Wildfire Smoke May Cause Arctic Cooling

July 22, 2008 -- It's hard to imagine that the raging blazes of wildfires could cool things down, but that is the conclusion of a new study.

Robert Stone of the University of Colorado, Boulder, and colleagues report that wildfire smoke that reaches the Arctic has the net effect of cooling the surface by reducing the amount of sunlight that makes it through.

The effect of smoke and other aerosol particles in the atmosphere is a large source of uncertainty in climate models. The new work removes some of that uncertainty.

"They have given us a much better understanding of what the effect of smoke is on the climate system," said Alan Robock of Rutgers University in New Brunswick, N.J.

The team made measurements in 2004 when widespread wildfires in Alaska and western Canada sent large plumes of smoke into the Arctic, including over their research station in Barrow, Alaska.

They measured the density of the smoke in the atmosphere and the net amount of energy from the sun hitting the surface to find the relationship between the amount of smoke and the reduction in energy reaching the ground.

When plugged into models, this information helped predict how the smoke would behave over other surfaces, such as the ocean, where the researchers could not make measurements.