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A recent study reveals that the smoke from wildfires can pose a threat to the recovery of Earth's ozone layer, and may even reverse it. The researchers from the Massachusetts Institute of Technology (MIT) explain that smoke from a wildfire can rise up into the stratosphere, where it can stay for over a year, and trigger chemical reactions that damage the ozone layer. The ozone layer protects our planet from the Sun's harmful ultraviolet radiation. The study, which was published in the journal Nature, examined the impact of the Black Summer megafire that occurred in eastern Australia from December 2019 to January 2020.
The fires -- the country's most devastating on record -- scorched tens of millions of acres and pumped more than one million tonnes of smoke into the atmosphere," according to recent research.
Scientists have identified a new chemical reaction caused by smoke particles from the Australian wildfires, which worsened ozone depletion. The fires likely contributed to a 3-5% depletion of total ozone in mid-latitudes of the Southern Hemisphere, affecting regions overlying Australia, New Zealand, and parts of Africa and South America.
The impact of the fires on the polar regions was also significant, with the edges of the ozone hole over Antarctica being eaten away. Smoke particles widened the hole by 2.5 million square kilometers, or 10 percent of its area compared to the previous year, by late 2020.
The long-term effects of wildfires on ozone recovery remain unclear, as the United Nations' recent report on ozone depletion's recovery track has not accounted for the impact of fires. The latest study suggests that as long as ozone-depleting chemicals persist in the atmosphere, large fires could trigger a reaction that temporarily depletes ozone.
"The Australian fires of 2020 were really a wake-up call for the science community," said Susan Solomon, a professor at MIT. "The effect of wildfires was not previously accounted for in [projections of] ozone recovery. And I think that effect may depend on whether fires become more frequent and intense as the planet warms."
