Geomagnetic reversal

At present, the overall geomagnetic field is becoming weaker; the present strong deterioration corresponds to a 10–15% decline over the last 150 years and has accelerated in the past several years...

The Earth's magnetic north pole is drifting from northern Canada towards Siberia with a presently accelerating rate — 10 km per year at the beginning of the 20th century, up to 40 km per year in 2003,^[11] and since then has only accelerated ^[12]. In the last decade magnetic north was shifting roughly one degree every five years.^[13]

http://en.wikipedia.org/wiki/Geomagnetic_reversal