Why do the earth's magnetic poles change places? The earth's magnetic poles are changing. Danger to navigation
The effects of a geomagnetic pole reversal may seem a little ominous, but don't worry: Scientists aren't sure when the next reversal will occur. Even if it happens, the risks will not be too high.
Observations of scientists
Scientists have discovered that large gaps have begun to form in the magnetic field, which signal that the Earth's magnetic poles will soon change places. There is an assumption that such a process will have an extremely negative impact on nature, and our planet will undergo powerful cataclysms. This conclusion was reached by Danish researchers at the Planetary Research Center. Their opinion is shared by scientists from America, France and England.
Scientific research shows that over the past centuries, the density of the Earth's magnetic field has decreased. This process emerged in 1989 in Canada. Solar winds penetrated the weak magnetic layer and caused electrical grid breakdowns. Quebec was without electricity for 9 hours.
It is believed that the magnetic field is accumulated by flows of molten iron that surround the planet's core. A Danish satellite detected a vortex in these flows that could cause a pole reversal. But scientists are confident that this will not happen in the near future.
A magnetic field
The iron-enriched outer layer of the Earth's core gradually cools, it breaks through colossal convection currents, which are also somewhat distorted by the Earth's own rotation. Thanks to a quirk of physics known as dynamo theory, this creates a powerful magnetic field between the north and south poles.
Although 99% of the magnetic energy remains in the core, the waves that travel into space generate potentially dangerous solar winds.
Magnetic poles are areas where the planet's magnetic field is vertical, causing the compass needle to point upward.
Throughout geological time, the magnetic poles have moved away. This phenomenon is known as "geomagnetic reversal." Although there are several hypotheses that try to explain this process, geophysicists are still not sure why it happens. It is obvious that the process is associated with turbulence and chaos inside the metallic outer core, but the specifics of the phenomenon have not been clarified.
Last offset
In any case, the last complete reversal occurred about 781,000 years ago. This process was named Bruns-Matuyama in honor of the discoverers. Its path can be traced through volcanic rocks, which, once formed, managed to freeze the planet's magnetic field in place. Until this point, the modern magnetic North Pole was located at the site of the South Pole, and their locations changed.
In any case, over the past 20 million years, the poles have swapped places once every 20,000-30,000 years. Mars lost most of its atmosphere when its magnetic field collapsed. However, we are not in danger.
The risks will not be high
NASA is at pains to emphasize that Earth's pole reversal is the norm, not the exception. It has always happened and will always happen. The last shift was observed 20,000 years ago.
Even if the shift is coming, it won't happen overnight. “The magnetic field data suggests that the reversal takes about 1,000 to 5,000 years or so,” Associate Professor Phil Livermore, an expert on Earth's geomagnetic region at the University of Leeds, told IFS Science.
Another problem is that the 20,000-year average has not yet been determined, and the process of pole reversal has not been observed throughout Earth's history.
Although the dipole strength is currently decreasing, it is not anomalous. Previous episodes of decay did not result in a reversal, but simply a dip in field strength over time.
“A reversal or general weakening of a planet's magnetic field does pose some potential threats, especially if it reaches only 10% of its full strength before rebounding again,” Livermore states.
However, the risks are likely not to be high. We know from the fossil record that plant and animal life has never been disrupted. NASA observed no noticeable changes in geological activity, be it seismic, volcanic or glacial. The Earth's rotation remained unchanged.
“The main concern is what could happen to our electrical infrastructure—satellites, electrical grids, etc.,” Livermore said.
The power supply will be disrupted
Satellites within the South Atlantic are a noticeable weak point in the magnetic field. It is already at high risk of damage.
What will be the consequences? Damage depends on space weather. This could lead to several large, long-lasting power outages on Earth.
However, biological life will likely remain intact. Animals that rely on magnet reception for orientation will be a little confused for a while. So don't worry. There is a lot of uncertainty in this problem, but there will certainly not be an apocalypse.
The magnetic field that the Earth has surrounds our planet like an invisible force shield. It protects living organisms from harmful solar radiation by deflecting charged particles. But the magnetic field can hardly be called stable, since it is constantly changing. Indeed, the history of our planet includes at least several hundred global reversals, when the north and south magnetic poles changed places. But when will this happen next time and how will it affect life on Earth?
