂e means that the individual or organization is successfully mitigating their impact on climate change.

How is CO₂e used in reporting?

CO₂e is a standard in corporate sustainability reports, carbon footprint calculations, and government climate targets.