Geomagnetic Field Dynamics and Paleomagnetism

The Earth’s magnetic field is generated by convective motions in the liquid outer core, a process known as the geodynamo. Over geological time, this field has undergone continual change in intensity and configuration, driven by interactions at the core–mantle boundary and within the core itself. Paleomagnetism—the study of remanent magnetisation in rocks, sediments and archaeological materials—provides the principal record of these variations beyond the era of direct observation. Key phenomena include secular variation, the gradual drift of field direction and strength on centennial to millennial timescales; geomagnetic excursions, brief departures from nominal polarity; and full polarity reversals, when the dipole component flips sign. Advances in spherical harmonic modelling and high‐resolution databases have revealed regional anomalies such as the South Atlantic Anomaly and have quantified the rates of dipole decay and recovery. These insights inform models of core dynamics, aid in dating sediments and archaeological artefacts, and improve our understanding of space‐weather shielding and cosmogenic isotope production throughout Earth history.

Research from Nature Portfolio

A high‐precision archaeomagnetic record from central Pacific ceramics has revealed that, superimposed on a millennium‐scale dipole weakening, there were short‐lived intensity spikes about a thousand years ago. These regional perturbations occurred asynchronously in Hawaii, Europe and Mesoamerica, underscoring the importance of non‐dipolar contributions in numerical geodynamo models. The findings challenge purely global dipole‐based reconstructions and emphasise the need to integrate local archaeological and volcanic records with field models of secular change.

Geomagnetic Field Dynamics and Paleomagnetism publication trend

The graph below shows the total number of articles in geomagnetic field dynamics and paleomagnetism across all publications each year (not limited to Nature Index journals).

Technical terms

Geodynamo: The mechanism by which fluid motions in Earth’s outer core generate and sustain the magnetic field.

Paleomagnetism: The study of the record of Earth’s magnetic field preserved in rocks, sediments and archaeological materials.

Dipole moment: A measure of the strength of the magnetic dipole component of the geomagnetic field.

Secular variation: Gradual changes in the direction and intensity of the geomagnetic field on timescales from decades to millennia.

Geomagnetic excursion: A short‐lived event during which the geomagnetic field deviates substantially from its normal polarity without completing a full reversal.

Paleointensity: An estimate of past geomagnetic field strength derived from magnetic remanence measurements.

References

1. Rapid regional perturbations to the recent global geomagnetic decay revealed by a new Hawaiian record. Nature Communications (2013).
2. Global Geomagnetic Field Evolution From 900 to 700 ka Including the Matuyama‐Brunhes Reversal. Journal of Geophysical Research: Solid Earth (2023).
3. One Hundred Thousand Years of Geomagnetic Field Evolution. Reviews of Geophysics (2019).
4. Robust Characteristics of the Laschamp and Mono Lake Geomagnetic Excursions: Results From Global Field Models. Frontiers in Earth Science (2019).
5. Analysis of an Updated Paleointensity Database (QPI‐PINT) for 65–200 Ma: Implications for the Long‐Term History of Dipole Moment Through the Mesozoic. Journal of Geophysical Research: Solid Earth (2019).
6. The South Atlantic Anomaly: The Key for a Possible Geomagnetic Reversal. Frontiers in Earth Science (2016).