During the reversal, the magnetic field will not be zero, but it will be weaker and take on a complex shape. His strength may be reduced to 10% of what it is now. In addition, several “north” and “south” poles may form, including at the equator.
On average, such geomagnetic reversals occur several times every million years. However, the interval between reversals is very irregular and can reach tens of millions of years.
Temporary and partial reversals may also occur, during which the magnetic poles move away from the geographic poles (perhaps even crossing the equator) before returning back to their original location. The last complete reversal of the poles occurred about 780,000 years ago. The temporary reversal, scientists say, took place about 41,000 years ago. This lasted less than 1000 years, and the actual polarity reversal lasted about 250 years.
Disappearance of energy
A change in the magnetic field during the reversal will weaken its protective effect, leading to increased levels of radiation on the Earth's surface and in the atmosphere. If this were to happen today, the increase in charged particles reaching Earth would lead to increased risks for satellites, aviation and ground-based electrical infrastructure. Geomagnetic storms, driven by the interaction of abnormally large amounts of solar energy with our magnetic field, give us insight into what we can expect if the magnetic shield weakens.
Consequences of geomagnetic storms
In 2003, the so-called Halloween storm caused local power outages in Sweden. In addition, flight routes had to be changed to avoid communication problems and radiation risks. The storm also led to the destruction of satellites and communication systems. But it was minor compared to other storms in the recent past, such as the 1859 Carrington event, which produced northern lights as far away as the Caribbean.
The impact of a major storm on modern electronic infrastructure is not fully understood. Of course, any time spent without electricity, heating, air conditioning, GPS or the Internet will have a big impact. Widespread power outages could cause economic disruption in the tens of billions of dollars per day.
Should we expect a mass extinction?
But what can we expect in terms of life on Earth and the direct impact of the reversal on our species? We cannot definitively predict what will happen, since modern humans had not yet emerged during the last complete reversal. Some studies have attempted to link past similar events to mass extinctions. It was assumed that some magnetic pole reversals and episodes of prolonged volcanism could be caused by a common cause. However, there is no evidence of any impending catastrophic event, and so we will likely have to contend with electromagnetic interference if the Earth's magnetic field begins to change.
We know that many animal species have some form of magnetoreception, which allows them to sense the Earth's magnetic field. They can use this feature to navigate between continents during migration. But it's unclear what impact the pole reversal might have on such species. It is clear that early humans did manage to survive a partial reversal event, and life on Earth as a whole has survived hundreds of complete similar events, as confirmed by the geological record.
Can we predict geomagnetic reversals?
The simple fact that the Earth's magnetic field is currently decreasing in size (by 5% per century) has led to proposals that it may change within the next 2000 years. But it will be difficult to give an exact date, at least for now.
The Earth's magnetic field is generated inside the liquid core of our planet. Just like the atmosphere and oceans, the path it takes is governed by the laws of physics. So in theory we can predict "core weather" by tracking this movement, just as we predict real-world weather by looking at the atmosphere and ocean. A pole reversal can be compared to a certain type of storm in the core, where the dynamics - and magnetic field - begin to go haywire (at least briefly) before returning to normal again.
Difficulties in forecasting
The difficulties of predicting the weather several days in advance are widely known, despite the fact that we live inside the atmosphere and directly observe it. Predicting how the Earth's core will behave is even more difficult, mainly because it is buried 3,000 km below the Earth's crust. Thus, our observations are scarce and indirect. However, we cannot say that we are completely blind: scientists know the main components of the material inside the core, and also that it is in a liquid state. A global network of ground-based observatories and orbiting satellites can also measure how the magnetic field changes, giving us insight into the movement of the liquid core.
The recent discovery of the jet stream within the core core highlights our evolving ingenuity and increasing ability to measure and study core dynamics. Combined with numerical modeling and laboratory experiments to study fluid dynamics in the planet's interior, our understanding is advancing at a rapid pace. The prospect of predicting changes in the Earth's core may be within reach.
Studies have shown that one side of the Blue Planet is rapidly growing, while the other is slowly melting. This conclusion was reached by a team of scientists consisting of Reno Degen and Peter Olson. They used numerical modeling, which determined that the axis of the Earth's magnetic field is in the first hemisphere. By the way, the next step will be taken in the near future. Most likely, the Earth is trying to swap south and north. However, scientists prefer to wait a little and only then answer this question.
