There seems to some contradictory information on the subject.
quote:
They've also learned what happens during a magnetic flip. Reversals take a few thousand years to complete, and during that time--contrary to popular belief--the magnetic field does not vanish. "It just gets more complicated," says Glatzmaier. Magnetic lines of force near Earth's surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird.
But it's still a planetary magnetic field, and it still protects us from space radiation and solar storms.
http://science.nasa.gov/headlines/y2...neticfield.htm