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Is Earth’s Magnetic Field Really About to Reverse?

A study of the most recent near-reversals of the Earth’s magnetic field by an international team of researchers, including the University of Liverpool, has found it is unlikely that such an event will take place anytime soon.

There has been speculation that the Earth’s geomagnetic fields may be about to reverse, with substantial implications, due to a weakening of the magnetic field over at least  the last 200 years, combined with the expansion of an identified weak area in the Earth’s magnetic field called the South Atlantic Anomaly, which stretches from Chile to Zimbabwe.

In a paper published in the Proceedings of the National Academy of Sciences, a team of international researchers modeled observations of the geomagnetic field of the two most recent geomagnetic excursion events, the Laschamp, approximately 41,000 years ago, and Mono Lake, around 34,000 years ago, where the field came close to reversing ,but recovered its original structure.

Intensity at Earth’s surface (left) and radial field (Br) at the CMB (right). Top: mid-point of the Laschamp excursion; bottom: mid-point of the Mono Lake excursion. (Credit: University of Liverpool)
Intensity at Earth’s surface (left) and radial field (Br) at the CMB (right). Top: mid-point of the Laschamp excursion; bottom: mid-point of the Mono Lake excursion. (Credit: University of Liverpool)

The model reveals field structures comparable to the current geomagnetic field at both approximately 49,000 and 46,000 years ago, with an intensity structure similar to, but much stronger than, today’s South Atlantic Anomaly (SAA); their timing and severity is confirmed by records of cosmogenic nuclides.

However, neither of these SAA-like fields developed into an excursion or reversal, Richard Holme, Professor of Geomagnetism at the University of Liverpool, said:

The strength and structure of the Earth’s magnetic field has varied at different times throughout geological history. At certain periods, the geomagnetic field has weakened to such an extent that it was able to swap the positions of magnetic north and magnetic south, while geographic north and geographic south remain the same.

Called a geomagnetic reversal, the last time this happened was 780,000 years ago. However, geomagnetic excursions, where the field comes close to reversing but recovers its original structure, have occurred more recently.

The magnetic field shields the Earth from solar winds and harmful cosmic radiation. It also aids in human navigation, animal migrations, and protects telecommunication and satellite systems.

It is generated deep within the Earth in a fluid outer core of iron, nickel, and other metals that creates electric currents, which in turn produce magnetic fields.

Provided by: University of Liverpool [Note: Materials may be edited for content and length.]

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Troy Oakes
Troy was born and raised in Australia and has always wanted to know why and how things work, which led him to his love for science. He is a professional photographer and enjoys taking pictures of Australia's beautiful landscapes. He is also a professional storm chaser where he currently lives in Hervey Bay, Australia.

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