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How Forest Fires May Cool the Northern Climate

Narrator: This is Science Today. Countering hypotheses that forest fires in Alaska, Canada and Siberia warm the climate, scientists at the University of California , Irvine have discovered that forest fires in northern regions, called boreal forests, may actually have a slight cooling effect on the climate. James Randerson, an associate professor of Earth System Science at the university, says their findings are counterintuitive.

Randerson: In that fires release lots of greenhouse gases to the atmosphere and so that may actually warm the climate, but we found that when you take into account all the different ways that the fire influences climate, including emitting ozone and little particles - aerosols - into the atmosphere and also inside the perimeter of the fire the reflectance changes.

Narrator: That's because trees are killed and their needles are gone.

Randerson: And so what ends up happening is the surface is more reflective. All the sunlight reflects off the snow and is scattered into space and so that leads to cooling and that's slightly stronger than the warming from the greenhouse gases.

Narrator: For Science Today, I'm Larissa Branin.