17 NOV 2011:
While deforestation is considered a critical factor in global warming since it causes the release of carbon, scientists say that in northern latitudes tree loss may actually have a net cooling effect. In an analysis of temperature data collected from Florida to Manitoba, researchers from 20 institutions found that in the boreal region — north of 45 degrees latitude — the surface temperatures in open grassy areas were cooler than in adjacent forests because the snow reflected the sun’s rays back into space. In those areas, researchers say, the darker forests absorbed the sun’s heat. “The cooling effect is linear with latitude, so the farther north you go, the cooler you get with deforestation,” said Xuhui Lee, a professor of meteorology at the Yale School of Forestry & Environmental Studies and the lead investigator of the study, published in the journal Nature. For instance, in regions north of Minnesota (45 degrees latitude) temperatures in deforested areas decreased by an average of 1.5 degrees F, while in areas south of North Carolina (35 degrees latitude), deforestation appeared to cause warming.