Lessons from Ozone

In 1974, two chemists at the University of California published a paper predicting that chlorofluorocarbons (CFCs) would destroy the ozone layer in the stratosphere that shields Earth from ultraviolet radiation. CFCs were used as propellants in aerosol cans and refrigerants in air conditioners, and while the paper’s authors didn’t yet have a hole to point to, they had atmospheric chemistry on their side.

The chemical industry’s response was to fund counter-research, hire lobbyists, and describe the scientists as alarmists whose work was too speculative to justify regulatory action. This was the same playbook that the tobacco industry had been running for two decades, and for a while it worked. The Alliance for Responsible CFC Policy, a trade group representing the manufacturers, argued that the science was uncertain. Industry representatives testified before Congress that banning CFCs would cost hundreds of thousands of jobs and devastate the American economy.

Du Pont, which held a large share of the CFC market, said in 1975 that it would stop making CFCs only if a worldwide scientific consensus emerged and the appropriate regulatory bodies took action. This was not a promise to act; it was a description of conditions the company presumably believed would never be met.

Eleven years later, in 1985, a team from the British Antarctic Survey reported a massive and growing thinning of the ozone layer over Antarctica every southern spring. Their data was so far outside expected ranges that they initially assumed their instruments were broken. NASA confirmed the finding using satellite data that, embarrassingly, had been sitting in archived files for years after automated quality-control software had flagged the anomalous readings as errors.

Industry resistance collapsed in just two years, and the Montreal Protocol was signed in 1987. The protocol’s design explains why it worked when so many other environmental agreements have not. It set binding phase-out schedules for ozone-depleting substances, with different timelines for developed and developing countries. It established trade sanctions against non-signatories, which meant that countries outside the agreement faced economic costs for staying out. And it created the Multilateral Fund, which transferred technology and money from wealthy countries to developing ones to help them adopt CFC alternatives. This last element is the one that gets least attention and does the most work.

The protocol’s structure gave it leverage that most international agreements lack. A country that refused to sign could not import controlled substances from signatory countries and could not export products made with those substances to them. By the early 1990s, enough of the global economy was covered by the agreement that staying outside it became genuinely costly.

Du Pont, which had spent years arguing that alternatives to CFCs were technically impossible, announced shortly after the protocol was signed that it had developed workable substitutes and would accelerate their commercialization. What had been technically impossible became technically straightforward once the regulatory framework made the old product unmarketable.

The substitutes developed to replace CFCs were hydrofluorocarbons—HFCs. They did not destroy the ozone layer. They did, however, turn out to be extremely potent greenhouse gases, some of them thousands of times more warming per molecule than carbon dioxide. In switching from one problem to another, the world had traded an acute crisis for a contribution to a chronic one.

The Kigali Amendment to the Montreal Protocol, adopted in Rwanda in 2016, addressed this. It added HFCs to the list of controlled substances and set phase-down schedules for them as well. Developed countries agreed to begin reductions by 2019; most developing countries by 2024 or 2028, with a small number of the hottest-climate countries, including India and Pakistan, given until 2032. The amendment was negotiated under the same structure as the original protocol, with the same Multilateral Fund available to support transitions. Climate scientists estimated at the time that full implementation of the Kigali Amendment would avoid up to 0.4 degrees Celsius of warming by 2100.

This is not is a story about individual consumers making better choices. Millions of people did not read scientific papers and switch to pump-action hairspray. The mechanism was a binding international agreement with differentiated obligations, a technology transfer fund, and trade sanctions against non-participants.

The lesson for climate change shouldn’t need to be spelled out, yet it rarely appears in public discussions. Renewable energy investment, corporate sustainability pledges, and carbon pricing mechanisms will all help, but the decisive ingredient for the ozone layer was a binding agreement with teeth. Similarly, if we want to mitigate the cognitive pollution caused by social media, country-by-country age verification isn’t going to make a difference.

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Parson2003

Edward A. Parson: Protecting the Ozone Layer: Science and Strategy. Oxford University Press, 2003, 9780195155143.

Roan1989

Sharon L. Roan: Ozone Crisis: The 15-Year Evolution of a Sudden Global Emergency. Wiley, 1989, 9780471522720.