Unfortunately, it seems to me, as only an interested laywoman and a Science2.0 blogger who is definitely not an expert on this subject, that there are few scientific experts in this field who appear to be able to confidently and convincingly answer these controversial questions. This may be because there are so many conflicting hypotheses surrounding the subject, a lack of conclusive data and a lot of speculation, which I am now also contributing to with this blog.
However, one thing is apparent to me, most of the ‘experts’ seem to agree that we are overdue for a geomagnetic pole reversal and that there are even signs that this has already started to happen. Is it possible then that scientists and politicians are not eager to share the fact that no one is really sure about what will happen as the magnetic field weakens, shifts and then flips?
My admittedly rather limited internet research indicates that no one really knows for sure why and when these pole reversals have happened in the past, what exactly their effects were or even when they will happen next and what the effects will be then, but that there are definitely plenty of conflicting hypotheses, all of which are not easy to test and prove for obvious reasons.
The History of Polar Reversals and Shifts
Some geophysicists claim that the process of magnetic pole shift takes hundreds of thousands of years and that it is 750,000 years since the last magnetic pole reversal occurred within an approximately 200,000 year cycle. Others hypothesize a much shorter 10,000 year cycle, and claim that the last reversal occurred about 11,500 years ago, and that there is evidence of a correlation between reversals and leaps in evolution, driven by the resulting radiation exposure resulting from a damaged geomagnetic field or magnetosphere, that usually protects us living organisms from the solar radiation that can cause cancer and mutate our DNA.
How the Geomagnetic Force is thought to work.
Apparently in the center of our planet Earth there resides a spinning solid iron ball, which researchers call the ‘inner core’. The ball is about the same temperature as the surface of the sun at approximately 5778 K (5505 °C) and it is like a world within a world or maybe even like a heart within a living body. The inner core is 70% as wide as the moon and spins at its own rate, faster than the Earth above it. This ball or ‘inner core’ is surrounded by its own molten ocean which is a very deep layer of liquid iron called ‘the outer core’. The Earth's magnetic field apparently originates from this ocean of molten iron, an electrically conducting fluid which is in constant motion. This liquid ‘outer core’ seethes and surges like a stormy sea, with currents and whirlpools powered by the Coriolis forces of Earth's rotation and these complex motions and interactions supposedly generate the geomagnetic field and the resulting magnetosphere through a process called the ‘dynamo effect’.
It is believed that the convection in the fluid outer core is driven by thermal and compositional buoyancy sources at the boundary between the inner and outer cores, which are produced by the effect of the Earth slowly cooling and the iron in the iron-rich fluid alloy solidifying onto the inner core creating latent heat and the light constituent of the alloy. These buoyancy forces then cause fluid to rise and Coriolis forces, due to the Earth's rotation, cause helical fluid flows. This fluid motion, like waves and currents in an ocean, apparently twists and shears the magnetic field, at the same time as it generates a new magnetic field to replace the current geomagnetic force as it diffuses away.
Evidence of Past Polar Reversals.
Paleomagnetic records indicate that the geomagnetic field has existed for at least three billion years and that if it were not being continually regenerated, it would probably have decayed after 20,000 years, as the temperature of the core is too high to sustain permanent magnetism on its own. Paleomagnetic records also show that the dipole polarity of this geomagnetic field has reversed many times in the past, in other words the north and south poles have already repeatedly reversed or ‘flipped’ and the mean time between reversals is roughly 200,000 years with individual reversal events often taking only a couple thousand years and occasionally possibly even much less time to occur. These ‘mean’ statistics may be a bit misleading though, if the ‘flips’ have occurred randomly over that period and according to Wikipedia the rate of reversals in the Earth's magnetic field has varied widely over time.
Wikipedia claims that ‘72 million years ago (Ma), the field reversed 5 times in a million years. In a 4-million-year period centred on 54 Ma, there were 10 reversals; at around 42 Ma, 17 reversals took place in the span of 3 million years. In a period of 3 million years centering on 24 Ma, 13 reversals occurred. 51 reversals occurred in a 12-million-year period, centering on 15 million years ago. These eras of frequent reversals have been counterbalanced by a few "superchrons" or long periods when no reversals took place. It was generally assumed that the frequency of geomagnetic reversals was random until 2006 when a team of physicists at the University of Calabria found that the reversals conform to a Lévy distribution, which describes stochastic processes with long-ranging correlations between events in time’.
