Geomagnetic reversal and pole shift

[ZacharyFino]

im having a hard time finding any reputable information or scientific backing to support the theory that our magnetic field will reverse and/or shift anytime soon. also would this mean that the equator areas would remain almost the same as before in terms of magnetic field?

 

[Evo]

Go here and click on the program transcript.

http://www.pbs.org/wgbh/nova/magnetic/

Our magnetic field flips quite frequently and we are due another soon.

 

[negitron]

There is, in fact, compelling evidence that we are seeing the beginning of just such a reversal now.

http://scienceblogs.com/highlyallochthonous/2009/02/is_the_Earth's_magnetic_field_a.php

 

[ZacharyFino]

i know that it has happened many times and people speculate we are "overdue" but since the numbers of years between are so large (in the hundred thousands) combined with the fact that the times between reversals vary a great deal, probabilities that it will happen in our life time don't seem any higher than maybe in a thousand years (if average stable times are your basis) i would like to know other things that increase the probability such as the magnetic field weakening, because with the limited resources i have to make a decision it just seems as though the probabilities of it happening within a hundred years arent any higher than say a thousand.

 

[ZacharyFino]

and maybe some insight involving the sun

 

[Evo]

i know that it has happened many times and people speculate we are "overdue" but since the numbers of years between are so large (in the hundred thousands) combined with the fact that the times between reversals vary a great deal, probabilities that it will happen in our life time don't seem any higher than maybe in a thousand years (if average stable times are your basis) i would like to know other things that increase the probability such as the magnetic field weakening, because with the limited resources i have to make a decision it just seems as though the probabilities of it happening within a hundred years arent any higher than say a thousand.

Did you read the transcript? Sounds like your questions are answered in there. And if you aren't into reading, there are nifty graphics that you can click on.

 

[negitron]

i know that it has happened many times and people speculate we are "overdue" but since the numbers of years between are so large (in the hundred thousands) combined with the fact that the times between reversals vary a great deal, probabilities that it will happen in our life time don't seem any higher than maybe in a thousand years

Astoundingly unlikely occurrences do happen, however. Geologically speaking, we are at the one instant in time when the Moon appears nearly exactly the same angular size as the Sun, leading to what must surely be among the rarest of sights in the whole Universe: a total annular eclipse.

 

[ZacharyFino]

Did you read the transcript? Sounds like your questions are answered in there. And if you aren't into reading, there are nifty graphics that you can click on.

i did read it and it is apparent it will happen soon, however the decreasing field may very well decrease and increase and decrease and increase until ultimately resulting in a geomagnetic reversal, there is nothing to say that this is the final field decreasing period that leads to the reversal, but we are obviously close to one. actually i was originally questioning the basis on the multiple theories and stories I've come across saying it will happen definitely around 2012-2030 without providing any true evidence or reputable sources. But thanks to these excellent sources you all have given me i have made my conclusion that it WILL happen soon but not in any DEFINITE small time period. oh yeah and that decent sources are becoming harder and harder to find due to the massive amount of rubbish flooding the internet!

 

[Evo]

i did read it and it is apparent it will happen soon, however the decreasing field may very well decrease and increase and decrease and increase until ultimately resulting in a geomagnetic reversal, there is nothing to say that this is the final field decreasing period that leads to the reversal, but we are obviously close to one. actually i was originally questioning the basis on the multiple theories and stories I've come across saying it will happen definitely around 2012-2030 without providing any true evidence or reputable sources. But thanks to these excellent sources you all have given me i have made my conclusion that it WILL happen soon but not in any DEFINITE small time period. oh yeah and that decent sources are becoming harder and harder to find due to the massive amount of rubbish flooding the internet!

Ah, you are referring to 2012 nonsense, it is just that...nonsense. You are absolutely right about those kinds of predictions.

 

[Andre]

Yes, what is soon?

The current decrease in field strenght doesn't signify anything, or like the owner of this webpage uses to say: the Earth magnetic field has never been so strong in million years, what else would you expect it to do, except going down? Note that there is a goldmine of geomagnetic publications on that page. This one is especially interesting, a comprehensive compilation of geomagnetic variation during the last 800,000 years.

So the field goes up and down seemingly at random. Sometimes the field collapses, a "paleomagnetic excursion" (PME), in some irregular semi cycle of about 80-100,000 years. The last one, the Laschamps PME was 40,000 years ago(*), not a reason to assume that we are due anytime soon. Also the real magnetic field reversals are not a common event. Althought during the last geologic period, the Czenozonic, it has semi cycles of several 100,000 years, the last one the Brunhes Matuyama event, happened 778,000 years ago, but there have also been "super chrons" of many million years.

You can also see why Langereis did that assessment about what-goes-up-must-come-down in the last thousand years. And finally; neither climate nor any catastrophic events are linked to any variation in the Earth magnetic field and the message is: don't worry, nothing is going on here.

(*) Edit: Note: at some places a more recent PME has been recorded at 25,000 years ago, the Mono Lake PME, however this was not on a global scale. Also an apparent field reversal at 10,000 years, the alleged Goteburg flip, was not reproduceable anywhere and it is assessed to be erratic.