But soon researchers will be able to find out why the magnetic field periodically changes its direction. As a rule, this happens once every few thousand years. By the way, in the event of such a turn of events, the power grids will lose their power, because the solar wind will be open to various communication systems. Already in 2003, the French knew that the poles might change places. Then everyone argued: compasses would stop working, and we would also not be able to move with the help of airplanes or control ships on the high seas.
In those years, Alexey Didenko, who is the director of the Institute of Physics, commented on this situation. According to him, the movement of the magnetic pole has become faster due to changes in the “internal engine” of the Blue Planet. According to the scientist, such actions lead to the generation of electric current, which appears in the so-called motors. Subsequently, their movements begin to shift, and the magnetic poles change their locations accordingly. Once every 250 thousand years, such motors show excessive activity. At the moment, this is exactly what we are seeing.
As a rule, after a pole shift, global cataclysms occur as geomagnetic protection is damaged. They are accompanied by saturation of solar radiation and other radiation from space. What are the consequences of this? First of all, the ozone layer becomes thinner, and the climate becomes increasingly humid. While the poles do not change their place, the weather also remains the same. This turn of events greatly affects the operation of flying vehicles. Although during the development of modern passenger aircraft models this factor is taken into account. This increases the level of security. If you are afraid to fly, then at least do it in the virtual world.
Reforms in the magnetic environment are manifested by anomalous natural phenomena, in particular heavy rains and cold weather. According to French scientists, the entire process will be completed after several decades. Although some talk about thousands of years. Such disagreements are not accidental, since magnetic poles are unpredictable. If they do change places, they might disappear altogether. The Danes say that this has already happened with the celestial bodies of the solar system. For example, on Mars the atmosphere evaporated after such incidents.
Rock samples taken in areas very distant from each other, which were close in age, showed the same, but “reverse”, current polarity. When such rocks were dated, it turned out that over the past five million years the Earth’s magnetic poles have changed places at least twenty-five times, that is, on average every two hundred thousand years! But this is only on average. The last such case was as much as 730 thousand years ago. It turns out that the planet has violated its schedule, and, apparently, a new reversal of the Earth’s magnetic field can now be expected very soon.
It must be said that such an event entails considerable consequences. This is not just a matter of tourists, who can get lost if they trust a compass that has betrayed them. What will happen to the magnetic orientation and guidance systems of, say, sea, air, and space ships? And in biology: in recent years it has been discovered that birds, fish, insects, bacteria orient themselves along the magnetic force lines of the Earth...
What about the climate of the planet? In normal times, charged particles emitted by the Sun generally do not reach the earth's surface; they are held hundreds of thousands of kilometers away by the Earth's invisible magnetic shield. Many of them, entering our magnetosphere, are captured by its lines of force and wander along them from one pole to the other and back. If, in preparation for the reversal of the poles, the magnetic field temporarily weakens, charged particles will be able to pierce its shield, burst into the upper atmosphere and become condensation nuclei for ice crystals there. An unprecedented mass of snow and rain clouds will appear, carrying excess moisture and cold.
Scientists have been thinking about terrestrial magnetism for a long time. An important step in his research was made by Carl Friedrich Gauss, a great theorist and experimenter at the same time. In the thirties of the last century, he sent magnetometers of his own design to many travelers and asked them to take measurements everywhere. Having collected the information, he used mathematical analysis to come to the conclusion: the Earth must have not one, but many dipoles (that is, a body having two magnetic poles) - one main one, crossing the entire planet, and several smaller ones, each of which extends from its core to one or another area on the surface.
Only in our days, when satellites equipped with magnetometers roam the near-Earth space, have we become fully convinced to what extent “Charlemagne” of physics was right. Indeed, about ninety percent of the strength and direction of the Earth’s magnetic field depends, as it were, on a giant magnetic bar lying along the axis of rotation of the planet. The rest is made up of smaller fields surrounding six to eight small similar magnets, which, instead of pointing towards the pole, point to various areas of Mongolia, Western Europe, Central Canada, Central Africa, the South Indian Ocean, the South Atlantic...
Neither one nor the other, however, are simply magnets. Now most geophysicists believe that all of the Earth's magnetic fields are generated by the movement of molten masses of iron in the planet's core, where the temperature is highest. Streams of liquid iron rise from the depths of the earth to the surface; approaching the earth's crust from below, they cool down and begin to sink, forming craters with a diameter of about a hundred or two kilometers.
