Earth’s magnetic poles are not likely to shift

Charged particles from the solar wind, which would normally strip away the ozone layer protecting the Earth from harmful UV rays, are mainly deflected by the planet’s magnetic field.

Earth’s magnetic poles are unlikely to shift, a new study claims.

There have been speculations that the Earth’s magnetic polarity is about to reverse following the appearance of a mysterious area in the South Atlantic where the intensity of the geomagnetic field is rapidly decreasing. The current changes, however, may not be unique, and a reversal may not be imminent after all, according to a recent study that compiles data dating back 9,000 years. The study has just been published in the Proceedings of the National Academy of Sciences.

The invisible barrier provided by the Earth’s magnetic field protects against solar winds and the very dangerous environment of space. However, the magnetic field is not stable and polarity reversals occur irregularly, on average once every 200,000 years. In other words, the North and South magnetic poles change places.

The Earth’s magnetic field has weakened by about 10% over the past 180 years. At the same time, a region of the South Atlantic, off South America, developed an abnormally weak magnetic field. This region, where satellites have repeatedly malfunctioned due to exposure to highly charged particles from the sun, is called the South Atlantic Anomaly. These changes have raised the possibility that the polarity may soon reverse. However, the new study suggests that may not be the case.

“We have mapped the changes in the Earth’s magnetic field over the past 9,000 years, and anomalies like the one in the South Atlantic are likely recurring phenomena linked to corresponding variations in the strength of the Earth’s magnetic field,” explains Andreas Nilsson, geologist at Lund University.

The results are based on analyzes of burnt archaeological artifacts, volcanic samples and sediment drill cores, all of which contain information about the Earth’s magnetic field. These include clay pots that have been heated to over 580 degrees[{” attribute=””>Celsius, volcanic lava that has solidified, and sediments that have been deposited in lakes or in the sea. The objects act as time capsules and carry information about the magnetic field in the past. Using sensitive instruments, the researchers have been able to measure these magnetizations and recreate the direction and strength of the magnetic field at specific places and times.

“We have developed a new modeling technique that connects these indirect observations from different time periods and locations into one global reconstruction of the magnetic field over the past 9,000 years”, says Andreas Nilsson.

By studying how the magnetic field has changed, researchers can learn more about the underlying processes in the Earth’s core that generate the field. The new model can also be used to date both archaeological and geological records, by comparing measured and modeled variations in the magnetic field. And reassuringly, it has led them to a conclusion regarding speculations about an imminent polarity reversal:

“Based on similarities with the recreated anomalies, we predict that the South Atlantic Anomaly will probably disappear within the next 300 years, and that Earth is not heading towards a polarity reversal”, concludes Andreas Nilsson.

Reference: “Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomaly” by Andreas Nilsson, Neil Suttie, Joseph S. Stoner and Raimund Muscheler, 6 June 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2200749119

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