Star Tribune: Aspen trees, the backbone of Minnesota’s paper industry, are liking the extra carbon dioxide in the air linked to global warming. New research published Friday found that aspen growth rates increased by 53 percent during the past half-century, as carbon dioxide in the atmosphere increased about 20 percent. "Trees eat carbon dioxide for a living," said Don Waller, study author and University of Wisconsin-Madison botany professor. As carbon dioxide increases in the air, he …