In 1974, a pair of scientists published a paper claiming that chlorofluorocarbons, a compound used in refrigerators, air conditioners, aerosol spray cans, and other devices, migrated into the atmosphere, where they damaged the ozone layer.  The ozone layer protects human beings from some of the harmful effects of the sun; the predictable consequence of its loss would be millions of skin cancer cases.  The scientists’ work was hotly contested; it eventually gained support in the scientific community, but there were also dissenters.  EPA would later regulate the use of CFCs in aerosols, but it was clear that unilateral regulation by the U.S. government would not solve the problem.  CFCs manufactured and used in any country could damage the ozone layer.

The American government turned to the Europeans, the other major manufacturers and users of CFCs.  Europeans, however, did not trust the science and expressed skepticism about the CFC theory.  After further scientific research established that an ozone hole had opened up above Antarctica, and that the likely cause was the emission of CFCs, the Americans dragged the still skeptical Europeans into a treaty regime that tightly regulated the use of CFCs and other ozone-depleting gases.  The Montreal Protocol is the most successful environmental treaty ever (the only successful environmental treaty?).  The hole has been gradually shrinking and is expected to disappear later this century.

The odd part of this story is that, while not everyone agreed with the scientists who found the link between CFCs and ozone depletion, and that indeed, like everything else, the link was uncertain, albeit likely, governments were able to agree on a treaty regime.  The leading supporters of a treaty were those tree-huggers in the Reagan administration, who were persuaded by a cost-benefit analysis that the benefits from a ban on CFC greatly exceeded the costs—with the benefits properly discounted given residual scientific uncertainty.  There were ozone skeptics, but no Ozone Skeptics.  There was a reasonable scientific theory but no models that got everything right all the time.  There was an observable hole (if you believed the scientists who measured it) but the physical processes that linked it to refrigerators and aerosol cans could obviously not be demonstrated to the public.

Where were the Climate Skeptics back then?  Or was ozonegate, like asteroidgate, a non-event because the climate is a “complex system” whereas, um….  Why didn’t “hierarchical and individualist” citizens find the Montreal Protocol “threatening to their identities”?  (Cf. Dave Hoffman on asteroidgate.)  Were scientists more honest in those days?  Commentators more sober?  The public more credulous?

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