Earth's Magnetic Field Fully Flips Fast?
Exciting and scary news about earth’s magnetic field. The latest research shows that our north and south magnetic poles could reverse not only in the near future but in as little as one human lifetime.
Imagine as a kid your compass app points to the north as it should but then for most of your life it doesn’t seem to know where to point anymore. Sometimes south, then west, then north-east. Finally at the end of your life your compass finally and permanently points to the south as it will for many hundreds of thousands of years.
This scenario could happen according to the latest research published in the November issue of Geophysical Journal International. The idea of Geomagnetic pole-reversal has been bandied about for many years and with good reason. Certain minerals in the past that were laid down as sediment for example (or became rock) align with the earths magnetic field. Their orientation becomes frozen revealing unquestionably that the magnetic field of the earth flips from time to time. The history of this happening is not as regular as you might think occurring anywhere between 100,000 and 1 million years. These periods are called chrons and the last major one happened 780,000 years ago. There was actually a brief complete reversal 41,000 years ago called the Laschamp Event. The entire process took only about 440 years during which our magnetic field strength was a fraction of what it is now. Despite this anomaly, complete reversals were generally thought to take 1 to 10 thousand years to complete during which time our field weakens and is erratic before fully reversing.
Now however, it seems this might be wrong.
Our wonderful force-field around the earth is generated by the core of the planet. The core is composed mostly of iron and is hellishly hot at 5,700 C (as hot as the surface of the sun). Despite this heat, densities are so high that the inner core is a solid instead of a liquid. The outer core however is less dense to such a degree that it is mostly a liquid. The heat from the inner core causes convection currents to flow between the cores which is swirled around due to the coriolis force induced by the earth’s rotation. This flowing iron generates electric currents which then cause magnetic fields to be created. This process creates more electric fields which, in turn, create more magnetic fields and so on in a self-sustaining process. This is our geodynamo which is responsible for our protective magnetosphere.
Researchers looking at alternating sediment and volcanic ash layers in the Sulmona basin near Rome were afforded a high resolution look recently when they dated the sediments using an argon-argon dating method. During the pole reversal 780,000 years ago, ash was being laid down during frequent volcanic eruptions which blanketed the basin with the ash. Looking at their frozen positions and comparing their ages though revealed that they went from a reversed state to the north/south orientation of today in as little as 100 years.
Co-author of the study, Paul Renne said:
“What’s incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years… We don’t know whether the next reversal will occur as suddenly as this one did, but we also don’t know that it won’t.”
So when will they flip again? Well, recent indications point to this happening sooner than we previously thought because our magnetic filed is actually weakening 10 times faster than earlier calculations suggested. Current estimates put it at within 3,000 years. When the reversal really gets going we expect to see a very dramatic weakening of the field with the magnetic north and south poles shifting all over the place until it finally settles down and re-strengthens again.
You’re probably wondering about how bad this could be for us. No evidence has been found that pole reversals are catastrophic to life. They happen frequently enough that if they were inimical to life, we’d surely have noticed that in the fossil record and most likely we wouldn’t even be here to notice it. Still, living through this wouldn’t necessarily be a walk in the park. Our electrical grid could suffer non-trivial damage as currents are induced in the wires similar to what we’d see if a coronal mass ejection hit the earth. A weakened and erratic magnetosphere would also allow the solar wind and cosmic rays to cause a rise in cancer rates. This problem could be greatly exacerbated if the transition time between chrons is more lengthy.
There is a bright side to all this luckily. Updating our compass apps will be easy. Plus, chances are, when this occurs we will have the technology at our disposal to minimize the negative effects of a pole reversal. Even better, with a disrupted magnetic field, you won’t have to live in the north or south to see beautiful auroras.
Image Credit: Nasa