The intense, widespread bushfires in Australia have injected huge amounts of smoke into the stratosphere in 2020. A study by researchers in Israel showed that these bushfires from 2019 to 2020 were so huge that they spewed as much smoke into the stratosphere as a large volcanic eruption.
The study, entitled "Record-breaking aerosol levels explained by smoke injection into the stratosphere" and published in the journal Science, showed that the record-breaking levels of aerosols over the Southern Hemisphere caused a considerable cooling over oceanic cloud-free areas.
The stratosphere is the second layer of the atmosphere, above the troposphere where humans live. The researchers said that their findings are a surprise as this is their first time recording such an injection of smoke to the stratosphere.
Smoke Comparable to a Volcanic Eruption
According to Phys.org, the amount of bushfires in Australia is comparable to that of the smoke released during the Mount Pinatubo eruption in the Philippines in 1991, the second-largest volcanic eruption of the 20th century.
Researchers said that the smoke drifted away from Australia to the east, then two weeks later returned to the country from the west.
Study co-author Ilan Koren, a professor at the Weizmann Institute of Science in Israel, said that the smoke completed a whole circulation in two weeks, a first of its kind.
The study suggests three factors that explain this phenomenon. First, the bushfires were so intense. Secondly, the event happened in the far southeastern part of Australia where the distance between the troposphere and stratosphere is smaller than anywhere else. Lastly, strong storms helped draw the smoke from bushfires up to the stratosphere.
Koren explained that understanding the environmental impact of smoke staying in the stratosphere is crucial. Usually, smoke that stays in the lower part of the atmosphere only stays for a few days or weeks. However, when it is in the higher part of the atmosphere it could stay for months to years.
Since the winds in the higher atmosphere are stronger, they could spread faster and farther than might be otherwise possible. It will basically become a thin smoke blanket that covers the hemisphere for many months, Koren said.
Effects of the Smoke on the Stratosphere
The researchers monitored the smoke activity in the stratosphere via satellite and could still see the smoke visible for six months, from January to June 2020, according to Channel News Asia.
They noted that it has become a little difficult to identify the smoke coming from the bushfires as there is other smoke too in the stratosphere that likely came from other sources. But Koren said that it is most likely that the smoke from the bushfires in Australia is still present today.
Moreover, they said that the main effect of smoke staying in the atmosphere for so long is that it can reflect radiation from the sun and can also absorb solar radiation that may cause a localized warming effect.
But overall, the smoke has a cooling effect that could disrupt processes, like algae photosynthesis in the southern hemisphere. Koren said that the consequences of the warming of the smoke are not yet clear.
Check out more news and information on Australian Bushfires on Science Times.
