The Earth's magnetic field is incredibly weak compared to any device that incorporates magnetism in its design. For example, I have a screwdriver bit holder that contains a tiny magnet, but it is sufficient to hold screws into the bits against gravity, so I don't have to hold a ladder, a screwdriver, a shelf, and a screw all at once. If background magnetism had any significant force then you would expect iron filings and small bits of metal to magically zoom off to the horizon.

There would be no effect on electrical or electronic machinery (generators, motors, PCs, phones). (Don't confuse earth's magnetism with solar storms, which are charged particles from the Sun and do mess with communications and sometimes overhead electrical cables.)

GPS is not magnetic - it uses radio signals from satellites.

The few things that might be affected include:

Magnetic compasses would "change ends". Presumably during the transition there would be a period of zero magnetic field, which would make orienteering slightly harder. Remember that compasses already suffer from "magnetic variation" because the magnetic poles do not align with the geographic poles: we would just have to work with a variation close to 180 degrees, effectively.

We would lose some radio wavelengths for long-distance radio. This is because the combination of solar wind and magnetic field trap several ionised layers high in the atmosphere, and these reflect radio round the curve of the earth. FM, satellite and DAB are line of sight and would not be affected.

The magnetic field also diverts the solar wind around the earth to a great extent. Reversing the direction would not matter, but during any period of transition the earth's surface could receive high amounts of solar particles which can disrupt DNA and mess with electronics - a permanent solar storm, effectively.

And we would probably lost the Aurora Borealis and Aurora Australis during any transition, too.

I have been participating in a discussion on the subject on another blog and frankly, although a lot of people have been worried about inversion of the magnetic poles, I cannot bring myself to share their concerns. Certain kinds of radiation (basically, all the uncharged particles, including photons) are not much affected by the magnetic field, the magnetosphere, so it should not make much difference to them.  All the charged particles get stopped very effectively by the atmosphere, whether the magnetosphere is present or not. It is not clear how much our magnetosphere currently intensifies the rate of charged particle bombardment at the poles, but to get some idea of how effectively the atmosphere stops and absorbs incoming  charged particles, have a look at some pictures of aurorae to see how far above the Earth they peter out. So I do not expect much biological effect anyway. Then there is the effect on the infrastructure, mainly electricity distribution and so on, though some people have been worried about electrochemical effects on pipelines and the like. The sometimes very damaging effects that we have had anyway, magnetosphere and all, have not been caused by charged particles penetrating the atmosphere, but by currents induced by charges moving high up in the sky. It it seems a fairly safe bet that we could expect differences in such behaviour if the magnetosphere was reduced or shifted, but at the same time, it is not at all clear that the effects would be more harmful than at present. Firstly let's  assume that magnetic storms would become a great deal more of a problem than we are used to (which is what most people think.) Then all we need do is to change our practices in infrastructure design, to accommodate more and larger surges. That would make a big hole in our infrastructure budget, because anything affecting infrastructure always is jaw-droppingly expensive. Forgetting magnetospheres for a while, just assume that all the wall plugs or light bulbs in Britain had to be changed all at once. Trivial? Sure. No new technology to design and train for, just send out a few electricians and get it over with, right? Well...  ...  ... sort of ... You would be talking of a bill of many billions at least! But you would not be speaking of the end-of-civilisation-as-we-know-it! Same with upgrading the distribution network, say I, except that the technology would not be so cut-and-dried. It might even be a good thing if it forced us to bring the infrastructure up to scratch. Already we suffer every time a squirt of charged particles comes our way! But it is by no means clear that the situation would in fact get any worse without the magnetosphere. It might be about the same as now, or even better. The magnetosphere not only deflects particles, but directs them into the high atmosphere in concentrated masses that are responsible for the problems that we occasionally suffer already. Without that shepherding, the surges should be smaller and more diffuse, even if more frequent. So, for my money, no big worry; more of an interesting experience. Fortunately we no longer are dependent on magnetic compasses for major navigation. Maybe someone will re-publish "Nature is Your Guide" by Harold Gatty, for the benefit of Boy Scouts. (They would benefit for sure, and so would a lot of other people!) Cheers,   Jon  

Paul, in case my previous reply strikes you as extravagantly irrelevant, confusing and confused, you may well have some justification. I was trying to look up some recently scrolled-off messages, and my confusion titre exceeded my scope of calibration. This blog software is driving me nuts!

Sorry about that!

Oh, and one thing I don't have is quantitative data about the magnetosphere or solar wind. In a non-quantitative way I can argue strongly that there is precious little support for any catastrophic consequences of exposure to ionised particles if we lose the magnetosphere.

That's about all!

Hello,

those "flips"  occur every 200 000 to 300 000 years.

The time for a "flip" is rather short in geological terms, but

nevertheless it takes some thousand years, first the field

weakens and vanishes, later the field grows strong again

in the opposite direction.

This is knowledge from reading Sciam over the past 30 years.

This process will not affect power nets, it is too slow.

(Faraday's law)

When magnetic storms come from sun and enclose earth,

the earths field is "compressed" a little bit, this causes

small variations in the field strength on earth. This effect  is

strongest close to the magnetic poles, problems (shutdown, fuses blow)

in Canadian power grids happen.

Georg