Earth’s magnetic field – the power of the geodynamo

7 Apr 2022

What mechanisms are behind the reversals of the Earth’s magnetic field? The geophysicist Stuart Gilder is coordinating a Priority Programme by the German Research Foundation (DFG) that explores this question.

© IMAGO Science Photo Library

The Earth’s magnetic field is an important shield protecting the planet against the constant bombardment of harmful cosmic particles from space. It is generated by a process called the geodynamo that goes like this: Temperature differences between the Earth’s core and its mantle, combined with the rotation of the Earth, set the liquid outer core in motion. As this core contains iron, electrical currents are generated and a magnetic field is created.

Because the magnetic field is constantly changing, the position of the magnetic pole is forever shifting. Several hundreds of times in the course of the Earth’s history, these shifts went so far as to produce complete reversals of the poles, as paleomagnetic investigations have shown. Based on the frequency of these reversals, researchers infer a connection with the dynamics of the Earth’s mantle, although the mechanisms are not yet well understood.

This is where a new Priority Programme just approved by the German Research Foundation (DFG) comes in. The goal of the DeepDyn (Reconstruction of the dynamics of the Earth’s deep interior over geological time) project coordinated by Professor Stuart Gilder from the Department of Earth and Environmental Sciences at LMU is to use paleomagnetic data and mathematical simulations to reconstruct the dynamics in the core-mantle system over geological time periods so as to understand what dictates the change in reversal frequency of the Earth’s magnetic field. The interdisciplinary project will include paleomagnetists, experts in modeling the geodynamo and the Earth’s mantle, seismologists, material scientists and biologists, all cooperating to investigate the effects of temperature changes at the boundary between core and mantle during the past 100 million years. “Our project will thus bring together expertise from all relevant fields for the first time,” says Gilder. “Among other things, we will be the first to combine simulations of the geodynamo and of the Earth’s mantle. Our inclusion of biology in our geophysical project – by investigating whether fossil remains of magnetotactic bacteria can help reconstruct the magnetic field – is also a first.”

As is usual with German Research Foundation Priority Programmes, scientists from all over Germany can now apply to take part with individual projects. Up to 30 projects will be funded for an initial period of three years, with the possibility of an extension by a further three years. The German Research Foundation will assess the scientific quality of the research projects and make a selection. DeepDyn is due to launch next year.

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