National Geographic: Global warming could actually chill down North America within just a few decades, according to a new study that says a sudden cooling event gripped the region about 8,300 years ago. Analysis of ancient moss from Newfoundland, Canada, links an injection of freshwater from a burst glacial lake to a rapid drop in air temperatures by a few degrees Celsius along North America’s East Coast. This event created a colder year-round climate with a much shorter growing season for about …