The chaotic source of our magnetic field
There has been increased attention on the Earth’s magnetic field in recent years. Scientists have noticed for some time that this protective barrier, which shields the planet from being roasted by cosmic radiation, is less reliable than we might hope. The field itself is generated by iron and other metals circulating deep in the Earth’s core. A doctor friend once described the beating heart as a chaotic, thrashing movement far removed from the peaceful thumps we take it to be. The planet’s core is similar. Iron and other metals are constantly moving as the intense heat and pressure at those depths work them like dough. As these metals move differently, the magnetic fields that they emit change accordingly. This can lead to weak spots in the field.
Scientists have also realized through sample dating that every 250,000 years or so, the polarity of the field flips entirely. We are long overdue for the next polar flip- it’s been over 700,000 years since Antarctica was at the North pole. There is a lot of hype about what exactly a flip in the magnetic field would mean, however. Spurred by the release of some new research on the inner workings of the core itself, I decided it was time to dig deep into what influences our magnetic field and what that means for us surface dwellers.
Weak spots – should we be afraid?
A large area of the magnetic field is currently weak enough to worry scientists. Known as the South Atlantic Anomaly(SAA), this weak spot lets through enough cosmic radiation to damage satellites that pass through unprepared. The SAA has been under increased scrutiny by the scientific community in an attempt to study the forces behind it. A recent study of archaeological objects from inside the weak spot has helped show that the core is greatly influenced by the layer of rocks surrounding it, and has been for quite some time. Scientists were able to gather burned clay fragments which included clues to the magnetic field at that time. These showed that the magnetic weak spot has re-occurred throughout history in the same spot. It seems that the SAA is not a new phenomenon, and is at least partly due to the influence of gigantic lumps of metal and rock lying very near the core in the area. Scientists believe that these huge structures, called superplumes, change the flow of metals in the core and can lead to molten iron and nickel leaking out into the surrounding rock. This leaking is thought to be one main component to the current weak spots in the magnetic field, and perhaps to the field flipping as well. An important question is what exactly will happen when it does so.
A flip might not be apocalyptic
As far as scientists can tell, the polarity of the magnetic field flipping would not be the apocalyptic event some would fear. The flip instead would take perhaps thousands of years. During that time our field will be weaker, which will allow more cosmic rays to enter our atmosphere than before. This should only be a hazard to satellites and other sensitive electronic equipment, which have delicate electrical components that are particularly sensitive. We may also need to wear more sunscreen as more solar radiation is let through. Once the field is flipped, a compass will show what is currently North as South, and all animals that rely on their magnetic sense of direction for migrations will certainly be very confused for a few years. There is no evidence that points to mass extinctions during any of the previous flips. Nature will certainly adapt quickly, leaving us to the task of replacing a lot of burnt out electronics.