Tiny ‘tar balls’ are very good at absorbing the sun’s energy
By Summit Voice
FRISCO — Soot from wildfires includes tiny tarball-like particles that focus sunlight and warm the atmosphere when they absorb light. The overall effect may contribute more to global warming than previously thought, researchers with Los Alamos National Laboratory said in a new study based on measurements during the huge 2011 Las Conchas Fire, which burned in the vicinity of the lab.
“We’ve found that substances resembling tar balls dominate, and even the soot is coated by organics that focus sunlight,” said senior laboratory scientist Manvendra Dubey, “Both components can potentially increase climate warming by increased light absorption.”
The Las Conchas fire emissions findings underscore the need to provide a framework to include realistic representation of carbonaceous aerosols in climate model, the researchers said.
“The fact that we are experiencing more fires and that climate change may increase fire frequency underscores the need to include these specialized particles in the computer models, and our results show how this can be done,” Dubey said.
Conventional wisdom is that the fire-driven particles contain black carbon or soot that absorbs sunlight to warm the climate, and organic carbon or smoke that reflects sunlight to cool the climate. But in the paper they published in Nature Communications the scientists from Los Alamos and Michigan Technological University analyzed the morphology and composition of the specific aerosols emitted by the Las Conchas fire.
Las Conchas, which started June 26, 2011, was the largest fire in New Mexico history at the time, burning 245 square miles. Immediately after Los Alamos National Laboratory reopened to scientists and staff, the team set up an extensive aerosol sampling system to monitor the smoke from the smoldering fire for more than 10 days.
The researchers used high tech instruments to analyze the aerosol samples and determined that spherical carbonaceous particles called tar balls were 10 times more abundant than soot.
Why is this important for climate?
“Most climate assessment models treat fire emissions as a mixture of pure soot and organic carbon aerosols that offset the respective warming and cooling effects of one another on climate. Dubey explained. “However Las Conchas results show that tar balls exceed soot by a factor of 10 and the soot gets coated by organics in fire emissions, each resulting in more of a warming effect than is currently assumed.”
“Tar balls can absorb sunlight at shorter blue and ultraviolet wavelengths (also called brown carbon due to the color) and can cause substantial warming,” he said. “Furthermore, organic coatings on soot act like lenses that focus sunlight, amplifying the absorption and warming by soot by a factor of 2 or more. This has a huge impact on how they should be treated in computer models.”
Filed under: climate and weather, Environment, forest fires, global warming, wildlife Tagged: | climate, Environment, Las Conchas fire, Los Alamos National Laboratory, Michigan Technological University, Wildfires