The change of the poles of the Earth: periodicity, consequences. Earth of the future

Our planet has a magnetic field, which can be observed, for example, with a compass. It is mainly formed in the very hot molten core of the planet and probably there was a large part of the Earth's lifetime. The field is a dipole, i.e., it has one north and one south magnetic pole. In them, the compass needle will point straight down or up, respectively. It's like a magnet on the refrigerator. However, the geomagnetic field of the Earth undergoes many small changes, which makes the analogy untenable. In any case, we can say that at present there are two poles observed on the surface of the planet: one in the northern hemisphere and one in the southern hemisphere.

The inversion of the geomagnetic field is the process by which the southern magnetic pole turns into the northern magnetic pole, and the one turns to the south one. It is interesting to note that a magnetic field can sometimes be subjected to an excursion, rather than a turn. In this case, it undergoes a large decrease in its total force, that is, the force that moves the compass needle. During the tour the field does not change its direction, but is restored with the same polarity, that is, the north remains north and south south.

How often does the Earth's poles change?

As evidenced by the geological record, the magnetic field of our planet has changed the polarity many times. This can be seen from the regularities found in volcanic rocks, especially those extracted from the ocean floor. Over the past 10 million years, an average of 4 or 5 reversals in a million years. At other moments in the history of our planet, for example, during the Cretaceous period, there were longer periods of the Earth's poles changing. They can not be predicted, and they are not regular. Therefore, we can speak only about the average inversion interval.

Is the Earth's magnetic field currently unfolding? How can this be checked?

Measurements of the geomagnetic characteristics of our planet have been carried out more or less constantly since 1840. Some measurements are even dated by the 16th century, for example, in Greenwich (London). If you look at the trends in the strength of the magnetic field during this period, you can see its decline. Projecting the data forward in time yields a zero dipole moment through approximately 1500-1600 years. This is one of the reasons why some believe that the field can be in the early stages of inversion. From studies of the magnetization of minerals in ancient clay pots, it is known that at the time of Ancient Rome it was twice as strong as it is now.

Nevertheless, the current strength of the field is not particularly low in terms of its range of values over the past 50,000 years, and almost 800,000 years have passed since the last change of the poles of the Earth. In addition, taking into account what was said earlier about the excursion, and knowing the properties of mathematical models, it is far from clear whether it is possible to extrapolate observational data for 1500 years.

How fast is the pole inversion?

A complete history record of at least one reversal is missing, therefore all statements that can be made are mainly based on mathematical models and partly on limited evidence obtained from rocks that have retained the imprint of the ancient magnetic field since their formation. For example, calculations suggest that a complete change in the poles of the Earth can take from one to several thousand years. It is fast by geological standards, but slowly in the scale of human life.

What happens during a turn? What do we see on the surface of the Earth?

As already mentioned above, we have limited data on geological measurements of the laws governing the variation of the field during the inversion. Based on models calculated on supercomputers, one would expect a much more complex structure on the planet's surface, in which there is not one southern and one northern magnetic pole. The Earth expects their "wanderings" from their current position towards and through the equator. The total field strength at any point of the planet can be no more than one tenth of its value at the present time.

Danger for navigation

Without a magnetic shield, modern technologies will be more exposed to the risk of exposure to solar storms. Satellites are the most vulnerable. They are not designed to withstand solar storms in the absence of a magnetic field. So, if the GPS satellites stop working, then all the planes will be landed.

Of course, there are compasses in the aircraft as backup, but they certainly will not be accurate during the magnetic pole shift. Thus, even the very possibility of failure of GPS satellites will be enough to land aircraft - otherwise they may lose navigation during the flight.

The ships will face the same problems.

Ozone layer

It is expected that during the inversion of the Earth's magnetic field, the ozone layer will completely disappear (and will reappear after this). Large solar storms during a turn can cause depletion of the ozone layer. The number of skin cancer diseases will increase 3 times. The impact on all living beings is difficult to predict, but can also have catastrophic consequences.

The change of the Earth's magnetic poles: consequences for the power systems

In one study, massive solar storms were called the probable cause of polar inversion. In another - the cause of this event will be global warming, and it can be caused by increased activity of the Sun. During the turn of the defense, there will be no magnetic field, and if there is a solar storm, the situation will worsen even more. Life on our planet will not be affected in general, and societies that do not depend on technology will also be in perfect order. But the Earth of the future will suffer terribly if the reversal happens quickly. Electric networks will cease to function (they can be disrupted by a large solar storm, and inversion will affect much more). In the absence of electricity there will be no water supply and sewerage, gas stations will stop working, food supplies will stop. The efficiency of emergency services will be in question, and they will not be able to influence anything. Millions perish, and billions will face great difficulties. Only those who have enough food and water in advance will be able to cope with the situation.

