http://story.news.yahoo.com/news?tmp...=/ap/pole_flip
magnetic field strength down ten percent in some areas over the last 150 years.
Excerpt:
>>_ 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. "Reversals are a rare event." <<