September 16, 2010

Twenty-three years ago on this date, 196 nation-states committed to ending ozone depletion by phasing out the use of chloroflurocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The CFC Phase-Out Management Plan is complete: CFCs can no longer be found anywhere in the commercial market. The HCFC Phase-Out Management Plan is scheduled to begin in earnest in 2013, with phasing out to be completed by 2030.

The Montréal Protocol may be the most successful environmental treaty ever created. Thus far, the global CFC reductions have resulted in a 10% drop in the (atmospheric) effective equivalent chlorine level between the 1994 peak and 2008. This is still a drop in the bucket: yet it is enough that the ozone layer is now finally starting to stabilise. Ozone depletion has not yet stopped, but it is slowing down. A statistically significant turnaround may even be detectable by as early as 2024. We can't expect it to be a fast thing: a single chlorine atom can keep on destroying up to 100,000 ozone molecules for as much as two years. If we continue along this track, we can hope for ozone levels to return to 1980 levels by around 2070: nearly eighty years of CFC-free recovery to balance out a single decade of careless CFC use.

(Back in those days, our weather forecasts did not include UV warnings; and we did not have to rely on sunscreen to protect us from our own native sun.)

It will take even longer for our ozone layer to return to its pre-CFC state. CFCs can survive intact for up to a century before they finally react with ultraviolet light to break down and, in the process, release those deadly chlorine atoms in the upper atmosphere. Some models predict that it will be a hundred and fifty years before the ozone "hole" over Antarctica ceases to exist.

We take this connection for granted today: but it took decades of research and argument to convince others that human-created CFCs were indeed having any kind of significant environmental impact. Frank Sherwood Rowland and Mario Molina were the first to connect the known reaction between chlorine and ozone with CFCs. Their 1974 seminal paper eventually won them the 1995 Nobel Prize for Chemistry: but not before strong opposition by DuPont almost quashed follow-up research. The findings were commonly dismissed as utter nonsense. At one point, Rowland nearly lost his job over his public statements.

Even then, the primary argument against the link between CFCs and atmospheric ozone loss was that natural sources of clorine far outweighed any human effect. It is true that natural sources of tropospheric chlorine are as much as five times greater than manmade sources. Yet for the ozone layer, only stratospheric chlorine levels matter: and there the reverse is true, since the levels of stratospheric chlorine depend on the kinds of long-lived chlorine compounds not seen in nature. The only stratospheric halocarbon which has a predominantly natural source is methyl chloride: and it is responsible only for 20% of all stratospheric chlorine.

Yet the 1970s was also a time when many environmental skeletons were beginning to surface, even against strong scientific, economic, and political opposition: a growing awareness that would culminate in the 1980 creation of Superfund sites. The DDT environmental hazards, known since the 1940s, had been made public and popular knowledge through Rachel Carson's 1962 book Silent Spring: but the book only put into words and reasons the declines in bald eagle and peregrine falcon populations that people had already been starting to notice. Cleveland's Cuyahoga river had just caught fire yet again for at least the thirteenth time: [i]Times[/i], covering the 1969 fire, described it as the river in which a person "does not drown but decays." Although the Love Canal debaucle was yet to surface, people could see the high incidence of birth defects and illnesses in the region for themselves. At the same time, the 1974 Watergate scandal shook the public's faith in beneficent authority.

Rowland and Molina were taken seriously enough that they were invited to testify before the United States House of Representatives in December 1974: which led to public funding to examine the findings. The essential validity of the hypothesis was confirmed by the United States National Academy of Sciences in 1976. Related research continued for most of the next decade: fought at every step by DuPont.

Possibly it might have stayed there, even with all the growing evidence showing a clear and growing danger. After all, the ozone layer is a long way away; and long-term solutions are never politically popular. As long as it was still functioning, the problem was not immediate, not the way a Soviet invasion of Afghanistan was, let alone a new theocracy and the national shock of the United States embassy in Iran being taken hostage. Jimmy Carter was out. (Sayyed Ruhollah Khomeini carefully timed the release of the hostages to ensure it.) Reaganomics was in.

In 1985, the British Antarctic Survey discovered the first "hole" in the ozone layer over Antarctica. Shortly afterward, a second hole was discovered near the north magnetic pole -- which placed it over inhabited land.

Even then, after most of the major CFC-producing nations had recognised the sudden immediacy of the problem and signed the Vienna Convention (the immediate precursor of the Montréal Protocol), DuPont was still running a public relations campaign of resistance. Again, the language coming from DuPont's Alliance for Responsible CFC Policy might seem very familiar: the science was still "too uncertain" to justify any change in policy. As late as 1987, DuPont representatives testified before the United States Congress that there was "no immediate crisis that demands unilateral regulation." Even today, echoes can still be heard of DuPont's blurring between the natural ozone cycle, which annually reduces polar ozone by some 30%, and the depletions caused by CFCs, which follow a completely different pattern and reduce the natural low by half again.

Had the various governments of the world taken DuPont at its word and seen no reason to change: where would we be now?

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