The earth has a large-scale dipolar magnetic field. The magnetic North and South poles are commonly understood as positions on the Earth where the geomagnetic field is vertical (i.e., perpendicular) to the ellipsoid. The Earth’s magnetic field shields us against high-energy particles from the Sun and outer space, thereby protecting our atmosphere and the life that it supports.
It has long been understood that the magnetic poles migrate over time. The most recent survey determined that the North Pole is moving approximately north-northwest at 55km per year. Based on the current World Magnetic Model (WMM) the 2020 location of the north magnetic pole is 86.50° N and 164.04° E and the south magnetic pole is 64.07° S and 135.88° E.
The Earth’s field has varied significantly over geological time, sometimes being weak, sometimes strong and periodically reversing direction completely. This pattern of changes have left a distinctive fingerprint on the surface of the Earth. Paleomagnetism is the study of rocks and seabed sediments which formed in ancient times to follow the long-time behaviour of the geomagnetic field. Magnetic minerals crystalize in cooling lava flows and orientate themselves towards the magnetic North pole. This magnetic record is permanently locked in the rocks once they harden.
It is widely believed that the Earth’s magnetic field is powered by a convection-driven dynamo in its liquid iron core. If there were no fluid motions in the core, any primordial magnetic field would have decayed away on a timescale of tens of thousands of years. Yet, the Earth has had a magnetic field for billions of years. Fluid motion in the outer core is thought to be driven by either natural convection or by buoyant plumes of light material released from the boundary of the inner core as pure iron crystalizes. The presence of dissolved radioactive heat sources is also possible .
Sreenivasan, B. (2010). Modelling the geodynamo: progress and challenges. Current Science, 99(12), 1739-1750.