Background Information: ChloroFluoroCarbons (CFCs)
Unlike some other greenhouse gases (nitrous oxide, methane, and carbon dioxide), CFCs do not occur in nature. They are humanly-created molecules used in industry for air conditioning, refrigeration, electronics, packaging, and foams. When these molecules leak into the air, they are very effective at trapping heat. When they drift up through the atmosphere, they also destroy molecules in part of the upper atmosphere (the ozone layer).
Because CFCs are now known to break down the ozone layer, many countries have agreed to phase out their production. That is the good news. Unfortunately, some of the new substitutes for CFCs still trap heat. Furthermore, they have long lifetimes in the atmosphere. So even though they do not destroy ozone, they still contribute to global warming. That is the bad news. Fortunately, environmentally-safe alternatives to CFCs do exist. Although they are not yet used by many manufacturers, water-and helium-based technologies might some day replace CFCs.
Yet another surprise is in store! Because of the growing concern over the ozone layer and the role played by CFCs, manufacturers of refrigerators, and air-conditioners, in recent years have been persuaded to switch to the use of the more ozone-friendly HCFC-22, a hydrofluorocarbon. Ironically, only in the early weeks of 1998, following a re-analysis of the archived air samples collected at Cape Grim on the north west coast of Tasmania, was it discovered that the atmosphere probably contains 135,000 tons of fluoroform, a previously unnoticed greenhouse gas with a global warming potential some 10,000 times greater than that of carbon dioxide, although of course it is present in much smaller quantities. Nevertheless, scientists in the University of East Anglia in the United Kingdom calculate that the current volume of fluoroform in the atmosphere has a global warming potential of 1.6 billion tons of carbon dioxide, or three times the annual emissions of carbon dioxide in Britain. Fluoroform is said to be increasing at the rate of 5% each year, so it cannot be ignored. The connection with refrigeration is that fluoroform, HFC-23, unfortunately is a waste byproduct of the manufacture of HCFC-22. It is used for a variety of purposes in its own right in industry including the lubrication of computer disks. Ironically again, the information became available just after the intergovernmental meeting in late 1997 at Kyoto, Japan, so that the agreement on practices to limit the release of greenhouse gases reached at that meeting completely ignored this newly-discovered danger. This was grim news in more ways than one. So, we have found yet another example of the difficulties involved in curing the ills of the environment. Here, as in many other cases, we have not cured the problem of CFCs. We have merely shifted the problem into another area.
