See my comments in Nbr 51: The movement of the north magetic pole in the last few years is striking.
As for the possible impact of a polarity shift... I think that we may be overlooking rather serious ramifications. The Van Allen Belt which deflects the majority of gamma radiation that emanates from the sun destined for the Earth, is an electromagnetic field that is created by the Earths polarity. If that polarity is neutralized - even for a few days, or weeks or years - the increased radiation impacting the Earth could have quite significant impacts. With that in mind, and I hate to admit, that the scenario presented in The Day After Tomorrow, could be quite ... uh, feasible (With the exception of that Liberty ice rink.)