Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What would be the consequences of a magnetic pole shift?

  1. Sep 30, 2009 #1
    What would be the potential consequences posed by a shift of the Earth's magnetic poles? I know this has happened many times before in Earth's several Billion year history. Hypothetically, what would happen if there was a shift tomorrow?
  2. jcsd
  3. Oct 1, 2009 #2
    Last edited by a moderator: May 4, 2017
  4. Oct 1, 2009 #3
    As the evidence mounts that Mars once had a strong magnetic field and an atmosphere, a theory (that the weakening/loss of Mars' magnetic field resulted in the loss of its atmosphere) gains strength.

    A planetary magnetosphere acts as a shield against incoming solar radiation. Loss or reduction of this field can allow the solar wind to "boil off" an atmosphere over time.

    As Earth's magnetic field reverses, the magnetosphere will become disorganized, Aurora will occur at mid-latitudes and there will be an extended decline in field strength which will allow more solar radiation to impact the atmosphere...

    The Pittsburgh Supercomputing Center, Carnegie Mellon University, University of Pittsburgh web site:
    has an interesting article on simulation of a magnetic field reversal:

    I wonder if anyone has done any modeling of the potential atmospheric effects of a field reversal on Earth.

    Another interesting report related to this issue is at:

    Brief disruptions which do not result in reversal are also known and are called geomagnetic excursions:
    It seems to me that such excursions (which involve disorganization and weakening of the field over relatively short time periods) will have effects on our atmosphere similar to a full reversal.
  5. Oct 1, 2009 #4


    User Avatar
    Science Advisor
    Homework Helper

    The summary mentions "in agreement with the astronomically derived value" - I cant get the article, how do you measure the field shift astronomicaly?
  6. Oct 1, 2009 #5


    User Avatar

    As others have already noted, a magnetic field reversal would take place gradually over a long period of time. During that time, earths magnetic field would weaken considerably. This would allow greater levels of cosmic radiation to reach the surface.

    However, there have been no noticeable die offs, climate changes or things of the like associated with the many reversals that have occured in the past. In addition, the average background radiation on the earths surface is currently very low and only a portion of it is from cosmic sources. From experience, we know that human can live in safety at considerably greater radiation levels than what is typically found on earths surface.

    People that live in Denver CO or frequently fly on airlines have considerably greater cosmic radiation exposure than people living at sea level who never fly. However, nobody is particulary concerned with the differance in cosmic radiation between these.
  7. Oct 1, 2009 #6

    This collaborative project will assemble a continuous Astronomical Time Scale (ATS) for the Mesozoic Era (65 to 251 million years ago) from orbitally forced paleoclimate cycles recorded in stratigraphic data. The results should improve estimates of rates and timings of a wide range of Earth system processes by at least an order of magnitude."

    It would appear that an astronomically derived age for a strata involves measurement of geological variables which can be linked to changes in Earth's orbit over time... further from ABSTRACT:

    "The grand "team" goal is to extend the ATS, now virtually complete for the Cenozoic Era (0 to 65 million years ago), to encompass the past 250 million years. The methods that underpin the Cenozoic ATS will be applied to the Mesozoic. Emphasis will be placed on the goodness of fit of stratigraphic signals to astronomical models, duplication of records from different regions, and high-resolution calibration to geomagnetic polarity signatures and integrated bio- and chemostratigraphy."
  8. Oct 1, 2009 #7


    User Avatar
    Science Advisor
    Homework Helper

    The HSE (= OSHA) is - it puts airline pilots in the top 5% of received dose even for radiation workers, more than typical nuclear power station workers.
    Concorde (flying higher than most other planes) was a particular problem - it even had radiation monitors and was forced to fly lower/slower on a bad day.
  9. Oct 1, 2009 #8

    From your post: "There won't be a magnetic polar shift tomorrow as takes on the average seven thousands years to happen."
    Your link to:
    includes the following:

    "It is generally accepted that Earth's magnetic field strength drops to low levels during polarity reversals, and the field direction progresses through a 180° change while the field is weak1. The time it takes for this process to happen, however, remains uncertain, with estimates ranging from a few thousand up to 28,000 years. Here I present an analysis of the available sediment records of the four most recent polarity reversals. These records yield an average estimate of about 7,000 years for the time it takes for the directional change to occur."

    Which I would interpret as saying that WHEN a reversal begins, magnetic field strength begins falling and does not return to full strength for an average of 7,000 years, at which time the field is fully oriented in the opposite direction. So, we are talking about a relatively weak magnetic field for 7,000 years... not something which will not happen for 7,000 years.

    I agree with you that "the potential consequences are unknown". Atmospheric effects of reversals in the past would be difficult to detect in the geologic record (7,000 years is by definition a non-geologic time span). That is the reason I would be interested in learning of any modeling which may have been done on the question.

    As I understand the issue, it is not an increase in solar radiation which reaches the surface of the Earth. The issue is high energy solar wind PARTICLES gradually stripping away our upper atmosphere due to a weakened magnetosphere... (my earlier post refering to "incoming solar radiation" should probably have been "incoming solar plasma").

