All kinds of people and organizations, from media to scientists, have been pushing back against the idea, popular among the Rush Limbaugh set, that recent bitingly cold weather disproves global warming. Rather, they say, global warming actually causes this extreme weather, by making the polar air mass more unstable. That's now the official line of the White House, which is embarking on a bit of a media blitz to deny the notion that one cold snap means climate change is a lie. In a video released Wednesday, President Obama's science and technology advisor, Dr. John Holdren, made the two-minute case....