Dirty snow may warm Arctic as much as greenhouse gases

The global warming debate has focused on carbon dioxide emissions, but scientists at UC Irvine have determined that a lesser-known mechanism – dirty snow – can explain one-third or more of the Arctic warming primarily attributed to greenhouse gases. Snow becomes dirty when soot from tailpipes, smoke stacks and forest fires enters the atmosphere and falls to the ground. Soot-infused snow is darker than natural snow. Dark surfaces absorb sunlight and cause warming, while bright surfaces reflect heat back into space and cause cooling. The study by Earth System Science researchers Charlie Zender (pictured), Mark Flanner and James Randerson was published Tuesday, June 5, in the Journal of Geophysical Research.