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Earth Sense: Jet stream in flux means more changeable weather
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While much of the northern and eastern U.S. shivered in frigid weather, parts of England experienced severe storms. Recent research suggests that these record-setting events were due to warming of the Arctic.

It’s important to realize that the atmosphere is in constant motion because we have only one heat source, the sun. Rotation of the earth therefore causes uneven heating and cooling, and the air is constantly trying to smooth out the differences. Bodies of air that have different temperature and moisture content have a hard time mixing.

About 8 to 10 miles above the ground, the differences play out most strongly. Those border zones between cold air and warmer air produce a very rapid line of wind flow called the jet stream.

In February, a push from the Arctic air mass made the jet stream swerve south and travel across England. Severe storms and flooding in Wales left thousands of homes without power. On the eastern side of the island, flood waters pushed up the Thames, bringing that river up to a 60-year high level.

London has been protected by a flood barrier since 1982, which closes when high water pushes up from the North Sea toward the city. This winter, it had to be closed 41 times to protect London, which, according to the Telegraph newspaper, accounts for a quarter of all closings in the barrier’s history. Watch for news articles criticizing the barrier when people living downstream of it find out that protecting London increases flooding in their own areas by making the river water pile up.

The wild waves in the jet stream that got England pounded by relentless storms and even paralyzed winter-hardy Chicago in record freezes are expected to continue. The old theory of global warming, which predicted higher sea levels and warmer temperatures in most places, is ready to be replaced by global variability. What we can expect is not a generally warmer situation but a more changeable one.

Because the jet stream bounces both north and south, for the Southern states this means times when it is located well north of us, bringing long stretches of rainless air from the Bermuda high into the region. In other words, the storms and freezes of this winter could well be followed by extended drought. This is a good time to plan for water conservation.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at