While Wyoming hasn’t had many forest fires this summer, plenty of smoke has blown in from fires in other states like Montana, California and Oregon. Atmospheric scientists at the University of Wyoming have been studying the soot from those fires to find out what role it plays in climate change. They’re chasing fires around the West this summer doing their research in a state-of-the-art mobile research lab.
UW Professor Shane Murphy said cars and power plants emit mostly black carbon which is the third largest cause of climate warming after carbon dioxide (CO2) and methane. But forest fire smoke also emits something called brown carbon—that's when the particles of soot are coated with tar—sand Murphy said that no one knows what effect it has on warming.
“Right now, climate models don’t really include brown carbon,” he said. “They need to add that and they’re working on adding that. But right now there’s a lot of uncertainty on how important it is, how long does it last, does it evaporate, does it get aged out as the smoke goes down wind? So we’re trying to figure those things out.”
The current theory is that brown carbon, which appears as white smoke, may actually have a cooling effect on climate because of its light color. But Murphy said that’s never been proven and it’s important to find out the truth because, as western states are growing hotter, larger and more frequent forest fires are likely.
“And so one of the things we’re focusing on is what fraction of the black and brown carbon comes from biomass burning because that, unlike the other sources you control, is probably going to increase in the future, right? It’s not going to go away and it might get worse,” said Murphy.
He said this is the first in a three-year study to answer the riddle of brown carbon’s role in climate change.