I watched a program about this a few months ago, it says our Magnetic Field is decaying and only has a few hundred/thousand years left.
http://www.icr.org/article/182/
Quote:
RAPID DECAY OF THE EARTH'S MAGNETIC FIELD
Quote:
It is known that the earth's magnetic field is decaying faster than any other worldwide geophysical phenomenon. A comprehensive ESSA Technical Report1 gives the values of the earth's magnetic dipole moment (the vector which gives the strength and direction of the magnet) ever since Karl Gauss made the first evaluation in 1835. The evaluations have been made about every 10 or 15 years since then. Each evaluation required accurate worldwide readings over an epoch (a year or so) and special mathematical reduction to "wash" out the "noise." These reliable data clearly show this relatively rapid decay. The report stated that on a straight line basis the earth's magnetic field would be gone in the year 3991 A.D. But decay is exponential and in this case has a half-life of 1400 years.

