Mass and Barnes’ views were backed in February 2014 when John Wallace from the University of Washington and four climate scientists from Princeton, Colorado State University, the National Centre for Atmospheric Research and University of Alaska Fairbanks published a letter in Science, pointing out that chilly bursts of cold Arctic air, more severe than the winter of 2013-14, occurred in the early 1960s, late 1970s and in 1983, “when the Arctic sea ice was thicker and more extensive than it is today” and well before the proposed shallowing of the bed of the polar jet stream.

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