How the world ‘fixed’ the ozone layer


At the beginning of the month, the news that the ozone layer will be completely restored in a few decades acted as a reminder of what humanity is capable of when it unites around a common goal. According to scientists, if current policies remain in place, the breach in the protective layer of the atmosphere over Antarctica should heal by 2066.

The work to close the hole in the ozone layer — in fact, there are some eroded spots, but the most critical one is near the south pole — began with a treaty reached in 1987.

The Montreal Protocol is an international agreement designed to phase out the production of substances responsible for the decline in ozone levels in the atmosphere. It entered into force in 1989 and has been adopted by 197 countries plus the European Union, making it one of the few universally ratified agreements in history.

It was preceded by years of negotiations. Since the mid-1970s, it has been known that chlorofluorocarbons (compounds based on carbon, chlorine and fluorine, known as CFCs) produced by human activities were destroying atmospheric ozone. But it wasn’t until 1985, when British researchers discovered a seasonal hole in the ozone layer over Antarctica, that the size of the problem became evident.

This layer protects the Earth from the Sun’s ultraviolet radiation, making the planet habitable — that is, its destruction posed a threat to all living beings and demanded immediate action. Even so, there was a gap between the scientific finding and the political drive to resolve the situation.

“The Montreal Agreement was being negotiated for about five years because of opposition from the industries”, says Paulo Artaxo, a specialist in atmospheric chemistry at USP. CFCs were used in aerosols, plastic foams, and especially in refrigeration equipment.

Despite resistance, the deal eventually went into effect — and the relatively limited scope of CFC sources and the economic power of the refrigeration industry were important to its effectiveness.

In 1991, a multilateral fund was also established to provide technical and financial assistance to developing countries to comply with the provisions of the protocol.

The recent announcement about restoring the ozone layer was made after a scientific assessment that takes place every four years, provided for in the agreement. The researchers pointed out that global emissions of CFC-11, a banned chemical used as a refrigerant and in insulating foams, have declined since 2018.

The report points out that, if the current situation continues, ozone levels between the polar regions should return to pre-1980 levels by 2040. The holes in the protective layer will take a little more time, but they must also be fully restored: until 2066 in Antarctica, and until 2045 in the Arctic, where it appears less frequently.

According to UNEP (United Nations Environment Programme), reversing the depletion of the ozone layer has protected millions of people from skin cancer and cataracts, allowed ecosystems to survive and slowed down climate change, helping to prevent global temperatures would rise by about 0.5°C.

An amendment added to the Montreal Protocol in 2016 called for a gradual reduction in the production and consumption of some hydrofluorocarbons (HFCs). These gases do not directly destroy ozone, but they do contribute to global warming. The estimate is that this amendment will prevent 0.3°C to 0.5°C of warming by 2100.

In the celebration of the 35th anniversary of the treaty that “fixed” the ozone layer, last year, the secretary general of the UN (United Nations), António Guterres, used the success of the agreement as an example to be followed in combating the crisis weather. “Only by mirroring the cooperation and swift action of the Montreal Protocol can we stop the carbon pollution that is dangerously warming our world.”

Although other agreements have been designed to address the climate issue, the effectiveness has fallen far short of what was desired. In the case of the Kyoto Protocol, for example, signed in 1997, the United States was opposed to ratifying it. At the time, the country was the biggest annual emitter of greenhouse gases, accounting for 25% of global emissions, and the American refusal doomed the effectiveness of the treaty.

“The Montreal Protocol saved five times more carbon-equivalent emissions than the Kyoto Protocol,” points out Natalie Unterstell, director of the Talanoa Institute for Climate Regulation and Risk. “[Ele] it’s also quite significant compared to what’s been happening so far with the Paris Agreement.”

Even though the Paris Agreement has also been adopted by all countries, nations have been leaving something to be desired: by failing to meet their emission reduction targets, they are making the goal of leaving global warming well below 2° increasingly distant. Ç. According to the 2022 Emissions Gap Report prepared by UNEP, the policies currently in place will lead to a temperature increase of 2.8°C by the end of the century.

Unterstell says he believes that the effectiveness of the agreement signed in Canada is based on the fact that the document regulates the production and consumption of CFCs between countries. “For the climate, a global carbon price mechanism could have the same effect, but it does not exist and is not even under discussion.”

“I think it’s possible to replicate the success [de Montreal] if there is economic regulation of the causes and risks of climate change. Until now, the instruments of international climate policy (and even in Brazil) are not regulatory”, analyzes the expert.

Paulo Artaxo, on the other hand, points to the power of the oil industry lobby in defining public policies as the main obstacle for climate agreements to prosper. “The issue of climate change is more difficult to resolve because of the control the oil industry has over most governments.”

He also recalls that less than 20 oil industries are responsible for around 80% of the oil extracted worldwide.

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