Bad News for Earth's Magnetic Field

jabex writes "Scientific American's website has an article about the overdue magnetic field flip. According to research published in the journal Nature, it could take anywhere from 2000-10000 years to complete. That's a long time without a protective magnetic field."

Comments

The Earth's magnetic field is overrated

[Rapid Home Offer]

Who needs the Earth's magnetic field, anyways? As long as I have my ozone layer, and my handy dandy lead codpiece, everything is going to be okay.

(Doesn't everybody have a lead codpiece?)

Re:The Earth's magnetic field is overrated

[Ieshan]

Protection from a tinfoil hat, you say?

Brings a whole new meaning to the term dickhead.

cautionary notice of threatened death.

[mkavanagh]

any mention of a certain bullshit hollywood production with the shittiest scientific basis for a film since the neverending story will result in death. of the poster. thanks for not getting yourselves killed.

no magnetic field, really?

[Bastian]

I'm no geologist, but it seems strange to me that in the process of a magnetic field reversal the earth's magnetic field would just go away for a few thousand years. Wouldn't the field just rotate over time, so that the magnetic north pole continues to drift until it is near the geographic south pole?

Re:no magnetic field, really?

[JGski]

It's apparently far more complex.

From what I've read on the web and seen on a PBS Nova program about the subject: during a flip the Earth's internal dynamo goes from ordered to chaotic. The movements is not just is a straight bee-line to the opposite side. The North pole, for example, has been drifting even of the last 30 years toward the south east. The field strength declines substantially and the magnetic fields change from bipolar (two poles: north and south) to multipolar ("poles" coming out of any which direction - the "Southern Anomaly" in the south Atlantic is apparently believed by some to be the onset of a tripolar field). When the actually collapse is imminent, these poles start moving quickly, as much as degrees of latitude or longitude per day or week.

Re:no magnetic field, really?

[therealmoose]

No, it's quite complicated (somewhat like a fluid system). Regions of the field spin around, strengthen, weaken, and drift around in complex 3d patterns for thousands of years according to the models (confirmed by geological finds). The net effect is that the field is significantly weaker (due to the lack of a uniform makeup, in part) and in some regions, some of the time, effectively nonexistant. It is not sufficient to deflect the radiation that it currently does while 'flipping'.

Re:no magnetic field, really?

[umofomia]

From what I've read on the web and seen on a PBS Nova program about the subject: during a flip the Earth's internal dynamo goes from ordered to chaotic.

Yep... I've seen this Nova too. It was pretty interesting. For the rest of you out there, here's a link to the show's web site, where you can also see an animation of a computer simulation of a polar reversal. During the reversal, the earth could have poles coming out of the equator even, and if you were able to witness it, you would even see auroras around those poles.

Re:no magnetic field, really?

[maraist]

I'm nervous pointing this out, but in our E&M class we were directed to a pseudo-science web site (our professor assures us that the presented pseudo-science violates certain well understood principles).

But among the dozens of pdf's this web site provides, one is on the ocean rift polar flips.
rift.pdf

In short, what it says is that as the mid-atlantic rift rips apart, hot magma comes to the surface, and that liquid is a lesser magnetic conductor (lower permeability) than the pre-existing high iron-content solid's crust. This plus the 1/r^2 magnetic strength of the source of earth's magnetism (namely the core of the earth) mean that the magnetic fields generated by the solid crust to the left and the right of the mid-atlantic fissure are MUCH stronger than that of the distant core.

The effect of having a closer magnet oriented in the opposite direction is that the next cooling layer of magma will orient it's magnetic field in the opposite direction of the previous layer (to complete the regional loop). Thus every new mid-atlantic fissure eruption / layer, causes a new anti-parallel magnetic field... Presumably, this is what geologists are measuring when they find magnetic poles pointing in differing directions.

As another warning, the wesite uses it's pseudo-science to demonstrate that certain E&M effects would be greater than our classical E&M says it would be for such a fissure reverse polarization.. So please take with a grain of salt.. None the less, I tend to like simpler solutions than a chaotic tri-poled earth magnetic field, or whatever currently is the explanation.. The crux of this pdf makes intuitive sence from a lay-persons' perspective.

Re:no magnetic field, really?

