Following novel research into effects of the 2019-2020 Australian wildfires on the ozone layer, Laura McBride, Ph.D., assistant professor of chemistry and biochemistry at Albright College, and Ross Salawitch, Ph.D., professor at University of Maryland’s Earth System Science Interdisciplinary Center (ESSIC) as well as Departments of Atmospheric & Oceanic Science and Chemistry & Biochemistry, have co-authored a Science Perspective article, “Australian wildfires depleted the ozone layer,” released Nov. 24 in Science magazine. Science Perspectives are peer reviewed, solicited articles.
“The Australian wildfires that occurred in late 2019 and early 2020 were extraordinary events, in terms of the amount of damage that occurred in Australia and the large pyro-cumulonimbus clouds that injected smoke into the stratosphere,” said McBride. “Understanding the effect of the wildfires on stratospheric ozone is at an early stage. This article explores the various mechanisms initiated by the wildfires that thinned the ozone layer, and suggests several methods to analyze the contribution of dynamic and chemical mechanisms to the reduction in stratospheric ozone.”
Although the Australian wildfires in 2019 and 2020 were observed to thin the stratospheric ozone layer, the researchers say that recent studies have attempted to determine whether atmospheric dynamic or chemical mechanisms initiated by the fires have caused the ozone thinning.
“The thickness of the ozone layer thinned appreciably over mid-latitudes of the Southern Hemisphere after smoke from the Australian wildfires reached the stratosphere”, said Salawitch. “Observations obtained by the NASA Microwave Limb Sounder instrument onboard the Aura satellite show a large increase in the abundance of chlorine monoxide following these wildfires, by a chemical process that is not yet understood. The vast majority of chlorine in today’s stratosphere results from decades of prior use and emission of chlorofluorocarbons and other ozone depleting substances. Even though the abundance of stratospheric chlorine is declining due to success of the Montreal Protocol, it will take many more decades before chlorine returns to the natural background level. These NASA satellite observations serve as a reminder that the thickness of the ozone layer can be threatened by the injection of suspended particulate matter (aerosols) into the stratosphere, either by wildfires, volcanoes, or perhaps deliberate injection of aerosols to slow the rate of global warming.”
“Improved understanding of the effect of massive wildfires on the ozone layer is essential because climate change is expected to increase the frequency and severity of wildfires,” said McBride.
McBride and Salawitch began their ongoing research into the Australian wildfires at the University of Maryland, while Salawitch was McBride’s advisor for her doctorate in chemistry. Recognizing the pair’s research conducted on the effect of humans and natural phenomena on the stratospheric ozone layer, the scholars were asked to write a Science Perspective article. A former NASA Jet Propulsion Laboratory research scientist, Salawitch joined the University of Maryland in 2007. McBride joined the Albright College faculty in 2022.