The Carbon Column – Carbon dioxide vs carbon dioxide equivalent

In this post I discuss greenhouse gas emissions and significance of carbon dioxide equivalent in reporting standards

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CO2 or CO2e?

Carbon reporting is becoming more and more popular. Businesses are accounting for carbon so they can set realistic targets to reduce their footprint.

Carbon reporting is not just about focusing on carbon dioxide, which is why there is CO2e or carbon dioxide equivalent.

The Greenhouse Gas (GHG) protocol is a standardised framework to help private and public organisations to measure and manage their GHG emissions.

Under this framework there are seven recognised GHG emissions businesses should capture for reporting: carbon dioxide (CO2), methane (CH4), nitrous dioxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), nitrogen trifluoride (NF3), and sulphur hexafluoride (SF6).

Greenhouses Gases are compounds that absorb electromagnetic radiation in the infrared spectrum. Waves in the electromagnetic spectrum come in different wavelengths, from long wave, low frequency radio waves at one end, to extremely small x-ray and gamma rays at the other end.

We can see visible light. Whereas we can’t see infrared waves are which are slightly longer, and we can’t see ultraviolet (UV) waves, which are slightly smaller.

The absorption of these infrared waves causes a warming effect.

Here is a fact for you.

The reason a microwave has the mesh coating on the inside of the door is to block the microwaves from getting through. The holes in the mesh are too small for them to get through! So next time you look at your microwave, you’ll see the mesh and realise it’s protecting you.

The GHGs mentioned are released during land use, combustion of fuels, processing, manufacturing, from leaking equipment, use in electrical systems, from livestock, agriculture, and other sources.

There are other GHGs such as water vapour (H2O) and ozone (O3). Not to be mistaken for Frozone, the character from the Incredibles films.

Water is not counted as harmful, as the temperature of our planet is not controlled by water vapour. Although ozone is technically considered a greenhouse gas, it is believed the benefits of ozone outweigh the contribution to the greenhouse effect. Ozone benefits the planet as it protects us from the harmful ultraviolet (UV) radiation from the sun.

You may recall the ban of certain types of harmful aerosols containing chlorofluorocarbons (CFCs) which deplete ozone. These harmful compounds remain our in the different layers in our atmosphere, giving them time to do the damage to ozone.


Yes, great, there are different compounds that cause warming. But why CO2e?

You may have seen the CO2, the molecular formula for carbon dioxide. You may have also come across CO2e or carbon dioxide equivalent. Carbon dioxide equivalent is the metric used to compare the GHGs mentioned above, based on their global warming potential (GWP). The global warming potential is the warming effect of the GHG relative to carbon dioxide.

For example, carbon dioxide has a GWP of 1 (usually considered over a 100-year time frame but this can vary). Methane has a GWP of 27.9. So, every tonne of methane emitted is the equivalent of 27.9 tonnes of carbon dioxide emitted.

The worst culprit is sulphur hexafluoride which has a GWP well over 20,000! That is pretty significant!

So, to simplify the GHG reporting, the GWP is designed to show the impact of GHG emissions relative to carbon dioxide.

This may not be a net zero topic, but it gives insight into one aspect of the climate challenges we face. Over the next few weeks, I’ll be diving further into reporting standards and discussing scope 1, 2 & 3 emissions.

If you have any thoughts on this or any other net zero topics, please get in touch