Turns out that the catastrophic Aussie bushfires acted like a volcanic eruption or nuclear blast, and slightly cooled the globe.
The 2019/20 Black Summer bushfires were unprecedented in every possible way. From their devastation to their sheer scale, the disaster was a terrifying wake-up call for our country. Yet, there was one particular impact that scientists were shocked to discover.
According to a study published in the Communications Earth and Environment Journal, the density and “super outbreak” of smoke caused by the fires actually blocked sunlight from the earth’s surface and resulted in a brief cooling effect.
It was found that the smoke plumes created “self-sustaining vortexes that circled the globe” which, surprisingly, acted as a planetary shade. “The Australian wildfires have basically revolutionised our understanding of the climate-altering potential of wildfires through stratospheric feedbacks,” Sorbonne University Scientist Sergey Khaykin wrote.
Now, we know what you’re all thinking. Did the Aussie bushfires just reverse global warming? Not even close.
According to the Washington Post, our last massive volcanic eruption in 1991 cooled the earth by 0.4 degrees Celsius. The impact of the Aussie fires was much less.
While the thunderclouds induced by the fires (a.k.a. PyroCb) and volcanic eruptions both send sun-blocking particles into the stratosphere, a PyroCb event will infuse gases from smoke particles, absorbing and releasing sunlight as heat in the surrounding air. Volcanic eruptions, rather, consist of sulfur dioxide that reacts with water vapour, forming droplets that reflect sunlight back into space.
However, the most mind-blowing discovery made is that the fires could have a similar impact to that of an atomic bomb blast. The whole sun-blocking process caused by a PyroCb event actually mirrors that of an atomic bomb explosion (on an atmospheric level, of course). Alan Robock from Rutgers University mentions that if a “bomb-induced” firestorm were to occur, the explosion would send smoke to the lower edge of the stratosphere, rising higher and higher until the clouds blocked sunlight from the Earth’s surface: just like the PyroCb outbreak did in Australia.
So, basically, Australians have been living through a nuclear winter for the last 12-months.
The Agency led the Earth observation taskforce to consider further action on bushfire risk management, in response to the devastating bushfires in 2019-2020. The report was then considered by the Royal Commission. Read the report here: https://t.co/Kbm9hXufoC pic.twitter.com/O5xzIpmBOU
— Australian Space Agency (@AusSpaceAgency) December 7, 2020
Scientists are still unclear as to the full impacts of the fires on the atmosphere. However, smoke from the fires can still be detected through satellites, with Khaykin predicting that the effects will last for at least a year.