If you’re reading this from any of lower 48 states of America, chances are that you’ve noticed it’s cold, incredibly cold. So dangerously cold that Indianapolis outlawed driving, New York has declared a state of emergency and in areas of the northern plains the wind chill factor is making it feel like negative 60. So it might seem a bit counter-intuitive to attribute such an extreme chill to global warming, but some researchers suggest just that. Jennifer Francis, a professor at Rutgers is one of several scientists who propose that decreases in Arctic sea ice due in part to man-made warming have lead to shifts in the jet stream that in turn force extreme and seemingly unlikely weather configurations.
Photo © akasped on Flickr
It’s an admittedly complex topic, one that has been derided by Rush Limbaugh as a “liberal hoax,” and one that prompted Andy Borowitz to craft one of his finest headlines to date (Polar Vortex Causes Hundreds of Injuries As People Making Snide Remarks About Climate Change Are Punched in the Face). Quite simply, it can be a bit hard to wrap one’s head around the idea that yes, warming trends can and do cause extreme cold.
So let’s start at the North Pole. As Climate Central notes, “The warmth in the Arctic made headlines in early December when the temperature hit 39°F in Prudhoe Bay, north of the Arctic Circle. That was the highest December temperature on record there since at least 1968, according to the National Weather Service.” These high temperatures sit within a trend of a decline in Arctic sea ice, one so troubling that some scientists have suggested that the Arctic might be completely void of summer sea ice by 2050.
The increased temperatures in the Arctic in turn alter the difference in temperatures between the North Pole and the equator, and it is the balance between these temperatures that drives jet stream. In this fantastic video, Francis describes the jet stream as a “river of wind high up in the atmosphere that goes completely around the northern hemisphere, it has a wavy path and these waves create the storms, the weather that we feel throughout the surface.” And it’s of particular importance because it creates the boundary between the cold air to the north and the warm air to the south.
So Francis and others pose that with a warmer Arctic, the jet stream is weakened, and takes a wavier, more meandering, irregular path. This meandering path can create situations such as the one we’re seeing at present—with the lower 48 states plunged into a deep freeze, while areas to the north are experiencing warmer than typical temperatures.
Of course, one short, extreme cold snap does not on its own indicate any substantial shift in climate—and the theory does have its critics within the scientific community. But Francis believes that the current weather does fit into a trend, explaining in an email to Climate Central: “The persistence of the pattern seems consistent with an amplified jet stream configuration that we expect to see occur more frequently as the Arctic continues to warm disproportionately.”
Via Climate Central