It is known that the Earth’s magnetic poles are unstable, which is due to the internal dynamo of the planet – the heterogeneity of the core and its asymmetry. Once every 300 thousand years, the poles even change places. But sometimes strange things happen, like 41 thousand years ago, when the poles begin to change very quickly – over the course of centuries. It’s bad that the magnetic field, weakening during such periods, begins to transmit cosmic rays and hard solar radiation – this does not end well.
Image source: European Space Agency
Chinese scientists reported their conclusions on observations of the dynamics of the planet’s magnetic poles in recent years. They cannot yet name the reason for the rapid drift of the magnetic poles, but they are firmly convinced that the magnetic field over the Western Hemisphere is rapidly weakening, and over the Eastern Hemisphere it is strengthening.
The turning point has occurred within the last 30 years. Using the latest models and data, scientists have reconstructed global changes in magnetic field strength since 1900. They found that from 1930 to 1990, magnetic field strength over North America increased and was higher than many other regions of the world. However, by 2020, magnetic field strength over the Western Hemisphere had fallen to a level barely above the global average. And if earlier the north magnetic pole shifted at a speed of 10 km per year, then after 2020 the rate of displacement increased almost seven times.
The constancy and strength of the planet’s magnetic field serves as a screen for high-energy particles from space and the Sun. The field also protects against solar plasma emissions when they are directed towards the Earth. The planet’s magnetic field formed two radiation belts of such particles, called Van Allen belts.
During a rapid polar reversal 41 thousand years ago, called the Laschamp event, the magnetic field strength dropped to 6% of its nominal value, resulting in the bombardment of the Earth’s surface with high-energy particles from space. It cannot be ruled out that the polar drift observed in recent years could lead to something similar. Our knowledge of the structure of the Earth is not complete enough to predict such phenomena.