 

[Ophiolite]

Yes, what is soon?

One of my senior lecturers viewed everything post Cambrian as superficial drift deposits. On that basis the reversal is due immediately, within the next half million years.

 

[LURCH]

and maybe some insight involving the sun

Funny you should mention that. I arrived at the theory (on my own; always shaky scientific ground) that the Sun might play a role in polar reversals. it seemed to me that, as the Earth's magnetic field becoes more and more unstable and disorganised, the Sun's own polar reversal (once every 11yrs or so) could trigger the flip.

I contacted http://complex.umd.edu/dynamo/index.html" , and he informed me that the flips appear to take thousands of years, so the Sun's 11yr cycle really doesn't fit the profile.

 

[Saul]

Funny you should mention that. I arrived at the theory (on my own; always shaky scientific ground) that the Sun might play a role in polar reversals. it seemed to me that, as the Earth's magnetic field becoes more and more unstable and disorganised, the Sun's own polar reversal (once every 11yrs or so) could trigger the flip.

I contacted http://complex.umd.edu/dynamo/index.html"[/URL], and he informed me that the flips appear to take thousands of years, so the Sun's 11yr cycle really doesn't fit the profile.[/QUOTE]

There is a significant amount of evidence that connects a roughly once in 10,000 year solar event (both that there is a roughly once in 10,000 year solar event and its effect on the planet) with abrupt geomagnetic field changes. It has been known for sometime that abrupt drops in planetary temperature coincide with abrupt changes in cosmogenic isotopes that are deposited on ice sheets and on the ocean floor concurrently with the abrupt cyclic drop in planetary temperature. (There is at present no explanation for the abrupt cyclic drops in planetary temperature.)

Until recently, however, there was no mechanism to explain how an abrupt drop in the geomagnetic field intensity could cool the planet. Recently there has been a theory develop that connects Galactic Cosmic Ray (GCR) intensity and planetary cloud cover. GCR are modulate by both geomagnetic field strength and the solar magnetic cycle strength. When the geomagnetic field is weaker the GCR changes affect lower latitudes on the planet which will if the mechanism is correct, increase the temperature effect of the GCR planetary cloud modulation by the solar magnetic cycle.

An external driver for the abrupt geomagnetic field changes would make sense as the hypothesized internal mechanism (for geomagnetic field reversals) requires as you note roughly 5000 years to reverse the geomagnetic field.

Specialists in the geomagnetic field area cannot explain the cyclic nature of the geomagnetic field reversals with an internal mechanism and it appears there are paradoxes (observations that do not make physical sense based on the current assumed geomagnetic field mechanism) associated with very quick geomagnetic field changes and geomagnetic field anomalies.

If the driver of the geomagnetic field reversals is a special solar event then changes on the planet's surface (such as on a long term basis the position of the continents or areas of the planet that are covered with ice sheets or the tilt of the planet when the event occurs) would affect the resultant.

[URL]http://eprints.whiterose.ac.uk/416/1/gubbinsd4.pdf[/URL]

[QUOTE]Recent palaeomagnetic studies suggest that excursions of the geomagnetic field, during which the intensity drops suddenly by a factor of 5 to 10 and the local direction changes dramatically, are more common than previously expected. The `normal' state of the geomagnetic field, dominated by an axial dipole, seems to be interrupted every 30 to 100 kyr; it may not therefore be as stable as we thought.

Recent studies suggest that the Earth's magnetic field has fallen dramatically in magnitude and changed direction repeatedly since the last reversal 700 kyr ago (Langereis et al. 1997; Lund et al. 1998). These important results paint a rather different picture of the long-term behaviour of the field from the conventional one of a steady dipole reversing at random intervals: instead, the field appears to spend up to 20 per cent of its time in a weak, non-dipole state (Lund et al. 1998). One of us (Gubbins 1999) has suggested that this is evidence of a rapid natural timescale (500 yr) in the outer core, and that the magnetic field is usually prevented from reversing completely by the longer di¡usion time of the inner core (2^5 kyr). This raises a number of important but di¤cult questions for geodynamo theory. How can the geomagnetic ¢eld change so rapidly and dramatically? Can slight variations of the geomagnetic field affect the dynamics of core convection signifcantly? If so, is the geodynamo process intrinsically unstable?[/QUOTE][url]http://www.nature.com/nature/journal/v374/n6524/abs/374687a0.html[/url]

[B]New evidence for extraordinarily rapid change of the geomagnetic field during a reversal[/B]

[QUOTE]Palaeomagnetic results from lava flows recording a geomagnetic polarity reversal at Steens Mountain, Oregon suggest the occurrence of brief episodes of astonishingly rapid field change of six degrees per day. The evidence is large, systematic variations in the direction of remanent magnetization as a function of the temperature of thermal demagnetization and of vertical position within a single flow, which are most simply explained by the hypothesis that the field was changing direction as the flow cooled.[/QUOTE]The solar event appears to coincide with an abrupt interruption of the solar magnetic cycle. The solar event would be the restart of the solar magnetic cycle.