[CheshireCatCO]

"None the less, I tend to like simpler solutions than a chaotic tri-poled earth magnetic field, or whatever currently is the explanation."

Yes, but surely you like an explanation that is *accurate* even more than you like one that is simple. I mean, I can think of simpler explanations for the striping quite easily. (Like, "There is no striping. These are not the droids you're looking for...") But they probably wouldn't reconcile with the various data very well. :-)

(Also, magnetic fields fall off as least like 1/r^3. The lowest order moment is a dipole, remember. At least until someone finds a magnetic monople, anyway.)

To get at the article you linked:

First of all, it suggests that the planets' fields are all oriented the same way with respect to their spins. Not true. See my post, above. Jupiter's field is oppositely oriented to that of Earth, for example.

It goes on to "point out" that Uranus's field is aligned with it's odd spin vector. Surprisingly little research with Google would have shown that to be very wrong. Uranus's spin and magnetic field axes are about 60 degrees apart. That's no where near alignment.

He (I'll assume that the author is male) procedes to blame large amounts of cobalt and iron in Earth's crust for the slightly off spin axis magnetic field axis. Large amounts? The overwelming majority of Earth's iron is in the core or mantle, not the crust. What is in the crust is fairly evenly distributed. It's hard to imagine that the symmetry is broken that much, isn't it? (Sorry I don't have the raw numbers for the distributation, but I doubt that anyone has worked it out.) But if the iron in the core wants to direct the field along the spin axis, how is the miniscule amount of iron in the crust going to "redirect" that field significantly over global scales? (Sure, you've got a bigger lever-arm at the crust than the core. But only by a factor of a few. We're being told that that offsets the massively higher concentration of iron in the core.) Also, why is Earth's field offset as well as titled? (No lever-arm helps you with that one.)

Another interesting error is the (apparent) assertion in the tidal breaking section that Earth will eventually spin 1/28 as fast to match the Moon's orbital period. That's half true, we will match the Moon's orbital period in about 5 billion years. (Just in time to be destroyed by the Sun's red giant phase. Yay!) But a simple knowledge of conservation of angular momentum tells you that we won't be spinning once every 28 days. It's more like a 89 day period, if you work it out. (Funny how he can use conservation of energy to apparently bolster his case when he wants to, but doesn't know what conservation of angular momentum is. While both are adhered to, with the latter it is much harder to "fake" a violation.)

Next up... mass extinctions. He claims that palentologists have determined that they (the extinctions, not the palentologists) occur every 32 million years. Hm. About five mass extinctions in the history of the Earth (the last 65 million years ago) are known (http://www.bagheera.com/inthewild/spot_massextinc tions.htm) spanning back 440 million years or so. That's 380 million years and 4 intervals between them. Quick math check... I get that that's one every 95 million years. (Is that what you get, too?) For proving that exctinction events aren't caused by impacts, that's pretty weak. (Based on the cratering record on the Moon, mainly, the calculated interval between mass exinction causing impacts is about 100 million years. Roughly speaking.)

Next bit of funniness. He claims that "Therefore a reversal in ion polarity would indeed reverse the Earth's magnetic field;" and then goes on to try to show that this is silly. Which is a strawman, since I don't know anyone who asserts that the ions will reverse polarity. How do you get ions to reverse polarity?? Unlike in chemistry, ions in astronomical contexts are essentially

Re:no magnetic field, really?

[meringuoid]

How do you get ions to reverse polarity??

Normally you'd begin by modifying the deflector dish.

Re:no magnetic field, really?

[solarlux]

I think you are referring to the "South Atlantic Anomaly" (not "Southern Anomaly")...

Re:no magnetic field, really?

[barakn]

None the less, I tend to like simpler solutions than a chaotic tri-poled earth magnetic field, or whatever currently is the explanation.

The sun provides an interesting example of polarity flips, which only take 11 years and thus are fairly well studied. The way it does it is different than Earth, as the sun's convective layer is what produces the field, and the convective layer extends to the surface. None the less, during the flip, the sun's surface sprouts many magnetic poles, almost always in pairs. We call them sunspots. Current theory suggests that the polarity flip actually occurs because the sun sheds the old polarity like a snake sheds its skin. It's not the sunspots or x-ray flares themselves that do it, it's the gigantic explosions known as Coronal Mass Ejections that violently heave enormous quantities of magnetic gas/plasma into space. The Earth can't shed a magnetic field this way, which might help explain why it takes so long. Multipole explanations of polarity flips are not that esoteric.

not to worry!

