Hi, That’s a good question. We know that the magnetic poles do flip due to evidence from sediment cores in the ocean. The time bewteen flips has varied from about a million years to about every 250,000 years although it’d been almost 400,000 years since the last flip so many scientists think we are overdue a flip. The word ‘flip’ makes it also sound more dramtic than it is – the magnetic field doesn’t suddenly flip but it gradually decreases in strength, becomes less structured before becoming more structured again with the magnetic pole now in the opposite hemisphere. This can take hundreds, even thousands of years. The magnetic pole is currently moving at quite a fast pace and, from detailed measurements we know that currently the south magnetic pole is moving by about 40 miles every year across Northern Canda. It is also moving about four times as fast now as it was 100 years ago.
The effects on Earth would be interesting. Firstly, our compasses would be effected, effecting basic navigation. A weakening of the magnetic field means we are more susceptable to high energy particles from the Sun (mainly electrons and protons) crashing into larger parts of our atmosphere. Currently these particles are deflected to towards the polar regions where they create the aurora (northern lights). As a consequence of this it would be possible to see the aurora from lot lower latitudes quite regularly. Finally, a lot of animals use the Earth’s magnetic field to navigate with (such as birds on long migration routes). I don’t think there will be a huge amount of problems with regards to the basic compasses and navigation since the changes are occurring over hundreds of years so we can deal with those. I would be more worried about the reduction in shielding from the high energy particles; not, for humans on the ground, since our atmosphere would protect us from most of it, but for satellites in orbit and also when we are on planes at higher altitudes. I am unsure of how the animal kingdom would adapt since I am not a biologist but they have adapted in the past to they could adapt to the changes. The only caveat to that is, last time the magnetic field flipped humans did not have such a large impact on wildlife as we do now.
Hope that answered your question 🙂