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Chris Higgins
Geomagnetic Reversal
by Chris Higgins - May 18, 2007 - 9:34 AM

What will happen when the Earth’s magnetic field reverses itself? We may find out in just a few short thousands (or tens of thousands) of years!

Magnet

The Earth’s magnetic field has reversed repeatedly over the course of geological history. During such an event, the magnetic poles flip, presumably affecting the magnetosphere (which helps to guide solar radiation to the poles, where the Aurora Borealis and Aurora Australis occur). The most recent reversal was ~780,000 years ago, and we don’t know much about what happened then. It seems that we could be in for another reversal “soon” - although when is a matter of some debate.

When the next reversal occurs, interesting things might occur: compasses will be affected (which would also have a big impact on GPS and mapping in general), migratory birds and fish may become confused, and some geologists think that the reversal could cause volcanic eruptions (due to stresses in rock strata). But of course, we don’t know for sure, since we haven’t been around to witness past reversals.

There’s plenty of interesting material on the web about geomagnetic reversals: a May 10 article from the Economist, a surprisingly thorough Google Answers post, and Wikipedia on geomagnetic reversals are good places to start.

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Comments (6)

  1. I don’t think GPS would be affected directly by a magnetic field change. It’s all based on the timing of radio signals and trigonometry.

    posted by Miguel on 5-18-2007 at 9:52 am

  2. Good point. There is some reference to GPS in one of those links — they refer to problems with satellites in general, though it’s not clear what exactly (magnetosphere changes?) would be going on there.

    posted by Higgins on 5-18-2007 at 2:05 pm

  3. I learned about this in physics. Or at least, I was supposed to. I got the questions about this wrong. While I am quite the physics fan, for some reason I could not remember anything about geomagnetic reversal. Go figure.

    Thanks for posting about this. You have helped me study for my finals in a few short days.

    posted by Lyla on 5-21-2007 at 11:30 pm

  4. In theory, GPS should still work, and most probably, will still work. Alas, they would be locating the same place but with the poles switched it wouldn’t be called the same place…
    …hopefully I’m explaining this coherently, let me try an analogy.
    If you were in a town and they changed the name, you would still be in the same place physically but the town would be named a different place.
    This may be totally illogical, but this is just a theory that popped into my head

    posted by Sarah on 11-1-2007 at 5:07 pm

  5. It’s not the effects to the magnetosphere that are worrying, it’s the effects to the ionosphere - considering that layer of the earth’s atmosphere is responsible for wireless, satellite and radio signal propogation, even a small disturbance can cause some very large consequences.

    A short time ago there was solar activity so intense, it caused enough feedback in telephone cables to set their insulation on fire - and that was just some abnormal solar activity. Think of what would happen if the entire ionosphere suddenly shifted in the electromagnetic spectrum or worse, completely vanished - radio signals may be impeded, blocked or scrambled to the point where they’re effectively useless.

    Radio transmitters are not powerful enough on their own to get signals from one side of the planet to the other - they rely on and exploit specific resonances in the ionosphere to travel, one of which is the Schumann resonance - altogether these behave as a waveguide, to direct and amplify radio/wireless/EM-spectrum based signals. As a species we’ve based practically our entire power grid, communications and networking technologies on this natural occurrence - if we don’t come up with something new soon we’re going to be in for a bit of a shock.

    posted by Nate on 1-10-2008 at 12:12 am

  6. I believe that Geomagnetic Reversal relates to the Galactic Alignment that is currently taken place and will be in full affect around the year December 21, 2012. The 2012 date has been confirmed by a number of scientists and confirmed by ancient Mayan calendars and text. The Mayans were amazingly accurate capturing the movement of our galaxy as it relates to time and have documented epics of time where there was destruction on the earth.

    I would love to hear comments regarding this potential parallel

    posted by Clay on 3-14-2008 at 8:11 pm

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