Earth's Magnetic Field: Should We Worry About Pole Sliding?
By Marcus Chown
Why do the Earth's magnetic poles move?
Although the Earth's magnetic field is very similar to that of a striped magnet, with a north and south pole, it is not as stable because it is created by complex processes within the Earth. These cause the magnetic poles to move.
Historically, the North Pole has moved about 15 miles a year. But since the 1990s it has accelerated and is now moving about 55 kilometers a year towards Siberia. It is speculation, but it could predict a ‘magnetic reversal’ in which the north and south magnetic poles change location. This has happened 171 times in the last 71 million years.
Earth's magnetic field models based on satellite observations have shown that the current roaming is the result of a battle between 'blobs' of extremely intense magnetic fields deep within the planet. As for the rotation of the Earth's magnetic field, no one is 100 percent sure why this happens.
How stable is the Earth's magnetic field?
The fact that the Earth's magnetic field depends on electric currents carried by molten material circulating in the turbulent interior of the planet means that it is substantially variable, as indicated by the current motion of the north magnetic pole (magnetic pole of south, surprisingly, is not moving fast).
But what is remarkable is that the magnetic field created by such violent internal convulsions is relatively stable in 99.9 percent of cases. It is the stability of the Earth's magnetic field and the reliability of the protection it has provided that has enabled life on Earth to continue for almost at least 3.8 billion years.