GHG

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Greenhouse gases (GHG): For the purposes of the GHG Protocol, GHGs are the seven gases covered by the UNFCCC: carbon dioxide (C02); methane (CH4); nitrous oxide (N20); hydrofluorocarbons (HFCs); perfluorocarbons (PFCs); sulphur hexafluoride (SF6), and nitrogen trifluoride (NF3).

Practical consideration – Carbon dioxide, methane and nitrous oxide are the most common GHGs emitted by an entity and will likely be included in a reporting entity’s emissions. Additionally, hydrofluorocarbons are emitted by many entities using refrigeration or air conditioning, so they are often included in a reporting entity’s emissions. The remaining synthetic GHGs (i.e., PFCs, SF6 and NF3) are more industry-specific and may not be emitted by all reporting entities.


The GHG Protocol addresses emissions of the seven GHGs defined by the UNFCCC8- carbon dioxide (C02), methane (CH4), nitrous oxide (N20), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3). These gases are classified as GHGs because they trap heat in the atmosphere. Some of the common sources of GHG emissions are as follows:

  • Carbon dioxide is primarily emitted through fuel combustion (or combustion of waste, wood, and other biological material) and industrial processes, with the burning of fossil fuels being the most significant source. Carbon dioxide can be removed from the atmosphere, or sequestered, through natural biological methods (e.g., absorbed by plants) or other processes.
  • Methane is primarily emitted during the processing or production of coal, natural gas and oil. Methane is also emitted by certain agricultural practices, livestock and the decay of organic compounds.
  • Nitrous oxide is primarily emitted from agricultural soil management, land use, industrial activities, burning fossil fuels and waste, and treating wastewater.
  • Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride and nitrogen trifluoride are synthetic GHGs (i.e., they do not have natural sources) that are primarily emitted from household, commercial and industrial processes. Hydrofluorocarbons are primarily used as refrigerants. Perfluorocarbons are a byproduct of aluminum production and are used in the manufacturing of semiconductors. Sulfur hexafluoride is used in magnesium production and in the manufacturing of semiconductors; it is also an insulating gas in electrical transmission equipment. Nitrogen trifluoride is used in the manufacturing of semiconductors.

The GHG Protocol acknowledges there are other GHGs (e.g., chlorofluorocarbons (CFCs), nitrogen oxides (NOx)) that are not covered by the UNFCCC and includes an optional disclosure for a reporting entity to separately disclose GHG emissions from other GHGs.