2012: No Geomagnetic Reversal

by Ian O'Neill on October 3, 2008

Could the magnetic field of the Earth really reverse in 2012? I wouldn't bet on it...

Could the magnetic field of the Earth really reverse in 2012? I wouldnt bet on it...

Apparently, on December 21st 2012, our planet will experience a powerful event. This time we’re not talking about Planet X, Nibiru or a “killer” solar flare, this event will originate deep within the core of our planet, forcing a catastrophic change in our protective magnetic field. Not only will we notice a rapid reduction in magnetic field strength, we’ll also see the magnetic poles rapidly reverse polarity (i.e. the north magnetic pole will be located over the South Pole and vice versa). So what does this mean to us? If we are to believe the doomsayers, we’ll be exposed to the vast quantities of radiation blasting from the Sun; with a reversing magnetic field comes a weakening in the Earth’s ability to deflect cosmic rays. Our armada of communication and military satellites will drop from orbit, adding to the chaos on the ground. There will be social unrest, warfare, famine and economic collapse. Without GPS, our airliners will also plough into the ground

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Using the Mayan Prophecy as an excuse to create new and explosive ways in which our planet may be destroyed, 20 12 2012 doomsayers use the geomagnetic shift theory as if it is set in stone. Simply because scientists have said that it might happen within the next millennium appears to be proof enough that it will happen in four years time. Alas, although this theory has some scientific backing, there is no way that anyone can predict when geomagnetic reversal might happen to the nearest day or to the nearest million years

Firstly, let’s differentiate between geomagnetic reversal and polar shift. Geomagnetic reversal is the change in the magnetic field of the Earth, where the magnetic north pole shifts to the South Polar Region and the south magnetic pole shifts to the North Polar Region. Once this process is complete, our compasses would point toward Antarctica, rather than northern Canada. Polar shift is considered to be a less likely event that occurs a few times in the evolutionary timescale of the Solar System. There are a couple of examples of planets that have suffered a catastrophic polar shift, including Venus (which rotates in an opposite direction to all the other planets, therefore it was flipped upside down by some huge event, such as a planetary collision) and Uranus (which rotates on its side, having been knocked off-axis by an impact, or some gravitational effect caused by Jupiter and Saturn). Many authors (including the doomsayers themselves) often cite both geomagnetic reversal and polar shift as being one of the same thing. This isn’t the case.

So, on with geomagnetic reversal

How often does it happen?

The Earths interior (University of Chicago)

The Earths interior (University of Chicago)

The reasons behind the reversal of the magnetic poles is poorly understood, but it is all down to the internal dynamics of Planet Earth. As our planet spins, the molten iron in the core flows freely, forcing free electrons to flow with it. This convective motion of charged particles sets up a magnetic field which bases its poles in the North and South Polar Regions (a dipole). This is known as the dynamo effect. The resulting magnetic field approximates a bar magnet, allowing the field to envelop our planet.

This magnetic field passes through the core to the crust and pushes into space as the Earth’s magnetosphere, a protective bubble constantly being buffeted by the solar wind. As the solar wind particles are usually charged, the Earth’s powerful magnetosphere deflects the particles, only allowing them into the polar cusp regions where the polar magnetic fieldlines become “open.” The regions at which these energetic particles are allowed to enter glow as aurorae.

Usually this situation can last for aeons (a stable magnetic field threaded through the North and South Polar Regions), but occasionally, the magnetic field is known to reverse and alter in strength. Why is this?

A chart showing Earth's polarity reversals over the last 160 million years. Black = "normal" polarity, White = "reversed" polarity. From Lowrie (1997), Fundamentals of Geophysics

A chart showing Earths polarity reversals over the last 160 million years. Black = normal polarity, White = reversed polarity. From Lowrie (1997)

Again, we simply do not know. We do know that this magnetic pole flip-flop has occurred many times in the last few million years, the last occurred 780,000 years ago according to ferromagnetic sediment. A few scaremongering articles have said geomagnetic reversal occurs with “clockwork regularity” – this is simply not true. As can be seen from the diagram (left), magnetic reversal has occurred fairly chaotically in the last 160 million years. Long-term data suggests that the longest stable period between magnetic “flips” is nearly 40 million years (during the Cretaceous period over 65 million years BC) and the shortest is a few hundred years.

