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

Reversal of Magnetic Field = No Magnetic Field?

[Spock the Baptist]

I didn't see any mention of a loss of the Terrestrial Magnetic Field in the article, only a change of polarity. The two (polarity reversal, and field loss) an not necessarily equivalent, at least over long time scales.

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.

Can GPS substitute?

[Thinkit4]

So our compasses would be screwy. Couldn't we use GPS to give direction?

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.

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: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

.

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: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.