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 Thursday.
At the current 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.
However, scientists at the fall meeting of the American Geophysical Union cautioned that scenario is an unlikely one.
"The chances are it will not," Bloxham said. "Reversals are a rare event."
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