Will that mean anyone using a compass will be out with there directions or does 40 miles not a significant change. It all sounds a bit worrying to me. I am surprised that it has not been mentioned before.
I remember when at school many years ago the magnetic poles were discussed it was known that at the north was variable in position. We were also told (source unknown) the earth's polarity had changed north to south (and possibly back again several times) during the overall history of earth.
There have been a number of articles on this subject over the years one click here provides a little history of the subject as well as a bit of science.
For those interested there is a PDF which plots its movement over a period of years click here. There is an article which includes this data and provides more of an explanation and history of this natural phenomenon click here.
At one time I had to understand the difference between true north, magnetic north and compass north. I also had to do the occasional aircraft compass swing which usually meant standing in the bitter cold in the windiest place.
that the earth's magnetic pole is constantly moving - sometimes it can move as much as 50 miles in a day. These constant wanderings (which are confined to a well-known oval area) are caused by the sun, which emits a constant stream of charged particles. These enter the earth's upper atmosphere and the resulting electric currents cause the magnetic North pole's short term wanderings.
The long-term movement of the Pole is different. The pole's official position has moved about 700 miles over the past 100 years, and if it keeps going at its present rate and in the same direction it will be somewhere in Siberia in around 45 years time.
Never mind airports, it must present Santa with a few navigational problems.