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Clearing forests not only releases carbon into the atmosphere, it also triggers worldwide shifts in rainfall and temperaturesthat are just as potent as those caused by current carbon pollution and that pose great risk to future agricultural productivity, researchers report . Deforestation in South America, Southeast Asia, and Africa may alter growing conditions in agricultural areas as far away as the U.S. Midwest, Europe, and China, the study in Nature Climate Change finds. The researchers calculate that complete tropical deforestation could trigger atmospheric changes leading to an increase of 0.7 degrees Celsius in global temperatures, in addition to warming caused by greenhouse gases released from the deforestation itself. That would double the observed global warming since 1850, the researchers note. They say their findings indicate that many of the predicted changes associated with widespread deforestation are already occurring — from Thailand, which is receiving less rainfall at the beginning of the dry season, to parts of the Amazon, where once-predictable rainfall has shifted notably.