Our planet has a magnetic field, which can be seen, for example, by means of a compass. It is basically formed in a very hot molten core of the planet and probably had most of the time of existence of the Earth. A 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 the magnet on the fridge. However, the geomagnetic field of the Earth undergoes many small changes that makes the analogy untenable. In any case, we can say that currently there are two poles observed on the surface of the planet: one in the Northern hemisphere and one in the South.
The inversion of the geomagnetic field is called the process by which the magnetic South pole becomes North, and that, in turn, becomes South. It is interesting to note that the magnetic field may sometimes be exposed to trips, and not the reverse. In this case, it is undergoing a large reduction in its total forces, i.e. the force that moves a compass needle.
During the tour field does not change its direction, and recovers with the same polarity, that is, North remains North and South South.
How often is a change of the poles of the Earth?
As evidenced by the geologic record, our planet’s magnetic field has changed polarity many times. This can be seen in the patterns found in volcanic rocks, especially extracted from the bottom of the ocean. Over the last 10 million years on average was 4 or 5 reversals per million years.
In other moments of our planet’s history, for example, during the Cretaceous period, had longer periods of change of poles of Earth. It is impossible to predict, and they are regular. So we can talk only about the average amount of inversion.
Is there a magnetic field of the Earth at the present time? How to test it?
Measure the geomagnetic characteristics of our planet have been more or less continuously since 1840. Some measurements even Dating XVI century, for example, in Greenwich (London). If you look at the trends in the strength of the magnetic field during this period, we can see its decline.
Projecting data forward in time gives zero dipole moment in about 1500-1600 years. This is one of the reasons why some believe that the field may be in the early stages of the inversion. From studies of the magnetization of minerals in ancient clay pots known that in Roman times it was twice more than now.
However, the current field strength is very low from the point of view of the range of its values for last 50 000 years, and since when was the last change of the poles of the Earth, it was almost 800,000 years. In addition, taking into account the mentioned earlier on the tour, and knowing about the properties of mathematical models, it is far from clear whether it is possible to extrapolate observations for 1500 years.
How fast is the inversion of the poles?
The full record history of at least one pivot is missing, so all the claims that you can make, mainly based on mathematical models and partly on limited evidence from rocks that retain an imprint of the ancient magnetic field from the time of their formation.
For example, the calculations give reason to assume that a complete change of the poles of the Earth can take from one to several thousand years. It is fast in geological terms, but slowly in the scale of human life.
What happens during a reversal? What we see on the surface of the Earth?
As mentioned above, we have limited evidence from geological measurements about the patterns of the field change during the inversion. Based on the models on supercomputers, one would expect a much more complex structure on the surface of the planet in which there is not one South and one North magnetic pole.
The earth expects their “journey” from its current position towards the equator and through him. The total field strength at any point of the planet may be no more than one-tenth of its value at the present time.
A danger to navigation
Without magnetic shield modern technology will be more at risk from solar storms. The most vulnerable are satellites. They are not designed to withstand solar storms in the absence of magnetic field. So, if the GPS satellites stop working, then all the planes will be planted on the ground.
Of course, in aircraft as a backup tool has a compass, but they are definitely not accurate during a magnetic pole shift. Thus, even the possibility of failure of the GPS satellites would be enough to land the aircraft otherwise they may lose the navigation during the flight. The court will face the same problems.
The ozone layer
It is expected that during the inversion of the magnetic field of the Earth ozone layer will completely disappear (and reappear after that). Major solar storms during a reversal can cause the depletion of the ozone layer. The number of cases of skin cancer will increase 3 times. Impact on all living beings are difficult to predict, but also can have disastrous consequences.
The change of the magnetic poles of the Earth: implications for power systems
In one study massive solar storm was named the probable cause of the polar inversions. In the other – the culprit of this event will be global warming, but it may be caused by increased solar activity.
During the reversal the magnetic field is not sewn up to be, and if there is a solar storm, the situation will deteriorate even more. Life on our planet will not be affected overall, and companies that do not depend on technology, will also be in order. But the future of the Earth would suffer terribly if the reversal happens quickly.
The electrical network will cease to function (they may bring them down a big solar storm, and the inversion will be affected much more). Without electricity, no water supply and Sewerage, gas stations will stop working, will stop the supply of food.
