[Alandriel (OP)]

The Earth’s magnetic field – pretty, isn’t it?



……prettier than me on a bad hair day by far !

It’s an electromagnetic dynamo that sustains itself through positive feedback: the flow of liquid iron in the outer corner together with the magnetic field generates an electric current which maintains the magnetic field which regenerates the current….. and so on.


                                     but


apparently this field is getting weaker, quite rapidly since 1850 or so and some say that his could be a precursor to the next magnetic back flip.


-   Will migratory birds get confused and end up goodness knows where?

-   Will compasses start pointing south?

-   What about all the technical paraphernalia that orbits the earth? Won't it wreck havoc with satelites ?

-   Are the southern / northern lights going to be seen in all zones as the shift occurs?



Any enlightenment and speculations / theories eagerly awaited  []

[ukmicky]

Hi Alandriel

We have already disscused this topic , i will look to see if i can find it for you

[ukmicky]

http://www.thenakedscientists.com/forum/index.php?topic=3011
http://www.thenakedscientists.com/forum/index.php?topic=3012.0
http://www.thenakedscientists.com/forum/index.php?topic=2324.0

[JimBob]

Yes, this has been discussed but nearly 3 years ago in one case.

It is relevant to point out that in geologic time the poles are constantly moving about. (North to south change about every 250,000 years.) In fact at any one time the earth may have more that one set of poles. It does now. If you take time to download all of the charts for total magnetic intensity you can see there are two north poles and two south poles and this does mean that compasses are effected by both. A compass however, point to the mean of the two poles. The geographic point used as the north and south pole are a result of the combine effects of these intensities.

I am not a very good geophysicist and can't explain it as my partner would, but in general what this means is that we are seeing a "pole shift" right now as we measure the fluctuations in the magnetic declination. In some places in Africa the poles appear to move over 1 degree every 10 years.

Fluctuation does not mean that we loose protection against cosmic rays or solar wind, it just means that the way the earth is bombarded changes while OVERALL protection never changes as the inner geomagnetic dynamo is always at work.

The changes seem to not have effected migrations patterns of birds - we have been watching the patterns and they remain constant as the field changes. The changes are slow enough from year to year that it seem migratory fowl adapt to these changes easily.

 

[lyner]

Is there any fossil evidence that, during the N-S shifts, there is any more genetic change? It wouldn't be too surprising, bearing in mind the likelihood of high levels of high energy radiation at ground level.
It sounds a scary prospect to me, more of a problem than the navigation one!

[JimBob]

Not that I am aware of. Climate change seems to be more of a problem and impetus for evolution than any excessive radiation.

I noticed I didn't add the link to the charts for present magnetic conditions. It is at:

http://geomag.usgs.gov/charts/

[Alandriel (OP)]

I've got my reading cut out. Thanks guys  [], especially JimBob for that super link

[I'm sure I'll be back with plenty of n00b questions]

[lyner]

impetus for evolution than any excessive radiation. [/quoe]
I was thinking of mutations.

[JimBob]

Mutations are the random events that VERY X 10⁶⁰⁰ (?) seldom produce an advantageous mutation for the organism AN this mutation is passed on to it's descendants and also is a dominant genetic expression. Mutation is evolution.