    Certainly, in the case of Mars, (where the atmospheric density is very low) greater amounts of solar radiation reach the surface. But this is not the scenario for a field reversal on Earth (unless it lasts for a few million years).

    My questions center on what particular components of our upper atmosphere will be affected and to what extent by the next field reversal. And, does anyone know of models for these effects.
    Last edited by a moderator: May 4, 2017
  10. Oct 3, 2009 #9
    The researcher that states it takes 7000 years for a magnetic reversal to take place is making that statement based on a model of an assume mechanism.

    The data show evidence of very rapid geomagnetic field changes increases and decreases of 15% to 30% in less than decade in large regions of the planet. (Check the thread on archomagnetic jerks.) Those type of rapid geomagnetic field changes are not possible with the current assumed geomagnetic field generating mechanism. If one does not understand the mechanism by which the geomagnetic field is generated and changes then it is not possible make to a prediction of the time it would take for a reversal to take place.

    As noted in the paper linked to below "Is the geodynamo process intrinsically unstable?" the geomagnetic field is currently cyclically dropping in intensity by a factor of 5 to 10 with a period of 30 kyr to 100 kyrs. The geomagnetic field strength is strongest during the interglacial period and weakest during the glacial period.

    The state of the science in geomagnetic field research is similar to that in geology when tectonic plate movement was discovered. Tectonic plate movement provides an explanation for surface geological observations that are not random. i.e. There is a logical explanation based on mechanism and the past location of the plates that explains the observations.

    There is no explanation as to why recently the geomagnetic field intensity is changing cyclically. There is no explanation as to how the geomagnetic field polarity has stayed the same for millions of years and then in other periods has changed in polarity roughly 200 kyr. This is an unsolved puzzle awaiting a break though. There is no explanation for extraordinary rapid geomagnetic field intensity and field direction changes.



    [QUOTE][B]New evidence for extraordinary rapid change of geomagnetic field during a reversal[/B]

    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]


    [QUOTE][B]Is the geodynamo process intrinsically unstable?[/B]

    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 30^100 kyr; it may not therefore be as stable as we thought.[/QUOTE]


    [QUOTE][B]The tectonic and geomagnetic significance of paleomagnetic observations from volcanic rocks from central Afar, Africa[/B]

    [B]Reheating and partial remagnetization by the overlying flow cannot explain either of the transitional directions because both differ significantly from that of the reversely magnetized overlying flow.[/B] The high-temperature component gives a VGP in the northern Pacific, whereas the lower-temperature component gives a nearly antipodal VGP south of Cape Town, South Africa. [B]Hence, the configuration of the geomagnetic field appears to have jumped nearly instantaneously from a northern-hemisphere transitional state to a southern-hemisphere one during this normal to reverse polarity transition.[/B]

    Last edited by a moderator: May 4, 2017
  11. Oct 3, 2009 #10

    From the Nature link in post #2 above;


    "The time it takes for this process to happen, however, remains uncertain, with estimates ranging from a few thousand up to 28,000 years. Here I present an analysis of the available sediment records of the four most recent polarity reversals. These records yield an average estimate of about 7,000 years for the time it takes for the directional change to occur."

    So, that researcher is actually reporting on his work to "average" the results of others' models and reports he has found some latitude related basis for variance from the 7,000 year average... or am I misunderstanding the brief summary at that link?

    The other thread;
    is fascinating! In my post (#3 above) I mention "geomagnetic excursions" and give a link to a wikipedia article on the subject. Are these "excursions" the same as the "jerks" you refer to?

    In your study of this subject, have you come across any work related to the expected atmospheric effects during a reversal/excursion/jerk?
    Last edited by a moderator: May 4, 2017
  12. Oct 3, 2009 #11
    I believe the researcher is either ignoring is not aware of the observations that invalidate the core causing the rapid geomagnetic field changes.

    There is correlation with super volcanic eruptions with the end of deep solar magnetic minimums.

    There are recurring burn marks on the surface of the planet with sets of burn marks all dated within a narrow time period in the same hemisphere. There are overlapping burn marks that show evidence of re-striking. The burn marks in one case are elliptical in shape and point along the same axis. Imagine the earth turning and strike after strike occurring from the ionosphere down to the surface of the planet.

    What it appears is the solar magnetic cycle is interrupted regularly and when it restarts there are massive coronal mass ejections (CME). The coronal mass ejections cause flash over from the ionosphere to the planet's surface. There is evidence that other stars like ours have these massive abnormal events.

    This observation of a region in which a group of volcanoes suddenly erupt together would be a location that has been struck by the flash over from the ionosphere to the planet's surface.

    Vulcanologist note this an anomaly as the volcanoes in questions do not share the same magma chamber. They hypothesize a sudden massive mantel change in one area as the cause. That is not a reasonable explanation for the observations as there is no internal mantel forcing function that can causes rapid changes in the mantel. (i.e. Mantel changes are on geological time scales.)

    The massive flash over from ionosphere to the planet's surface also explains how super volcanoes form.


    Last edited by a moderator: Apr 24, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook