Will the earth's magnetic poles flip?

Due to the north and south magnetic poles of the earth and the solar wind (a steady stream of particles from the sun), the huge magnetic field around the earth will change shape. Scientific Visualization Studio of National Aeronautics and Space Administration. This article was originally published in Dialogue. This paper is dedicated to the voice of life science experts: columns and opinions.

The earth's magnetic field surrounds our planet like an invisible force field-it protects life from harmful solar radiation by deflecting charged particles. Far from being static, this field is constantly changing. In fact, the history of our planet includes at least hundreds of global magnetic pole reversals, and the north and south magnetic poles have exchanged positions. So when is the next time, and how will it affect life on earth? "

In the process of inversion, the magnetic field will not be zero, but will take a weaker and more complicated form. It may drop to 10% of the current intensity, the magnetic pole is on the equator, and even multiple "north" and "south" magnetic poles appear at the same time. However, the interval between reversals is very irregular and can last for tens of millions of years.

There can also be temporary and incomplete reversals, called events and shifts. In this case, the magnetic pole leaves the geographical magnetic pole before returning to its original position, and may even cross the equator. The last complete reversal took place in Brunhes Matuyama about 780,000 years ago. A temporary reversal, the Lashan incident, occurred about 4 1000 years ago. It lasted less than 1000 years, while the actual polarity change lasted about 250 years.

Power failure or mass extinction "changes in the magnetic field will weaken its shielding effect in the reversal process, thus increasing the radiation level on the earth's surface and above." If this happens today, the increase of charged particles reaching the earth will increase the risk of satellite, aviation and ground power infrastructure. The geomagnetic storm, driven by the interaction between solar energy and the unusually large eruption of magnetic field, allows us to experience the effect that can be achieved by weakening magnetic shielding in advance.

In 2003, the so-called Halloween storm caused a power outage in Sweden's local power grid, requiring flights to be diverted to avoid communication interruption and radiation risk, and interrupting satellites and communication systems. However, this storm is insignificant compared with other recent storms, such as the carrington event in 1859, which caused Aurora to go south to the Caribbean.

The impact of a major storm on today's electronic infrastructure is still not completely clear. Of course, any time there is no electricity, heating, air conditioning, global positioning system and internet, it will have a great impact; Large-scale power failure will lead to economic losses, up to billions of dollars every day. As far as the direct impact of life and reversal on our species on earth is concerned, we can't say what will happen if modern humans don't exist in the last complete reversal. Some studies try to link past reversals with mass extinction, which shows that some reversals and the extension of volcanic activity may be caused by the same reason. However, there is no evidence that there will be any catastrophic volcanic activity in the near future, so only when the magnetic field reverses quickly can we cope with electromagnetic shock.

We do know that many animal species have some form of magnetic reception, which enables them to sense the earth's magnetic field. They can use it to help navigate long distances during the migration process. But it is not clear what effect this reversal may have on these species. Obviously, early humans did survive the La Shang incident, and life itself survived hundreds of times of total revenge.

Can we predict geomagnetic reversal? "A simple fact is that we have completely reversed the Expiration. The fact that the Earth's magnetic field is decreasing at a rate of 5% per century has led people to suggest that the magnetic field may be reversed in the next 2000 years. But it will be difficult to set an exact date-at least for now.

The earth's magnetic field is produced by the slow stirring of molten iron in the liquid core of our planet. Just like the atmosphere and the ocean, its motion mode is also governed by the laws of physics. Therefore, we should be able to predict the "core weather" by tracking this movement, just as we can predict the real weather by observing the atmosphere and oceans. Reversal can be compared to a special type of storm at the core, where dynamics and magnetic fields are confused (at least for a short time) and then stabilized again.

As we all know, although we live in the atmosphere and observe it directly, it is very difficult to predict the weather for more than a few days. However, predicting the core is a more difficult prospect, mainly because it is buried under 3000 kilometers of rock, so our observations are few and indirect. However, we are not completely blind: we know the main component of the core substance, which is liquid. A global network consisting of ground observation stations and orbiting satellites also measures changes in the magnetic field, which gives us a deep understanding of how the liquid core moves.

Recently, a jet plane was found in the core, which highlights our growing creativity and ability to measure and infer the core dynamics. Coupled with numerical simulation and laboratory experiments to study the fluid dynamics inside the planet, our understanding has developed rapidly. It may not be out of reach to be able to predict the prospect of the core.

Phil Livermore, associate professor of geophysics at Leeds University, and Jon Mulder, associate professor of geophysics at Leeds University.

This article was originally published in Dialogue. Read the original. "