[Tumbleweed]

I'm sure the Highlander will invent a shield to protect us when the time comes.

Dipole to quadrupole to reversal...

[lcde]

I can't find the article on google right now, but the last time i read about this in between the reversal of earths magnetic pole it turns into a quadrupole or higher order for a couple of hundreds of years then it finishes.

Still we won't lose our magnetic field unless our core solidifies, but a field reversal or a higher order magnetic field will allow different polorization of solar winds and other EM noise that would be different that what we have now. We also might not be as well protected against the solar flares during the sun's cycle.

mutations?

[nomel]

Maybe all the particles from the sun that will hit us will cause mutations! Maybe that's what happened before.

I can see it now...
"Play hard, play tough. Nike lead lined athletic wear."

Re:mutations?

[nomel]

yes! Looking into this a little more, the time figure are close...

Perhaps this explains the jumps in evolution observed every 100,000 years or so.

from this article
"The time between magnetic reversals on the Earth is sometimes as short as 10,000 years and sometimes as long as 25 million years; the time it takes to reverse is only about 5,000 years."

Someone should look into this!

Get ready for a new body! Woohoo! :p

.

The poster is a moron

[psyconaut]

"That's a long time without a protective magnetic field".

Actually, haven't you wondered how life existed during previous flips? We don't lose our protection....it's polarity shifts....

-psy

Re:The poster is a moron

[Phexro]

Thank you, I was about to post something similar.

It's a long time to us puny humans, but it's the blink of an eye in the planetary timescale.

are we sure Halliburton

[morelife]

or one of its subsidiaries isn't doing this remotely?

Re:Can GPS substitute?

[bluGill]

Learn to navigate without a compass. I live in an area with many iron deposits, we learned long ago that a compass is not a reliable tool for navigation. We learn other tricks. (Starts at night, guesstimate the time and use the sun during the day). Combine that with knowing about what the land should look like and you can get close enough. Not as easy or are reliable a a compass in other areas, but it works.

Goodbye Van Allan Belt, Hello Cosmic Rays

[StateOfTheUnion]

The original linked article isn't very informative. There will probably be a period of no significant magnetic field while the field is reversing . . . Here's an article about a simulation that to everyone's surprise, actually predicted the reversal.

Goodbye Van Allan Belt, Hello Cosmic Rays . . .

Way Overdue

[jazman_777]

The magnetic field flip, the super-volcano in Yellowstone, the San Andreas Fault, the demise of SCO. Have I missed anything? A Red Sox or Cubs World Series winner?

I for one...

[wronskyMan]

welcome our new cosmic ray overlords! (Well, for at least a couple thousand years)

Re:You sound as if you know what you're on about..

[CheshireCatCO]

Appart from the general off-topic nature of that rambling post, it shows a poor understanding of the data, unless someone has utterly failed to clue me in on some breaking developments in astronomy. (Possible, but my collegues like talking about their work too much for me to think that that's likely.)

You'd better show me a paper that suggest that gravitational redshift doesn't happen, because I have yet to hear of it. And since that'd be Nobel-quality work, showing that GR breaks down (where it should hold up), I'd be surprised if the research happened. In fact, I attended an entire comps on GPS. While GR was certainly discussed, since they need to take it into account for GPS to work, no corrections to that theory were mentioned. Seems sort of odd that the speaker would talk about GR without mentioning that it broke down.

And I have yet to see a steady-state model that matches the data very well at all. The whole "cosmic microwave background" thing is hard to get around. Since I just attended a lecture by a well-known cosmologist and he didn't say a word about the Big Bang being "broken", I will have to once again ask you to back up your rather grandiose assertions.

As for planetary magentic fields:

There are lots of ways that Mercury can have a fluid core, still. The most commonly argued one is to have more sulfur mixed in. This should lower the freezing point sufficiently to keep it molten still. It's also worth noting that Mercury has an unusually large core for its size. This might play in to things.

