Originally posted by TransformX
When M & S published their paper, it was a pure hypothesis, based on some lab experiments. There was no, zero, zilch proof in 1974, not even sufficient to justify calling it a theory. In reality, most scientists even classed it as piffle. Further research upgraded it to a more plausible theory by 1978 and, for once, the USA applied the precautionary principle in that year by being the first to ban CFC propellants in most aerosol cans, even though there was still no proof, in the lab or in the atmosphere. Even by 1987, when the Montreal Protocol was signed and several years after Joe Farman discovered the so-called "ozone-hole", the atmospheric scientists were still about evenly divided between CFCs and natural phenomena being the cause. It was not until September 1988 that NASA actually provided the irrefutable proof by the analysis of samples taken from the Antarctic vortex at very high altitudes, using a modified U2 plane. Even then, the hardest naysayers persisted in their errors for another 5 or 6 years. Within 1 week of the publication of the NASA results, DuPont turned their coat from "we shall do nothing about restricting the manufacture of CFCs other than what is forced upon us" to "we shall do everything in our power to help protect the ozone layer" (my paraphrases, not direct quotes).
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