[Reading Science] Mega Wildfires, Even Worse 'Climate Villains'

NASA and US Scientists
Analysis of Wildfire Smoke Components
Discovery of 'Brown Carbon' Emitting 4 Times More Heat than Black Carbon
"Much Worse Impact on Global Warming Than Predicted"

Recent research has revealed that the mega wildfires occurring worldwide in recent years have had a more devastating impact on global warming than previously expected. A substance found in wildfire smoke, which has a much greater effect on warming than previously known, has been newly identified.

[Image source=Yonhap News]

On the 10th (local time), NASA announced that it had discovered a previously unknown substance called "dark brown carbon" in smoke samples collected from three mega wildfires caused by lightning in the western United States during 2019. The related paper was also published on the 7th in the international journal Nature Geoscience.

This substance is abundantly present in wildfire smoke and has been found to strongly absorb heat. Professor Rohan Mishra of the University of Washington, who participated in the study, explained, "It appears to be a substance formed similarly to black carbon or soot at the very front edge of high-temperature wildfires," adding, "It accounted for more than half of the total heat absorbed by the collected wildfire smoke."

The NASA research team collected and analyzed smoke from wildfire sites at an altitude of 10 km using aircraft between July and August 2019. They also gathered smoke samples on the ground about 3 km away from the wildfires using mobile equipment. As a result, the team discovered dark brown carbon, which differed from conventional black carbon. Black carbon is a general term for carbon components produced by the incomplete combustion of organic materials. It absorbs sunlight and converts it into heat, making it a primary driver of the greenhouse effect. It is known to be the second largest contributor to global warming after carbon dioxide.

The newly discovered dark brown carbon molecules absorbed slightly less light per particle than black carbon. However, their quantity in wildfire smoke was four times greater. Additionally, dark brown carbon absorbs light across the entire spectrum?from near-infrared to ultraviolet and visible light?and emits it as heat. While typical organic aerosols lose their light-absorbing ability within about a day in the atmosphere due to photochemical bleaching caused by sunlight, dark brown carbon exhibits resistance to this process, allowing it to persist much longer.

These findings suggest that the recent series of mega wildfires on Earth are having a far more critical impact on global warming. The research team emphasized, "Considering the unexpected effects of dark brown carbon in wildfire smoke, collaboration is needed to discuss revisions to existing climate models," and warned, "The influence of wildfires on global warming and the urgency of climate change mitigation efforts must not be underestimated."

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