Magnetic Field Reversal: South Atlantic Anomaly Isn't a Problem Yet

Cue a collective sigh of relief.

There are easily a dozen ways the age of humans could come to an end. At this point, an antibiotic-resistant plague, sea level rise, and global famine are all equally plausible ways for humans to get wiped off the face of the Earth. Fortunately, according to a new study in Proceedings of the National Academy of Sciences, we might be able to cross one possibility off the list: magnetic pole reversal.

In a paper published Monday, an international team of researchers provides evidence that the current disturbance in Earth’s magnetic field does not indicate that it’s about to reverse polarity, contrary to what some experts have recently suggested. Over the past few months, several scientists have expressed concern about magnetic field weirdness happening in Earth’s magnetic field above the region between Chile and Zimbabwe — referred to as the South Atlantic Anomaly — speculating that it might lead Earth’s magnetic field to reverse entirely. But by examining past historical periods when magnetic conditions were similar to those today, the new study’s authors show the South Atlantic Anomaly most likely won’t result in an excursion — a partial pole change that’s usually accompanied by a reduction in field strength — or even a full reversal. Phew!

Researchers say magnetic field anomalies, like the one occurring over Africa right now, happened in the distant past but didn't turn into full reversals or excursions.

Brown et al/ PNAS

In these scenarios, over the past tens of thousands of years, they explain, anomalies like we’re seeing now usually resolved on their own, without major consequences. Sure, what’s happening now may seem unusual on the scale of centuries, but on the scale of millennia, they seem less strange. To reach this relieving conclusion, the authors examined other periods throughout Earth’s geological history in which similar weakening of the magnetic field showed up. In a couple notable instances, centered at 49 thousand years ago and 46 thousand years ago, anomalies appeared in Earth’s magnetic field, but they eventually resolved. The researchers say that our current conditions are close enough to these historical situations that we can safely say this current anomaly should resolve itself in a similar way.

“This suggests that the current weakened field will also recover without an extreme event such as an excursion or reversal,” write the study’s authors. Cue a wave of relief: If either of these events actually occurred, the consequences on Earth would be significant. While we don’t fully know what would happen, both events would likely affect satellite communications, animal migration, and our level of protection from solar winds. Most noticeably, our compass needles will point to Antarctica as “north.”

Of course, these events happen over thousands of years, so we can’t yet say for sure whether they’re right. But if geological history is any indication, we’re better off worrying about other more probable causes of our demise.

Nonetheless, the South Atlantic Anomaly has caused communication issues for satellites that pass through it, so even if a reversal or excursion probably won’t kill us, we’ll need to deal in some way with the strange reality of a changing magnetic field.

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