Some other Planetary and Solar Polar Reversals and their Effects.
Other celestial bodies also have geomagnetic forces, fields and reversing poles. Mars apparently experienced a magnetic crisis four billion years ago and has been devoid of a magnetic field, an appreciable atmosphere, and possibly of life ever since. The Sun also does a magnetic pole reversal approximately every 11 years, usually at the peak of each sunspot cycle. The next one is hypothesized to be due in 2012, hence probably the sudden recent increase in solar flares which have been affecting satellite communications, in preparation for the next solar polar ‘flip’.
In comparison to the Sun, the Earth pole reversals are far less frequent, however the current magnetic force field appears to be weakening and this weakening effect is often hypothesized to precede a geomagnetic pole reversal event on Earth. The most visible signs of Earth's magnetic field are auroras, which are caused by charged particles from space interacting with the atmosphere as they flow into the north and south magnetic poles.
Figure 1. An Aurora
Effects of the Geomagnetic Force.
The geomagnetic force protects the planet from the lethal effects of solar winds, radiation and cosmic rays and supports and maintains the location of the north and south poles. The weakening of the Earth's magnetic field has been happening for 2000 years, some scientists claim and in the past 20 years the magnetic field has become so erratic and unstable that airport and aeroplane equipment has needed to be readjusted for this change in the Earth's geomagnetic field behavior.
The Earth’s geomagnetic field is in a constant state of change, according to researchers like scientist Larry Newitt of the Geological Survey of Canada who regularly goes hunting with a compass for his quarry, which is Earth's north magnetic pole, which is then usually found in an increasingly distant new location from the last record taken. Scientists have known for some time that the magnetic poles move. James Ross first located the north pole in 1831 after an epic arctic journey during which his ship became icebound for four years. No one returned to the north pole again until the next century when in 1904, Roald Amundsen found the current north pole and discovered that it had moved at least 50 kilometres from the original site moving then at an average of less than 1 kilometre per year.
The pole kept moving slowly northwards during the 20th century, at an increasing average speed of 10 km per year, but lately in the 21st century it has been accelerating and relocating at a new average of more than 50 kilometres per year. At this rate it will soon exit North America and reach Siberia if it doesn’t 'flip' beforehand.
The Earth's magnetic field is changing in other ways too. Compass needles in Africa are drifting about 1 degree per decade. And globally the magnetic field has weakened 10% since the 19th century. After a meeting of the American Geophysical Union, many newspapers carried the story "Is Earth's magnetic field collapsing?" However, according to a more optimistic scientist Gary Glatzmaier of the University of California at Santa Cruz, ‘the ongoing 10% decline doesn't mean that a reversal is imminent. "The field is increasing or decreasing all the time," he says. "We know this from studies of the paleomagnetic record." Earth's present-day magnetic field is, in fact, much stronger than normal. The dipole moment, a measure of the intensity of the magnetic field, is now 8 x 1022 amps x m2. That's twice the million-year average of 4 x 1022 amps x m2'.
It has also been suggested that this ongoing weakening of the geomagnetic force may be correlated to some of the climate change effects that we are already experiencing, as it has also been hypothesized that drastic changes in the Earth’s magnetic field could cause tectonic plates to shift and move, trigger earthquakes and volcanic activity, and cause massive storms on the surface of the Earth, while the weather patterns are in the process of readjusting.
Evidence of a Declining Geomagnetic Force and Past Polar Reversals.
The evidence of a declining geomagnetic force field is apparently recorded in every clay dish that has ever been fired on this planet. During this process the iron minerals in the clay record the exact state of Earth's magnetic field at the time it was baked. Pots from ancient to modern times reveal just how dramatically this field has changed and show that there has been a rapid fall in recent years. The rate of change is also higher in these clay dishes over the last 20 years than it has been for any time in the past 5,000 years. The evidence is that the earth’s geomagnetic force is going from a strong field down to a weak field, and that it's doing this very rapidly.
