Can the Earth’s magnetic field shut down and flip in only two centuries?

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A new study of a stalagmite in China suggests that the Earth’s magnetic field can reverse polarity in as little as two centuries, not the thousands of years as previously thought.

He and his ANU colleague Dr Xiang Zhao from the Research School of Earth Sciences contributed to the study of the paleomagnetic record from 107,000 to 91,000 years ago that is based on precise magnetic analysis and radiometric dating of a stalagmite from a cave in southwestern China.

The stalagmite, which is one metre in length and eight centimetres in diameter, has a candle-like shape and ranges in colour from yellow to dark brown. “The record provides important insights into ancient magnetic field behaviour, which has turned out to vary much more rapidly than previously thought,” Professor Roberts said.

In the past century or so the Earth’s magnetic field has weakened by about 10%. Some scientists think it possible this presages a possible magnetic reversal, which is apparently overdue. However, up until now it was assumed from available data that any reversal would take thousands of years for the magnetic field to shut down and then restart with a flipped polarity. This new data says the shutdown can happen within the span of one human life.

It is unclear to me if this increases our risk or decreases it. The magnetic field acts to protect us from the solar wind and other space radiation. When it shuts down there will be consequences, many negative, that we now can’t even predict. If a reversal is beginning now but takes longer to happen we will have at least a thousand years to plan and adapt, but the period of shut down will be far longer, causing more harm. If it happens quickly we will have to scramble to adapt, but the period of harm will be very short, and thus might not have time to cause significant harm.

Either way, this result is decidedly uncertain, based on a single stalagmite. No one should take it too seriously without further confirmation from other evidence.



  • Mike Borden

    Assuming the power flow could be maintained, would the magnetic field generated by CERN be effective enough to protect the earth from solar radiation if such an event were to occur? From what understand, at 8Tev CERN is capable of producing a magnetic field about 100,000 times that of earths own.

  • David Eastman

    Field strength vs field size… The magnetic fields generated by equipment like that used at CERN aren’t very large, and in fact the area where the field has meaningful strength, but isn’t so strong as to actually be hazardous, is pretty darn small.

  • wayne

    A complete amateur myself, but I concur with David.

    Even at the LHC, the magnetic field drops off considerably (drastically) within a meter or two of the magnets. (it’s like’ 1/10th at 1 meter, but don’t quote me on that)
    (if this wasn’t the case, everyone’s electronics would get fried at a distance, every time they fired it up.)

    >>This is not for the LHC magnets, but does illustrate a similar drop-off curve for field strength/distance.

  • Alex Andrite

    oh oh. Then what ? No more “North Star” ? I will just have to turn my compasses around or something.
    Seriously though, on a similar subject, I find the research on Sol’s poles flipping to be amazing.

  • Tom Billings

    Field size is indeed the proper criterion in this. In the 2000s, NIAC paid Dr. Winglee, at Un. of Washington Plasma Physics Dept. to investigate “Plasma Magnets”, for the purpose of catching the solar wind in a “Magnetic sail” It seemed feasible from his published work.

    The key here is how many could be made in just how much time, to work over the hundreds of kilometers those experiments indicated were possible. If you orbit several thousand of these magnetic sails, with just the field strength to shield the Earth, and not enough to be accelerated out of Earth orbit by the solar wind, then we would have a replacement for the earth’s magnetic field, in that function where it shields Earth’s life forms.

  • Mike Borden

    That makes sense Wayne. Thank you.

  • wayne

    if the interweb is to be believed:

    “The Earth’s magnetic field varies depending on your location on the Earth’s surface. In regions near the magnetic poles, such as Siberia, Canada, and Antarctica, it can exceed 60 microteslas (0.6 gauss), whereas in regions farther away, such as South America and South Africa, is around 30 microteslas (0.3 gauss). Near the poles, the field strength diminishes with the inverse square of the distance, whereas at greater distances, such as in outer space, it diminishes with the cube of the distance. Where the prime meridian intersects with the equator, the field strength is about 31 microteslas. >a typical bar magnet has a field strength of 10 milliteslas, a strong electromagnet 1 tesla, LHC superconducting magnets 8-9 Tesla, a strong lab magnet 10 teslas, and the surface of a neutron star, about 100 megateslas.”

    What is a Tesla & how does that effect Space?

  • Edward

    When a flip occurs, it is not a simple process. It does not resemble a magnet flipping around but has a complex mixing of jumbled magnetic fields. North and south magnetic poles can pop out of the Earth’s surface in a variety of places. Even in normal times, the magnetic north and south poles can move about, making it harder to use our compasses to find true north. No wonder we use GPS for navigation rather than our shipboard or airplane magnetic compasses.

    Right now, we have a weird phenomenon called the South Atlantic Anomaly, which space travelers (manned and unmanned) have been concerned about since shortly after the space age started, because of the increased radiation in that area. It is similar to a weakening of the Earth’s magnetic field, there, but is caused by the magnetic poles not corresponding to the rotational poles. The Van Allen belts come close to the Earth, there, causing radiation problems for satellites and manned spacecraft. Some of its effects can be noticed on the ground.

    The following is a five-minute video that gives a brief overview of what is believed to happen during a magnetic flip (5 minutes)

  • Love our magnetic field, but a reversal would not be the end of the world. We’d still have the atmosphere, and that ain’t bad.

    With the multiple poles during a flip, maybe a locality could experience a flip on the order of a few centuries. The global field might take the expected longer time to completely coalesce to the new direction.

    Couldn’t help but notice they’re not even studying a stalagmite near the time of a reversal. Only off by, what, half a million years.

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