As brutal cold spilled out of the Arctic and enveloped much of the U.S. Upper Midwest and Great Lakes in late January, news stories tied the event to global warming. Here’s a sampling of headlines:

“Brace for the Polar Vortex; It May Be Visiting More Often” (NY Times)

“The Polar Vortex And How It’s Related To Global Warming (Forbes)

“Polar Vortex Linked to Climate Change (WGBH)

An increasing but still contested body of science suggests that rapid and intense warming in the Arctic