Some 2012 theories suggest that the Earth’s geomagnetic reversal is connected to the natural 11-year solar cycle. Again, there is absolutely no scientific evidence to support this claim. No data has ever been produced suggesting a Sun-Earth magnetic polarity change connection.

So, already this doomsday theory falters in that geomagnetic reversal does not occur with “clockwork regularity,” and it has no connection with solar dynamics. We are not due a magnetic flip as we cannot predict when the next one is going to occur, magnetic reversals occur at seemingly random points in history.

What causes geomagnetic reversal?

The model Earth, can a magnetic field be modelled in the lab? (Flora Lichtman, NPR)

The model Earth, can a magnetic field be modelled in the lab? (Flora Lichtman, NPR)

Research is afoot to try to understand the internal dynamics of our planet. As the Earth spins, the molten iron inside churns and flows in a fairly stable manner for millennia. For some reason during geomagnetic reversal, some instability causes an interruption to the steady generation of a global magnetic field, causing it to flip-flop between the poles.

In a previous Universe Today article, we discussed the efforts of geophysicist Dan Lathrop’s attempts to create his own “model Earth,” setting a 26 tonne ball (containing a molten iron analogue, sodium) spinning to see if the internal motion of the fluid could set up a magnetic field. This huge laboratory experiment is testament to the efforts being put into understanding how our Earth even generates a magnetic field, let alone why it randomly reverses.

A minority view (which, again is used by doomsayers to link geomagnetic reversal with Planet X) is that there may be some external influence that causes the reversal. You will often see associated with the Planet X/Nibiru claims that should this mystery object encounter the inner Solar System during its highly elliptical orbit, the magnetic field disturbance could upset the internal dynamics of the Earth (and the Sun, possibly generating that “killer” solar flare I discussed back in June). This theory is a poor attempt to link several doomsday scenarios with a common harbinger of doom (i.e. Planet X). There is no reason to think the strong magnetic field of the Earth can be influenced by any external force, let alone a non-existent planet (or was that a brown dwarf?).

The magnetic field strength waxes and wanes…

Variations in geomagnetic field in western US since last reversal. The vertical dashed line is the critical value of intensity below which Guyodo and Valet (1999) consider several directional excursions to have occurred.

Variations in geomagnetic field in western US since last reversal. The vertical dashed line is the critical value of intensity below which Guyodo and Valet (1999) consider several directional excursions to have occurred.

New research into the Earth’s magnetic field was published recently in the September 26th issue of Science, suggesting that the Earth’s magnetic field isn’t as simple as we once believed. In addition to the North-South dipole, there is a weaker magnetic field spread around the planet, probably generated in the outer core of the Earth.

The Earth’s magnetic field is measured to vary in field strength and it is a well known fact that the magnetic field strength is currently experiencing a downward trend. The new research paper, co-authored by geochronologist Brad Singer of the University of Wisconsin, suggests that the weaker magnetic field is critical to geomagnetic reversal. Should the stronger dipole (north-south) field reduce below the magnetic field strength of this usually weaker, distributed field, a geomagnetic reversal is possible.

The field is not always stable, the convection and the nature of the flow changes, and it can cause the dipole that’s generated to wax and wane in intensity and strength,” Singer said. “When it becomes very weak, it’s less capable of reaching to the surface of the Earth, and what you start to see emerge is this non-axial dipole, the weaker part of the field that’s left over.” Singer’s research group analysed samples of ancient lava from volcanoes in Tahiti and Germany between 500,000 and 700,000 years ago. By looking at an iron-rich mineral called magnetite in the lava, the researchers were able to deduce the direction of the magnetic field.

The spin of the electrons in the mineral is governed by the dominant magnetic field. During times of strong dipolar field, these electrons pointed toward the magnetic North Pole. During times of weak dipolar field, the electrons pointed to wherever the dominant field was, in this case the distributed magnetic field. They think that when the weakened dipolar field drops below a certain threshold, the distributed field pulls the dipolar field off-axis, causing a geomagnetic shift.

