Scientists say Arctic warming could be to blame for blasts of extreme cold

 Washington Post -  Rising global temperatures mean winters are getting milder, on average, and the sort of record-setting cold that spanned the country Friday is becoming rarer. But at the same time, global warming may be altering atmospheric patterns and pushing harsh outbreaks of polar air to normally moderate climates, according to scientists who are actively debating the link. Drastic changes in the Arctic, which is warming faster than anywhere else on Earth, are at the center of the discussion. Shifts in Arctic ice and snow cover are triggering atmospheric patterns that allow polar air to spread southward more often, according to recent research. “We’ve seen the same situation basically the last three years in a row,” said Jennifer Francis, senior scientist at the Woodwell Climate Research Center in Massachusetts. “Here we go again.”