The 2021 wildfire season has broken world records, leaving land charred from California to Siberia. The risk of fires is increasing and a report released by the UN last month warned that wildfires are on track to increase by 50% by 2050. These fires destroy homes, plant life and animals burning, but the risk does not stop. the. In the magazine A land on March 18, researchers detail how brown carbon released by burning biomass in the Northern Hemisphere is accelerating warming in the Arctic and warn that this could lead to even more wildfires in the future.
Flaming wildfires are accompanied by vast plumes of brown smoke, composed of airborne brown carbon particles. This smoke poses health risks and can even block the summer sun, and researchers have suspected it could also contribute to global warming.
In 2017, the Chinese icebreaker ship Xue Long headed to the Arctic Ocean to examine what aerosols were floating in the clean Arctic air and identify their sources. The ship’s scientists were particularly curious about how the brown carbon released by wildfires affected the climate and how its warming effects compared to those of the denser black carbon from burning fossil fuels at high temperatures, the second strongest warming agent after carbon dioxide.
Their results showed that brown carbon contributed to warming more than previously thought. “To our surprise, observational analyzes and numerical simulations show that the warming effect of brown carbon aerosols over the Arctic is up to about 30% of that of black carbon,” explains the author. Principal Pingqing Fu, atmospheric chemist at Tianjin University.
Over the past 50 years, the Arctic has warmed at three times the rate of the rest of the planet, and wildfires appear to be contributing to this gap. The researchers found that brown carbon from burning biomass was responsible for at least twice as much warming as brown carbon from burning fossil fuels.
Like black carbon and carbon dioxide, brown carbon warms the planet by absorbing solar radiation. Since warming temperatures have been linked to increased wildfires in recent years, this leads to a positive feedback loop. “Increased brown carbon aerosols will lead to global or regional warming, which increases the likelihood and frequency of wildfires,” Fu said. “Increased wildfires will emit more brown carbon aerosols, further heating the earth, making wildfires more frequent.”
For future research, Fu and his colleagues plan to study how wildfires change the composition of aerosols from sources other than brown carbon. Specifically, they are interested in the effect of fires on bioaerosols, which come from plants and animals and can contain living organisms, including pathogens. In the meantime, Fu urges that attention be focused on forest fire mitigation. “Our results underscore how important it is to control wildfires,” he says.
This work was supported by the National Natural Science Foundation of China.
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