The red dots show the positions of the magnetic north pole from 1831 to 2019, while the lines show the direction of the magnetic field. Around 50 years ago, the pole was moving along at around 15 km a year, but now it is accelerating and heading from the Canadian Artic towards Siberia at around 55 km a year. Credit: DTU Space/ ESA.
Over the last century, the position of the magnetic north pole has shifted from the Canadian Arctic to Siberia. But, according to a new study by researchers in Italy and Spain, this shift was part of a longer trend, with the magnetic pole alternately 'dribbling' between the two regions for the past 22,000 years1.
Studying how the geomagnetic field has changed in the past provides valuable data to understand the dynamics in the Earth’s liquid outer core. In 2019, the World Magnetic Model, maintained by an international collaboration and crucial for navigation systems, was updated due to an acceleration of the magnetic pole's movement towards the Siberian region. “Two areas of strong magnetic flux beneath Canada and Siberia are engaged in a tug-of-war, with Siberia having the upper hand and bringing the magnetic pole closer”, explains Chiara Caricchi from the National Institute of Geophysics and Volcanology (INGV), in Italy, lead author of the study. “To check whether this had happened in the past, we analysed six sediment cores from Svalbard and reconstructed the evolution of the paleomagnetic field in this region”.
During their deposition, magnetic minerals behave like compass needles and orient themselves according to the direction of the Earth’s magnetic field. “While direct observation is obviously limited to the last few centuries”, says Caricchi “the use of paleomagnetic methods allows us to explore much wider time ranges in the past and makes it possible to improve our knowledge of the dynamics of the Earth's outer core”.
Caricchi and her colleagues calculated the Flux Concentration Factor (FCF), a measure of how the magnetic flux concentrates in a specific point instead of pervading a larger area, for Canada and Siberia. They found that the ancient pole shifted towards the area with a higher FCF. “This is the first time the FCF has been used to study changes in the paleopole position”, says Saioa A. Campuzano, of the Institute of Geosciences (IGEO) in Madrid, Spain, who was also involved in the study.
The researchers were able to reconstruct the pathways of the paleopole over the last 22,000 years, following its track back and forth between the Canadian and Siberian shores. The path has followed both clockwise and counter-clockwise trajectories, with centuries of stability and centuries of accelerated movement, driven by the appearance and disappearance of strong magnetic field patches.However, around 3,200 years ago the pole shifted to lower latitudes, reaching Norway. “This shift could be related to the appearance of a strong magnetic flux under the Middle East, a phenomenon observed before and known as the Levantine Iron Age Anomaly,” says Caricchi.
