A team of WashU scientists has simulated smoldering wildfires in the lab in order to study the effects of their smoke on the atmosphere.
Black carbon, or soot, has already been identified as a major agent in atmospheric warming, but less is known about the effects of an organic particulate matter in smoke called brown carbon. Rajan Chakrabarty and Brent Williams, both aerosol scientists in the Department of Energy, Environmental & Chemical Engineering in the School of Engineering & Applied Science, and their labs found that brown carbon aerosol changes from light-absorbing to light-scattering the longer it remains in the atmosphere. When it is first emitted, the smoke is brown and has a warming effect on the atmosphere. But over several days in the atmosphere, the smoke gradually turns white and has a significantly reduced warming effect. The resulting white smoke roughly contributes to roughly a 46 percent reduction in light absorption compared with the brown smoke.
The findings will be useful for fine-tuning climate-change models and help federal agencies to better understand wildfires.