Devastating floods destroyed towns in Germany and Belgium. A ruthless heat wave broiled the Western U.S. and Canada. Heavy rains paralyzed a Chinese industrial hub home to 10 million people. These recent weather phenomena are being intensified by the changing climate.
But the link between these far-flung extremes goes beyond warming global temperatures. All of these events are touched by jet streams, strong and narrow bands of westerly winds blowing above the Earth’s surface. The currents are generated when cold air from the poles clashes against hot air from the tropics, creating storms and other phenomena such as rain and drought.
"Jet streams are the weather — they create it and they steer it,” said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center. "Sometimes the jet stream takes on a very convoluted pattern. When we see it taking big swings north and big dips southward we know we’re going to see some unusual weather conditions.”