You can't make it up XXXXVI - worldwide cold caused by global warming (08 jan 14)
All US states are experiencing below freezing temperatures
Counterintuitively, the big freeze across the US could be a result of global warming, argues Andrew Freedman.
Arctic warming is altering the heat balance between the North Pole and the equator, which is what drives the strong current of upper level winds in the northern hemisphere commonly known as the jet stream. Some studies show that if that balance is altered then some types of extreme weather events become more likely to occur.
During the past week, while much of North America has seen frigid temperatures, weather maps show a strip of orange and red hues, indicating above-average temperatures, across parts of the Arctic, Scandinavia, Europe and Asia.
This fits with a theory known as "warm arctic, cold continents". "Such patterns bring comparatively mild conditions to the Arctic while places far to the south are thrown into a deep freeze," writes Freedman.
He also includes a very accessible explanation of why exactly it happened, writing that "a weaker polar vortex was moving around the Arctic like a slowing spinning top, eventually falling over and blowing open the door to the Arctic freezer".