Earth's magnetic field is not likely to reverse any time soon

Polar reversals have happened before, and although the average time between them has been 200,000 years, these events occur at irregular intervals. There is a strange and mysterious zone in the South Atlantic where the strength of the magnetic field is waning quickly. This odd phenomenon has led some to speculate that the Earth’s magnetic field is moving towards flipping or reversing itself. Now, a new study shows that a polar reversal is unlikely any time soon. 

Over the last 180 years, Earth’s magnetic field has decreased as the strange area in the South Atlantic with a weak magnetic field has grown in size. This spot often causes satellites to falter due to exposure to highly charged particles from the sun and is known as the “South Atlantic anomaly.” 

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

The researchers were able to map the magnetic field by looking at volcanic rock samples, core drillings, even clay pots heated to temperatures over 580 degrees celsius. When rocks are heated to such temperatures, the liquid magnetic components align themselves with the Earth’s magnetic field. As the rocks cool, they harden into a snapshot of the magnetic field at the time. 

“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,” said Nilsson.

With this magnetic field record in hand, the scientists were able to compare the modern magnetic field, anomalies included with past iterations and come to the conclusion that a reversal is not imminent,  

“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,” concluded Nilsson.

The study is published in the journal Proceedings of the National Academy of Sciences.

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By Zach Fitzner, Earth.com Staff Writer