The magnetic field is one of the most fundamental features of the Earth,” Singer said. “But it’s still one of the biggest enigmas in science. Why [the flip] happens is something people have been chasing for more than a hundred years.”

Our meandering magnetic pole

 The movement of Earth's north magnetic pole across the Canadian arctic, 1831--2001 (Geological Survey of Canada)

The movement of Earth's north magnetic pole across the Canadian arctic, 1831--2001 (Geological Survey of Canada)

Although there appears to be a current downward trend in magnetic field strength, the current magnetic field is still considered to be “above average” when compared with the variations measured in recent history. According to researchers at Scripps Institution of Oceanography, San Diego, if the magnetic field continued to decrease at the current trend, the dipolar field would effectively be zero in 500 years time. However, it is more likely that the field strength will simply rebound and increase in strength as it has done over the last several thousand years, continuing with its natural fluctuations.

The positions of the magnetic poles are also known to be wondering over Arctic and Antarctic locations. Take the magnetic north pole for example (pictured left); it has accelerated north over the Canadian plains from 10 km per year in the 20th Century to 40 km per year more recently. It is thought that if the point of magnetic north continues this trend, it will exit North America and enter Siberia in a few decades time. This is not a new phenomenon however. Ever since James Ross’ discovery of the location of the north magnetic pole for the first time in 1831, it’s location has meandered hundreds of miles (even though today’s measurements show some acceleration).

So, no doomsday then?
Geomagnetic reversal is an engrossing area of geophysical research that will continue to occupy physicists and geologists for many years to come. Although the dynamics behind this event are not fully understood, there is absolutely no scientific evidence supporting the claim that there could be a geomagnetic reversal around the time of December 21st, 2012.

Besides, the effects of such a reversal have been totally over-hyped. Should we experience geomagnetic reversal in our lifetimes (which we probably won’t), it is unlikely that we’ll be cooked alive by the Solar Wind, or be wiped out by cosmic rays. It is unlikely that we’ll suffer any mass extinction event (after all, early man, homo erectus, lived through the last geomagnetic shift, apparently with ease). We’ll most likely experience aurorae at all latitudes whilst the dipolar magnetic field settles down to its new, reversed state, and there might be a small increase in energetic particles from space (remember, just because the magnetosphere is weakened, doesn’t mean we wont have magnetic protection), but we’ll still be (largely) protected by our thick atmosphere.

Satellites may malfunction and migrating birds may become confused, but to predict world collapse is a hard pill to swallow.

In conclusion:

  • Geomagnetic reversal is chaotic in nature. There is no way we can predict it.
  • Simply because the magnetic field of the Earth is weakening does not mean it is near collapse. Geomagnetic field strength is “above average” if we compare today’s measurements with the last few million years.
  • The magnetic poles are not set in geographical locations, they move (at varying speeds) and have done ever since measurements began.
  • There is no evidence to suggest external forcing of internal geomagnetic dynamics of the Earth. Therefore there is no evidence of the solar cycle-geomagnetic shift connection. Don’t get me started on Planet X.

So, do you think there will be a geomagnetic reversal event in 2012? I thought not.

Once again, we find another 2012 doomsday scenario to be flawed in so many ways. There is no doubt that geomagnetic reversal will happen in the future for Earth, but we’re talking about time scales anything from an optimistic (and unlikely) 500 years to millions of years, certainly not in the coming four years

Sources: NASA, US News, SciVee, How To Survive 2012, AGU

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Hello! My name is Ian O'Neill and I've been writing for the Universe Today since December 2007. I am a solar physics doctor, but my space interests are wide-ranging. Since becoming a science writer I have been drawn to the more extreme astrophysics concepts (like black hole dynamics), high energy physics (getting excited about the LHC!) and general space colonization efforts. I am also heavily involved with the Mars Homestead project (run by the Mars Foundation), an international organization to advance our settlement concepts on Mars. I also run my own space physics blog: Astroengine.com, be sure to check it out!

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