Mars lacks a global field (today) because it has almost certainly cooled off too far. (If we assume the same composition as the Earth, anyway.) This is supported by the lack of ongoing volcanism or tectonics, which also require a molten interior to proceed. However, in the past Mars *did* have a global field. This is quite consistent with the theory, since it would have been warmer inside.

As far as I know, no one has ever suggested that Venus's retrograde spin is the cause of the lack of a magnetic field. That's fairly silly, since the field doesn't know which "way" the planet is spinning anyway. (Magnetic field on other planets are can be found oriented both ways with respect to their planets' spins and we know that Earth's field has changed direction.) However, the astute person would have noticed that Venus does spin very, very slowly. This would generally lead to a small or non-existant field, since planet spin is thought to be tied in to the dynamo process. (There's a strong correlation between field strength and planet's angular momentum, for example.) Of course, Mercury only spins 3 times faster, but that's still something.

I'd also love to see your proported research showing field changes if 90 minutes or less. How in the heck do you DATE to that accuracy? You can't, unless you pretty much just watched it cool. (In which case, why didn't every compass on Earth notice the switch?)

No one is saying that we totally understand cosmology or magnetic dynamoes. But to suggest that we're "whistling in the dark" is to down-play the wonderful and careful work of far too many people to let you get away with saying that here. We might not have the details all down, but I'd say that we're doing alright on the theories.

It Came From the Core of the Earth!!!

[dexter riley]

Oh, relax. The Core was just a 1950's science-fiction movie with modern glitzy effects. Unobtanium! Sonic drills punching holes in the sides of mountains! Reversing the ship's polarity! If you had gone in accepting that it was a B movie, minus the men in rubber monster suits, you would have had a much better time.

Anyway, I'll go out on a limb here and recommend you skip The Day After Tomorrow , coming soon to a theater near you.

If we have no magnetic field...

[Jorkapp]

Without a magnetic field, we will have (comparatively) little protection against gamma rays from the sun. There are only 3 solutions to living on earth without a magnetic field:

1) Living above ground with SPF 10000 sunscreen being constatly applied
2) Living above ground with a Class 5 hairiness - like those seen on Steve Allen and CowboyNeal
3) Living below ground

Since I hate putting on sunscreen, option 1 is ruled out. Since I don't like Steve Allen, option 2 is also ruled out.

Thus leaving us with option 3. Underground living. It seems bearable. As long as CS is still playable under 30m of bedrock, I'm happy.

punctuated equilibrium

[orn]

The fossil record shows that the Earth goes through periods of time where there is an incredible amount of speciazation - new critters pop into being very quickly. I've read other stuff that suggests that this is simply due to the die-offs: since there's a niche available, something moves to fill that niche.

Could this be a contributing factor or even a causative agent? The normally low error rate in genetic reproduction takes a big spike due to more particles getting through the Van Allen belts?

Re:punctuated equilibrium

[Anonymous Coward]

Could this be a contributing factor or even a causative agent? The normally low error rate in genetic reproduction takes a big spike due to more particles getting through the Van Allen belts?

It could be even simpler than that. Evolution is essentially the movement towards a creature that is better suited towards the environment it is in. When that environment changes rapidly, there will be loads of ways in which a population could differentiate itself to become a better match.

Re:Reversal of Magnetic Field = No Magnetic Field?

[Spazmasta]

From what I read, it sounded like the time of "no magnetic field" was the time during the reversal process - after the reversal is over, everything will be just fine, it's the process that we're worried about, where the magnetic fields aren't quite aligned like they are now, but scattered in a way to diminish the protective effects we get from it.

Re:Can GPS substitute?

[thomastheo1]

what if you have to navigate a wal-mart parking lot on a a cloudy day?

Re:Yeah, yeah, yeah...

[BerntB]

Tell me of any seriously revolutionary idea which you know was accepted with open arms by all.

But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown.

-- Carl Sagan

Also note that there are quite a few more clowns than very good and misunderstood scientists. :-)

Etc, etc.

Go read a book on the scientific method.

Re:Yeah, yeah, yeah...

