Where is North?

I am sure we have all looked at a compass and thought the needles pointing to geographic north. However it’s actually pointing toward the North Magnetic Pole, a separate distinct location that has the peculiar characteristic that it is constantly moving. Its shifted so fast that between 1990 and 2005,it began moving nearly 50–60 kilometres annually from the Canadian Arctic toward Siberia. Although the movement of the pole has since slowed, its movement still requires magnetic navigation models used in aviation, surveying, and other technologies to be updated frequently (Livermore et al. 2020; National Centers for Environmental Information [U.S.] and British Geological Survey 2025).

Now you may be asking how does the north pole actually move? Well this movement actually starts nearly 2,900 kilometres beneath the surface of the Earth, within the outer core composed of liquid iron. The magnetic field is produced by two processes: thermal convection, and compositional convection. Thermal convection is created when liquid iron near the top of the outer core cools and becomes denser, causing it to sink. Simultaneously, as the solid inner core crystallizes, the surrounding liquid has lighter elements released into it making it more compositionally buoyant and driving additional circulation of liquid iron within the core. Together, the thermal and compositional buoyancy help sustain convection, and as the liquid iron moves it generates electric currents responsible for creating the Earth’s magnetic field or in other words the geodynamo (Landeau et al. 2022).  The migration of the magnetic pole is a consequence of this behavior because as the circulation changes the current changes which reshapes the magnetic field (Livermore et al. 2020).

Predicting this movement, however, presents a fundamental mathematical challenge. Scientists cannot directly observe the outer core, meaning they must reconstruct its behaviour from magnetic measurements collected at Earth’s surface and by satellites. This creates an inverse problem: many different configurations of the flow of liquid metal can produce very similar magnetic observations, which can prevent researchers determining the underlying dynamics (Pais et al. 2004).

To first go about this large task first scientists represent Earth’s magnetic field using spherical harmonics functions that describe spatial patterns across a sphere at different scales. By combining these functions researchers are able to model the magnetic field at very different scales (Glassmeier and Tsurutani 2014). This allows for understanding how the field behaves currently but prediction still faces a barrier. The underlying problem of understanding the motion of the core remains, in order to do so researchers use the frozen-flux approximation, which assumes that magnetic advection by the liquid iron is much greater than magnetic diffusion. By using this, variations in the magnetic field can be used to estimate the flow and predict how the field might evolve (Roberts and Scott 1965; Whaler and Beggan 2015).

Researchers can then use their own unique approaches to turn these uncertain estimates of core motion into forecasts of changes in Earth’s magnetic field which can help ultimately determine how the North Magnetic Pole migrates. For example, an ensemble Kalman smoother was used, combining multiple possible core-flow estimates with magnetic observations to refine predictions (Gwirtz et al. 2025). Another approach that has been used is utilizing physical equations embedded into neural networks to predict the evolution of the magnetic field (Shakespeare-Rees et al. 2026). Another approach was modelling core-flow acceleration as oscillatory rather than increasing, which allows the forecasting of magnetic field changes (Madsen et al. 2026). However, these forecasts cannot capture geomagnetic jerk which introduces discrepancies between predicted and observed evolution of the magnetic field (Whaler and Beggan 2015).

Predicting Earth’s magnetic field is a monumental task requiring the prediction of how an inaccessible, constantly evolving fluid continues to move. Despite many advances, forecasts remain imperfect but serve as a vital, evolving baseline which we require.

References
Glassmeier, K. H., and B. T. Tsurutani. 2014. “Carl Friedrich Gauss – General Theory of Terrestrial Magnetism – a Revised Translation of the German Text.” History of Geo- and Space Sciences 5 (1): 11–62. https://doi.org/10.5194/hgss-5-11-2014.

Gwirtz, Kyle, Terence Sabaka, and Weijia Kuang. 2025. “A Secular Variation Candidate for IGRF-14 Based on Core-Flow Inversion via an Ensemble Kalman Smoother.” Earth, Planets and Space 77 (1). https://doi.org/10.1186/s40623-025-02289-4.

Landeau, Maylis, Alexandre Fournier, Henri-Claude Nataf, David Cébron, and Nathanaël Schaeffer. 2022. “Sustaining Earth’s Magnetic Dynamo.” Nature Reviews Earth & Environment 3 (4). https://doi.org/10.1038/s43017-022-00264-1.

Livermore, Philip W, Christopher C Finlay, and Matthew Bayliff. 2020. “Recent North Magnetic Pole Acceleration Towards Siberia Caused by Flux Lobe Elongation.” Nature Geoscience 13 (5): 387–91. https://doi.org/10.1038/s41561-020-0570-9.

Madsen, Frederik Dahl, Ciarán D. Beggan, William J. Brown, Richard Holme, Jonas Bregnhøj Lauridsen, and Kathryn A. Whaler. 2026. “IGRF-14 Secular Variation Prediction From Core Surface Flow Acceleration.” Earth, Planets and Space 78 (1): 29. https://doi.org/10.1186/s40623-025-02347-x.

Pais, M. A., O. Oliveira, and F. Nogueira. 2004. “Nonuniqueness of Inverted Core‐Mantle Boundary Flows and Deviations From Tangential Geostrophy.” Journal of Geophysical Research: Solid Earth 109 (B8): 2004JB003012. https://doi.org/10.1029/2004jb003012.

Roberts, Paul H, and Susan M Scott. 1965. “On Analysis of the Secular Variation.” Journal of Geomagnetism and Geoelectricity 17 (2): 137–51. https://doi.org/10.5636/jgg.17.137.

Shakespeare-Rees, N., P. W. Livermore, C. J. Davies, et al. 2026. “Forecasting Secular Variation Using Physics-Informed Neural Networks for IGRF-14.” Earth, Planets and Space 78 (1): 98. https://doi.org/10.1186/s40623-026-02427-6.

“State of the Geomagnetic Field 2025.” 2025. Noaa.Gov, ahead of print. https://doi.org/10.25923/2gcf-s393.

Whaler, K. A., and C. D. Beggan. 2015. “Derivation and Use of Core Surface Flows for Forecasting Secular Variation.” Journal of Geophysical Research: Solid Earth 120 (3): 1400–1414. https://doi.org/10.1002/2014jb011697.