Happy birthday to the Montreal Protocol – the most successful environmental treaty of all time?

Each year, the 16^th of September is celebrated by the United Nations as International Day for the Preservation of the Ozone Layer, or ‘Ozone Day’ for short, to mark the signing of the Montreal Protocol, which turns 35 today.

Success worth celebrating

The Montreal Protocol on Substances that Deplete the Ozone Layer was developed in the late 1980s, in response to the latest science on ozone depletion. To date, it is the only United Nations environmental agreement to have been ratified by every country in the world, and has made demonstrable progress: 99% of ozone-depleting substances controlled by the Montreal protocol have been phased out, and the ozone layer is slowly healing. Recovery is slow, as ozone-depleting substances remain in the atmosphere for a long time, even after they’ve stopped being used, but it’s expected that the ozone layer will return to pre-1980 levels around the middle of this century.

The ‘world avoided’

Without the Protocol, ozone depletion would have continued and spread to other regions, allowing more UV-B radiation to reach the Earth’s surface. Computer modelling of a ‘world avoided’ suggests that the Montreal Protocol will prevent around 2 million cases of skin cancer per year by 2030, as well as protecting the ecosystems necessary for food production and carbon storage.

In light of these accomplishments, and its relatively quick progress (especially when compared to global agreements on climate change), the Montreal Protocol is often considered to be the single most effective agreement on international environmental protection. So what does its success tell us about effective global governance, and what can be learned?

A discovery that would transform the work of scientists and policy-makers

The Montreal Protocol developed quickly in the light of new scientific evidence. In the mid-1970s, scientists discovered that the ozone layer was thinning due to the accumulation of gases containing halogens – chlorine and bromine – in the atmosphere. Later, in the mid-1980s, the unexpected discovery of a ‘hole’ in the ozone layer by a team of researchers from the British Antarctic Survey further raised the alarm. They suggested that the hole over Antarctica was caused by the chlorofluorocarbons (CFCs) used in many products, from fridges to hairspray, and this finding was later confirmed by independent data. But the science was not necessarily settled at the outset – atmospheric scientist Susan Solomon recalls that the agreement was being signed at the same time as aircraft measurements of ozone-depleting compounds were being taken over the Antarctic – in an early example of the use of the ‘precautionary principle’. Evidence about the extent of the risks of ozone depletion was uncertain, but the stakes were high, and policy-makers moved fast.

Faced with rapidly advancing research and potential new findings, the Protocol set a schedule for the monitoring and control of nearly all ozone-depleting substances. Crucially, this schedule would be reviewed and could be adjusted in the light of new scientific or economic information. Compliance measures were designed to be non-punitive in the first instance, providing room for feedback and learning before expulsion.

With exceptional ozone holes discovered in 2020 and 2021, scientists from the Copernicus Atmosphere Monitoring Service (CAMS) are closely monitoring development of the 2022 Antartic ozone hole through the Southern Hemisphere spring.

As recent research shows unexpected emissions of several ozone-depleting sustances, it must be hoped that the Protocol can continue to respond.

Animation courtesy of Copernicus Atmosphere Monitoring Service, ECMWF.

For more on the ozone hole in 2020 and 2021, see:

An adaptive approach

Whereas climate policy processes have been characterized by global negotiations (with the ambition of global agreement), the Montreal Protocol was not global from the start: it initially focussed on industrialized countries with the highest consumption of ozone-depleting substances, but was increasingly ratified by developing countries as well. Countries had a common responsibility for the ozone layer, but had not contributed equally to its depletion. The costs of compliance for developing countries were therefore met by a multilateral fund from developed countries, and developing countries were given more time to phase out ozone-depleting substances. The result was that all 142 developing countries had phased out 100% of CFCs, halons and other ozone-depleting substances by 2010. In addition, restrictions on trade with countries that had not ratified the agreement helped to get more countries to participate and avoided the ‘free rider’ problem.

Given that a few companies and sectors dominated production and use of ozone-depleting substances, the Montreal Protocol saw a role for industry from the outset, and provided a framework that allowed them to plan research and innovation in step with the targets for compliance. The threat of penalties for non-compliant firms, including trade measures, and consumer alarm about the health dangers of CFCs put pressure on companies to act. There was a clear business opportunity for companies that could provide different chemical formulations and new technologies.

Experimentation in the face of uncertainty

The success of the Montreal Protocol was the result of an unprecedented level of cooperation by the international community, and collaboration between public and private sectors. In their recent book, ‘Fixing the Climate: Strategies for an Uncertain World’, Charles F. Sabel and David G. Victor argue that the Protocol’s success lies in its design, and the way it’s characterized by experimentalism and learning by doing. They note that the Protocol emerged from a ‘thin’ consensus at the outset – there was limited agreement among negotiators on the risks of damage to the ozone later, but the uncertainty provided fertile ground for innovation from the outset. Indeed, the provisions in the protocol are not very detailed. Instead, front line actors such as chemical companies and local regulators, had to work out how to find solutions through collaboration. This allowed innovations to be developed within the context in which they’d be used. Progress was not always linear, but regular monitoring supported cooperation.

A new approach to governance

Of course, chemical compounds and the sectors in which they’re used are an easier target than the full spectrum of greenhouse gas emitters. But Sabel and Victor say that the kind of ‘experimentalist governance’ which characterized the Montreal Protocol could foster the urgently required emissions reductions that decades of global climate diplomacy have failed to deliver.

“The world has a lot to learn from the Montreal Protocol that can guide other areas of cooperation, such as on global warming. But for too long people have learned the wrong lessons—they haven’t focussed enough on the special role that the Montreal institutions played in pushing experimentalism and helping the parties learn which experiments worked.”
David G. Victor, Professor of Innovation and Public Policy; Co-director, Deep Decarbonization Initiative, UC San Diego

Most diplomacy, they suggest, ‘largely follows and aids on-the-ground experimentation and problem solving, rather than leading the charge’. As such, we should not expect solutions to the climate crisis to come from multilateral talks or top-down global agreements. The transformations required must arise locally, with broad participation from stakeholders, and a process of cooperation emerging from learning through experiments.

Image: The Antarctic Ozone Hole in 2021. NASA Earth Observatory image by Joshua Stevens, using data courtesy of Paul Newman and Eric Nash/NASA/Ozon e Watch, and GEOS-5 data from the Global Modeling and Assimilation Office at NASA GSFC.