According to the most common hypothesis among geophysicists, these funnels generate powerful magnetic fields. In this case, theorists proceed from the assumption: the inner region of the planet at one time received a dose of magnetic properties from an external source: from the Sun or from some other celestial body. Further, molten iron, like any electrical conductor, moving in a magnetic field, generates electricity, which amplifies this field, which in turn amplifies electricity, and so on. This principle is used, for example, to build a small dynamo driven by a wheel and providing current to a bicycle headlight. Hence the name - “dynamo theory of terrestrial magnetism”.
Despite its apparent simplicity, the dynamo theory does not answer all questions with equal confidence. For example, how is it that so many funnels of molten iron (according to some estimates, there can be up to fifty of them!), each rotating in its own direction, can create magnetic fields, overwhelmingly pointing in one direction - roughly speaking, parallel to the North-South axis ?
There is a widespread opinion among geophysicists that the very rotation of the planet brings order to the entire system of curved streams of molten iron involved in the funnels. It is not for nothing that the apical part of such flows - their arched stream passing under the very surface of the Earth - usually has the direction North - South, and not West - East. If it were not for the rotation of the Earth, there would not be a predominant direction, but would be random. And the magnetic field obediently follows the instructions of the iron jet.
However, it is impossible to completely get rid of the influence of random forces. The Earth's dipole usually does not exactly coincide with the planet's rotation axis, but seems to circle around it. The tip of the dipole results in moving across the Earth's surface at a speed of about eight kilometers per year. Sometimes its direction can coincide with the axis of rotation, sometimes it deviates from it by ten to fifteen degrees. Now, for several decades now, the difference between them is approximately eleven degrees.
Paleomagnetologists have noticed: in fragments of ancient pottery, in sedimentary geological rocks that are more than ten thousand years old, the total deviations of the dipole axis from the axis of rotation are reduced to zero. And yet this does not explain why the geomagnetic field should suddenly not just oscillate slightly around the poles, but change its direction by 180 degrees. A completely different answer was required here. It obviously lies in the nature of the behavior of the iron craters of the earth's interior. If the top layer of a given funnel flows mainly to the North, then the magnetic field formed by it points to the North, and if the top of the funnel moves in a southerly direction, then its field also points to the South. The general direction of the magnetic field of the entire Earth as a whole simply depends on what the majority of funnels “vote” for at a given time.
This very democratic model reassures us that before the Earth's magnetic poles decide to switch places, nature will give us advance warning. The planet’s magnetic field will first weaken for a long time, and only then “turn inside out.” And since such a steady weakening of the strength of the geomagnetic field, which usually takes at least two thousand years, has not yet been observed, experts say with certain confidence that at least until 3986 we can safely trust the planet’s magnetic shield.
The north will become south, the south will become north, and all life on the planet will die - such a terrible picture is painted by American scientists. Russian experts do not agree with them
ALARMING CASTLING
American experts from Johns Hopkins University (USA) recently gave a scare: a change of magnetic poles is coming. They made this conclusion after they found out that chaotic processes occur in the earth’s core. One side of the solid inner core (the other part of the core is the outer and liquid - Ed.) of the Earth is slowly growing, while the other is slowly melting.
Such lopsided growth of the earth's core could provoke a rapid shift of the magnetic north pole to the east, and as a result, north and south will switch places, predicts study author Peter Olson. - The movement of magnetic fields has also been confirmed by satellite data. I don’t know when a planetary cataclysm will occur. Chaos in the core makes it difficult to make long-term forecasts.
But his colleagues from other countries are more categorical. Danish scientists from the Copenhagen Research Institute of Space claim that a polarity reversal will occur in 40 years. And employees of the Parisian Earth Institute are convinced that in 100. And they paint pictures of a real apocalypse.
Here are the “smallest” troubles that this castling brings: navigation and electronic equipment will fail, and birds and fish will be lost in space.
And the worst thing is that the climate will change. The ozone layer will thin or disappear completely. A stream of solar radiation, usually deflected by a magnetic “shield,” will fall on the planet from space. And the weather will become unpredictable. Winters will become harsher, summers will become drier. Heavy rains and floods will create the threat of a global flood. Earthquakes change the face of the planet. Our whole life will be at risk.
