Australia's "Black Summer" bushfires of 2019 and 2020 injected massive amounts of smoke particles high into the atmosphere, producing unexpected and extreme perturbations in stratospheric gases beyond any seen in the previous 15 years of measurements, researchers report.
Some of these changes have the potential to destroy ozone – a crucial atmospheric component responsible for protecting Earth's surface from the Sun's harmful ultraviolet radiation. The findings illustrate the large and long-lasting impact that increasing wildfire activity worldwide can have on Earth's atmosphere. As a result of climate change, extreme wildfires are on the rise worldwide.
Such severe wildfires can create pyrocumulonimbus (pyroCb) clouds – enormous heat-induced plumes known to inject massive amounts of smoke and other combustion gases high into the stratosphere, which can affect climate and atmospheric composition in currently ill-defined ways. In this study, Peter Bernath and colleagues used infrared spectrometer data from the Atmospheric Chemistry Experiment (ACE) satellite to evaluate the impact of smoke particles from the "Black Summer" fires, which raged across Australia in late 2019 and early 2020.
According to the findings, this influx of smoke resulted in extreme disturbances in stratospheric gas concentrations, including increases in chlorine-bearing compounds, which have the potential to destroy ozone. Bernath et al. say that their ACE observations suggest that as severe wildfires become more frequent, their effects will become an increasingly important factor in the global ozone budget of the future.
For reporters interested in trends, a March 2021 study in Science found that stratospheric smoke injection from the 2019-2020 Australian wildfires contributed to record-breaking levels of atmospheric aerosols over the Southern Hemisphere, which caused marked cooling over cloud-free ocean regions.
Source: https://www.aaas.org/