Further evidence of geomagnetic pole reversal and a weakening geomagnetic force can be found in several locations on the ocean floor, including one that bisects the Atlantic Ocean, these are called Oceanic Ridges or Rifts and are located where the sea floor is being forced apart. Magma, which contains iron, erupts as lava on to the ocean floor and as it solidifies it is quickly magnetized in the directions of the magnetic poles. The extent and direction that it is magnetized can then be easily measured.
Scientists studying the magma on the ocean floor on either side of the ridges or rifts found that periodically, the iron components were magnetized in an opposite direction and that since the magnetizing relied upon the magnetic properties of the north and south magnetic poles, it was concluded that also periodically, in a time frame that has been measured at being about ten millennium, the poles reverse, just as they do on the sun but in a much shorter time frame. These same scientists claim that the last reversal occurred about 11,500 years ago.
There is further hypothetical evidence that we are already in the transition phase that precedes a polar reversal as shown in the growing areas of magnetic anomaly, field lines that are moving the wrong way and signaling an ever weaker and chaotic state for our protective magnetosphere shield. NASA has verified that there is evidence of a positive magnetism energy at the south pole, which is normally supposed to exist in the north pole only. The South pole is supposed to only have a negative magnetic charge. In the past 150 years, it has also been claimed that there has been a migration between the north and south poles and their respective magnetic charges of positive and negative magnetic reversal.
According to a report issued by the British Geological Survey (BGS), there is evidence to suggest that the magnetic reversal has begun. The BGS has taken this position after careful analysis of a region of the Earth known as the South Atlantic Anomaly (SAA). It's an area where the magnetic field is in a state of flux and has weakened noticeably. The data shows the anomaly is growing rapidly and spreading west from South Africa, indicating that the Earth's liquid core is changing. "This may be early evidence of a forthcoming reversal in the direction of the Earth’s internal magnetic field," states the article on the BGS website.
Geomagnetic Models
Several scientists have attempted to create models to simulate the workings of Earth’s geomagnetic fields and her geomagnetic poles. Physicist Dan Lathrop re-created the molten iron dynamo at Earth's core by using 240 pounds of highly explosive molten sodium in 1995. In probably a slightly less risky model, Gary Glatzmaier and Paul Roberts have created a computer simulation called the ‘geodynamo’ that not only creates a self-sustaining magnetic field which was the first to do this, but after simulating the passage of 36,000 years, the field it generated spontaneously flipped. You can view the animation generated by the Glatzmaier-Roberts computer model and see what hypothetically happens during a reversal at http://es.ucsc.edu/~glatz/geodynamo.html
Glatzmaier and Roberts claim that ‘The resulting three-dimensional numerical simulation of the geodynamo, run on parallel supercomputers at the Pittsburgh Supercomputing Center and the Los Alamos National Laboratory, now spans more than 300,000 years. The simulated magnetic field has an intensity and a dipole dominated structure that is very similar to the Earth's (Figure 2) and a westward drift of the non-dipolar structures of the field at the surface that is essentially the same as the 0.2 degrees/year measured on the Earth. Our solution illustrates how the influence of the Earth's rotation on convection in the fluid outer core is responsible for this magnetic field structure and time dependence’.
Figure 2.
‘A snapshot of the 3D magnetic field structure simulated with the Glatzmaier-Roberts geodynamo model. Magnetic field lines are blue where the field is directed inward and yellow where directed outward. The rotation axis of the model Earth is vertical and through the center. A transition occurs at the core-mantle boundary from the intense, complicated field structure in the fluid core, where the field is generated, to the smooth, potential field structure outside the core. The field lines are drawn out to two Earth radii. Magnetic field is rapped around the "tangent cylinder" due to the shear of the zonal fluid flow’.
Causes of Geomagnetic Pole Reversal
Scientific opinion is divided on what hypothetically causes geomagnetic pole reversals and flips. Some theories hypothesize that they are due to events internal to the system, that generate the Earth's magnetic field, others propose that they are due to external events.
