The only thing that’s constant is change. We all know this. It even applies to the Earth’s magnetic poles.
Once every few centuries, the direction of the compass changes. Instead of pointing north, it points south. And this happens because the Earth’s poles switch places. But not before the Earth’s magnetic field shows signs of weakening first.
The Earth’s magnetic field is like a giant forcefield that protects our planet from harmful cosmic radiation and solar winds. The reason this field exists is the presence of iron surrounded by molten metal in the Earth’s core. As the Earth rotates and the core temperature changes, the molten metal on the outer core boils and churns, creating magnetic field lines.
For the longest time, scientists have estimated that magnetic field weakening happens at the rate of 5% every century. Based on new data, however, the rate seems to be happening much faster — at 5% per decade. This suggests that instead of the flip happening in another 2,000 years, it might be happening sooner.
When poles flip, the magnetic field won’t be gone completely; it will just be alarmingly weaker, down to around 10% of its present strength. Plus, it can also mean the temporary presence of several north and south poles existing simultaneously.
With a weakened magnetic field, the Earth will become exposed to higher and more deadly levels of radiation. If this was to happen today, satellites, aviation, and ground-based electrical infrastructure will all be at risk. Satellites orbiting our atmosphere can get damaged, disrupting all forms of communication. Flying aircraft will need to be rerouted to avoid mid-air collisions. Electric and electronic infrastructure might get shut down, leaving us without electricity and no Internet. And if by chance a powerful solar storm happens to hit us when our magnetic field is at its weakest, it can easily result in an armageddonic scenario that will destroy our technology and cost us billions.
Pole reversal can be temporary (known as an event) and incomplete (referred to as an excursion). In such case, the magnetic poles move away from the poles and move nearer (or sometimes crossover) the equator, before eventually returning to their original positions. The last temporary reversal — called the Laschamp event –happened nearly 41 millennia ago, lasting for less than 1 millennium, with the pole change lasting for about 250 years. On the other hand, the last full reversal — known as the Brunhes-Matuyama reversal — happened some 780 millennia ago.
Because humanity didn’t exist yet during the last full reversal, there’s no telling what its direct impact on us will be. Neither can we predict for sure how animal species will react. What we do know is that humans can survive through a temporary reversal; life in general can still thrive after a full reversal; but it’s uncertain if human life can survive a full reversal.
It’s bad enough that we don’t know what its effect on us might be. It’s even worse that we have yet to develop the technology that can help us predict when magnetic pole switching will happen because this will entail predicting how the Earth’s core moves.
And being buried below 3,000 kilometers of rock, it can’t be easy.
But, we’re getting there. With the recent discovery of a jet-stream within the Earth’s core, we’re proving that our ability to infer what might be happening deep beneath our planet is improving. Eventually, we’re bound to get it right. Once we reach that level then we’ll hopefully know what we’re in for.