Remember 2020? It was the longest decade of our lives. I know we all think it was the Year of the Pandemic, but who remembers the bushfires in Australia that kicked off this nightmare of a year? 

It turns out that those bushfires actually had a larger impact on the global climate than the pandemic lockdowns. Yes, we all stayed home and commuted less, decreasing emissions and clearing up the air around many cities around the world. However, in a new study published in Geophysical Research Letters, scientists analyzed how the climate changed over the year, and they found that while the lockdowns did have a slight warming effect due to a decrease in air pollution and an increase in sunshine reaching the Earth’s surface, that was all offset by the effects of the bushfires. Per the press release: …the Australian bushfires cooled the Southern Hemisphere to such an extent that they lowered Earth’s average surface temperatures. This is because sulfates and other smoke particles interact with clouds to make their droplets smaller and reflect more incoming solar radiation back to space, reducing the absorption of sunlight at the surface.

The smoke from the fires made it up to the stratosphere and circled the Southern Hemisphere. Now, the difference between the lockdown and the fires is only 0.01 degrees Celsius, which doesn’t sound like much, but consider how long the pandemic lockdown has lasted and how brief the fires were by comparison. Wildfires are a problem that is only going to get worse as more extreme weather creates drought conditions in various parts of the world. And before anyone says “but it was a net cooling effect” remember that it was cooler in one hemisphere than the other, and that moved tropical storms farther north than usual. Please, please don’t go set the world on fire to combat climate change, folks.

More Information

AGU press release

“Coupled Climate Responses to Recent Australian Wildfire and COVID-19 Emissions Anomalies Estimated in CESM2,” J. T. Fasullo et al., 2021 July 27, Geophysical Research Letters