[Undark] One day in 1905, the French geophysicist Bernard Brunhes brought back to his lab some rocks he’d unearthed from a freshly cut road near the village of Pont Farin. When he analyzed their magnetic properties, he was astonished at what they showed: Millions of years ago, the Earth’s magnetic poles had been on the opposite sides of the planet. North was south and south was north. The discovery spoke of planetary anarchy. Scientists had no way to explain it.
Today, we know that the poles have changed places hundreds of times,
most recently 780,000 years ago. (Sometimes, the poles try to reverse
positions but then snap back into place, in what is called an excursion.
The last time was about 40,000 years ago.) We also know that when they
flip next time, the consequences for the electrical and electronic
infrastructure that runs modern civilization will be dire. The question
is when that will happen.
In the past few decades, geophysicists have tried to answer that
question through satellite imagery and math. They have figured out how
to peer deep inside the Earth, to the edge of the molten, metallic core
where the magnetic field is continually being generated. It turns out
that the dipole — the orderly two-pole magnetic field our compasses
respond to — is under attack from within.
The latest satellite data, from the European Space Agency’s Swarm trio,
which began reporting in 2014, show that a battle is raging at the edge
of the core. Like factions planning a coup, swirling clusters of molten
iron and nickel are gathering strength and draining energy from the
dipole. The north magnetic pole is on the run, a sign of enhanced
turbulence and unpredictability. A cabal in the Southern Hemisphere has
already gained the upper hand over about a fifth of the Earth’s surface.
A revolution is shaping up.
If these magnetic blocs gain enough strength and weaken the dipole
even more, they will force the north and south poles to switch places as
they strive to regain supremacy. Scientists can’t say for sure that is
happening now — the dipole could beat back the interlopers. But they can
say that the phenomenon is intensifying and that they can’t rule out
the possibility that a reversal is beginning.. It’s time to wake up to the dangers and start preparing.