Greenhouse gases (GHG)
Definition
Greenhouse gases (GHG) are the gases that trap heat in the atmosphere. Carbon accounting covers the seven gases of the Kyoto Protocol and expresses them in tonnes of CO2 equivalent (tCO2e).
The seven gases are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3).
Each gas has a global warming potential (GWP): how much heat it traps over a period, usually 100 years, compared with CO2. Multiplying a quantity of gas by its GWP converts it into CO2 equivalent, so a company can add all its emissions into one figure.
Go further
- Scopes 1, 2 and 3: what each scope covers
- Carbon footprint methods: Bilan Carbone®, GHG Protocol, ISO 14064