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Science

Earth's Magnetic Field Weakens 10 Percent 90

Posted by michael from the boy-scouts-getting-lost dept.
caryw writes "Interesting story from the AP. 'The strength of the Earth's magnetic field has decreased 10 percent over the past 150 years, raising the remote possibility that it may collapse and later reverse, flipping the planet's poles for the first time in nearly a million years, scientists said Thursday. At that rate of decline, the field could vanish altogether in 1,500 to 2,000 years, said Jeremy Bloxham of Harvard University. Hundreds of years could pass before a flip-flopped field returned to where it was 780,000 years ago. But scientists at a meeting of the American Geophysical Union cautioned that scenario is an unlikely one. "The chances are it will not," Bloxham said. "Reversals are a rare event."'"
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Earth's Magnetic Field Weakens 10 Percent More

Earth's Magnetic Field Weakens 10 Percent

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  • X Men (Score:5, Funny)

    by AtariAmarok ( 451306 ) on Friday December 12, 2003 @10:46AM (#7700389)
    Now, when Magneto is weakest, it is the time for the X-Men to strike and remove the threat of the Brotherhood of Evil Mutants forever!

  • Wasn't this on PBS? (Score:4, Informative)

    by Micro$will ( 592938 ) on Friday December 12, 2003 @10:59AM (#7700566) Homepage Journal
    Or was it Discovery channel?

    Apparently this is supposed to happen every 600,000 years. During the flip everyone on Earth will be exposed to elevated levels of cosmic/solar radiation increasing the chances for cancer. The good news is we'll have multiple auroras all over the planet as the fields move around.
  • but we're overdue
  • This issue was covered prety thoroughly on PBS's NOVA [pbs.org] a couple of weeks back.

    My TiVo captured it but I'm not going to let my kids watch it because it's pretty alarmist IMO (and, frankly, there's nothing we can do about it anyway).

    Or maybe we can [imdb.com]?

    • Re:This was on NOVA a week or two ago (Score:5, Interesting)

      by dgodwin ( 732273 ) on Friday December 12, 2003 @12:24PM (#7701666)
      I didn't think it was too "alarmist" as towards the end they talk about the only major negative effects of a weakened magnetic field and eventual switch is a slight increase in cancer (compared with all the cancer in the world as we know it today.) It also presented the possibility of having more than 2 poles, and a positive effect of the was having the auroras being visible all over the Earth. I showed this in my Earth Science classes this weeek, as we just started talking about how magnetic reversals are recorded in igneous rock, and is one of the pieces of evidence for sea floor spreading and plate tectonic theory.
      • Well, the first half of it had a certain OMG WE ALL GONNA DIE tone to it that I didn't expect from Nova. After that it all settled down and got to the "Yeah, background radiation will go slightly up, but hey, more auroras!" gist of it.
      • The biological effects of pole reversal/collapse is a subject of much debate, but it seems the height of ego to say it will be pretty, slightly cancerous, and that's about it.

        The following quote is from here [lsumc.edu]. But there are any other good resources out there.

        "There have in fact been two periods in which mass extinction of a number of species, composed of a great number of individuals, occurred. One of these, at the close of Permian period, was characterized by the disappearance of nearly half of the spe

  • Geomagnetic field weakening (Score:2, Interesting)

    by Anonymous Coward
    As usual, I will probably be marked as flamebait, but sometimes people read rather than mod, so I'll post anyway. Creationists have done discussions on the earth's magnetic field before, which is one method that shows a young date for the earth: http://www.creationresearch.org/crsq/articles/39/3 9_1/GeoMag.htm [creationresearch.org]
    • Well, you were wrong, you were modded offtopic, not flamebait. A metamod should mark that unfair, as your link was ontopic. The creationist arguments about the magnetic field are pretty weak, though. The author shows that the total observable energy of the magnetic field over a century has declined, but admits that the data is good only for the last thirty years. He claims that as proof the field's energy has been steadily declining ever since creation. Unless God handed International Geomagnetic Refe
      • No particular reason. I guess I felt it was less likely I'd be modded down if I was AC - which means the article will actually still be visible. Some people seem to feel there's some crusade worth waging, rather than actually talking about it.
        • Yes, a post made as AC would be less likely to be modded down than a post you make while logged in, but that is because AC posts start at 0, while your logged-in posts start at 2 (with bonus.) A post at 0 is less likely to be modded down than one at 2, simply because it is already lower. Even with it having been modded up, the AC post is (currently) only at 1, and so is less visible than if you had posted it logged in and it had no moderation done to it.

