Almost everyone is aware that carbon dioxide is a greenhouse gas, and that it has the potential to lead to significant global warming. The current atmospheric level of CO 2 is around 350 ppm, and it is increasing by almost 2 ppm per year, primarily as a result of our use of fossil fuels. These gases contribute to global warming because they absorb energy in the infrared part of the spectrum. This traps some of the heat reflected from the earth's surface that would otherwise escape into space.
Different gases absorb infrared radiation at very different rates.
SF 6 and SF 5 CF 3 are almost entirely derived from industrial sources, although the actual source of SF 5 CF 3 is not clearly understood. The current atmospheric levels of SF 6 and SF 5 CF 3 are around 4.0 and 0.12 ppt respectively. Firstly, SF 5 CF 3 is described as the most effective known infrared absorber, approximately 20,000 times more effective than carbon dioxide. Thirdly, and most significantly, is that SF 5 CF 3 is essentially inert in the atmosphere. It does not appear to get broken down chemically, and each molecule may be expected to last for over a thousand years, and perhaps for several thousands of years on average.