The devastating fires in Australia of 2019-2020 spread so much smoke particles through the stratosphere that it covered the southern hemisphere for months and generated record levels of atmospheric aerosols, according to an Israeli study with satellite measurements published today in the journal “Science.”
The forest fires, which as a whole calcined an area similar in size to that of Syria, caused an atmospheric impact comparable “to that of a moderate volcanic eruption”, which meant “an extreme increase” of particles in the air, with rates shot in 2020, “some of the highest ever.”
This “anomaly”, caused by “the intensity” and the widespread extension of the fires in the oceanic country, greatly affected the stratosphere, the upper layer of the atmosphere, where a haze loaded with millions of tons of smoke spread. .
Israeli scientists Ilan Koren, from the Weizmann Institute of Sciences, and Eitan Hirsch, from the Israel Institute for Biological Research, reached this conclusion by recording high levels of aerosol optical depth, a measurement used to calculate the charge of these substances in the atmosphere and its radioactive effects.
Atmospheric aerosols are solid or liquid particles suspended on the surface of the earth or the atmosphere, they affect the global climate and their emission causes pollution on a planetary level.
In 2020, substances derived from Australian smoke exceeded the monthly average for the southern hemisphere, and was “three times higher” in January, the Weizmann Institute said in a statement.
These alterations “even eclipsed” the levels of aerosols recorded after the volcanic eruption of Mount Pinatubo in 1991, the largest in the last 100 years, the study highlights.
The researchers gathered information with data obtained through various satellites, with which they demonstrated that the particle peaks came from fires in southeastern Australia.
Through satellite data they also identified a stratospheric haze that covered part of the southern hemisphere. This reached its peak in the first three months of 2020, and lasted until July.
In this period, as far away as Chile, “people breathed in particles from the fires” in Australia, Hirsch explains.
After entering the stratosphere, where the air moves in a constant and linear manner, in source streams, the particles spread “slowly around the entire hemisphere.”
In turn, they “remained in the air” longer than they usually are in the lower atmospheric layer, where they dissipate in a few days, the scientist points out.
But the consequences of this phenomenon were hardly noticeable on the ground: “The air could have seemed a little more misty, or the sunsets a little redder”, as it happens in volcanic eruptions, says Koren.
According to him, another of the effects of the smoke was the cooling of the affected ocean regions, although it is still unknown how much this could have influenced the marine environment or weather patterns.
“In California, Australia and the tropics there are always fires” and “we may not be able to stop them”, but it is important to take into account their precise location to know different effects that they can cause “on our atmosphere”, concludes Koren.