What has Earth's magnetic field ever done for us? The role of the geodynamo in creating a habitable planet (Sedgwick Club Conference)

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• Dr Claire Nichols - University of Oxford
• Tuesday 23 April 2024, 16:30-17:00
• Department of Earth Sciences, Tilley Lecture Theatre.

If you have a question about this talk, please contact Lucas Measures.

When considering why Earth is the only known habitable – and inhabited – world in our solar system, its magnetic field is often included as one of the many factors resulting in such favourable conditions for life. This is because magnetic fields protect planetary surfaces from harmful cosmic radiation and prevent the atmosphere from being eroded by the solar wind. Earth’s magnetic field is generated by the geodynamo; vigorous convection of electrically conductive molten metal in the outer core results in the dipolar magnetic field that surrounds our planet. We can use the signals preserved by magnetic minerals in rocks to examine the strength of Earth’s magnetic field back through geological time. However, this becomes increasingly challenging as metasomatic and metamorphic events cause these minerals to be altered or entirely replaced. Paleomagnetic records suggest that Earth’s magnetic field has been similar in strength for the last 3.5 billion years. However, there are many time periods with sparse data, and the existing data come with many caveats. New experimental approaches are now allowing paleomagnetists to revisit Earth’s early magnetic field history in a new light by combining magnetic microscopy, geochronology and petrology. By recovering more accurate records of Earth’s magnetic field strength through time questions such as how the geodynamo behaved prior to the nucleation of the inner core, and the role of Earth’s magnetic field in mediating atmospheric escape, can be addressed properly for the first time. These observations will be critical for determining whether the magnetic field really played a crucial role in creating habitable conditions on Earth’s surface.

This talk is part of the Sedgwick Club talks series.

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• Department of Earth Sciences seminars
• Department of Earth Sciences, Tilley Lecture Theatre
• Sedgwick Club talks

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