[CheshireCatCO]

In other words, you have nothing that you can put forth to show what you're talking about. You're resorting to accusing scientists of censoring your results, when in fact we'd be all *over* something revolutationary and new. History is full of examples of this: GR was generally quickly accepted. So was quantum mechanics (the best and brightest young physicists flocked to it in the early part of the 20th century). The Giant Impact model of the Moon's formation took hold quite quickly, too. Sure, we don't just drop an old position. But scientists will listen to new data and theories and if there's anything there at all, usually you'll find a number of them quickly jumping into the new field. (That's how you make a name for youself, after all.)

Basically, your post has all the hallmarks of a crackpot's rantings, I'm sorry to say.

Go on, ignore the references ya coward! (-:

[leonbrooks]

In other words, you have nothing that you can put forth to show what you're talking about.

So says the man who has not read a word of the two references cited in the GP?

Go back and read them, then try again. Meanwhile...

we'd be all *over* something revolutationary and new

As long as:

• It wasn't too terrifyingly different (ie, not too different from our current worldview - or to put it differently, it has to be modestly "revolutationary and new");
  
• we thought we had a plausible answer to quench it with, or at least weren't more than a hairsbreadth away from figuring it out ourselves;
  
• we don't have to rework too much existing theory if we accept it

Without those qualifiers, your assertion is codswallop.

The Giant Impact model of the Moon's formation took hold quite quickly, too.

Pity it's still under heavy dispute then, isn't it? (-:

You might also want to think about a couple of decades in terms of "quickly accepted" and the difference between acceptance of a theory de novo when contrasted with the acceptance of a theory which has already been abuilding for years.

Maybe it's just me, but I rate the functionality of an idea far more highly than its peer acceptance rate.

usually you'll find a number of them quickly jumping into the new field. (That's how you make a name for youself, after all)

I call bullshit. That's how you get fired, or at least get a black mark on your research record which cripples your career.

The "heroes" adopt incremental improvements ahead of the pack. The vast majority of true pioneers, willing to avidly and openly explore genuinely revolutionary ideas, get pilloried for years, sometimes decades, and many die scorned only to have people come around to an understanding of what they were doing long after they're safely buried.

J Harlan Bretz, for example, was sidelined and scorned for forty years before his ideas were even investigated, and for the justification of hearing one of the investigators who was finally cajoled into actually taking a trip out to look at the Washington badlands for an actual look at the rocks exclaim "how could we have been so blind?"

His sin? Heresy. His theories, which are now mainstream and shatteringly obvious in hindsight, challenged the dominant orthodoxy in geology. They sailed too politically close to ideologically sensitive areas, to "political" boundaries which have absolutely nothing to do with science and everything to do with philosophical prejudice, and which still exist.

It's a brave and stubborn scientist who candidly investigates truly novel theories.

Now get off your ass and read, boy!

Re:Go on, ignore the references ya coward! (-:

[fluffy666]

Maybe it's just me, but I rate the functionality of an idea far more highly than its peer acceptance rate.

It is just you. Personally, I look for theories that are consistent with the evidence.

I call bullshit. That's how you get fired, or at least get a black mark on your research record which cripples your career.

I call prove it.

The vast majority of true pioneers, willing to avidly and openly explore genuinely revolutionary ideas, get pilloried for years, sometimes decades, and many die scorned only to have people come around to an understanding of what they were doing long after they're safely buried.

Nice use of the old False Dichotomy argument there. Apparently Newtonian gravity, the Periodic table, quantum physics, etc, etc. were not revolutions(!), but the discovery of a glacial lake dam burst was. Hmmm.

Geology is an especially good subject for this, swince although people have been studying geology in general (or gathering evidence), the basic framework was not really put in place until the 1970s with the development of plate tectonics. Accurate radiometric dating, micropalentology, stable isotope analysis and many other techniques are also pretty recent - yet often essential in proving or disproving old theories. In turn this means that old educated guesses can be proven or disproven. To point that out and then whine on about heresey is, quite frankly, just silly.

It's a brave and stubborn scientist who candidly investigates truly novel theories.

It's also a very brave scientist/person who can turn around and say 'I was wrong' when the evidence disproves their pet theory. Could you do that?

Re:Can GPS substitute?

[sharkdba]

Starts at night, guesstimate the time and use the sun during the day

You have the stars at night.