What is causing the magnetic north magnetic pole to drift?

Climate Change and Sustainability July 24, 2020

A research paper co-authored by RSK Consultant Geophysicist Matthew Bayliff has provided a detailed insight into what is causing the earth’s magnetic north magnetic pole to drift. The wandering of the magnetic north pole, which has moved from Canada towards Siberia in recent years, has long been a topic scientific fascination.

“The north magnetic pole is the area on earth where the magnetic field lines are vertical,” explains Matthew, whose university dissertation formed the basis for the research paper. “This is known to constantly drift. Before 1990, for example, it had a speed of about 0–15 km per year and remained around the Canadian side of the Arctic. However, since 1990, this has accelerated to 50–60 km per year in a direction towards Siberia.”

The blue line indicates the drift of the north magnetic pole, as calculated from the magnetic field models. The red dots show the in-situ observations of the north magnetic pole, whereas the red dots show the position calculated from the field models. The dashed and white lines indicate predictions of possible future drift.

The movement of the north magnetic pole has direct implications, as many navigation systems, such as smartphones, rely on magnetic field models to operate. The acceleration has thus resulted in the need for more frequent updates of the field models so that they remain accurate.

“When the north magnetic pole’s position was first recorded, a team had to venture into the Arctic and physically locate the point where the field lines were vertical,” says Matthew. “But now, with advancements in satellite technology and a network of ground-based magnetic observatories, accurate field models of the earth’s magnetic field can be produced. This gives an approximate location of the north magnetic pole and a lot more information on the global magnetic field.”

Using these models, the paper outlines what has determined the rapid acceleration in the drift. Two “negative flux lobes” on the core–mantle boundary have been in a tug of war, with the Canadian lobe weakening and the Siberian lobe strengthening, which has led to this acceleration in the drift. It is believed that these changes in the flux lobes on the core–mantle boundary is linked to changes in the flow of molten material within the outer core. But the drift will not stop there.

A, B and C are field models from 2019. D, E and F models are from 1990. A, B, D and E are models from the earth’s surface, whereas C and F are from the core–mantle boundary. In 1990, the two large lobes were of about equal size and intensity. However, by 2019 the Siberian lobe was larger and more intense than the Canadian lobe.

“With the magnetic field models, we have estimated that the pole will continue to drift on its current trajectory to 390–660 km from its current position over the next decade,” says Matthew. “For an accurate position and changes in the drift we will have to wait for future magnetic field models to be produced.”

This research has shown large-scale variations in the global magnetic field. However, small scale magnetism can also be observed and is influenced by many shallow surface features ranging from unexploded ordnance to buried mineshafts. If you require any magnetic surveys for such features, please contact the RSK geophysics team at mbayliff@rsk.co.uk or +44(0)7741 725908.

You can read the paper in full at Nature Geoscience. BBC has also reported on the findings.

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