CASPER, Wyo —A research paper led by University of Wyoming atmospheric scientists found that models sometimes overstate the warming effect of wildfire smoke in the atmosphere.
“The study addresses the impact of wildfires on global climate, and we extensively used the NCAR-Wyoming supercomputer (Cheyenne),” said Shane Murphy, a UW associate professor of atmospheric science.
“Also, the paper used observations from UW and other teams around the world to compare to the climate model results. The main conclusion of the work is that wildfire smoke is more cooling than current models assume.”
The extent to which smoke absorbs sunlight, and thus heats the atmosphere, is affected by the composition, size and mixing state of biomass burning aerosols, UW said.
Field measurements of wildfire smoke by UW and other teams around the world found that the smoke was lighter and less light-absorbing than most models assume.
“We were able to trace the disagreement between the model and observations to how the models represented the individual smoke particles, or aerosols, in the model,” said Hunter Brown, the paper’s lead author. Brown graduated from UW in the fall of 2020 with a Ph.D. in atmospheric science.
Observations and models from Africa, South America, Southeastern Asia, and boreal fire regions were chosen because these are the largest contributors to biomass burning smoke emissions in the world, according to Brown.
After researchers made aerosol improvements to the model, African wildfire smoke still tended to be more absorbing than observations.
“Generally, hot, dry grassland fires in Africa and Australia tend to have much darker smoke, which is more absorbing, while cooler, wetter boreal forest fires in North America and Northern Asia tend to have much brighter smoke, which is less absorbing,” UW said.
The paper, titled “Biomass Burning Aerosols in Most Climate Models Are Too Absorbing,” was published Jan. 12 (today) in Nature Communications, an open-access journal.
