By fighting the ozone hole, we have helped to curb climate change

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this one at hakaimagazine.com.

In 1985, the British Antarctic Survey alerted the world that a giant hole was forming in the Earth’s protective ozone layer in the atmosphere high above the South Pole. World leaders quickly came together to find a solution. Two years later, the United Nations decided to ban chemicals responsible for eroding the layer of the stratosphere that protects the Earth from ultraviolet radiation from the sun. Known as the Montreal Protocol Agreement, it is still one of the most widely ratified treaties by the United Nations.

The Montreal Protocol was a victory for diplomacy and the stratosphere. But unbeknownst to its signatories at the time, the deal was also an unexpected safeguard against climate catastrophe. Ozone-depleting substances (ODS) that created the hole over Antarctica are also responsible for causing 30 percent of the temperature rise we saw globally from 1955 to 2005, new research shows. .

Michael Sigmond, a climate scientist at Environment and Climate Change Canada, is the lead author of a new study that calculates the greenhouse effect trapping power of ODS. The contribution of substances to global warming is, he says, greater than most people realize.

The Montreal Protocol regulates nearly 100 ozone-depleting chemicals. Many fall under the umbrella of chlorofluorocarbons (CFCs), chemicals popularized in the 1930s for use in aerosol cans, plastic foams, and refrigeration. Compared to the range of toxic and flammable alternatives they replaced, CFCs were seen as wonder chemicals and by the early 1970s, the world was producing nearly one million tonnes of them a year.

CFCs are inert, so they don’t react with other gases. Instead, they tend to accumulate in the atmosphere and drift wherever the wind takes them, remaining suspended in the air for 85 years or more. Once they reach the stratosphere, the second layer of Earth’s multilayered atmosphere, CFCs begin to decompose. They’re destroyed by being torn apart by photons, explains Dennis Hartmann, a climate scientist at the University of Washington who he wasn’t involved in the research. That reactive ruckus is what causes the hole in the ozone layer.

In the troposphere, the lowest level of the atmosphere, where fewer photons reach, ODS act as long-lived greenhouse gases. In 1987, scientists knew that ODS trapped some solar radiation, but they didn’t know how much. Only recently have scientists pieced together evidence that ODS is actually one of the most harmful heating agents of the past half century.

The effects of this heating are magnified at the poles. The work of Sigmond and his colleagues shows that if ODS had never been mass-produced, if the concentration in the atmosphere had remained at 1955 levels, the Arctic today would be at least 55% colder and there would be 45 % more sea ice every September.

ODS production stabilized in the 1990s. But because they are so long-lived, these gases keep moving and the warming they cause is still on the rise. Yet it could have been much worse. By banning ODS, the Montreal Protocol unwittingly prevented 1°C of warming by 2050.

With the Montreal Protocol, world leaders rallied around an urgent cause. In the process, we have inadvertently phased out the second largest force in global warming. The unanticipated benefits for the global climate, says Susann Tegtmeier, an atmospheric scientist at the University of Saskatchewan who was not involved in the study, can be seen as a very welcome and very positive side effect.

While it took a lot more negotiation and innovation to begin removing the main driver of climate change, carbon dioxide, the Montreal Protocol demonstrates the power of collective action and shows how tackling environmental problems can help us in ways we can’t. we waited.

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this one athakaimagazine.com.

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