    • Uh, very convincing (Score:5, Informative)

      by Hamster Lover ( 558288 ) on Friday December 12, 2003 @03:11PM (#7703861) Journal
      First, there is overwhelming evidence that the dipole component of the magnetic field has diminshed, reversed and strengthened only to diminish and reverse again many times.

      Second, the measured dipole field strength is only one component of the total field strength. Extrapolating the age of the earth based on the dipole field strength alone is not based on any accepted science.

      "Scientific" Creationists like to believe that they're using science to support their theist assertions, but that is just the problem. Science does not presuppose any conclusion and is effectively neutral any subject until logic, reason and experimentation point the way.

  • In Soviet Russia... (Score:4, Funny)

    by Lshmael ( 603746 ) on Friday December 12, 2003 @11:23AM (#7700853) Homepage
    ...the poles reverse...oh wait...

  • Ummm... (Score:4, Interesting)

    by Anonymous Coward on Friday December 12, 2003 @11:31AM (#7700966)
    "The weakening -- if coupled with a subsequently large influx of radiation in the form of protons streaming from the sun -- can also affect the chemistry of the atmosphere, said Charles Jackman of NASA (news - web sites)'s Goddard Space Flight Center.

    That can lead to significant but temporary losses of atmospheric ozone, he said.

    Ozone Holes??

  • Not weakened 10%! (Score:5, Informative)

    by Anonymous Coward on Friday December 12, 2003 @11:32AM (#7700972)
    The north-south polarity may have weakened 10%. The totality of the field remains the same. The north-south polarity appears to be randomizing as it realigns into a south-north flip.

  • rare? maybe, but (Score:3, Insightful)

    by Random832 ( 694525 ) on Friday December 12, 2003 @11:33AM (#7701001)
    "The chances are it will not," Bloxham said. "Reversals are a rare event."'"
    but overdue. these aren't governed by random chance like gambling; there _is_ a cycle

    • Re:rare? maybe, but (Score:5, Interesting)

      by GeoGreg ( 631708 ) on Friday December 12, 2003 @02:34PM (#7703418)
      Maybe. Many natural events can be modeled quite well as random variables following a particular distribution. I don't know whether magnetic field reversals follow such a pattern. However, the rate of reversals has varied significantly with time. For instance, there was a 37 million year period of stability during the Cretaceous period. More recently, the time between reversals has varied from less than one million to around 5 million years. And reversals in the mid- to late-Jurrasic were more frequent than any time since. (see this link [agu.org]).

      The mechanism behind magnetic field reversals is poorly understood. I haven't seen any statistical analysis, but I would be interested to know if magnetic field reversals can best be modeled as periodic or as random, with some sort of variation about an expected value. It may be more accurate to say that the probablility of a reversal in any given year is increasing, rather than saying we are "overdue". Or maybe that is just splitting hairs.

      • It may be more accurate to say that the probablility of a reversal in any given year is increasing, rather than saying we are "overdue". Or maybe that is just splitting hairs.
        I don't see the difference between the two phrasings, personally... that's what "overdue" means to me when referring to a natural event. the statement that just because it's rare means it's unlikely implies that there's a fixed probability of it happening on any given day.
    • there _is_ a cycle

      Not really, it's pretty chaotic. I took a first-year Earth Sciences course at my university, there were charts of pole reversals over time. Sometimes they happen quite frequently, sometimes it takes bloody forever.
    • The earth is a non-closed, changing system, so things can change without full predictibility. Overdue-ness is not something we can completely predict, we can only guess at it based on historic data.

  • can we fake one (Score:3, Interesting)

    by kippy ( 416183 ) on Friday December 12, 2003 @11:54AM (#7701291)
    This is just a hair-brained idea a-la "I Love Lucy" but would it be possible to generate a fake magnetosphere in the event that we are without one for a few hundred years?

    IANAP but would it be possible to place a giant electromagnet at L1 and have it deflect incoming Solar wind and particles?

    It would probably have to be very powerful and possibly large (nuclear powered, 100 KM long) but would that work?

