Wildfires Lingering Heat: Brown Carbon’s Story
Results show absorption properties of brown carbon depend more on burn conditions than fuel type, providing important information to model climates.
The Science
The smoke from wildfires spreads for miles and contains particles or aerosols that can trap or reflect the sun’s heat. Black carbon, a strongly absorbing aerosol, is an important global warming agent produced by fires and considered in climate models. Other organic aerosols that absorb solar radiation, and referred to as brown carbon, are also released. This brown carbon contributes to the warming effect, but its properties are not as well understood. .Researchers studying brown carbon released by burning plant matter found that brown carbon’s light absorption (warming effect) properties depend more on burn conditions) than fuel type.
The Impact
This research will help improve climate models that incorporate both black and brown carbon properties and quantify the effects of wildfires and other fires and how they contribute to warming now and in the future.
Summary
Brown carbon has not been treated in detail in climate models because its absorption properties and composition are highly variable. To address this gap, scientists at Carnegie Mellon University and the University of Montana have collaborated with Los Alamos National Laboratory researchers funded by the U.S. Department of Energy Office of Science’s Atmospheric System Research program. The team has made discoveries that will enable climate modelers to more accurately represent both black and brown carbon emissions from biomass burning as part of climate model simulations. The scientists conducted a set of laboratory experiments that quantified the absorption properties of emissions from a range of common biomass fuels as well as diesel. They showed that the absorption properties of brown carbon from biomass burning depends more on burn conditions (that is, the intensity of the burn and the amount of oxygen supplied to the combustion process) than fuel type and that compounds with extremely low volatility are responsible for the absorption.
Contact
Allen Robinson
Carnegie Mellon University
alr@andrew.cmu.edu
Funding
Portions of this research were supported by the National Science Foundation (Grants ATM-0936321 and AGS-1256042). The project also received support from the Atmospheric System Research program of the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science (F265 and ER65296).
Publications
R. Saleh, R., et al., “Brownness of organics in aerosols from biomass burning linked to their black carbon content.” Nature Geoscience 7(9), 647 (2014). [DOI: 10.1038/ngeo2220].
Highlight Categories
Performer: University , DOE Laboratory
Additional: Collaborations , Non-DOE Interagency Collaboration
