These are man-made gases that can stay in the atmosphere for centuries as a greenhouse gas. There are four main types:
These are organic compounds that contain hydrogen (H), fluorine (F) and carbon (C). They are extensively used in refrigeration and air conditioning systems as a substitute for the earlier chlorofluorocarbons.
Chlorofluorocarbons contain fluorine, chlorine (Cl) and carbon. They have been considerably phased out under the 1987 Montreal Protocol because of their recognised effect on the ozone layer.
Although HFCs have less effect on the ozone layer they still have a high potential acting as a greenhouse gas. Their Global Warming Potential varies from 140 to 11,700 over a 100 year period. In 2016, the Kigali Amendment to the Montreal Protocol set targets and timetables to replace HFCs with more environmentally friendly alternatives.
These compounds contain fluorine and carbon and are powerful greenhouse gases. Their Global Warming Potential over 100 years range from 6,500 to 9,200. They were introduced as a replacement for chlorofluorocarbons in manufacturing semiconductors and as refrigerants. These chemical are covered by the Kyoto Protocol along with carbon dioxide, methane, nitrous oxide, HFCs, and sulphur hexafluoride (SF6)
Sulfur hexafluoride (SF6)
This is an inorganic compound (no carbon) that contains a central sulfur (S) atom and fluorine atoms. It is a very potent greenhouse gas with a Global Warming Potential over 100 years of 16,300. SF6 is used in the electrical and magnesium industries. It is covered by the Kyoto Protocol.
This is an inorganic compound that contains nitrogen (N) and fluorine that is used in the microelectronics industry. It is a greenhouse gas with a Global Warming Potential of 17,200 over a 100 year period. It is covered by the Kyoto Protocol.
This is the last of the major groups of greenhouse gases we will look at.
Now we can consider the current thinking of the Intergovernmental Panel on Climate Change (IPCC) to get a much more detailed view of current evidence for and about climate change.