Researchers have looked to the past to determine whether the weakening magnetic field is indicative of an imminent pole reversal (Credit: Peter Reid, The University of Edinburgh)
We owe our existence to the Earth’s magnetic field, the invisible barrier that protects the planet from the harsh radiation of space. But this shield is far from static, and tends to wane and even reverse at semi-regular intervals. With the magnetic field currently weakening, there’s been a lot of talk in recent years that another flip might be imminent, but a new study has looked at the history of these events and found that a reversal probably isn’t about to happen.
The cause for concern starts with what’s known as the South Atlantic Anomaly (SAA). In this area, stretching across the Atlantic Ocean from Chile to Zimbabwe, the magnetic field is substantially weaker than elsewhere in the world. Ever since this region was discovered in 1958, it’s been growing, as part of an overall weakening of the entire magnetic field over the last few centuries.
The end result of that trend appears to be the reversal of the poles. Historically, magnetic north and south switch places every 200,000 to 300,000 years, and we’re actually well overdue for such an event – it’s been about 780,000 years since the last one. Although doomsayers love to shout about how a pole reversal would rain down hellish amounts of radiation onto Earth, NASA says that our biggest concern would just be buying new compasses.
But how likely is that scenario, anyway? To find out, researchers from the University of Liverpool, GFZ German Research Center for Geosciences and the University of Iceland looked to past fluctuations in the field. A weakening magnetic field doesn’t always mean the poles are about to reverse – more often than not the field recovers its original structure, and this waning-recovering event is known as a geomagnetic excursion.