The fiery destruction of the Australian hotspots of the black summer between 2019 and 2020 provided an ominous insight into the range of fire in our hot and dry world, and the impact of unseen hell is still being measured.
Just a few weeks ago, scientists noticed that the amount of smoke emitted from the fire into the atmosphere was equal to a large volcanic eruption. Now researchers say the giant cloud of smoke was so huge that it measurably warmed the stratosphere for months.
In a new study led by first author and climate moderator Pengfei Yu of China’s Jinan University, scientists simulated the appearance and development of plumage, showing that the worst documented forest fires in Australian history have left a lasting impact on the region’s skies.
“Extreme forest fires can inject smoke into the upper troposphere and even into the stratosphere under favorable meteorological conditions,” the researchers write in their paper. “The more smoke is injected, the longer it will last and the wider it will be.”
In the case of the Black Summer fire, the flames sent nearly a trillion grams (approximately 0.9 teragrams) of smoke particles into the stratosphere, which researchers explain as the largest amount ever recorded in the satellite era.
This smoke mass consisted of different types of smoke particles, including organic carbon (OC, which includes brown carbon, called BrC) and black carbon (BC).
Each of them has different effects of capturing heat in the atmosphere, with BC capturing the most heat, due to the way it heats the surrounding air after absorbing sunlight.
According to researchers ’calculations, the Black Summer feathers consisted of about 2.5 percent black carbon, which helped provide a warming effect in the stratosphere that lasted the rest of the year.
“Simulations suggest that the smoke remained in the stratosphere throughout 2020 and that it measurably heated the stratosphere by about 1-2 K [Kelvin, equivalent here to 1-2 degrees Celsius] more than six months, ”the team explains.
“Our study highlights that record forest fire smoke can cause lasting impacts on stratosphere dynamics and chemistry.”
In addition to warming the stratosphere, the researchers say the record-breaking smoke event would have a reduced effect on stratospheric ozone levels, destroying ozone molecules in the mid-high latitudes of the southern hemisphere and likely creating a higher ozone hole temporarily.
Although researchers admit that observations of aerosols that produce stratospheric warming have been made before, this is the first time that scientists have measured the phenomenon to this extent, given the record results of the Black Summer fires.
The findings are reported in Letters on geophysical research.