A new study on biomass-burning aerosols shows that smoke from wildfires has more of a cooling effect than most recent climate models have suggested.
The findings will help scientists to more accurately predict the effect of wildfires — such as Australia's recent bushfire crisis — on the climate.
Comparing climate predictions to real data
Wildfires release biomass-burning aerosols into the atmosphere which are characterized by the resulting smoke clouds that can be seen a long distance away from the source.
The composition, size, and mixing state of biomass-burning aerosols determine the visual properties of these smoke clouds, and the properties determine how much the smoke clouds absorb or scatter solar radiation.
For their research, the group of scientists compared climate models' predictions to large amounts of wildfire data collected around the world as well as in laboratory experiments. They found major differences between the predictions and the real data.
Discrepancies in the data
"We collected field data from across the globe, and we found that the models make a lot of assumptions about the physical and optical properties of the biomass-burning aerosols, and those assumptions were not accurate," Xiaohong Liu, a professor in the Department of Atmospheric Sciences at Texas A&M University, explained in a press release.
The researchers found that many of the most advanced climate models simulate biomass-burning aerosols or smoke as either more light-absorbing or darker, than what they observed in the ensuing data.
Climate models such as the ones observed in the study are used to create important climate change reports, such as the Intergovernmental Panel on Climate Change (IPCC) Assessment that is published roughly every seven years.
Improving wildfire climate predictions
The team highlighted the complex nature of wildfire predictions and stated that their work will help to account for a layer of complexity that has been somewhat overlooked thus far:
"The smoke is very complicated — North American forest fire smoke is very different than Australian bush fire smoke, because of the different types of fuel and burning conditions," Liu said. "They can produce darker or brighter smoke, and the chemical evolution of the smoke in the atmosphere can be very complicated."
Liu also explained that, overall, "our study shows that biomass-burning has a more net-cooling effect than previously thought."
The team says its research provides the scientific community with a better understanding of the properties of biomass-burning aerosols so that it can improve the models and predictions for the effects of wildfires on the climate — a feedback loop that has the potential to be devastating for our planet.