A while back on either history channel or nat geo (im talkin early 2000s) there was a doomsday theory centered around this, that the polls could flip or shift, and have done so many times. They mentioned that every time they flipped there was some correlating cataclysm that occured.

Their theory went more or less as follows: Earth spins on a single axis, and it is not completely spherical but elongated at the equator (Oblate spheroid). If the polls were to shift drastically enough then there would be a new axis (new north and south poles) and that the Earth will have to readjust its "oblate" shape to compensate for the new axis. Now because of plate techtonics it is entierly possible for the shape to adjust, but that if this change happened rapidly they believed it would cause some apocalyptic cataclism due to all the continents, plates etc realigning (Earthquakes, great floods, hurricanes, tidal waves, all volcanoes erupting, crackens waking up, darth vader etc.)

Not sure how plausable any of that is or if theres real truth there but could make for a good doomsday movie.