Smoke particles from wildfires can erode ozone layer

Mar 9, 2023 - by Staff

Wildfire smoke that rises to the stratosphere can trigger chemical reactions that erode the protective ozone layer shielding Earth from the Sun's damaging ultraviolet radiation, new research finds.

The study, led by scientists at the Massachusetts Institute of Technology with a co-author at the National Center for Atmospheric Research (NCAR), focused on catastrophic Australian fires that raged from December 2019 into January 2020. The fires — the country's most devastating on record — scorched tens of millions of acres and pumped more than 1 million tons of smoke into the atmosphere.

The research team identified a new chemical reaction by which smoke particles from the Australian wildfires made ozone depletion worse. By triggering this reaction, the fires likely contributed to a 3-5 percent depletion of total ozone at mid-latitudes in the Southern Hemisphere, in regions overlying Australia, New Zealand, and parts of Africa and South America.

The researchers’ model also indicated the fires had an effect in the polar regions, eating away at the edges of the ozone hole over Antarctica. By late 2020, smoke particles from the Australian wildfires widened the Antarctic ozone hole by 2.5 million square kilometers — 10 percent of its area compared to the previous year.

It's unclear what long-term effect wildfires will have on ozone recovery. The United Nations recently reported that the ozone hole, and ozone depletion around the world, is on a recovery track, thanks to a sustained international effort to phase out ozone-depleting chemicals. But the new research suggests that as long as these chemicals persist in the atmosphere, large fires could spark a reaction that temporarily depletes ozone.

"As this research demonstrates, wildfire smoke can have a profound influence on stratospheric chemistry," said NCAR scientist Doug Kinnison, a co-author of the paper. "Clearly more research is needed to fully understand the impact associated with pyrocumulonimbus smoke, especially if wildfires become increasingly more frequent and intense due to climate change."

The study was published this week in Nature. It was supported, in part, by NASA and the U.S. National Science Foundation, which is NCAR's sponsor. For more, see the MIT news release.

Title: Chlorine activation and enhanced ozone depletion induced by wildfire aerosolAuthors: Susan Solomon, Kane Stone, Pengfei Yu, D. M. Murphy, Doug Kinnison, A. R. Ravishankara, and Peidong Wang Journal: Nature

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