Protecting the Ozone Layer Versus Reducing Greenhouse Gas Emissions

June 15, 2022
Est. Reading: 5 minutes

Myths, Partial truths, and Some Fresh Perspectives

F.S. Rowland and Mario Molina, authors of the seminal 1974 article first describing the potential for ozone depletion due to use of manmade chemicals called chlorofluorocarbons (CFCs).
F.S. Rowland and Mario Molina, authors of the seminal 1974 article first describing the potential for ozone depletion due to use of manmade chemicals called chlorofluorocarbons (CFCs). Photo credit: UC Irvine

Given the increasing frequency of natural disasters linked to climate change, there is an urgent need to accelerate GHG emission reductions. One source of lessons is the Montreal Protocol, the remarkably successful international agreement to protect the ozone layer.[1] Based on a career of over 40 years working on both issues, I believe there are still lessons from the Protocol that could help address climate change.

The Montreal Protocol, signed in 1987, began as an agreement adopted primarily by a small group of industrialized nations to reduce use of manmade chemicals, chlorofluorocarbons (CFCs), thought to damage the ozone layer. The study of atmospheric chemistry was receiving increased attention in the early 1970s thanks to environmental concerns about high altitude aircraft. Two scientists at U.C. Irvine, Sherwood Rowland and Mario Molina, tested CFCs in their lab and found that catalytic reactions would result in a reduction in ozone, in turn allowing more dangerous ultra-violet radiation to reach the earth. Their findings were published in a short article in 1974.[2] The significance of their work was recognized by the award of the Nobel Prize in Chemistry in 1995.[3]

Little more than a decade later, the Montreal Protocol was adopted, the signatories primarily a small group of industrialized nations then responsible for most use of CFCs. The initial commitment was a 50 percent reduction in production and consumption of the chemicals over a decade, but the Protocol was subsequently amended six times to expand and accelerate a phaseout. And it worked; the ozone layer is expected to fully recover between 2035 and 2060.[4] The Protocol has also made significant contributions to reducing global warming (CFCs were also potent greenhouse gases).[5]

International initiatives to address climate change overlapped with the evolution of the regime to protect the ozone layer and involved many of the same scientists, diplomats, and environmental advocates. The Intergovernmental Panel on Climate Change, the scientific panel that produces periodic international consensus reports on the state of climate science, was created in 1988 and negotiations on an international climate agreement began shortly thereafter. A climate convention was signed at the June 1992 Earth Summit by over 100 countries[6] but remarkably little has been accomplished. Emissions of greenhouse gases have steadily increased and there is now more carbon dioxide in the atmosphere than at any time in at least 4 million years.[7]

The obvious question is why the world had so much early success protecting the ozone layer but has failed so miserably to address climate change. Scholars have advanced many answers[8] but, in my view, quite a few are simply wrong, while others have merit but are inadequate. Some key factors of most current relevance are rarely mentioned or insufficiently emphasized.

1. Popular assertions that are simply wrong

· It was (or should have been) easy.[9] To the contrary, industry aggressively attacked the science and delayed action by several years. Assessments of expected ozone depletion varied with each new research paper, sometimes reducing the perceived need for action, until proof of the theory was found.

· DuPont had breakthroughs making alternatives. DuPont had identified alternatives many years before agreeing to regulation but stopped all development work in 1980 seeing no market demand for more expensive products.[10] Alternatives had to be found for 240 diverse applications, there were rarely drop-in substitutes, and eventually many solutions were found that did not rely on chemicals at all.[11]

· The science of ozone depletion was stronger, and the ozone hole proved it. The basic physics of climate change have been known since the mid-19th century while ozone depletion from manmade chemicals was a theory first identified in 1974. And the Montreal Protocol was adopted prior to proof that the ozone hole was due to CFCs — a true application of the precautionary principle.[12]

2. Explanations with some merit — but not the whole story

· The chemicals that threatened the ozone layer were nowhere near as economically important as fossil fuels and thus regulations were not nearly as difficult to justify. True, but in 1992 it would have been sufficient to limit growth in fossil fuel consumption consistent with readily available opportunities for cost-effective energy conservation.[13] In contrast, the Montreal Protocol was amended in 1990 to require a near complete phaseout of ozone depleting chemicals in a decade.

· The threat of ozone depletion was less complicated and more easily communicated. One oversimplified example being an increase in skin cancer (of some relevance a risk greater for Caucasian populations). In contrast “global warming” had the sound of something tolerable and for some even desirable.[14]

· The chemical industry had a culture of science in contrast with the oil company’s focus on extraction of resources. However, both had considerable scientific expertise and did significant research on the potential for environmental damage from their products well before the threat of regulation.[15] There were early voices of concern about climate change within the oil industry like Lord Browne, CEO of BP.[16]

3. Important factors rarely mentioned or insufficiently emphasized include

· The public support for environmental action that followed the first Earth Day in 1970;

· The fortuitous, limited group of 24 countries that signed the initial ozone agreement, avoiding many of the difficult trade-offs with developing countries;

· The emergence of a “dream team” of scientists, bureaucrats, diplomats, and cooperative industry officials dedicated and effectively supporting action; and

· The absence of precedents providing industry with experience for blocking strategies, later applied effectively to obstruct progress under the climate convention.[17]

These facts suggest several important lessons from the MP of applicability to climate change including the importance of public awareness and support; the advantage of working initially in a “coalition of the willing”; adopting a “start and strengthen” approach; and working collaboratively with industries by sector to identify solutions. I will expand on these strategies in a subsequent article but a book I co-authored with Durwood Zaelke and Stephen O. Andersen, Cut Super Climate Pollutants Now!, provides a good brief review of this history.

[1] Full title: the Montreal Protocol on Substances that Deplete the Ozone Layer. See generally For the full text and list of signatories, see more on

[2] M. Molina and F.S. Rowland, “Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone,” Nature 249, 810–812 (1974).




[6] For a general introduction and overview see


[8] The best include L. Dotto and H. Schiff, The Ozone War (1978); R. Benedick, Ozone Diplomacy (1991); S. Cagin and P. Dray, Between Earth and Sky (1993); S. Andersen and K.M Sarma, Protecting the Ozone Layer: the United Nations History (2002); S. Andersen and D. Zaelke, Industry Genius: Inventions and People Protecting the Climate and Fragile Ozone Layer (2003); and E. Parson, Protecting the Ozone Layer (2003).

[9] E. Linden, Fire and Flood (2022)

[10] S. Cagin and P. Dray, Between Earth and Sky (1993)

[11] S. Andersen and D. Zaelke, Industry Genius: Inventions and People Protecting the Climate and Fragile Ozone Layer (2003)


[13] Energy: Strategies to Rescue the Economy and Save the Planet




[17] J. Sebenius, “Toward a Winning Climate Coalition,” ch. 13 in Negotiating Climate Change, I. Mintzer and A. Leonard, eds.(1994)

Alan Miller is a former climate change officer in the International Finance Corporation (2003–13) and climate change team leader, Global Environment Facility (1997–2003). Besides other engagements, Alan is an active editor for Climate Conscious submissions on Medium.

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