Earths magnetic field

[colinha]

When the Earths magnetic field reverses at some future date, will it just rotate or will it reduce to zero and increase to its new opposite new position?
The difference is that the protection from solar radiation will disappear in the latter case causing severe damage to ecosystems.

[boxtops]

why will the protection disappear?

[Huderon]

http://www.geomag.bgs...cation/reversals.html might be worth reading

[DTCwordfan]

You will have to buy a new compass.

[jake-the-peg]

From what I recall there will be 50 - 100 years without a magnetic field

It has happened many times before and the ecosystem has survived but there will doubtlessly be issues.

Some people think that we could be in for a reversal reasonably soon (geologically speaking that is)

[ChuckFickens]

"From what I recall there will be 50 - 100 years without a magnetic field"

Didn't realise you were that old, jtp. :)

[dave50]

What causes it to reverse?

[jake-the-peg]

What I recall reading - cheeky bu66er!

I'm not sure anybody is precisely sure Dave.

The magnetic field comes from the spinning metalic core and it's almost certainly to do with convection currents of the liquid outer core.

We do know it's strength has dropped 10% in the last 150 years or so

[jomifl]

We will get to see the aurora australis without having to go to the south pole, so not all bad..

[Old_Geezer]

http://www.bbc.co.uk/news/uk-14678002

I can see why one would be concerned about protection from solar radiation disappearing, because there is already a "South Atlantic Anomaly" where satellites could be affected. I'm unsure whether this means a wider scale problem for life on Earth though. Maybe we all need factor 100,000 sun screen ?

[beso]

jomifl \\We will get to see the aurora australis without having to go to the south pole, so not all bad.. //

Ironically (or should that be ionically) probably not. The auroras are caused by the charged particales being driven to the poles by the geomagnetic field and concentrated.

[jomifl]

Beso, I was just being silly as it would still be the aurora borealis as it's name is determined by the name of the geographic pole where it exists rather than it's magnetic polarity(I believe). incidentally do you know if there is there any difference in the 'spectrum' of ions that occur at the poles and the consequent light effects?

[flobadob]

I think it's a slow process, the poles are constantly changing.

[rov1100]

They had an interesting program about this on Horizon...should be available still on BBC I-tube. Scientists were doing meaurements about the inner earth and its liquid core. By measuring earthquakes from one side of the Earth to the opposite side they were able to fathom its makeup. For instance although there is a molten layer swilling about there is a central solid core.

They correlated this with space measurements being taken and a spike occurred shutting all communications for a brief second. They found an area in South America caused the faulty readings where compasses lost their ability to function. This area is spreading and within a decade or two it will be large enough for the poles to slip and reverse polarity.

[rov1100]

Obviously should be BBC I-Player

[jomifl]

Not obvious to me Rov.