http://www.cnn.com/2003/TECH/science/12/12/magnetic.poles.ap/index.htmlSAN FRANCISCO (AP) -- The strength of the Earth's magnetic field has decreased 10 percent over the past 150 years, raising the remote possibility that it may collapse and later reverse, flipping the planet's poles for the first time in nearly a million years, scientists said.
At that rate of decline, the field could vanish altogether in 1,500 to 2,000 years, said Jeremy Bloxham of Harvard University.
Hundreds of years could pass before a flip-flopped field returned to where it was 780,000 years ago. But scientists at a meeting of the American Geophysical Union cautioned that scenario is an unlikely one.
"The chances are it will not," Bloxham said Thursday. "Reversals are a rare event."Ah, but wouldn't it be interesting if it did? (Objectively, anyway, since the climatic effects during a reversal might not be so lovely.)
Edit: At least, the above would be my guess, since the articles suggests that even a temporary weakening could decrease ozone levels.
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