According to an analysis published today, the extreme bushfires that raged in southeastern Australia in late 2019 and early 2020 released 715 million tons of carbon dioxide into the air, more than twice the emissions previously estimated based on satellite data. nature.
“This is a staggering number,” said David Bowman, a fire ecologist at the University of Tasmania in Hobart, adding that scientists may have to reconsider the impact of extreme fires on the global climate, which are now not only Raging all over Australia and passing through Western America And Siberia. “Fire is really important now.”
However, it’s not all bad news.Another paper is in nature According to the report, most of these carbon plumes may have been indirectly absorbed by the huge proliferation of phytoplankton in the Southern Ocean.
The worst fire ever recorded
this Unprecedented fire As many as 74,000 square kilometers of eucalyptus forests or eucalyptus forests in southeastern Australia were burned, an area larger than that of Sri Lanka.
Previous estimates of the global wildfire emissions database based on satellite data indicate that between November 2019 and January 2020, the fire released approximately 275 million tons of carbon dioxide during its peak.
But Ivar van der Velde, the lead author of the first paper, said the new analysis shows that this number is seriously underestimated. “These models often lack the spatial and temporal details to explain the full impact of these fires,” said van der Velde, an environmental scientist at the SRON Netherlands Institute for Space Research in Utrecht and the Vrije Universiteit Amsterdam.
He and his team set out to make better estimates based on finer-grained data from the tropospheric monitoring instrument TROPOMI on the European Space Agency’s Sentinel-5 Precursor satellite.
TROPOMI takes daily snapshots of the carbon monoxide levels in the atmospheric column below it. Researchers use this data to calculate more accurate bush fire carbon monoxide emissions, and they use it as a proxy for calculating carbon dioxide emissions.
Their final figure-715 million tons-is almost 80 times the typical amount of carbon dioxide emitted during the three peaks of the summer bushfire season in southeastern Australia.
Bowman said this number is similar to the number calculated by his team based on the area of burning forest, but much higher than the number based on previous satellite emissions measurements.
Cristina Santín, a wildfire researcher at the Spanish National Research Council in Asturias, said the key question is how these forests will recover. Wildfires have long been considered a net zero carbon event, because when vegetation re-grows, the emissions they release are recaptured-but the increase in frequency and intensity of fires in Australia may mean that ecosystems will never fully recover. She said that if these fires “threat the restoration of the ecosystem, then we really need to worry”.
Reason for hope
However, the second paper published today may give researchers hope. This indicates that the emissions from the bushfire crisis were almost offset by the huge phytoplankton blooms recorded in the Southern Ocean during the summer of 2019-20.
Research co-author Richard Matear, a climate scientist based in Hobart at the Australian Government’s Commonwealth Scientific and Industrial Research Organization, said these findings demonstrate how wildfires directly affect ocean processes. “The system is connected.”
He and his colleagues discovered that during the fire, a large amount of nutrient-rich black smoke was drawn into the ocean thousands of kilometers away. Within a few days, these aerosols injected much-needed iron into the water to nourish phytoplankton. The carbon absorbed by these phytoplankton is equivalent to 95% of the fire emissions.
Bowman said that the ocean seems to have achieved “amazing craftsmanship—just like a magician.” But he and other researchers said that more work needs to be done to understand where the carbon absorbed by plankton ultimately goes and whether it will return to the atmosphere.
Both studies revealed surprising findings, indicating that “we don’t know as much about fire as we really need,” Santín said-she said we need to deal with this better, because “fire is in the carbon Emissions will become more and more important. Cycle”.
This article is reproduced with authorization and has been First published September 15, 2021.