The operation of emergency services will be called into question, and they will not be able to make an impact. Millions will die and billions will face great difficulties. Only those who pre-stocked with food and water, will be able to cope with the situation.
The danger of cosmic radiation
Our geomagnetic field is responsible for blocking about 50% of the cosmic rays. Therefore, in the absence of the level of cosmic radiation will double. Despite the fact that this will lead to an increase in mutations, lethal consequences it will not have. On the other hand, one of the possible causes of the pole shift is an increase in solar activity.
This can lead to an increase in the number of charged particles reaches our planet. In this case, future Earth will undergo great danger.
Will I lose the life on our planet?
Natural disasters, disasters are unlikely. The geomagnetic field is in a region of space called the magnetosphere formed by the solar wind.
The magnetosphere deflects not all high-energy particles emitted by the Sun with the solar wind and other sources in the Galaxy. Sometimes our light is particularly active, for example, when there are a lot of spots, and it can send clouds of particles towards Earth.
During these solar flares and coronal mass ejections, astronauts in earth orbit, you may need additional protection to avoid higher doses of radiation.
So we know that our planet’s magnetic field provides only a partial, but 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 that stops all but the most active solar and galactic radiation.
In the absence of magnetic field the atmosphere will continue to absorb most of the radiation. Air shell to protect us as effectively as a layer of concrete thickness of 4 m.
Human beings and their ancestors lived on Earth for several million years during which there was a lot of inversions, and there is no obvious correlation between them and development of mankind. Similarly, the time reversal does not coincide with periods of extinction, as evidenced by geological history.
Some animals, such as pigeons and whales use the geomagnetic field for navigation. Assuming that a reversal takes a few thousand years, so it lasts many generations of each species, then these animals can adapt very well to the changing magnetic environment, or develop other methods of navigation.
About magnetic field
Source of magnetic field is the iron-rich liquid outer core of the Earth. It makes a complex motion resulting from convection heat deeply inside the nucleus and rotation of the planet. The fluid flow continuously and never stops, even during reversal.
It can only be terminated after the exhaustion of the energy source. Heat is produced partly due to the conversion of a liquid nucleus in a solid located in the center of the Earth. This process takes place continuously for billions of years. At the top of the core, which is located 3000 km below the surface beneath the rocky mantle, liquid can move in the horizontal direction with a speed of tens of kilometers per year.
Its movement across the existing power lines produce 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 to stabilize the so-called “geodynamo” required diffusion, in which there is “leakage” of the field from the nucleus and its destruction.
Ultimately, the fluid flow creates a complex pattern of the magnetic field on the Earth’s surface with a complicated change in time.
Simulation of geodynamo on supercomputers demonstrated the complex nature of the field and its behavior over time. The calculations also showed inversion of the polarity when there is a change of the poles of the Earth. In these simulations the strength of the main dipole decreases to 10% of the normal value (but not zero), and the existing poles can travel around the globe together with other temporary North and South poles.
Solid iron inner core of our planet in these models plays an important role in managing the process of reversal. Because of its solid state it can’t generate magnetic field by advection, but any field that is formed in the liquid outer core may diffuse or spread in the internal. Advection in the outer core seems to be regularly trying to invert.
But while the field is trapped in the inner core, diffuses not at first, real change of the Earth’s magnetic poles will not occur. In essence, the inner core resists diffusion of any “new” fields, and perhaps only one out of every ten attempts is a reversal successful.
It should be emphasized that, although these results are exciting in themselves, it is unknown whether they can be attributed to the real Earth. However, we have a mathematical model of the magnetic field of our planet over the past 400 years, with early data based on observations of sailors of merchant and naval fleet.
Extrapolation on the internal structure of the globe shows the growth over time of areas of reverse flow in the core and mantle. At these points the compass needle is oriented, in comparison with the surrounding regions, in the opposite direction – into or out of the nucleus.
These sites with a return flow in the southern part of the Atlantic ocean primarily responsible for the weakening of the main field. They are also responsible for the minimum voltage, called Brazilian magnetic anomaly, the center of which is located under South America.
In this region of the particles with high energies can approach the Earth more closely, causing increased radiation risk for satellites in low earth orbit. Much remains to be done to understand the properties of the deep structure of our planet.
It is a world where the values of pressure and temperature similar to the parameters of the surface of the Sun, and our scientific understanding reaches its limit.