I know we’ve discussed this before, but it’s coming, and it may not even be Bush’s fault or attributable to global warming:

The Earth could be about to turn upside down. The planet’s magnetic field is showing signs of wanting to make a gigantic somersault, so that magnetic north heads towards Antarctica, and magnetic south goes north. Compasses will point the wrong way, and migrating birds, fish and turtles are going to be very confused.
Just when this will happen, how long it will take and what the consequences will be, is difficult to fathom. What is not in doubt, though, is that it will happen. About every half a million years or so, the Earth’s magnetic field flips upside down.

Of course, if you’ve seen The Core (show of hands: worst science in a movie ever?) we know that we can solve this with the simple application of earth-boring technology and nuclear bombs. Seriously, what problems can’t be solved with earth-boring technology and nuclear bombs?