Wildfire Smoke Eroded Ozone Layer By 10 Percent In 2020: Study

When something burns and produces smoke, those smoke particles—otherwise called wildfire aerosol—can drift into the stratosphere, where they hang out for a year or more. According to a study published Wednesday in the journal Nature, chemists and atmospheric scientists have found that suspended wildfire aerosol sparks chemical reactions that ultimately degrade the ozone layer, or the thin atmospheric layer responsible for shielding Earth from the Sun.

The newly-discovered chemical reaction increases hydrochloric acid’s solubility. While hydrochloric acid is already present in the atmosphere, MIT found that larger hydrochloric acid quantities activate chlorine in the air and increase ozone loss rates when warmer temperatures strike. This spells danger for the storied hole in the ozone layer, which environmental activists, scientists, and policymakers have been fighting to shrink for several years.

Wildfire smoke was particularly destructive in 2020, when near-constant blazes caused more than $4.5 billion in damage globally. Many of these wildfire woes occurred in Australia, where the “Black Summer” megafire burned from December 2019 through January 2020. According to MIT’s research, wildfire aerosols released during this period widened the ozone hole over Antarctica by 2.5 million kilometers by the end of the year. That’s a 10% size increase.

The Antarctic ozone hole in 2022. (Credit: NOAA)

This research unintentionally complements another study we covered this week, in which an international team of scientists showed that multiple environmental positive feedback loops exacerbate climate change. The US Environmental Protection Agency (EPA) says that holes in the ozone layer can lead to changes in plant metabolism and aquatic food webs. Ozone erosion can also spur changes in terrestrial and aquatic biogeochemical cycles, potentially resulting in biosphere-atmosphere feedbacks that feed atmospheric warming. Studies show that atmospheric warming can trigger wildfires, resulting in a nasty cycle.

Thankfully, recent attempts to mitigate damage to the ozone layer have been quite successful. International treaties like the Montreal Protocol have helped phase out the use of ozone-depleting pollutants. The world’s gradual adoption of electric vehicles might have also helped. The US National Oceanic and Atmospheric Administration even found that the Antarctic ozone hole was slightly smaller in 2022 than in 2021 and far smaller than in 2006 when its size peaked. That said, it’s difficult to know right now whether these efforts are enough to compensate for the ozone damage caused by wildfire smoke.

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