Pole shift

[Revy]

also known as reversal of the Earth's magnetic field. I watched a documentary on this on NatGeo and it was scary how they said we were overdue for one. I can't remember them going into much detail on what would happen but they said that civilization as we know it would collapse because the electricity would go down, I also think that they said drastic climate changes (even more so than now) would happen.

maybe it will happen in 2012...after all, NASA says that the Sun is going to reverse polarity in that year. but a solar pole shift is supposed to be different and happens more frequently...while an Earth pole shift is supposed to be frightening and catastrophic.

[JazzRemington]

Polarity shifts happen quite frequently. I can't recall how often they happn, but they've occurred while human civilization existed and nothing bad happened.

[AK]

I nearly shat myself reading something about this a few years back.

[piet11111]

Polarity shifts happen quite frequently. I can't recall how often they happn, but they've occurred while human civilization existed and nothing bad happened.

It never happened to a high tech society.

[RedAnarchist]

What exactly would happen anyway?

[JazzRemington]

What exactly would happen anyway?

Nothing.

Also, I looked into pole shifts a little and from what I can tell it's just an hypothesis that isn't fully accepted by scientists. The poles do wander, but only at a rate of 1 degree every few million years.

[Revy]

Ever heard of the South Atlantic Anomaly? It's a hole in the upper atmosphere through which high levels of radiation from the Van Allen belt enter. And it's known to be growing.

according to this (http://www.bgs.ac.uk/research/highlights/southAtlantic2010.html), the last reversal was 800,000 years ago.

[JazzRemington]

Are yout alking about shifts in the MAGNETIC field or the poles of the Earth? Those are two different things. Pole shifts are debatable, from what I've read, but the magnetic fields of the earth do shift every once in a great while.

[Manifesto]

I am not saying that the Earth's poles will shift I don't see how thats possible at the rate people are thinking of at least. But according to NASA (http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html) during the change the it gets more complicated and does not disappear as some people seem to think. Also the North Magnetic Pole is apparently moving at 40km a year.

[mikelepore]

The danger is, if the magnetic field reverses polarity, there could be a significant amount of time where the field intensity is near zero. High speed protons and electrons from the sun would reach the earth's surface. It would disturb the electron configurations in the genetic material of some number of people and cause cancer.

[Manifesto]

........It just gets complicated not disappear.
http://www.nasa.gov/images/content/54559main_comparison1_strip.gif

[mikelepore]

Not disappear, but we don't know the magnitude either. The magnetic field of the earth has a magnitude of about 1 gauss, and, as it is, we're not all dropping dead from solar radiation or having deformed babies. If the system gets disturbed, nobody knows.

Also we can't tell from the thicknesses of the layers of magnetic rocks how much time such a disturbance usually lasts, because in geological time a hundred years or more is only an instant. We just find a layer of magnetite crystals with the domains pointed one way, and right above them is a layer with the domains pointed a different way. If we are exposed to the solar wind or coronal ejections for a short time we may encounter no problems, or be able to hide behind barriers, but if it goes on for a long time then I believe people won't survive.

[Manifesto]

Ok it just seemed like by almost completely zero you thought it meant it would disappear. What do you mean by "Also we can't tell from the thicknesses of the layers of magnetic rocks how much time such a disturbance usually lasts" though? But since this happens say around every million years hard to say what would happen to humans but my guess is that it would be little different from other animals.

[mikelepore]

When lava solidifies, if it contains a significant amount of iron, which basalt (oceanic crust) does, the new rock forms small grains in which all the iron atoms are rotated a particular way, to have their atomic magnetic fields aligned parallel to the earth's magnetic field. The rock stores a permanant record of where the earth's poles were when the rock was formed. So if you look at layers of younger rock on top of older rock, or if you look at the side-by-side regions of basalt that squirted out of the mid-Atlantic ridge at various times, you can see a timeline of the earth's magnetic poles moving around. The change of the poles is sudden, relative to the geological scale of time, so we don't have any data about what happens at the moment the flip occurs. It probably can't be sudden relative to human time, because it takes a while for the convection in the earth's mantle to take a new path, or the crust to slide on the mantle.