New research from NASA scientists suggests emissions of black soot alter the way sunlight reflects off snow. According to a computer simulation, black soot may be responsible for 25 percent of observed global warming over the past century. Soot in the higher latitudes of the Earth, where ice is more common, absorbs more of the sun’s energy and warmth than an icy, white background. Dark-colored black carbon, or soot, absorbs sunlight, while lighter colored ice reflects sunlight. Soot in areas with snow and ice may play an important role in climate change.