Washington Post: It's quite cold across much of the United States right now, thanks to the dread "polar vortex." Bitterly cold. Horrifically cold!
So what does this tell us about global warming? Not much. Sorry. A cold snap in the U.S. can't disprove global warming any more than you can get rid of a fever by sticking your hand in ice water. (Similarly, the record heat hitting Australia right now doesn't, on its own, prove all that much.) But since a lot of people -- like Donald Trump -- seem confused on this point,...