Astonishing as it may seem, the earth’s magnetic poles do flip. Studies have proved that the magnetic poles of the earth appeared some 3,450,000,000 years ago. Over time, the intensity on both poles gets weaker and weaker. Consequently, flipping takes place. This change in a planet’s magnetic field such that the positions of the north pole and south pole interchange themselves is called as ‘geomagnetic reversal’. Till date there have been hundreds of such reversals; it is a constant process. On an average, there is a gap of a million years between two reversals. In the last 20 million years, the earth has developed a tendency to changes its magnetic polarity every 200,000 to 300,000. However, it has been very long since the last flip of earth’s magnetic poles has happened. The last flipping of earth’s magnetic poles took place some 800,000 years ago, hence, it is a universal truth that the flipping is going to take place again. Many scientists suggest that the next reversal will occur in the next few thousand years while others believe that the pole reversal will occur certainly within the next 1,500 years.
Why Does Earth’s Magnetic Poles Flip?
Early in the 20th century, scientists observed that some volcanic rocks were magnetized opposite to the direction of the local Earth’s field. This was the first event when the phenomenon of the earth’s magnetic pole reversal was discovered. The credit of estimating the timing of magnetic reversal for the first time goes to a Japanese geophysicist Motonori Matuyama in 1920. He observed that rocks with reversed fields were all of early Ice Age (2,588,000 to 11,700 years ago) or older.
Once that the earth’s magnetic behavior had been fully understood by scientists, it was concluded that the fundamental reason for the reversal of earth’s magnetic poles is the change in the fluid portion of the iron core in the earth.
More specifically, earth’s magnetic poles flip because the iron atoms in the liquid core of the earth reverse their alignment (like infinitesimal magnets) due to the fluid rotation in the earth’s core. The period of this field reversal (to complete) depends upon the rotation rate and its electrical conductivity.
The Most Recent Flipping of Earth’s Magnetic Poles
As we have already mentioned above, the last recent filliping of the magnetic poles dates back to some 786,000 years ago. This was named Brunhes-Matuyama event. However, the pole reversal is not a sudden event. It’s not like it is just another day and boom, the poles flipped! The process is pretty spontaneous and time taking; it may take up to 20,000 years for complete reversal. It took nearly 100 years to complete the process of full flipping for the last time. Thus, scientists have proposed several theories stating the presence of multiple polarities on the ends (during the transition states; sometimes also known as excursions).
At this time, the reversal rate is decreasing ten folds the natural magnetic weakening rate.
The Consequences Of Pole Reversal
First of all, it is important to make it clear that in no way pole reversal is going to be a threat to humanity (human race). There is no evidence of mass extinctions due to the flipping of earth’s magnetic field in the past years. It is quite a common myth that looks believable that the pole reversal will lead to the death of all the organisms due to the magnetic fields during (or post) this flipping.
One of the popular consequences that are believed to volunteer after the pole reversal is power-cut on the global level. Yes, the flipping of the magnetic field will weaken its shielding effect allowing heightened levels of radiation on and above the Earth’s surface. With no doubt, the absence of electricity will affect the world widely. Billions of the people across the world who use TV, Computers, GPS, or any other electric device will be compelled to through this phase. Since there will be this power cut on the global scale, the planet earth will also witness blackout.
Apart from the blackout, magnetic field transition would let the aurora borealis (also known as the “Northern Lights”) at any latitude.
Other obvious changes include the failure of a compass to detect the directions during the transient state.
A Take Home Message
Due to the rotation of fluids in the earth’s core, the alignment of patches of iron atoms gets reversed. This leads to the interchange of positions of the magnetic north pole and magnetic south pole of the earth. This reversal may occur every 200,000 years to 1,000,000 years. The most recent flip took place nearly 786,000 years ago (during the stone age), popularly known as the Brunhes-Matuyama event. Scientists have predicted the occurrence of next reversal within 1500 years. Going back in history, people started to discover the flipping of earth’s poles in the early 20th century. In 1920, a Japanese geophysicist Motonori Matuyama estimated the time elapsed in this phenomenon for the very first time. During the late 1930s, the concept of earth’s magnetism was clear to people, hence scientists proposed several theories on the earth’s pole flipping.
The pole reversal is not an overnight phenomenon. The transition state may last for a century to some 20,000 years. For example, the last pole reversal lasted for 100 years. During this transient state, there may exist multiple magnetic poles at the same time, making it difficult to judge the directions. However, pole reversals are in no way a threat to the life. There is no evidence of mass extinctions or explosions that happened during (or after) the flipping of earth’s magnetic poles. However, there are a few consequences that will come into existence during (or after) this phenomenon. According to studies, the shielding effect during this phase will lead to the power cut at a global level which will effect billions of electricity users by creating a blackout. Aurora borealis would also be witnessed due to the magnetic field transition.