The International Day for the Preservation of the Ozone Layer falls every year on September 16. While it is healing and on the path to recovery by 2060, currently measuring about 7.6 million square miles, wildfire smoke from Australia’s Black Summer has destroyed 1% of the ozone layer, a recent assessment found.

Smoke from the 2019-2020 Australian bushfires have destroyed high-altitude ozone circling above the Southern Hemisphere, threatening the recovery progress on the ozone layer and one of the most successful climate restoration stories. 

A recent assessment by the United Nations and the World Meteorological Association showed that the ozone layer is on track to being healed by 2060. But according to two new scientific studies, smoke from wildfires could impede progress following a discovery that smoke particles from the Australian fires triggered a chain of chemical reactions that destroyed 1% of the ozone layer. 

A hole in the ozone layer has formed above the Antarctic continent for nearly 50 years. As the ozone layer serves as a protective shield against the sun’s ultraviolet (UV) radiation, exposure can result in increased risks of skin cancers. 

The hole in the ozone layer kept growing until the year 2000 before it stalled and started to shrink. Some of the reasons behind the drastic increase in chlorofluorocarbons (CFCs) – toxic atoms that break down the Earth’s ozone layer – especially during the 1930s was an exponential increase in refrigerants, air conditioning, aerosol sprays, ad foam blowing agents.

It was not until the 1970s that scientists realised that CFCs could react with atmospheric ozone, produce oxygen and depleting the protective ozone layer. The Vienna convention saw the Montreal Protocol being signed in 1987 to phase out CFCs. The extremely successful Protocol is also the only UN treaty that has ever been ratified in every country.

By 2019, the ozone hole had diminished to its smallest since the 1980s at a peak area of 16.4 million km2. The hole is currently about 7.6 million square miles wide. That’s 1.3 million square miles smaller than last year.

ozone layer hole

Image 1: The antarctic ozone hole

But during that same year, Australia wildfires razed down 42 million acres, destroyed thousands of buildings, as well as killing dozens of people and 3 billion animals. It also created a cloud of smoke so large that it rose into the stratosphere that circled the southern hemisphere. Using data gathered by the Canadian Space Agency, researchers at the University of Waterloo in Canada found that smoke particles from the fires disrupted the delicate chemical processes that maintain the ozone layer.

“Smoke was not supposed to do this,” Peter Bernath, an atmospheric chemist at the University of Waterloo, who co-authored one of the studies. “It was completely unexpected that smoke made these atmospheric changes. So this is new chemistry.”

Smoke from the Australian bushfires resulted in a 1% decrease in the ozone in March 2020, which is a significant number as it takes a decade for the ozone layer to recover 1-3%. In another study led by Bernath, wildfire smoke led to a rise in compounds, such as hypochlorous acid, which react with ozone molecules to break them apart. 

Together these findings demonstrate possible future implications and how fires are preventing the ozone layer from healing, especially as more frequent and severe wildfires are expected across the globe. The UN warns that global wildfires are set to rise by 50% by 2100, with regions that were previously unaffected by wildfires such as the Arctic will experience burnings as well. 

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