The Earth’s magnetic field continues to be a source of mystery for geologists and planetary scientists. Thanks to improved techniques of detecting measuring the geomagnetic field, scientists now know that the Earth’s magnetic field is weakening - despite having no explanation for the phenomenon. Other studies have found cracks opening in the magnetic field, potentially allowing more cosmic radiation to bombard us unfortunate saps here on the planet’s surface. To make magnetic matters more mysterious (and terrifying), a massive new magnetic anomaly has been detected in the southern hemisphere under Africa. What does this mean for the Earth’s magnetic field and the living things who depend on it for protection?
Unfortunately, we don’t know yet. But no news is better than bad news, right? The region of the Earth’s magnetic field under study is known as the South Atlantic Anomaly and stretches under the southern Atlantic ocean from Chile to Zimbabwe. In this region, the geomagnetic field comes closer to the Earth’s surface than anywhere else on Earth, reaching down to an altitude of 200 kilometres, or 120 miles. This makes it a prime site for studying the magnetic field since the low altitude means the effects of the field can be detected much easier. In the case of discovering this new anomaly, researchers from the University of Rochester examined 1,000-year-old pottery made by the Bantu people to search for magnetic minerals baked into the clay which serve as a type of record. The minerals in the pottery revealed similar magnetic anomalies occurred in 400-450 AD, 700-750 AD, and sometime between 1225-1550 AD.
University of Rochester Earth and Environmental Sciences professor John Tarduno led this new study of the South Atlantic Anomaly. In a university press release announcing the discovery, Tarduno says while its too early to draw conclusions about pole reversal or any type of cataclysmic event, this anomaly deserves serious study so that scientists and world leaders can be aware of any potential harmful effects:
We were looking for recurrent behavior of anomalies because we think that’s what is happening today and causing the South Atlantic Anomaly. We’re getting stronger evidence that there’s something unusual about the core-mantle boundary under Africa that could be having an important impact on the global magnetic field. The possibility of a continued decay in the strength of the magnetic field is a societal concern that merits continued study and monitoring.
There is a growing body of evidence suggesting Earth’s magnetic poles have reversed many times over the planet’s history, or even that Earth once had more than two magnetic poles. It’s still unknown what effect(s) a pole reversal might have today in an age dependent on electronics.