Earth's Magnetic Field Weakening

  1. I was watching a NOVA episode that talked about how there are clear signs that Earth's Magnetic Field is weakening at a fairly rapid rate -- a found it very interesting. According to the scientists interviewed, it's undeniably weakening but no one has an explanation. At its current rate of dissipation, the Earth's magnetic field will be absent in a thousand years.

    One theory, however, suggests that the Earth is preparing to shift poles (north becomes south and south becomes north). In the past this has happened fairly frequently (approximately once every 200,000 years). The thing is, it hasn't happened in the past 780,000 years and seems we are a bit overdue.

    Any opinions on whether you believe the Earth's magnetic field may be getting ready to flip?
  2. jcsd
  3. i read about that somewhere else. it is due to swap in the next couple of 1000's of years (i think), and it would be interesting to see a compass point the other way!
  4. Phobos

    Phobos 1,982
    Staff Emeritus
    Science Advisor
    Gold Member

    All the talk I hear about it from scientists pertains to a flip. I have not heard predictions (from scientists) about it disappearing altogether.
  5. chroot

    chroot 10,351
    Staff Emeritus
    Science Advisor
    Gold Member

    A flip has to involve a disappearance of the field first. The field dissipates to zero, and then rebuilds. When the field comes back, it can come back either in the same polarity as before, or with opposite polarity.

    - Warren
  6. I'm no expert of course, but according to the NOVA documentary on this subject, the scientists do not expect a complete disappearance of the magnetic field if it intends to flip. They only predict a drop of strenght to as low as 10-20% of what it is today. That in itself seems scary enough. Also they predict this drop to occur during the next 1000 years, but they do not have any idea when the actually flip will occur.

    The earth could remain in the 10-20% strength level for another 1000 years which has occurred in the past. It is also said that during this time the magnectic field will not have a designated north or south pole. In fact a compass would be completely useless since polarities of north and south will appear in various parts of the earth. The danger of having a magnetic field so low in strenght is that the solar winds will be able to penetrate the earth's atmosphere with greater intensity and greater radiation. The good thing about it will be that aurora lights will be seen almost all over the world.
  7. Kerrie

    Kerrie 1,129
    Staff Emeritus
    Gold Member

    isn't there a point in the hudson bay that used to be where the north pole once was?
  8. Look to Mars for Evidence of Magnetic Field Reversals

    Mars' magnetic field recently reactivated (according to Viking data). This was confirmed by more recent observations from later US probes.
    Comets/asteroids and massive solar storms have the ability to strip away or reverse planetary magnetic fields. The Russians and James McCanney have done some good work on this subject.
  9. LURCH

    LURCH 2,507
    Science Advisor

    There is also a thread about this in the "Earth" Sciences Forum (in "Other Sciences"). Polar inversions are a natural behavior of dynamos, so it is suspected that the Earth's magnetic field is created by a large dynamo in the core.

    I have also heard it suggested that polar inversion accounts for the starnge alignment (or missalignment) of neptune's magnetic poles. We may actually be observing them in mid-flip. This of course is not the only proposed explanation, and makes no account for the alignment of the axial poles.
  10. I am not familiar with that. I have heard, however, that there are areas near the north and south pole today in which a compass would be confused and spin or point in the wrong direction (not north). Some of this has to do with the difference between True North and Magnetic North. But scientists have also discovered anomalies in the southern area of the earth in which north magnetic polarities occur and areas in the north where south magnetic polarities occur. It is suggested that as the Earth's magnetic field weakens, more of these anomalies will occur until the final polar shift completes.