Internal Events
According to Wikipedia ‘Many scientists believe that reversals are an inherent aspect of the dynamo theory of how the geomagnetic field is generated. In simulations, it is observed that magnetic field lines can sometimes become tangled and disorganized through the chaotic motions of liquid metal in the Earth's core. During these periods, the direction and magnitude of the magnetic field observed at any point on the surface fluctuate, and net field strength is reduced by dipole-dipole interactions’.‘In some simulations, this leads to an instability in which the magnetic field spontaneously flips over into the opposite orientation. This scenario is supported by observations of the solar magnetic field, which undergoes spontaneous reversals every 9–12 years. However, with the sun it is observed that the solar magnetic intensity greatly increases during a reversal, whereas all reversals on Earth seem to occur during periods of low field strength’.
External Events
Wikipedia also claims that ‘Some scientists, such as Richard A. Muller, believe that geomagnetic reversals are not spontaneous processes but rather are triggered by external events which directly disrupt the flow in the Earth's core. Such processes may include the arrival of continental slabs carried down into the mantle by the action of plate tectonics at subduction zones, the initiation of new mantle plumes from the core-mantle boundary, and possibly mantle-core shear forces resulting from very large impact events. Supporters of this theory hold that any of these events could lead to a large scale disruption of the dynamo, effectively turning off the geomagnetic field. Because the magnetic field is stable in either the present North-South orientation or a reversed orientation, they propose that when the field recovers from such a disruption it spontaneously chooses one state or the other, such that a recovery is seen as a reversal in about half of all cases’.
My Own Hypothesis (My now defunct hypothesis below was temporarily removed but has now been reinserted between the brackets and in italic font, simply to help lessen any confusion to readers of the comments section at the end of this blog, which has references to this hypothesis).
My laywoman’s hypothesis or speculation is probably unfounded because the combined masses and production rates of neutrinos and the amount of energy involved in powering these nuclear reactor, neutrino and collider experiments, is probably negligible in comparison to the enormous energies and masses believed to be involved in sustaining the Earth’s geomagnetic force. These worldwide nuclear reactor, collider and neutrino experiments are hopefully not influencing the current decline in the Earth’s geomagnetic force or the movement of the poles, even though recently a revised calculation suggests that around 3% of particles 'go missing' from all nuclear reactor experiments, see 'The amazing disappearing antineutrino' and 'The Reactor Antineutrino Anomaly' paper at http://arxiv.org/PS_cache/arxiv/pdf/1101/1101.2755v4.pdf
Just for the record here is my hypothesis:-
[I have my own rather worrying and hopefully completely unfounded hypothesis that the sudden increase in north and south pole relocating movement since the 1980s and the increasingly weakening geomagnetic force may also somehow be related to the corresponding increased generation of relatively new non-extraterrestrial missing energy in the form of unidentified particles that are being created in nuclear reactors, particle accelerators and collidor experiments which are increasingly taking place around the world since the 1980’s and which did not occur much before.
Prior to this the Earth’s geomagnetic force has protected the inner and outer cores from similar extra-terrestrial energies and particles before they were created beneath her protective magnetosphere shield in these Earth-bound experiments. These experiments may even possibly be creating significant quantities of the hypothetical 4th generation massive sterile neutrinos as they travel oscillating their way through the Earth while possibly being altered by the MSW or ‘matter effect’ resonance, interacting only with gravity and other neutrinos and therefore potentially interacting with the Earth’s inner and outer cores’ geomagnetic force fields in some unknown manner.
Wikipedia claims that 'Sterile neutrinos would still interact via gravity, so if they are heavy enough, they could explain cold dark matter or warm dark matter. Sterile neutrinos may also mix with ordinary neutrinos via a Dirac mass. The sterile neutrinos and ordinary neutrinos may also have Majorana masses. In certain models, both Dirac and Majorana masses are used in a seesaw mechanism, which drives ordinary neutrino masses down and makes the sterile neutrinos much heavier than the Standard Model interacting neutrinos. In some models the heavy neutrinos can be as heavy as the GUT scale (~1015 GeV)'.
