The magnetic field of the Earth is like a shield of protection that saves the atmosphere and life on Earth from the bombardment of hazardous charged particles from space. However, the strength of the magnetic field is not constant and is subject to change that will be accompanied by many consequences.
Studies have documented that the Earth's magnetic field changes direction and the reversal happens every several hundred thousand years. The process is often preceded by a drastic weakening of the geomagnetic field.
Some of the trends are pointing to the fact that a reversal of Earth's magnetic field is due.
The prime signal of it is the depletion of the magnetic field at the rate of 5 percent a century. This is considered a forerunner to the reversal of the magnetic poles, and the consequences will include a breakdown of communication systems and heavy damage to energy infrastructure and electricity transmission systems.
South Atlantic Anomaly
So, it is reasonable to assume that the reversal of the geomagnetic field can happen in the next 2,000 years. However, an exact date for the reversal in geomagnetic field is too hard to predict.
Over the years, the magnetic power of the Earth has been declining at an alarming rate, especially in the last 160 years. This weakening has been explicit in a vast area in the Southern Hemisphere between Zimbabwe and Chile and known as the South Atlantic Anomaly.
Data from observatories show that an unusual feature of reversed polarity beneath southern Africa exists at the core-mantle boundary where the liquid iron in the outer core overlaps with the relatively hard part of the Earth's interior.
The geomagnetic field is generated by the flow of molten iron in the liquid outer core of Earth. In the South Atlantic Anomaly, the magnetic field is weak and satellites orbiting the region are vulnerable as protection against radiation is too low and satellite electronics are exposed to radiation risk.
At this part, there is a reversal of polarity vis-a-vis the average global magnetic field. According to experts, this patch is the main contributor to the South Atlantic Anomaly, with simulations having shown that such patches like the one below Southern Africa do appear preceding geomagnetic reversals.
The last magnetic reversal, called Brunhes-Matuyama, happened 780,000 years ago, while a temporary reversal took place 40,000 years back. The latter lasted less than 1,000 years and the change in polarity lasted for 250 years.
The consequence of a changing magnetic field will be the influx of high radiation from outer space. There is the example of how solar radiations have ripped out the atmosphere of Mars and left the planet inhabitable.
Increased radiation from a weakened magnetic field will endanger satellites, aviation systems, and electrical infrastructure as floodgates of charged particles to Earth will be opened.
Geomagnetic storms triggered by the interaction of large loads of solar energy with the Earth's magnetic field will be another consequence.
The pole reversal will also shift out the latitudes of the northern lights to other latitudes. This is because a weakening magnetic field lets in more radiation to reach the planet's surface. Intensified solar radiation will also increase cancer rates.
A recent instance of a small scale geomagnetic storm was the Halloween storm in Sweden in 2003, where the local electricity grid went bust and flights changed routes to avoid a communication blackout and dodge radiation risk. Disruption of satellites and communication systems were also reported.
A larger-scale electromagnetic storm as in the 1859 Carrington event even pushed the aurorae lighting to the distant Caribbean.