NASA's response to the pole flip...
47. Earth's Magnetic Field Flip
I know that both the Earth and the Sun undergo a regular shift in their magnetic poles. The Sun's cycle is 11 years and I believe the Earth's is around 26,000 years. Is it true that Earth's pole reversal is due and is going to occur at the same time (or near) to the Sun doing the same thing? When this happens would the Earth and the Sun not react in a similar manner to two identically charged magnets coming together and repel? It seems that our own North Pole tracking data shows that it is already beginning to migrate. When it completes it's reversal what consequences will there be for a civilisation, based on electrical devices? Is the closeness of the Sun not a major factor is global warming?
The Sun shifts it's magnetic field every 11 years, and it has already happened for this solar cycle. The Earth's magnetic field flip is much more erratic and has happened approximately 25 times in the last 5 million years. It's been about 740,000 years since the last flip, however, so we're long overdue. There is evidence that we may be heading towards a reversal (the dipole magnetic field is weakening and the higher order terms are increasing), but we can't predict when it would happen. Depending upon how quickly the field reversal happens, it could cause problems for things like electric power lines and oil pipelines, and if the field goes to near zero, it might cause a higher background radiation at the ground, but there is no evidence that previous reversals have had any major biological effect. The forces due to the interaction of the solar and terrestrial magnetic fields are only very small perturbations.
How do the magnetic poles reverse? Is it for the same reason that the Sun's poles reverse?
Both the Sun and the Earth are electromagnets, not permanent magnets (despite the Earth's core being made up of iron and nickel). So it is electric currents moving through the plasma of the Sun and the molten rock of the Earth's interior that generate the magnetic fields. These currents have instabilities that build up until the field reverses to relieve stress. The fact that the magnetic pole moves is tied in with the same instabilities, but the flip probably happens pretty quickly on Earth (less than ~ 1000 years is all they can tell).
Dr. Eric Christian
[link to helios.gsfc.nasa.gov