Montreal Protocol

• 1. Introduction

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  The Montreal Protocol carries a distinction no other treaty in United Nations history holds: it is the only international agreement ever ratified by all 198 parties, including every UN member state, the Cook Islands, Niue, the Holy See, the State of Palestine, and the European Union. That unanimous endorsement is striking enough. But the subject that united them is more so. A family of invisible industrial chemicals, invented in laboratories and pumped into aerosol cans and refrigerators for decades, was quietly tearing a hole in the layer of gas that shields all life on Earth from ultraviolet radiation.

  Signed on the 16th of September 1987 in Montreal, Canada, the Protocol committed nations to phasing out the very substances their industries depended on. It was, as former UN Secretary-General Kofi Annan later said, "perhaps the single most successful international agreement to date."

  How did a treaty that rewired the global chemical industry get every country on Earth to sign? How did scientists go from a laboratory hypothesis to a binding international agreement in fewer than fifteen years? And what happens when the replacement chemicals turn out to carry dangers of their own?

• 2. The Science Behind the Crisis

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  In 1974, Frank Sherwood Rowland and Mario Molina at the University of California, Irvine began studying what happened to chlorofluorocarbons once they entered the atmosphere. What they found was troubling. CFC molecules were stable enough to drift upward into the middle of the stratosphere, where ultraviolet radiation finally broke them apart. That breakdown released chlorine atoms, and Rowland and Molina proposed that those atoms would trigger the breakdown of large amounts of ozone in the stratosphere.

  Two years later, the U.S. National Academy of Sciences released a report confirming the scientific credibility of the ozone depletion hypothesis. Even so, industry was slow to take alarm seriously. As late as 1987, DuPont testified before the U.S. Congress that "we believe there is no imminent crisis that demands unilateral regulation." Du Pont Chair Richard E. Heckert repeated that position in a letter to the U.S. Senate as late as March 1988, writing that "scientific evidence does not point to the need for dramatic CFC emission reductions."

  The most dramatic piece of evidence arrived in 1985, when British Antarctic Survey scientists Joe Farman, Brian Gardiner, and Jon Shanklin published results showing abnormally low ozone concentrations above Halley Bay near the South Pole. The colorful, time-lapse NASA images of the ozone hole that followed were viscerally shocking in a way that equations could not be. Negotiators in Montreal found them impossible to ignore.

  That same year, an independent assessment spearheaded by NASA and sponsored by the United Nations Environment Program and the World Meteorological Organization concluded that continued CFC emissions at 1980 rates would reduce global average ozone by around 9 percent by the latter half of the century. The U.S. Environmental Protection Agency translated that figure into human terms: more than 150 million new cases of skin cancer among Americans alive or born by 2075, resulting in more than 3 million deaths.

• 3. The Road to Montreal

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  In 1982, representatives from 24 countries gathered in Stockholm, Sweden to begin work on a global framework for protecting the ozone layer. The following year, the United States, Canada, the Nordic countries, and Switzerland proposed a worldwide ban on "nonessential" uses of CFCs in spray cans.

  In 1985-20 nations, including most major CFC producers, signed the Vienna Convention, which set up a framework for negotiating international regulations on ozone-depleting substances. From the moment the ozone hole was discovered, it took only 18 months to reach a binding agreement in Montreal.

  Central to that speed was Mostafa Kamal Tolba, the head of the United Nations Environment Programme at the time. Tolba was considered the "father of the Montreal Protocol" for his role in pulling nations toward agreement.

  Industry's posture also shifted, unexpectedly. The Alliance for Responsible CFC Policy, an industry group founded by DuPont, had spent years arguing the science was too uncertain to justify action. Then, in 1986, the Alliance issued a statement acknowledging that large future increases in CFCs would be unacceptable to future generations. Three months before the protocol negotiations formally began, U.S. industry announced support for new international controls. It was a reversal that cleared a major political obstacle and helped negotiations conclude on schedule.

• 4. How the Phase-Out Works

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  Article 5 of the Protocol creates separate obligations for developing countries, allowing them additional time to reach compliance. Article 10 establishes a financial mechanism to help those countries meet the costs of switching away from ozone-depleting substances.

  For the main group of CFCs covered under Annex A, production and consumption in wealthier, non-Article 5 countries was frozen at 1986 base levels on the 1st of July 1989. The schedule then called for a 75% phasedown by 1994 and complete phase-out by 1996. Developing countries under Article 5 had more time: their consumption and production were frozen at an average of 1995-97 amounts, with a 50% phasedown required by 2005 and full phase-out by 2010.

  Halons, used in fire suppression systems, followed a separate timetable. Wealthier nations had to freeze halon production and consumption at 1986 levels on the 1st of January 1992, with complete phase-out by 1994. Article 5 parties had until 2010.

  The protocol built in limited exemptions for cases where no substitute was available. Metered dose inhalers used to treat asthma and chronic obstructive pulmonary disease were initially exempt. Halon fire suppression systems on submarines and aircraft also received an exception, though not for general industrial use.

