Here is a topic we will study during the E&M portion of our AP Physics C course - the magnetic field of the Earth. Over the past few centuries, scientists know the magnetic field, created from the motion of the molten iron core of the planet, has been weakening. New data from the Swarm satellite show the field is declining about 10 times more rapidly than previously thought, or perhaps it has been happening at an accelerating pace over the past century of measurements. Either way, this declination of strength suggests the possibility of the Earth moving into another episode of magnetic pole reversal. Computer simulations show that a decline begins prior to when a reversal takes place, and the Earth has not seen a reversal for some 800,000 years - this is quite a bit longer than the 200,000 year average over geologic time, so some would say we are 'overdue' for a reversal. So, perhaps within the next 500-1000 years, a reversal will occur.
We do not know the full consequences for civilization, since the last time it happened we have no witness accounts or accurate data. We would expect higher doses of cosmic radiation, but it is not clear (as far as I can tell) what the health and biological consequences of this would be. Other concerns would be the effect of higher radiation rates on the electronics on the ground, such as telecommunications networks, wireless technologies, and the power grid.
Check out the Scientific American article.