Temperatures are cold enough in Minnesota and North Dakota to develop frostbite in five minutes. Wind chill brings the temperatures as low as 50 below.
…the occasional cold snap—even one as extreme as much of the U.S. is experiencing now—doesn’t change the overall trajectory of a warming planet. Weather is what happens in the atmosphere day to day; climate is how the atmosphere behaves over long periods of time. Winters in the U.S. have been warming steadily over the past century, and even faster in recent decades, so it would take more than a few sub-zero days to cancel that out.
But not only does the cold spell not disprove climate change, it may well be that global warming could be making the occasional bout of extreme cold weather in the U.S. even more likely. Right now much of the U.S. is in the grip of a polar vortex, which is pretty much what it sounds like: a whirlwind of extremely cold, extremely dense air that forms near the poles. Usually the fast winds in the vortex—which can top 100 mph (161 k/h)—keep that cold air locked up in the Arctic. But when the winds weaken, the vortex can begin to wobble like a drunk on his fourth martini, and the Arctic air can escape and spill southward, bringing Arctic weather with it. In this case, nearly the entire polar vortex has tumbled southward, leading to record-breaking cold, as you can see [in the] graphic.
So, what does the freezing of America have to do with global warming? Here is the answer, courtesy of Bryan Walsh:
What does that have to do with climate change? Sea ice is vanishing from the Arctic thanks to climate change, which leaves behind dark open ocean water, which absorbs more of the heat from the sun than reflective ice. That in turn is helping to cause the Arctic to warm faster than the rest of the planet, almost twice the global average. The jet stream—the belt of fast-flowing, westerly winds that essentially serves as the boundary between cold northern air and warmer southern air—is driven by temperature difference between the northerly latitudes and the tropical ones. Some scientists theorize that as that temperature difference narrows, it may weaken the jet stream, which in turns makes it more likely that cold Arctic air will escape the polar vortex and flow southward. Right now, an unusually large kink in the jet stream has that Arctic air flowing much further south than it usually would.