Scientist: If increases in greenhouse gases stay on pace, species will go extinct at an ever-increasing rate, according to a study published last week (May 1) in Science. In the worst-case scenario, global warming will contribute to wiping out one of every six species. Perhaps most surprising is that extinction risk does not just increase with temperature rise, but accelerates, curving upward as the Earth warms, Mark Urban, a University of Connecticut ecologist and the author of the study, told Smithsonian.com....