Glossary
How it works
Gases do not warm the planet equally. To add them up, each one is converted to the amount of carbon dioxide that would cause the same effect over 100 years.
That multiplier is called global warming potential. The IPCC publishes the values and they change with each report, so an inventory should always say which ones it used.
The values
| Gas | Potential over 100 years |
|---|---|
| Carbon dioxide | 1 |
| Methane, non-fossil | 27 |
| Methane, fossil | 29.8 |
| Nitrous oxide | 273 |
| Sulfur hexafluoride | 24,300 |
These are the values from the IPCC Sixth Assessment Report.
An example
2 t of methane × 27 = 54 tCO2e
Two tonnes of non-fossil methane weigh as much in a footprint as 54 tonnes of carbon dioxide.
Where you will see it
In the total of any emissions inventory, in emission factors and in reduction targets. If a footprint figure does not say tCO2e, ask which gases it includes.
