A new study argues that Earth’s magnetic poles are unlikely to flip.
There has been speculation that Earth’s magnetic polarity is about to reverse as a result of the appearance of a mystery area in the South Atlantic where the geomagnetic field strength is rapidly dropping. The present changes, however, may not be unique, and a reversal may not be imminent after all, according to a recent study that compiles data going back 9,000 years. The study was recently published in the Proceedings of the National Academy of Sciences.
The invisible barrier provided by the magnetic field of the Earth protects against solar winds and the highly dangerous environment in 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 switch places.
The Earth’s magnetic field has weakened by around 10% during the last 180 years. At the same time, a region in the South Atlantic, off the coast of South America, has developed an abnormally weak magnetic field. This region, where satellites have malfunctioned several times due to exposure to highly charged particles from the sun, is called the South Atlantic Anomaly. These changes have raised the possibility that polarity could soon reverse. However, the new study suggests that this may not be the case.
“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”, says Andreas Nilsson, a geologist at Lund University.
The results are based on analyzes of burnt archaeological artifacts, volcanic samples, and sediment drill cores, all of which carry information about the Earth’s magnetic field. These include clay pots that have been heated up to over 580 degrees 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.