SCIENCE: Magnetic Shifting of Poles

The Earth's geomagnetic field is what causes a compass to point north. The geomagnetic field itself fills the planet itself, as well as extending into space. However, it usually finds its main purpose on the surface of the Earth, with compasses. For example, magnetite material may arrange itself to be aligned with the geomagnetic field. 

Every few hundred thousand years, the earth's magnetic fields flip. For example, one effect of this would be that compasses would point south instead of north.

Would such an event have any major negative effects on life on Earth?

Historically, from what scientists have discovered from looking at the fossil record, the answer is, surprisingly, no. According to the fossil record, this shift has never really had much of an impact on life. 

There would be other effects, however. For instance, it would allow for an Aurora Borealis to occur at any latitude. 

(Information From "halexandria.org")