Scientists have known for decades that the earth's magnetic field reverses from time to time, and that magnetic north fluctuates. Some wise guy (the Buddha) said once that everything changes all the time, and the only thing which doesn't change is the process of change. Anyway, the basic idea is that the magnetic field is not a static thing but varies and moves and changes.
Somehow in some circles the Pole Shift phenomenon has become quite a big deal. Many books are out there warning of the Pole Shift and drastic changes to the earths geography due to the pole shift. Some of it's hyped up nonsense, but the truth is that I don't think we have a clear idea of what will happen when the next pole shift occurs. Will it just be a change-around of the magnetics and we'll all have to buy new compass's? Or will mountain ranges crumble and islands rise from beneath the ocean?
Who knows? Dunno.. but this video is of a scientist talking about some of these issues. She is someone whose life work is studying the fluctuation of the earth's magnetic field, and she has a lot of good information to share.