Judging by the fossil remains of animals and plants over the past 540 million years, during polar reversals, sharp leaps in the evolution of the biosphere occur, and most living organisms die, says Renaud Degen from Johns Hopkins University (USA). - It is possible that it was as a result of such castling that the dinosaurs died.
Fantastic hypotheses are also put forward
As a result of the change in the Earth's magnetic poles, Atlantis and other civilizations that once inhabited our planet perished, say geologists William Ryan and Walter Pitman from Columbia University. - And even Mars became uninhabited, since the magnetic field disappeared during the polar reversal, which in turn led to the evaporation of the atmosphere on the Red Planet.
Is the fate of Mars awaiting us? For comments, we turned to the Deputy Director of the Institute of Physics of the Earth named after. O.Yu.Schmidt RAS, Doctor of Technical Sciences Vyacheslav Koneshov.
POWERFUL MAGNET INSIDE THE PLANET
Vyacheslav Nikolaevich, are we really threatened by a planetary catastrophe?
Fortunately, no,” the professor reassured us. - Throughout the history of the Earth, the magnetic poles have changed places several times over the 8.5 billion years of the Earth’s existence. And the planet is alive, and we are with it today. The change of magnetic poles is a common history of the existence of a magnetic field on our planet.
How did the Earth's magnetic field arise? Someone put a powerful magnet inside our planet?
We live on a shell called the surface of planet Earth. The shell is called the "lithosphere". And inside this egg with a radius of 6,370 km there is a mantle with different layers, a liquid and a solid core. The shell is thin. Under the oceans - 10-15 km, under the continents - 50-60 km. And so the movement of the mantle generates the Earth's magnetic field. This is what the universally accepted theory of the geomagnetic dynamo states.
Does the mantle move clockwise or counterclockwise?
No, it moves as it wants. Can change its speed and direction. Moreover, this movement does not depend on the geographic axis of rotation of the planet (the magnetic pole and the geographic pole do not coincide, their deviation from each other is 7 degrees. - Ed.). And since the mantle is the main and very large mass of the planet, it moves very slowly. Therefore, it cannot quickly change its movement. It's like a powerful truck that can't turn 180 degrees at full speed. And do you think that in 40 or 100 years the poles will change places? Complete absurdity!
Does the anomalous behavior of the core affect our “truck”?
This theory has the right to life for a simple reason: inside the planet, the core consists of two fractions - there is a liquid part of the core and there is a solid part. The solid center of the planet itself. And the anomaly in the central part of the core, which consists of pure metals, iron, for example, somehow affects the Earth’s magnetic field. But the core itself does not create a magnetic field and, therefore, does not affect the polarity reversal.
Okay, but if not in a hundred years, but in a thousand, the magnetic poles change places, what will happen?
Nothing! Now you have arrived in Australia, where the shadow falls not to the north, but to the south. Would that bother you? Also, when the magnetic needle of the compass points in a different direction, no one will feel either hot or cold from this change. Over the past billion years, the current magnetic north pole began moving in northern Australia, traveled across the Pacific Ocean to the position of our geographic pole, and is now moving in the opposite direction. So what! The main thing is that the magnetic field is maintained. After all, it protects humanity from the harsh radiation of space.
And if the field disappears, will the planet be burned by cosmic rays?
The question is not for me, I think that it will simply be uncomfortable for humanity to live. But the end of the world will not come.
Half a century ago, the north magnetic pole was moving at a speed of 10 km per year, in the early 2000s - 40 km per year? Is he running faster now?
Yes, his speed increased a little.
It turns out we could get lost in the forest?
We used to navigate by the needle of the magnetic compass. But even then, those who were engaged in real navigation still had a map of magnetic declination, which showed how different the position of the north pole was from the geographical one. In our latitudes this difference is 7 degrees, and for other latitudes there are maps of magnetic declination. This was important for the navigator. But now these declination maps are no longer so important, because now all of humanity is mainly guided by satellite navigation (GPS), which determines the coordinates. Gyrocompasses and inertial navigation aids are installed on ships and aircraft - they duplicate the operation of satellite systems. The practical significance of using a magnetic field for navigation is decreasing, although magnetic compasses are installed everywhere.
Is the climate not changing due to polarity reversal? And the weather reports are already very alarming: floods, downpours, incredible heat.
The Earth's magnetic field affects climate, but not so significantly. For example, certain cycles appear in its spectrum - secular or 11-year ones. But humanity has always lived calmly under these cycles.