It may be small consolation for those living in smoke-engulfed regions of Oregon and California but the thousands of fires may be giving the Arctic some cooling relief.

"Smoke in the atmosphere temporarily reduces the amount of solar radiation reaching the surface,” according to Robert Stone, an atmospheric scientist at the University of Colorado and National Oceanic and Atmospheric Administration's Cooperative Institute for Research in Environmental Sciences. “This transitory effect could partly offset some of the warming caused by the buildup of greenhouse gases and other pollutants."

Stone co-authored a report on what researchers from several agencies learned when they studied the effect smoke had on climate in the July 22 issue of Journal of Geophysical Research-Atmospheres.

The researchers believe the smoke in the atmosphere can lead to increased atmospheric stability because smoke tends to cool the tundra while warming the smoke layer. "We think that this influence of smoke aerosol on clouds further affects the balance of radiation reaching the surface in the Arctic," Stone said in a written statement.

They studied the climate impact from fires that burned 10,000 square miles of forest in Alaska and western Canada in 2004. Data from the NOAA climate observatory near Barrow, AK, indicated that aerosol optical depth (AOD), a measure of the total absorption and scattering of solar radiation by smoke particles, that summer increased a hundredfold from typical summer AOD.

They also observed, through modeling, how smoky conditions might change the amount of solar radiation reaching the Earth's surface.

The scientists pointed out that cooling from forest fires is affected by many variables including the severity of the fire season, how smoke is dispersed geographically, and how smoke absorbs and scatters solar radiation.

Other agencies contributing to the research included the Global Monitoring Division, Earth System Research Laboratory, NOAA, Boulder; Space Vehicles Directorate, Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts; Remote Sensing Division, Naval Research Laboratory, Washington, D. C.; Center for Remote Sensing, Department of Geography, Boston University, Massachusetts; and Science Systems and Applications, Inc., Hampton, Virginia, a company.

Citation:

Stone, R. S., G. P. Anderson, E. P. Shettle, E. Andrews, K. Loukachine, E. G. Dutton, C. Schaaf, and M. O. Roman III (2008), Radiative impact of boreal smoke in the Arctic: Observed and modeled, J. Geophys. Res., 113, D14S16, doi:10.1029/2007JD009657.