Nature World: Last winter was a rough one for many North Americans, with polar vortexes bringing Arctic temperatures as far south as Florida. Meanwhile, residents on the continent's west enjoyed a relatively mild winter. According to new research this weather pattern, brought on by a "curvy" jet stream, has become more pronounced in the last 4,000 years and may become more so as the climate gets warmer.
Writing in the journal Nature Communications, a team of scientists including University of Utah geochemist...