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Refrigerants originally selected for their safety, cost, stability compatibility with materials, and excellent performance (such as R12 for refrigerators and automobile air conditioners and R22 for residential air conditioners) have been the subject of major controversy in recent years.
Data of ozone concentration in the stratosphere suggested a depletion, and theoretical models placed part of the blame on chlorofluorocarbons such as R12. Not all researchers agree with these conclusions, which are based on complex mathematical models with relatively simplistic approximations (among these are the values and nature of the turbulent transport coefficients) and assumptions (such as the effect of other constituents and dynamics in the atmosphere). The disagreement is also based on the limited data and recognition that there are major temporal and spatial scales that demand long-time data and trends for proper inferences [Anderson et al., 1990]. The outcome has been a complete phase-out of R12 and its replacement by alternatives such as 134a (more costly but estimated to be more "environmentally friendly").
Similar models for the potential greenhouse effect of refrigerants have led to the inference that refrigerants such as R22 might have an undesirably high "global warming potential". The data on "global warming" are subject to even more controversy than those for ozone depletion. There are long-scale effects related to the orbital motion of our planet that might mask any global warming effects attributed to refrigerants like R22. Nonetheless, there is currently a strong effort to replace R22 as well as R12.
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