Wikipedia gives many examples of large experimental particle laboratories , nuclear reactors and neutrino experiments that are possibly generating significant amounts of this type missing energy and unidentified particles. These include the Large Hadron Particle Collidor (LHC) and OPERA at CERN in Geneva, the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) which collides heavy ions such as gold ions and polarized protons. The DESY at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The Hadron Elektron Ring Anlage (HERA) in Hamburg, Germany, which collides electrons and positrons with protons. MINOS at Fermilab, in Batavia, United States which also has the Tevatron, which collides protons and antiprotons and was the highest energy particle collider in the world until the Large Hadron Collider surpassed it on 29 November 2009. KEK, in Tsukuba, Japan which has K2K, a neutrino oscillation experiment and Belle, an experiment measuring the CP violation of B mesons. SLAC National Accelerator Laboratory in Menlo Park, United States has PEP-II, which collides electrons and positrons. Many more particle accelerators also exist on the planet.]
What will happen if a Polar Flip Occurs?
Beyond knowing that pole reversal happens, little is known or certain about the process or what will happen when it does occur next and what signs will precede such an event, so it isn’t easy to scientifically predict when it will happen and what will happen when it does. It has been claimed that just prior to, and just after some pole reversals in the past, there has been evidence of a disruption to plant and animal species and of rapid climate changes. Wikipedia points out that ‘Homo erectus and their ancestors certainly(?) survived many previous reversals, though they did not depend on computer systems that could be damaged by large coronal mass ejections’.
At the time of one of the hypothetized reversals 11,000 years ago, our planet was ‘locked in an ice age, with great ice sheets that covered most of the globe and immediately afterward, the ice started to recede rapidly, a condition that continues today’. It has been hypothesized that Woolly mammoths went extinct when the Gothenburg magnetic reversal occurred some 11,500 years ago and that the Earth collapsed into a catastrophic Ice Age when the Mono Lake magnetic reversal took place 23,000 years ago. Did Non-anthropogenic Climate Change cause Neanderthal extinction 30,000 years ago when he encountered climate change caused by a geomagnetic pole reversal?
Some hypotheses suggest that the effects of the pole reversal may have terrible consequences in a short period, and others predict that it may be more gentle and take more than a hundred years, if it happens over a longer period. Since human beings have never been through a pole shift that they know of in our recorded history, no one really knows how a pole shift is going to work or what the results will be. Geophysicist Rob Coe of the University of California at Santa Cruz, may have however found a lava record in Oregon that charts magnetic mayhem that ensued during a previous period of reversal. Without a doubt GPS satellite and navigation systems all over the planet would become chaotic.
If a pole shift does take place, some hypothesize that the axis and magnetism of Earth would also be changed, the poles would flip and reverse so that the south pole has a positive magnetic charge instead of a negative magnetic charge, and the north pole has a negative magnetic charge instead of the positive magnetic charge it now has.
I think that possibly the worst outcome predicted as a hypothetical possibility that I have read, is that the geomagnetic force and consequently the protective magnetosphere breaks up into multiple haphazard poles or even ceases to exist altogether for a period of time and the sun's radiation, solar winds and cosmic rays have no obstacle to shield them from reaching some parts of the planet, causing the surface of the Earth to possibly become temporarily uninhabitable. Without this protection hypothetically many plants might not be able to grow, animals could die, and so possibly could any humans who were left on the surface. Let’s hope that these hypothetical worst case scenarios are wrong, if however they turn out to be right then those old mines, underground caves and railway lines and nuclear bunkers may come in very handy.
Internet References
http://arxiv.org/PS_cache/arxiv/pdf/1101/1101.2755v1.pdf
http://arxiv.org/PS_cache/arxiv/pdf/1101/1101.2755v4.pdf
http://en.wikipedia.org/wiki/Geomagnetic_reversal
http://es.ucsc.edu/~glatz/geodynamo.html
http://www.bgs.ac.uk/research/highlights/southAtlantic2010.html
http://www.helium.com/items/2093767-scientists-magnetic-polar-reversal-m...
http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html
http://www.nature.com/news/2011/110401/full/news.2011.202.html
http://www.pbs.org/wgbh/nova/magnetic/about.html
http://www.pbs.org/wgbh/nova/magnetic/reversals.html
This blog was written by Helen Barratt who's Science20 profile is at http://www.science20.com/profile/helen_barratt
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