Whenever there’s any talk about (hypothetical) dramatic changes in Earth’s equilibrium, especially from a geological standpoint, such as how would Earth fare without oxygen for only 5 seconds, what if the core cooled down, or if the planet stopped rotating altogether, more often than not, the end result would usually come out as some sort of terrible apocalypse.
Well, here we are again, talking about yet another geological change in terms of Earth’s magnetic field: what would happen in the event of Earth’s magnetic field reversing, such as if the North pole and South pole flipped? Let’s see what would happen.
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Could such a reversal even occur in the first place?
Yes, it definitely could! As it turns out, Earth has already experienced a number of ‘pole reversals’ in the past.
Yes, geological records show that there have been hundreds of pole reversals since Earth was first formed. It turns out that Earth’s magnetic field has shifted between periods of ‘reverse polarity’ (when the direction of the field was opposite to what it is now) and ‘normal polarity’ (when the direction of the field was the same as it is now). Such periods in the geological history of Earth are called ‘chrons’.
And yes, the reversal of Earth’s magnetic poles can still occur. In fact, pole reversals naturally occur every 450,000 years or so, on average. The last reversal occurred around 780,000 years ago during the Stone Age, when man was still learning a thing or two about making fire.
The process, spread out over millions of years, does change the polarity of Earth’s magnetic field. Given that the magnetic field of the planet originates from the core, the process of field reversal also originates there. It starts when patches of iron atoms become aligned in opposite directions. When the number of such reverse-aligned atoms gets too high, they dominate the core, causing the overall magnetic field of the planet to reverse.
What if the magnetic poles actually flipped?
According to Jean-Pierre Valet, who conducts research on geomagnetic reversals at the Institute of Earth Physics in Paris, the most dramatic impact of a magnetic pole reversal would be seen in the form of a diminished magnetic field of the planet. When the field is undergoing a reversal, essentially assuming the opposite polarity, it takes a certain amount of time to completely realign in the opposite direction. As with any geological process, the reversal of our planet’s magnetic field is not an immediate shift, but rather a slow, gradual event.
It’s during this transition that the magnetic field would be the weakest and would therefore be the toughest for Earth’s inhabitants to bear.
Effects on Earth
Earth’s strong magnetic field shields the planet from powerful, harmful radiation, such as Coronal Mass Ejections, or CMEs, which occur from time to time on the Sun and sometimes race directly towards our planet. We would be far more vulnerable to such emissions if we lacked a strong magnetic field.
Multiple holes in the ozone layer would form rapidly in Earth’s atmosphere as highly charged particles released from the Sun during these solar flares would bombard the planet. These holes, although not permanent, would dramatically increase the likelihood of diseases caused by harmful solar radiation, such as skin cancer.
Species that rely on magnetic fields for navigation, including whales, migratory birds, turtles and bees, would be dealt a serious blow during such a reversal.
What About Human Extinction?
Although many unwanted and unexpected effects may result from geomagnetic reversal, it’s unlikely that it would cause a global apocalypse. According to Monika Korte, the scientific director of the Niemegk Geomagnetic Observatory at GFZ Potsdam in Germany, “Even if the field becomes very weak, at the Earth’s surface, we are shielded from radiation by the atmosphere. Similarly as we cannot see or feel the presence of the geomagnetic field now, we most likely would not notice any significant change from a reversal.”
Geophysicists all over the world have begun to observe a downward trend in the strength of Earth’s magnetic field, indicating that we may already be in the early stages of our next reversal! All the causes and effects pertaining to geomagnetic reversal hypothesized by researchers are, at the end of the day, hypotheses. As of now, we don’t really know for sure what would prevent a field reversal or protect us from any of its ill effects. In other words, go ahead and make your plans for sea voyages without the fear of your compass needle suddenly pointing towards Antarctica.