Conventional wisdom holds that planting trees–any trees–will help slow climate change because of the trees’ ability to absorb carbon dioxide. A new study shows that’s not necessarily so: where the trees are makes a big difference in how they’ll affect the earth’s climate, with some trees actually contributing to global warming. Researchers at the Lawrence Livermore National Laboratory modeled the effect of deforestation on temperature for boreal, temperate and tropical regions. In the tropics, keeping trees around helped to lower regional temperatures, as expected, but in the boreal zones, the trees actually caused slight warming. That’s because the ability of the trees to hold heat, and to keep the snow from reflecting sunlight back into space, offsets the amount of carbon dioxide they remove from the air. In the temperate zones, the effects cancelled out, leaving no net effect on temperature. The lead author of the study hastened to add that they are not recommending deforestation of boreal areas, but that the study confirms the value of reforesting in the tropics.
Source: John Simpson. Careful where you plant that tree. ScienceNOW Daily News, April 10, 2007. Photo: Boreal forest in Alaska by NOAA.