GHG is an abbreviation for greenhouse gases which are the different gases that contribute to the greenhouse effect (global warming).

Greenhouse gases can be defined as the gaseous components in the atmosphere, being both natural and man-made, which absorb and release radiation at specific wavelengths. This is done within the spectrum of infrared radiation emitted by the Earth’s surface, its atmosphere and clouds. This phenomenon causes the greenhouse effect. The main greenhouse gases in the Earth’s atmosphere are water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3).

The six most important GHGs emitted by humans, according to The Kyoto Protocol, are:
• Carbon Dioxide (CO2)
• Methane (CH4)
• Nitrous Oxide (N2O)
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)
• Sulphur Hexafluoride (SF6)