  • Why should we care? (Score:2, Informative)

    by Coppit ( 2441 )
    Losing the magnetic field would cause some big problems. First, the magnetic field acts as a shield which diverts the solar wind to the poles. (That's the aurora we see.) I don't know about you, but I don't want to wear sunblock every day.

    Second, much of our electronic communications would be interrupted without this protection. For more information see this FAQ [phy6.org]

    • Sunblock wouldn't help much against high energy protons, electrons and alpha particles. UV light isn't deflected by magnetic field.

      OTOH, I don;t think anyone expects the mag field to disappear - just move.

      • Re:Why should we care? (Score:5, Informative)

        by barakn ( 641218 ) on Friday December 12, 2003 @01:45PM (#7702735)
        I think there's a problem with those high energy protons destroying ozone (mentioned in TFA), so sunblock might be necessary. And even if the total field doesn't weaken, during the reversal the dipole moment of the field will, leaving quadrupoles or octopoles or something. A magnetic field parallel to the ground is a good shield against charged particles, but a perpendicular field (a pole) actually guides charged particles towards the ground, hence phenomena such as aurora. If a pole erupts in my neck of the woods, I'd seriously consider moving elsewhere. Or dust off the ol' tinfoil hat and put it on.

  • Didn't we already discuss this ? (Score:4, Informative)

    by freuddot ( 162409 ) on Friday December 12, 2003 @12:03PM (#7701418)
    Magnetic Poles May Be About To Flip [slashdot.org].

    So, all the discussions about end-of-the-world, and creating our own magnetic field are already available there. ;-)

    J.

  • There was a great Nova about this (Score:5, Informative)

    by michaelggreer ( 612022 ) on Friday December 12, 2003 @12:16PM (#7701550)
    It was called "Magnetic Storms." A little sensationalistic, but it does appear that we are a few millennia overdue for a flip. A flip is preceded by just this kind of drop in magnetic force, as "islands" of positive polarity start appearing in the negative area and visa-versa. Already a big one near Antarctica.

    Take a look at the website [pbs.org]. It has a great video of a simulated flip [pbs.org]. Scary stuff.
    • That stupid show was more than a little sensational it was downright alarmist. I already knew about the pole switching phenomenon so it didn't scare me but if you hadn't heard of it before they made it seem like doomsday. Of course tv watchers today are so desensitized it probably didn't have that much of an impact.
    • The "overdue" claim is arguable: sometimes it hasn't flipped for very long periods.

      The whole 10% decrease thingy bugs me. It looks like a complicated oscillation. Yes, today's level it 10% less than 30 years ago, but higher than it was a couple of hundred years ago. So what?

  • Paleomagnetism is Real. (Score:5, Insightful)

    by cupofjoe ( 727361 ) on Friday December 12, 2003 @12:23PM (#7701650)

    I, too, agree with those who have cited the period nature of these types of events.

    The scientific tracking of this phenomenon - within the bounds of a burgeoning field called paleomegnetism [google.com] - has shown that such events have been seen already.

    If I remember correctly, the seafloor around the Mid-Altantic Ridge shows local magnetic field lines (embedded in rock) that exhibit directional reversal on a regular basis. The regular, gradual creation of new seafloor on both sides of this band of spreading magma locks in the direction of Earth's general magnetic field at the time of formation - showing, some think, that these occurrences are regular and repeatable.

    And yes, we're definitely overdue. But, we're also overdue for a planet-killing asteroid impact, so I guess there's nothing to worry about. What's a little field instability among friends?

    It should be noted, however, that there is some notion that periods during which magnetic shielding is lost probably does wonders for increasing evolutionary branching. Think of all the natural selection that gets done under such extreme environmental pressure...


    Sorry for the ramble. IANAP, by the way, but IAAPT (teacher).

  • My compass collection... (Score:5, Funny)

    by Big Sean O ( 317186 ) on Friday December 12, 2003 @12:32PM (#7701775)
    ...is about to go on eBay.
  • see, this is a great example of how 'left'/'right', 'up'/'down', 'positive'/'negative', 'clockwise'/'counterclockwise', and other conventions can be clung to and allowed to distort the truth.

    for example, you care really badly which way compasses point, or more generally you care a lot about the polarity of magnetic fields staying how they are.

    oh, really? well, do you care much at all about which way around the toilet your water swirls as it goes down the drain? of course you don't -- and it's a good thing

  • Pointless estimation? (Score:5, Interesting)

    by barakn ( 641218 ) on Friday December 12, 2003 @01:14PM (#7702360)
    At that rate of decline, the field could vanish altogether in 1,500 to 2,000 years, said Jeremy Bloxham of Harvard University. Hundreds of years could pass before a flip-flopped field returned to where it was 780,000 years ago.

