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Why Do and When Will Earth's Magnetic Poles Reverse? Will This Affect Climate Change?

Earth's Magnetosphere: Why do Earth's Magnetic Poles Reverse?

Will This Affect Climate Change?

effects of the solar wind on the shape of earth's magnetic field.Earth is has it's own protective magnetic shield, called the magnetosphere. The magnetosphere blocks much of the harmful solar and cosmic particle radiation.  This magnetic field is immense, but actually quite weak, only about 1 Faraday in strength. But did you know that our magnetic field reverses itself every so often?  The north pole becomes the south pole and vice versa. Earth's magnetic pole reversals have happened throughout Earth's history. The last one occurred 780,000 years ago.

What generates earth's magnetosphere?

Illustration of the dynamo mechanism that creates Earth's magnetic field: convection currents of fluid metal in Earth's outer core, driven by heat flow from the inner core, organized into rolls by the Coriolis force, create circulating electric currents, which generate the magnetic field.The magnetosphere is generated by the spinning outer core near the center of earth.  The outer core is liquid iron and nickel. When a magnet spins, it produces a magnetic field.

The drawing shows the dynamo mechanism that creates Earth's magnetic field: convection currents of fluid metal in Earth's outer core, which are driven by heat flow from the inner core, organized into rolls by the Coriolis force, create circulating electric currents, which generate the magnetic field. Credit: Andrew Z. Colvin, CC BY-SA 4.0, via Wikimedia Commons.

The invisible lines of the magnetic field travel in a closed, continuous loop, flowing into Earth at the north magnetic pole and out at the south magnetic pole. The solar wind compresses the field’s shape on Earth’s Sun-facing side, and stretches it into a long tail on the night-facing side. See the 2 diagrams at right showing the effects of the solar wind on the shape of earth's magnetic field.

How important is earths magnetic field?

 The magnetosphere shields us from our atmosphere being stripped away by solar wind, particle radiation from coronal mass ejections (eruptions of large clouds of energetic, magnetized plasma from the Sun’s corona into space), and from cosmic rays that come from deep space.

Without a functioning magnetosphere, earth would rapidly become like Venus, a boiling hot planet, lacking water and an atmosphere. The current theory is that Venus' magnetosphere stopped and it's atmosphere and water were blown away by the solar wind. effects of the solar wind on the shape of earth's magnetic field.

What's this about the poles reversing?

Earth’s magnetosphere experiences periodic pole reversals. During a pole reversal, Earth’s magnetic north and south poles swap locations. Sir James Clark Ross first discovered the North Magnetic Pole in northern Canada in 1831.

Since 1831, the pole has been moving across the Canadian Arctic toward Russia. NCEI scientists with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder calculated the movement of both the North and South Magnetic Poles from 1590 to 2025.

How often do the pole's reverse?

Paleomagnetic records show us that Earth’s magnetic poles have reversed 183 times in the last 83 million years, and at least several hundred times in the past 160 million years. The time intervals between reversals varies, but average about 300,000 years, with the last reversal taking place about 780,000 years ago. The reversal can take about 1,000 years to complete. The last reversal occurred between 772,000 and 774,000 years ago. Since then, the field has almost reversed 15 times, called an excursion, dropping in strength significantly but not quite reaching the threshold needed before rising again. Earth: Inside: layers, cores


How do we know poles have reversed?

The reversal it leaves fossilised magnetisation in rocks on Earth. In other words, it leaves a permanent unique magnetic record in the fossils, which can be dated. By taking cores samples of sediments from the sea floor, like a long straw that can extend down up to 300 metres with the help of a drill, we can look back in time and see when these reversals occurred.

Here's how it works: 

When the tectonic plates form along the oceanic ridges, the magnetic field that exists is “frozen” into the rock as they cool below about 700°C. The slowly moving plates act as a kind of tape recorder leaving information about the strength and direction of past magnetic fields. By sampling these rocks and using radiometric dating techniques, it has been possible to reconstruct the history of Earth's magnetic field for roughly the last 160 million years.

If one “plays the tape backwards,” the record shows Earth’s magnetic field strengthening, weakening, and often changing polarity.


What causes the pole reversal?

Scientists don’t know what causes pole reversal or why it occurs at an inconsistent frequency, but they speculate that it may be due to convection processes within the Earth’s mantle.

What will happen to us and earth when the magnetic poles reverse?

Impacts of space weather on technologyAs Earth's magnetic shield pauses and reverse, it is thought likely that it could causes malfunctions in:

  • communications satellites
  • astronauts in low-Earth orbit communications would fail
  • cosmic rays would no longer be blocked and will irradiate anything living on the surface.

‘The geomagnetic field has been decaying for the last 3,000 years,’ said Dr Nicolas Thouveny from the European Centre for Research and Teaching of Environmental Geosciences (CEREGE) in Aix-en-Provence, France. ‘If it continues to fall down at this rate, in less than one millennium we will be in a critical (period).’  Dr Thouveny is one of the principal investigators on the five-year EDIFICE project, which has been running since 2014.  Dr Thouveny and his team looked at two particular forms of elements that allowed them to probe the history of our planet’s magnetic field in greater detail.

What will happen to life on earth?

