SANTA FE, N.M. — Scientists need to shed their black-and-white view of wildfire smoke and include “brown carbon” in their climate models, researchers at Los Alamos National Laboratory report in a new study.
The research suggests that smoke from wildfires may contribute to climate change in ways that scientists have never considered, said Manvendra Dubey, a senior climate scientist at LANL.
The new study, published this week in the journal Nature Geoscience, offers climate scientists a better way of modeling the effects of smoke in the atmosphere.
Existing climate models now recognize only two types of smoke from wildfires: black carbon, which absorbs sunlight and contributes to warming; and organic carbon, which scatters sunlight, cooling the atmosphere, Dubey said.
The two opposing effects cancel each other out, he said. As a result, climate models now predict that wildfires have little effect on climate.
The new research shows that smoke from wildfires is more complex than this black-and-white model.
LANL scientists, and others from Carnegie Mellon University and the University of Montana burned a wide variety of fuels and studied the smoke in a laboratory.
The study showed that smoke from wildfires behaves differently from what existing models assume, Dubey said.
Smoke “actually comes in shades of brown,” he said. “What is called organic carbon in climate models includes brown carbon.”
Black carbon, also called soot, consists almost entirely of carbon. Dubey described brown carbon as a “complex soup” that contains black carbon and a variety of other compounds.
Some brown carbon has an effect similar to that of black carbon, he said, by absorbing sunlight at blue and ultraviolet wavelengths, giving it the ability to heat the atmosphere.
The findings suggest that many climate models underestimate the warming effects of wildfires, he said. The study also provides scientists with techniques that will allow them to account for the effects of brown carbon in their climate models.
The study has important implications, because climate scientists predict a growing number of the hot wildfires, which emit large amounts of brown and black carbon, Dubey said.