    As I recall from the Nova program, a field reversal was essentially caught in the act by a single layer of lava. The interior of the lava flow had frozen in it a magnetic field 6 degrees different from the field frozen in the top and bottom of the flow, which cool faster due to contact with the atmosphere and the ground. This happened in a short period of time (days or weeks?). So saying "at that rate of decline" is pointless, as the rate of change would probably increase during a reversal. To illustrate, I'd like to point out that the north magnetic pole has been migrating further north [nrcan.gc.ca] at an accelerating pace. Although the link's text claims the acceleration occurred around 1970, their map shows it started sometime between 1904 and 1948, with perhaps a brief deceleration in the '60s.

    And the sun is becoming more active at the same time. Things could get quite interesting on our little planet.

  • Curious (Score:5, Funny)

    by JediTrainer ( 314273 ) on Friday December 12, 2003 @02:35PM (#7703434)
    I think I saw a documentary on this. It's related to the centre of our planet stopping spinning or something like that, and they need to send some nukes down there to restart it.

    I think the documentary was called 'The Middle', 'The Core', 'The Deep'... something like that.
  • So should I freak out or not -- it really doesn't say so (does it?)...

  • AL GORE + KYOTO PROTOCOL === SAVE THE MAG FIELD (Score:3, Funny)

    by JeffMagnus ( 133746 ) on Friday December 12, 2003 @04:52PM (#7705143) Homepage
    If Americans had elected in Al Gore in '00, we'd have the Kyoto Protocol in place and mans affect on the magnetic field would have returned to 1988 levels!

    The Republicans are robbing us of our magnetic field!!!!!!!

  • Finally! (Score:5, Funny)

    by Malfourmed ( 633699 ) on Friday December 12, 2003 @07:16PM (#7706782) Homepage
    flipping the planet's poles for the first time in nearly a million years

    At last, Australia will be on top of the world again!!

  • Why should we worry? (Score:1, Funny)

    by Anonymous Coward
    I mean really, no matter how bad the radiation gets outside, it's not like we're gonna be feeling it. Hey, maybe with all the skin cancer, being pasty white will even be considered a sign of good health, and geeks will reign supreme.

    Nah, wishfull thinking...

  • "the field could vanish altogether in 1,500 to 2,000 years"

    I'll cross that bridge when we get to it.
  • The strength of the Earth's magnetic field has decreased 10 percent over the past 150 years... At that rate of decline, the field could vanish altogether in 1,500 to 2,000 years

    I just excreted .25 kg (just a wild guess; rounding to a fourth) into the toilet in the last 5 minutes, i.e., my body mass has decreased .15% over the past 5 minutes. At that rate of loss, my body could vanish altogether in 25 hours!

    (I may not have done the math right (it's almost 4am), but you get the point.)

  • Could this be why big animals roam the earth in cycles? Less gravity... bigger animals? First big insects (dragonflies with two feet wingspans), big saurians, big mammals... what's next? Shaq?
  • for global warming? more radiation = more heat in the atmosphere.

    could it also be the reason for Ozone Holes and higher cancer rates?
  • about 7 years ago I was told to look out for the polar switch. The psuedo tribal folks that were predicting it figured it meant that Antartica (the land mass) would switch places with the North Pole. They were predicting that the insides of the earth were going to flip flop, so that it would in effect be upside down. They called this the 'earth changes', and that the earth's crust would be completely ravaged by earthquakes and lava flows, mountains would fall and new ones would rise, cities would be buried,

  • Field, shmield. See? I can rhyme! (Score:1, Interesting)

    by Anonymous Coward
    It's interesting to see that the majority opinion on the temporary loss of a net magnetic field (i.e., no magentosphere) would be nothing more than an inconvenience for satellite communication and herald the introduction of SPF 80.

    IAAP. If we assume the Earth had no magnetosphere, and the soloar wind was not being routed to the poles, then the Earth would essentially be a very massive comet.

    Solar wind has a lot of linear momentum (the proton density is small, but protons have lots of mass). Momentum is a

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