In addition, wildfires pose a huge threat in terms of climate change, not only due to the impact of emissions on the atmosphere, but there's also the impact of particles (soot, dust and volatile organic compounds) settling down on snow and ice, speeding up their demise through albedo changes. This contributes to the rapid decline of the sea ice and snow cover in the Arctic, a decline that has been hugely underestimated in many climate models.
Furthermore, global warming and accelerated warming in the Arctic cause extreme weather conditions in many places, an impact that is again underestimated in many climate models.
A team of scientists from Los Alamos and Michigan Technological University, led by Swarup China, points out that continued global warming will make conditions for wildfires worse, as was already noted in earlier studies, such as this 2006 study. They also point at the conclusion of a recent study that more biomass burning will lead to more ozone, less OH, and a nonlinear increase of methane's lifetime.
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| Mixing and classification of soot particles. Field-emission scanning electron microscope images of four different categories of soot particles: (a) embedded, (b) partly coated, (c) bare and (d) with inclusions. Approximately 50% of the ambient soot particles are embedded, 34% are partly coated and 12% have inclusions. Only 4% of the particles are bare soot (not coated or very thinly coated). Scale bars, 500 nm. Right, spherical tar balls dominate in the emissions. |
The scientists recently completed an analysis of particles from the Las Conchas fire that started June 26, 2011, and was the largest fire in New Mexico's history at the time, burning 245 square miles. One of the scientists, Manvendra Dubey, said:
“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. 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.”
