Around 800,000 years ago, if you had been navigating via compass your compass’ point would have aimed at Antarctica rather than the Arctic. That may sound like an insane phenomenon to experience, but pole reversals have happened many times over our planet’s history.

Many a’ doomsday prepper have suggested that a pole reversal is the signaling of the end of days. However, pole reversals are the norm and scientists estimate reversals have happened at least hundreds of times over the last 3 billion years.

What Causes a Reversal?

Researchers from the CNRS and Institut de Physique du Globe in France have been able to link the frequency of reversals to tectonic plates scattered around the globe. While the reversal itself takes place within our earth’s liquid core, it is still sensitive to what is happening on the surface or within in Earth’s mantle.

Our planet’s magnetic field is created from the flow of liquid iron deep within the core. A reversal of the magnetic field occurs whenever that liquid iron is not symmetrical with the equatorial plane. This breaking of the symmetry doesn’t happen overnight, typically starting in one area located at the boundary between the core and mantle.

After a thorough study of the surface area of those continents that previously made up the supercontinent of Pangea, researchers were able to determine that the degree of asymmetry in the molten metal varies at the same rhythm as the magnetic reversal rate.

What Happens When Our Magnetic Field Reverses?

Since we’ve had numerous magnetic reversals over the course of our planet’s history, it’s clear it doesn’t signify the end of the world. The small patches of reverse-alignment will grow and grow until they dominate the rest of the core causing an entire magnetic field flip. The most dramatic change that goes along with a pole reversal is the large decrease in total field intensity. The change isn’t sudden, happening gradually so there is never a time when the field isn’t strong enough to keep doing its job. However, with the field weakened, coronal mass ejections released by the sun are more likely to get through the earth’s shield creating holes in our ozone layer. While life on earth won’t cease to exist during a pole reversal, it may get more difficult for a while.

For the past 160 years, the strength of our magnetic field has been decreasing at a rate faster than usual. The last magnetic pole reversal was around 780,000 years ago so we’re well overdue!

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