  Decision-making under the Protocol was designed to follow the evidence. An expert Scientific Assessment Panel published findings on ozone depletion in 1989, 1991, 1994, 1998, and 2002. A Technology and Economic Assessment Panel, established in 1990, evaluated alternative technologies and reported directly to the parties without political editing.

• 5. Money, Compliance, and Defection

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  The Multilateral Fund for the Implementation of the Montreal Protocol was created to bridge the gap between what developing nations needed and what they could afford. Any country whose annual per capita consumption and production of ozone-depleting substances falls below 0.3 kilograms qualifies for assistance. As of the data cited in the source, 147 of the 196 parties met that threshold.

  The Fund is managed by an executive committee with equal representation: seven industrialized countries and seven Article 5 countries, elected annually. Four implementing agencies carry out its work on the ground: the United Nations Environment Programme, the United Nations Development Programme, the United Nations Industrial Development Organization, and the World Bank. Pledges reached US$3.1 billion over the period from 1991 to 2005. Those funds paid for converting manufacturing processes, training workers, covering royalties on new technologies, and setting up national ozone offices.

  Compliance has been high overall, but not universal. Significant black-market production of CFCs was reported in Russia in 1997, destined for the European Union throughout the 1990s. Illegal markets were also detected in Taiwan, Korea, and Hong Kong. Related U.S. violations were enabled by fraudulent reporting under poor enforcement mechanisms.

  A more recent breach surfaced in 2018, when scientists monitoring the atmosphere after the 2010 CFC-11 phaseout date found evidence of continued industrial production, most likely in eastern Asia. A separate monitoring study detected fresh atmospheric releases of carbon tetrachloride from China's Shandong province, beginning sometime after 2012, accounting for a large share of emissions that exceeded global estimates under the Protocol.

• 6. The HFC Problem

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  When CFCs were phased out, the chemical industry moved to hydrochlorofluorocarbons as a transitional substitute. HCFCs have a much lower ozone depletion potential than CFCs, but they are potent greenhouse gases. Their atmospheric concentrations rose sharply as a result of the substitution.

  The industry then moved to hydrofluorocarbons, or HFCs, which contain no chlorine and pose no threat to the ozone layer. But HFCs are powerful greenhouse gases with a global warming potential comparable to the original CFCs. On a molecule-for-molecule basis, these compounds are up to 10,000 times more potent greenhouse gases than carbon dioxide. A 2009 study calculated that a fast phasedown of high-GWP HFCs could potentially prevent emissions equivalent to up to 8.8 gigatonnes of CO2 per year by 2050, and could avoid up to 0.5 degrees Celsius of warming by 2100 under the high-HFC growth scenario.

  The Federated States of Micronesia proposed an amendment to address high-GWP HFCs starting in 2009. The United States, Canada, and Mexico followed with a similar proposal in 2010. After seven years of negotiations, the 28th Meeting of the Parties in Kigali, Rwanda, reached agreement in October 2016 on what became the Kigali Amendment.

  Under the Kigali Amendment, which entered into force on the 1st of January 2019, parties committed to reducing HFC production and consumption by at least 85 percent from their 2011-13 average. Developing countries including China, Brazil, and South Africa must reach that 85% reduction by 2045. India, Iran, Iraq, Pakistan, Saudi Arabia, Kuwait, and other developing nations have until 2047 to cut their HFCs by 85% of their 2024-26 average. On the 17th of November 2017, Sweden became the 20th party to ratify the Kigali Amendment, pushing it past the ratification threshold that guaranteed it would take effect.

• 7. Recovery and What Remains

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  The ozone hole over Antarctica is slowly recovering as a direct result of the Protocol. Climate projections now indicate the ozone layer will return to 1980 levels by approximately 2040 across most of the world, by 2045 over the Arctic, and by 2066 over Antarctica.

  Those timelines have shifted over the years. The 2002 Scientific Assessment had predicted a return to 1980 levels by the middle of the 21st century. The 2022 reassessment pushed the Antarctic date out to 2066, a delay attributed to revised calculation formulas as well as observed atmospheric changes.

  A 2015 U.S. Environmental Protection Agency report estimated the Protocol will prevent more than 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataracts in the United States alone.

  Within 25 years of signing, the parties had phased out 98 percent of the ozone-depleting substances contained in nearly 100 hazardous chemicals. By October 2022, the State of Palestine had become the last party to ratify the original Protocol, bringing the total to 198.

  Challenges remain on the agenda. Recent Meetings of the Parties have addressed illegal imports of heating, ventilation, and air conditioning equipment; HFC-23 by-product emissions; the management of recovered halons; stratospheric aerosol injection; and proposals to improve access to climate-friendly cooling equipment in developing countries. The Protocol that began by targeting a handful of spray-can chemicals in 1987 now sits at the intersection of ozone science, climate policy, trade law, and industrial development, with a 2047 deadline still years away for some of the world's largest developing economies.