USA Today: The world could see as many as 20 additional hurricanes and tropical storms each year by the end of the century because of climate change, says a study out today. The study was published Monday in the Proceedings of the National Academy of Sciences (PNAS), written by top climate researcher Kerry Emanuel of the Massachusetts Institute of Technology. On average, about 90 tropical cyclones form each year around the world, Emanuel says. ("Tropical cyclone" is an umbrella term that includes hurricanes,...