Forest fires warm the stratosphere (nd-aktuell.de)

Smoke rises into the stratosphere during the 2019/20 Australian bushfires.

Photo: NASA

The Australia bushfires 2019/20 It was devastating to people, nature and the climate. Not only were images of burning forests scattered around the world, but thick clouds of smoke and soot that traveled 11,000 kilometers across the Pacific Ocean to Argentina and Chile from hundreds of fires in New South Wales and Victoria. Below, 143,000 square kilometers of land have been burned, more than 3,000 homes and other buildings have been destroyed, an estimated three billion terrestrial vertebrates have died in the fire, and air quality has dropped to dangerous levels in every southern and eastern state. According to a study published in January 2022 in the scientific journal Advancing Earth and Space Sciences (AGU), annual carbon dioxide in Australia2The fingerprint doubled after the fire.

Smoke and soot not only spread horizontally halfway around the world, but also rose vertically, so much so that stratospheric aerosols caused the hottest temperatures in 30 years. The stratosphere is the second layer of Earth’s atmosphere at an average altitude of about twelve kilometers, just above the altitude at which planes fly. The temperature in the stratosphere usually does not vary much due to events at the Earth’s surface, apart from volcanic eruptions.

One was published in Nature magazine study From the University of Exeter it was found that smoked aerosols from the Australian fire disaster reached the stratosphere. The stratosphere suddenly warmed by as much as three degrees Celsius over Australia and 0.7 degrees worldwide in the first four months of 2020, according to the study by the research group led by lead author Lily Damani Pearce. This was the highest temperature rise since the eruption of Mount Pinatubo in the Philippines in 1991. The warming of the stratosphere and the large ozone hole over Antarctica are likely caused largely by pyrocomulonic clouds. These high-level storm clouds, formed from large fires, transport huge amounts of smoke and aerosols into the lower stratosphere, which then spread all over the world.

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The ozone hole that formed over Antarctica after the 2020 fires was the longest-lived and one of the largest and deepest in decades, according to the World Meteorological Organization (WMO). A research team led by Peter Bernath, a specialist in atmospheric chemistry at Canada’s University of Waterloo, found that smoke from the Australian bushfires in March 2020 caused ozone levels to drop by 1%. It doesn’t sound like much, but it matters because it takes a decade for the ozone layer to recover to one to three percent.

The ozone layer helps absorb ultraviolet rays from the sun, protecting life on Earth from harmful effects such as skin cancer. The ozone hole was the major environmental issue in the 1980s, due to worldwide excessive use of the chemical compound CFC as a propellant and solvent. in legally binding “Montreal Protocol” In 1987, the international community committed to phasing out the production and use of CFCs and some other industrial chemicals. In 2012, scientists in the Antarctic observed a reversal in the direction of ozone for the first time. Two years later, the World Meteorological Organization declared that the ozone hole would not be a problem by 2050 at the latest if this trend continued.

Experts are concerned about another trend after discovering the impact of Australia’s massive fires on the ozone layer. Scientists largely agree that climate change will lead to more frequent and extreme natural disasters such as wildfires in the future. In recent years, this has been the case not only in Australia or California, but also in Brandenburg, at home.

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The 1974 hit “What Goes Up Must Come Down” was written by American soul singer Tyrone Davis. So did the tiny aerosol particles in smoke and ash from the winds that fell between New Zealand and South America into the South Pacific, fertilizing the waters and causing algal blooms at unprecedented rates — not necessarily a bad thing. “Our results provide strong evidence that pyrogenic iron from wildfires can fertilize the oceans, potentially leading to a significant increase in uptake carbon by phytoplankton. Nature in September 2021 study. The algal blooms caused by the Australian bushfires are so dense and extensive that the subsequent increase in photosynthesis temporarily absorbs a significant portion of the carbon dioxide.2– It can offset emissions from fires. But it is still not clear how much carbon dioxide2The amount absorbed by the algal bloom remains safely stored in the ocean and the amount is released back into the atmosphere. “Determining this is the next scientific challenge,” Kassar asserts.

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