Smoke from forest fires destroys the ozone layer

The fires that ravaged Australia in 2020 weakened the ozone layer, the filter that protects the Earth from solar radiation. And the worst is yet to come according to the researchers.

In 2019 and 2020, deadly fires burned approximately 46 million acres of Australian landbillowing thick clouds of smoke into the sky, earning them the nickname of Black Summer. According to two studies, the bushfires that affected eastern Australia would have deepened the hole in the ozone layer by 3 to 5%. And this is probably just the beginning, warns the scientific community.

Smoke from forest fires destroys the ozone layer

If the fires (the largest ever recorded in the country) have left behind only disasters and ashes, according to a study published in the journal Scienceces thick smoke would also have seriously damaged the ozone layer in the southern hemisphere. “Australia’s fires injected acidic smoke particles into the stratosphere, disrupting the chlorine, hydrogen and nitrogen chemistry that regulate ozone,” said Peter Bernath, a chemist at the University of Waterloo and lead author of the study. After analyzing satellite data collected as part of the SCISAT (Canadian Space Agency) atmospheric chemistry experiment at the time of the “black summer” fires, Bernath and his colleagues found that smoke rising from the area had partially damaged the ozone layer.

Weakness confirmed by a research group from MIT (Massachusetts Institute of Technology), which also established a correlation between black smoke from the Black Summer and the “depletion” of the ozone layer. The study, published in Naturewhich focused on the smoke from the megafire, identified a chemical reaction by which smoke particles from Australian wildfires are thought to have aggravated ozone layer depletion. This chemical cascade, producing chlorine monoxide, one of the most harmful molecules for the ozone layer, would have contributed to a 3-5% depletion of total ozone in the mid-latitudes of the southern hemisphere (Australia, New Zealand and parts of Africa and South America.)

The domino effect of climate change on ozone

In this “cloud” of bad news, however, the MIT team found that wildfire-induced ozone damage was temporary. Once the fumes dissipate, the ozone layer would appear to return to its pre-fire state. An observation that unfortunately is not enough to dispel fears. Indeed, according to the MIT team, this type of temporary ozone destruction is likely to increase in the future if the severity and frequency of major wildfires increase over time. A risk more than probable since according to a study published in Science Advances the last 20 years have seen marked increases in the size and frequency of wildfires. And according to the scientific community, the climate crisis and excessive greenhouse gas emissions will create conditions conducive to megafires “Projected changes in climate suggest we will see larger and larger fires in the future. Our analyzes show that these changes are already happening,” said Virginia Iglesias, environmental scientist at Earth Lab and lead author of the paper.

The violent Australian bushfires are a direct testimony to this, as are the 2020 and 2021 wildfires that ravaged the west coast of the United States and this year’s huge fires that have swept through Colorado. “The worst fires are yet to come,” said William Travis, deputy director of the Earth Lab and co-author of the study.

Why should we care about the ozone layer?

The ozone layer is like a contact lens placed just above the Earth. Although it seems very fragile, this shield nevertheless protects us from 95% of ultraviolet rays. The weakening of this protective layer is notably responsible for the appearance of skin cancers, premature aging of the skin and is also an important risk factor for cataracts. (clouding of the lens responsible for a progressive decline in vision). In addition, excessive UV radiation can also significantly harm wildlife and marine life and reduce crop yields.

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