Danger of cosmic radiation

Our geomagnetic field is responsible for blocking approximately 50% of cosmic rays. Therefore, in its absence, the level of cosmic radiation will double. Despite the fact that this will lead to an increase in mutations, it will not have lethal consequences. On the other hand, one of the possible reasons for the pole shift is an increase in solar activity. This can lead to an increase in the number of charged particles reaching our planet. In this case, the Earth of the future will be in great danger.

Will life survive on our planet?

Natural disasters, cataclysms are unlikely. The geomagnetic field is in the region of space called the magnetosphere, formed by the action of the solar wind. The magnetosphere is not deflected by all the high-energy particles that emit the Sun with the solar wind and other sources in the Galaxy. Sometimes our luminary is especially active, for example, when there are many spots on it, and it can send clouds of particles in the direction of the Earth. During such solar flares and coronal mass ejections, astronauts in near-earth orbit may need additional protection to avoid higher radiation doses. Therefore, we know that the magnetic field of our planet provides only partial, and not complete, protection against cosmic radiation. In addition, high-energy particles can even be accelerated in the magnetosphere.

On the surface of the Earth, the atmosphere acts as an additional protective layer, stopping everything except the most active solar and galactic radiation. In the absence of a magnetic field, the atmosphere will continue to absorb most of the radiation. The air sheath protects us as effectively as a layer of concrete 4 m thick.

Without consequences

Human beings and their ancestors lived on Earth for several million years, for which many inversions occurred, and there is no obvious correlation between them and the development of mankind. Similarly, the time of reversals does not coincide with the periods of extinction of species, as evidenced by geological history.

Some animals, such as pigeons and whales, use a geomagnetic field for navigation. Assuming that the turn takes several thousand years, that is, lasts for many generations of each species, then these animals can adapt well to the changing magnetic environment or develop other methods of navigation.

More technical description

The source of the magnetic field is the iron-rich liquid outer core of the Earth. It performs complex movements that are the result of convection of heat deep inside the core and the rotation of the planet. The motion of the fluid is continuous and never stops, even during a turn. It can cease only after the exhaustion of the source of energy. Heat is produced in part because of the transformation of the liquid core into a solid core located in the center of the Earth. This process takes place continuously for billions of years. In the upper part of the core, which is located 3,000 km below the level of the surface beneath the rocky mantle, the liquid can move horizontally at a speed of tens of kilometers per year. Its motion across existing lines of force produces electric currents, and they, in turn, generate a magnetic field. This process is called advection. In order to balance the growth of the field, and thereby stabilize the so-called. "Geodynamo," diffusion is necessary, in which a "leakage" of the field from the nucleus and its destruction takes place. Ultimately, the fluid flow creates a complex picture of the magnetic field on the surface of the Earth with a complex change in time.

Computer calculations

Modeling geodynamo on supercomputers demonstrated the complex nature of the field and its behavior over time. The calculations also showed an inversion of the polarity, when the poles of the Earth change. In such simulations, the strength of the main dipole weakens to 10% of the normal value (but not to zero), and existing poles can wander around the globe together with other temporal northern and southern poles.

The solid iron inner core of our planet in these models plays an important role in controlling the reversal process. Because of its solid state, it can not generate a magnetic field by advection, but any field that is formed in the liquid of the outer core can diffuse, or spread into the internal one. Advection in the outer core, it seems, regularly tries to invert. But while the field, locked in the inner core, does not diffuse at first, the real change of the magnetic poles of the Earth will not happen. Essentially, the inner core resists the diffusion of any "new" field and, perhaps, only one out of every ten attempts of such a reversal is successful.

Magnetic anomalies

It should be emphasized that, although these results are fascinating in themselves, it is not known whether they can be attributed to the real Earth. Nevertheless, we have mathematical models of the magnetic field of our planet for the last 400 years with early data based on the observations of merchant and navy sailors. Their extrapolation to the internal structure of the globe shows the growth over time of the regions of the reverse flow at the core and mantle boundary. At these points, the compass needle is oriented, in comparison with the adjacent areas, in the opposite direction - inside or out of the core. These sites with a reverse flow in the southern Atlantic Ocean are primarily responsible for weakening the main field. They are also responsible for the minimum tension, called the Brazilian magnetic anomaly, whose center is located near South America. In this region, high-energy particles can approach the Earth more closely, causing an increased radiation risk for satellites in low Earth orbit.

Much remains to be done for a better understanding of the properties of the deep structure of our planet. This is a world where the values of pressure and temperature are analogous to the parameters of the surface of the Sun, and our scientific understanding reaches its limit.