It's happened many times before, here's an article with all the info!
Alternation of the Earth's magnetic polarity. The Earth's internal magnetic field reverses, on average, about every 300,000 to 1 million years. This reversal is very sudden on a geologic time scale, apparently taking about 5,000 years. The time between reversals is highly variable, sometimes less than 40,000 years and at other times as long as 35 million years. No regularities or periodicities have yet been discovered. A long interval of one polarity may be followed by a short interval of opposite polarity
http://www.answers.com/topic/geomagnetic-reversal
I don't think anything can be done about it, it's a natural thing that's always been going on, and we've survived it before!
The sun also swithes poles all the time, in fact every 7 to 15 years.