Australia's wildfires released as much smoke as a massive volcanic eruption, study finds

An aerial view of bushfires burning south of Canberra, Australia, on January 31, 2020.

(CNN)Australia's devastating recent wildfires thrust as much smoke into the Earth's atmosphere as a powerful volcanic eruption, causing cooling over the region's oceans with potentially long-lasting impacts, according to the authors of a new study.

Dozens of people died in Australia's 2019-2020 bushfire season, which was one of the worst on record. More than 10 million hectares of land burned and over a billion animals are estimated to have died, with many species pushed close to extinction.
Using data from two satellite missions, scientists found "record-breaking AOD (aerosol optical depth) levels resulting from smoke from the Australian bushfires that were injected into the stratosphere," according to the study, conducted by researchers at the Israel Institute for Biological Research and the Weizmann Institute of Science.
    In the early months of 2020, smoke from the fires was carried 35 kilometers (about 22 miles) up to the stratosphere, the atmosphere's second layer, far above where commercial planes fly.
      Aerosols in the atmosphere's lowest layer -- the troposphere -- have a much shorter lifetime, lasting anywhere from minutes to weeks. But there are no rain clouds in the higher stratosphere to wash out pollutants -- meaning aerosols there can last months or even years, said the study, published Thursday in the journal Science.
        A plume of bushfire smoke in Karatta, Australia, on January 11, 2020 in Karatta, Australia.
        This is typically seen when explosive volcanic eruptions send aerosols high into the stratosphere, which can cause meteorological changes in precipitation or soil conditions. But lacking the incredible blast power of volcanoes, it's much rarer for wildfire smoke to reach the stratosphere.
        After months of massive fires in Australia, aerosol levels over the southern hemisphere increased by more than 50% compared to the averages of the previous 17 years, the researchers said. Levels "even eclipsed those measured after the eruption of Mount Pinatubo, the second-largest eruption of the 20th century."
          Mount Pinatubo erupted in the Philippines in 1991, ejecting huge amounts of ash, smoke and sulfur dioxide high into the stratosphere. For more than two years afterward, strong stratospheric winds spread these aerosol particles across the world, significantly cooling the Earth's surface by absorbing sunlight. The average global temperature dropped by 1 degree Fahrenheit (0.6 degrees Celsius) in the 15 months after the eruption, according to NASA.