When this happens, these cosmic rays collide with more and more atoms in our atmosphere, such as nitrogen and oxygen. This produces variants of elements called cosmogenic isotopes, such as carbon-14 and beryllium-10, which fall to the surface. And by studying the quantities of these in cores, we can see when polarity reversals took place.

When will this happen next?

Polarity reversals give warning signs: the magnetic field weakens by about 90% to a threshold level. This process can take thousands of years, and during this time, the lack of a protective magnetic shield around our planet allows more cosmic rays reach earth's surface - and the organisms, like us, living there. to hit us. As the field ebbs and recovers its strength; it allows cosmic rays to penetrate.  The last excursion occurred 40,000 years ago, and evidence suggests we are heading in that direction again.

‘The geomagnetic field has been losing 30 percent of its intensity in the last 3,000 years,’ said Dr Thouveny. ‘From this value, we predict it will drop to near zero in a few centuries or a millennia.’

However, the USGS poo-poo's the idea, saying: Aurora (Northern Lights)

Are we about to have a magnetic reversal? Almost certainly not.  Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those same paleomagnetic records also show that the field intensity can vary significantly without resulting in a reversal. So a reduced intensity in the magnetic field does not necessarily mean that a reversal is about to occur. Moreover, the decrease in intensity is not a dramatic departure from normal. For all we know, the field may actually get stronger at some point in the not-so-distant future. Predicting the occurrence of a reversal based on the current state of the magnetic field is extremely difficult. Reversals are not instantaneous--they take place over a period of hundreds to thousands of years. We wouldn’t know that a reversal is happening until it was half over.

Yes, the same government that now admits lying to the American public about the existence of UFO's for the past 70 years, tells you not to worry.  Right....

Implications for Climate Change

This is the big unknown.  Most scientists say they do not think a reversal of magnetic poles would have a large impact upon life on earth.  But no one was there to see when it happened in the past, and the technologies, satellites, power grids, cell phones and computers did not exist during the last reversal, so it's really anyone's guess at this point.

See this page for much more information about the earth's layers, core and structure.


Many references are included by embedded links to the sources in the text above. Below are others:

  1. NOAA - NCEI and CIRES scientists created an animation showing changes in declination location and the “wandering” of the North Magnetic Pole over the last 50 years. Watch how the isogonic lines converge at the Pole. View historic data back to 1590 with our Map Viewer.
  2. NOAA Earth's Magnetic fields - The magnetic poles are defined as the area where dip (I) is vertical. You can compute this area using magnetic field models, such as the World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF). You can also survey for the magnetic pole, using instruments that measure the magnetic field strength and direction. In practice, the geomagnetic field is not exactly vertical at these poles, but is vertical on oval-shaped loci traced on a daily basis, with considerable variation from one day to another, and approximately centered on the dip pole positions. Magnetic declination (D) is unreliable near the poles. More information is available at wandering poles.
  3. NASA Earths magnetosphere protecting our planet from harmful space energy/
  4. USGS - Auroras and Earthquakes: Strange Companions - Release Date: JULY 6, 2020 In 1722 and 1723 a London clockmaker, George Graham, observed daily and consistent variations on one of his instruments, a “Needle upon the Pin” (a compass), for which he had no explanation. Swedish scientists obtained some of Graham’s instruments to record what is now known to be the variations in Earth’s magnetic field. In 1741, they noticed a significant deflection
  5.  -  Earth’s inner core may be reversing its rotation. Such a turnaround might sound bizarre, but isn’t likely to have profound effects on life. Scientists have proposed that Earth’s solid inner core (yellow in this diagram) rotates faster than the rest of Earth. A new study suggests the core’s rotation has recently paused, and is reversing direction.
  6. Scientific American - Earth’s Magnetic Field Reversal Took Three Times Longer Than Thought, A new study suggests the last field reversal 773,000 years ago took 22,000 years to occur, which could explain some of the inner workings of our planet’s core
    By Jonathan O'Callaghan on August 7, 2019
    "scientists know the last reversal took place about 773,000 years ago, but exactly what happens in our planet’s core to bring about the change is unknown. A new study, however, could help clarify the underlying cause because it suggests that reversal takes much longer than we thought. The findings also have potential implications for humanity during the next flip. In their paper published today in Science Advances, Brad Singer of the University of Wisconsin–Madison and his colleagues calculate that Earth’s last magnetic field reversal took roughly 22,000 years."
  7. Nature Geoscience - Multidecadal variation of the Earth’s inner-core rotation - Yi Yang    & Xiaodong Song    Differential rotation of Earth’s inner core relative to the mantle is thought to occur under the effects of the geodynamo on core dynamics and gravitational core–mantle coupling. This rotation has been inferred from temporal changes between repeated seismic waves that should traverse the same path through the inner core. Here we analyse repeated seismic waves from the early 1990s and show that all of the paths that previously showed significant temporal changes have exhibited little change over the past decade. This globally consistent pattern suggests that inner-core rotation has recently paused. We compared this recent pattern to the Alaskan seismic records of South Sandwich Islands doublets going back to 1964 and it seems to be associated with a gradual turning-back of the inner core as a part of an approximately seven-decade oscillation, with another turning point in the early 1970s.
  8. The Wall Street Journal - Earth’s Inner Core May Be Reversing Its Rotation, Study Finds
    The change may shave the length of the day by a fraction of a millisecond over the course of a year.