Global Warming, Jet Stream Working in Tandem to Heat Up Northern Hemisphere

The winter warming of the Northern hemisphere in recent years is ultimately caused by global warming, but the more proximate cause is change in the jet stream, NASA researchers report in today’s issue of the journal Nature. Although mean global temperatures have risen by less than 1 degree Fahrenheit since the 19th century, winter temperatures in the Northern Hemisphere have climbed by as much as 9 degrees in the last 35 years.

Global warming, the researchers say, has speeded up the jet stream, which moves masses of air from west to east. Because oceans retain heat in winter better than land, the jet stream carries heat from the Pacific Ocean to the North American continent.

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Compiled by Times medical writer Thomas H. Maugh II