Climate Central: Human-caused greenhouse gas emissions are like a cat burglar. They're hard to see and harder to catch in the act. However, they're prone to leaving fingerprints, and scientists, acting as detectives, have been looking for those fingerprints as evidence has mounted that greenhouse gases are causing global average temperatures to increase. The latest discovery, announced Monday in a paper in the Proceedings of the National Academy of Sciences, makes the case that those emissions are causing changes...