Don’t start running around like your hair’s on fire, but this might actually matter. The Earth’s magnetic field is so discombobulated over South Africa that some scientists believe we’re seeing the opening strains of a planet-wide polarity change.
What have scientists observed?
We already knew that the poles of the Earth’s magnetic field sometimes reverse, which is to say their direction flips from herding particles in to shooing them out, or vice versa. And the Earth’s magnetic field isn’t perfectly even, either. It’s sort of lumpy and thin in places. This is because the innards of our planet aren’t perfectly evenly distributed. There’s one particular region of the planet, toward the South Pole, where the liquid iron core meets with a hot, dense patch of the mantle. Studies of the planet’s magnetic field show that its poles are reversed over that patch.
Above it, that ferromagnetic weirdness results in an overlapping region of weirdness in the planet’s magnetic field called the South Atlantic Anomaly. The protective Van Allen belts there get really weird; they fade in intensity, and they dip way down close to the surface.
That region poses an annoying, but well understood problem for space travel and satellites. Hubble doesn’t take observations when it’s orbiting above the Anomaly. There’s a report that in 2012, SpaceX’s Dragon spacecraft experienced magnetic interference from the Anomaly and had to reboot systems as a result. The Anomaly may even be responsible for how Hitomi spun itself apart.
Why is all this happening? What’s perturbing the magnetic field? The core is liquid, it’s moving inside the planet, and it changes the contours of the magnetosphere along with it. Earth’s magnetic field has been weakening sharply over the last 160 years, right over the South Atlantic Anomaly.
Evidence from fired clay from Bantu-speaking civilizations some 5,000 years ago tells us that the planet’s magnetic field was acting just like this, right there over South Africa, back then. Modeling tells us that this magnetic behavior preceded a planetary-scale flip in geomagnetic alignment that would have resulted in extreme electromagnetic strangeness on the surface. Basically, the Anomaly got big enough that it took over, and flipped the entire planet’s poles inside out.
NASA’s simulation of what Earth’s magnetic fields might look like during a geomagnetic reversal. Yikes.
What does a geomagnetic pole reversal mean for us?
This isn’t going to be one of those end-of-the-world articles. That said, if the poles do flip, we could be in for some electromagnetically interesting times. Magnetic fields deflect electrons, which would change how electricity behaves on a subtle level. The inconsistencies in the planet’s magnetosphere could kneecap satellite observations and act like a poltergeist in computerized systems.
“Such a major change would affect our navigation systems,” according to two geophysicists from the University of Rochester, “as well as the transmission of electricity. The spectacle of the northern lights might appear at different latitudes. And because more radiation would reach Earth’s surface under very low field strengths during a global reversal, it also might affect rates of cancer.”
Tin foil is electrically conductive, though, so make sure you keep your head well grounded. If you shape the foil right, it’ll act like a Faraday cage around your skull and keep the polarity switch from frying your brain.