The historical movement of these poles indicates a change in the global geometry of the Earth's magnetic field. It may even indicate the beginning of a field reversal – a "flip" between the north and south magnetic poles.

The latest version of the World Magnetic Model (WMM), one of the key tools developed to model the change in Earth's magnetic field, has been released. The WMM is a spherical harmonic model of the Earth’s main magnetic field and its slow temporal change.

The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force). [58]

Earth's magnetic field is generated by fluid motions in its liquid outer core lying deep below the surface. Changes in the modern field are well-mapped using low earth orbiting satellites and ground observations, but these are very modest.

If one “plays the tape backwards,” the record shows Earth’s magnetic field strengthening, weakening, and often changing polarity. Magnetic North and South Poles have even reversed or “flipped,” which is known as geomagnetic pole reversal.