How wildfires made the ozone hole worse

Australia’s massive 2020 “Black Summer” bushfires, which injected nearly a million tons of soot and other particulate into the stratosphere, strengthened and prolonged a spinning hole in the ozone above Antarctica, a new study finds.

The blazes around New Year 2020 were particularly large, giving birth to what a paper published on Thursday in Scientific Reports described as a massive “smoke infused thunderstorm.”

One such storm created a vortex that maintained shape for two months, making a 20-mile vertical conduit into the upper atmosphere, where sulfates and other burning byproducts were funneled, causing the air to absorb more heat.

The results were more like a massive volcanic eruption than a wildfire, the study said, adding that the last such warming event was the 1991 eruption of Mount Pinatubo. 

But they also had a contradictory, cooling impact — which helped give new strength to an old environmental threat. 

The ozone layer, which shields the Earth from solar radiation, is a high-altitude belt marked by a higher than usual presence of oxygen molecules bound together in a distinctive bipod shape by the constant battering of photons from the sun. 

An unusual and strangely stable “hole” in the ozone above Antarctica reached near record proportions in the period before the fires — and stuck around unusually long after them. 

That Antarctic hole, which is in fact an area of lower ozone concentrations, is the same one that aroused alarm in the 1980s, leading to the banning of the refrigerant chemicals choloflorocarbons under the 1987 Montreal Protocol, according to NASA’s Earth Observatory. 

The layer is not expected to fully recover until 2041. 

By 2021, the hole had grown to larger than average — reaching the size of North America, the U.S. government said.  

The study released Thursday argues the bushfires were to blame by disrupting a complex relationship between high altitude ozone layers and the polar vortex.

The polar vortex is a spinning seasonal system of storms above the poles that in essence keeps the cold in, according to the 2015 Encyclopedia of Atmospheric Sciences. Like a rider on a bicycle, the faster it moves, the more stable it is. 

Its usual spring breakdown precedes the transfer of the polar weather system from a winter state of cooling to a summer state of warming, the Encyclopedia said. 

The breakdown of ozone by chemicals that the bushfires released helped delay the normal seasonal collapse of the vortex — which in turn helped keep the existing ozone hole in place longer than usual.