    Wow. I find really fascinating. I would like to hear more about it and will probably research it on my own. Any sites that you know of that shares this info?
  11. The Martian Magnetic Spectre

    Woops, posted the same stuff twice, and can't work out how to delete it.
    Last edited: Nov 25, 2003
  12. The Martian Magnetic Spectre

    All my Viking data is unfortunately in paper form, and I can’t locate it on the Internet yet (not surprising). But I’ll start from NASA’s latest admission, in August 1997. Here goes;

    From the “Martian Magnetic Field Missions”;

    Here’s the Press Release from NASA (woops, better bury this one someone thought!);

    Because then they claimed they were “localised”;

    It then became “crustal”, rather than of “dynamo” origin;

    The next bits from;

    “Mars does not have a strong dipole magnetic field and so does not have auroras circling its poles. However at one time it had a strong magnetic field which was recorded in molten volcanic rocks creating stripes like those due to continental drift on earth.
    Red and Blue stripes on Mars record an ancient Martian magnetic field which changed its polarity.”

    Here’s a nice little paper called “Paleomagnetic Pole Positions And Reversals Of Mars” by J. Arkani-Hamed.

    Martian Magnetic Anomalies;
    Here’s the NASA stuff (even they concur – although its mostly typical pseudo-scientific “double-speak”);

    Here’s a nice quote from NASA, in the below website;
    “Second, the Martian magnetic field may have reversed direction less frequently, which would have given more time for any one field direction to imprint itself in the steadily moving crust, resulting in wider bands.”

    and an oldie from ’78;

    That’s the saga from 97.

    Other froot-loops like myself and some Russians have been doing some fringe work on the reactivation of Mars’ magnetic field. I don’t have a website, and I’m sure how many of you understand the Russian way of things (eg. they refer to space as the “vacuum medium”). For an idea on how comets/asteroids effect magnetic fields, have a suss at McCanney’s site;

    If anybody wants a summary of the Viking data, drop me a line.
  13. russ_watters

    Staff: Mentor

  14. Video

    This Video might be intresting because I saw the Nova video also and this is from it (I watched it in school)

    it's on the left side click on the picture (sorry if this is spam I don't think it is.)

    this talk about the entire world changing poles is making my stomach weird fealing lol.

    i'm hoping I get to live after the Magnetic poles switch that will be so cool.(i'm 15 so i'm not sure :S)
    Last edited: Mar 7, 2006
  15. I read that by studying lava samples it was determined the Earth’s magnetic field has reversed about 18,000 times in 20 million years--I wonder what will happen to us if it were to occur in our lifetime
  16. Chronos

    Chronos 10,348
    Science Advisor
    Gold Member

  17. Vanadium 50

    Vanadium 50 18,470
    Staff Emeritus
    Science Advisor
    Education Advisor

    Where did you read that? This sounds very, very high. That's every 1100 years.
  18. Not to worry; the super volcano under Yellowstone will blow, removing the need to worry about compasses not working or excess RADiation from the Sun.
  19. Yes the earth's geomagnetic field is weakening. Why it is weaken, why it weakened in the past, and will it continue to weaken is not known.

    The following comments are on based a presentation by Gubbins where he discussed geomagnetic observations that currently have no explanation in some detail. (i.e. He explained why current mechanisms could not explain what is observed.)

    It has been found that the geomagnetic field intensity drops in magnitude by a factor of 5 to 10 from current levels for approximately 20% of the time. The abrupt drops in the geomagnetic field intensity are called geomagnetic excursions (failed field reversals). The geomagnetic excursions correlate with abrupt changes on the planet surface. One theory hypotheses that the abrupt changes on the surface of the planet earth causes the abrupt changes to the geomagnetic field.

    Last edited: Apr 23, 2010
  20. The following are more papers by authors that are trying to understand what causes the geomagnetic excursions. As the geomagnetic excursions correlate with abrupt climate change one theory is the increase in the ice sheet mass changes the planet's inertia which in turn cause the geomagnetic excursion. That is an interesting hypothesis. The geomagnetic excursion also correlate with the end of the interglacial periods. There must be some event that abruptly causes the planet to cool again and again. A side affect of that forcing event is it causes a geomagnetic excursion.
Know someone interested in this topic? Share this thead via email, Google+, Twitter, or Facebook

Have something to add?