Atmospheric gas that traps the heat and is responsible for warming the earth and climate change. The major greenhouse gases are: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N20). Less prevalent – but very powerful – greenhouse gases are hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF). Those gases are regulated under the UNFCCC, the Montreal Protocol, the Kyoto Protocol and the Paris Agreement. Many ozone depleting substances controlled by the Montreal Protocol are also greenhouse gases.