4.21.2008 7:58 AM

Global Warming May Have Shifted Jet Stream

Weather Worldwide Is Ushered in by the Jet Stream

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Photo: NOAA

By Dan Shapley

In a change that is consistent with global warming computer models, the jet streams that govern weather patterns around the world are shifting their course, according to a new analysis by the Carnegie Institution published in Geophysical Research Letters.

From 1979 to 2001, "the jet streams in both hemispheres have risen in altitude and shifted toward the poles. The jet stream in the northern hemisphere has also weakened," the institution reported.

The jet stream guides weather patterns across the globe. The reason that El Niño and La Niña – warming and cooling patterns in the Southern Pacific Ocean – play such a large role in world weather, for instance, is because the temperature of the distant ocean affects the flow of the jet stream.

The migration of the jet stream is small – just 12 miles poleward per decade – but the scientists warned that "if the trend continues the impact could be significant." For instance, hurricanes might become more frequent or intense, as the jet stream ushers more tropical and subtropical storms into North America.

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