LiveScience.com reports today that the magnetic north pole is drifting towards Russia, which has caused two Florida airports to renumber their runways. The site adds that this is a natural, ongoing process:
The Earth has an iron core, and movement within its outer part is likely responsible for sustaining a magnetic field, which constitutes much of what we measure at the Earth's surface. As a result, the Earth resembles something of a giant magnet with two poles: magnetic north and magnetic south. However, its field is not perfectly symmetrical and has undulations that are always moving around, according to Jeffrey Love, a research scientist with the U.S. Geological Survey's Geomagnetism Program.
The magnetic poles don't line up with the geographic ones, and the difference between them is an angle called declination. As if this wasn't enough of a nuisance for navigators, the Earth's magnetic field drifts, causing the angle of declination to change over time. "In fact, it drifts about one-fifth of a degree a year at lower latitudes, such as Florida. "So that means if you wait five years, the compass will be off by one degree," Love said."
Runways are designated according to points of a compass, so every few years they need to be changed to reflect the drifting magnetic field. Nova concurs that the drift is normal:
If all the compasses in the world started pointing south rather than north, many people might think something very strange, very unusual, and possibly very dangerous was going on. Doomsayers would have a field day proclaiming the end is nigh, while more rational persons might head straight to scientists for an explanation.
Fortunately, those scientists in the know—paleomagnetists, to be exact—would have a ready answer. Such reversals in the Earth's magnetic field, they'd tell you, are, roughly speaking, as common as ice ages. That is, they're terrifically infrequent by human standards, but in geologic terms they happen all the time. As the time line at right shows, hundreds of times in our planet's history the polarity of the magnetic shield ensheathing the globe has gone from "normal," our current orientation to the north, to "reversed," and back again.
The Earth is not alone in this fickleness: The sun's magnetic shield appears to reverse its polarity approximately every 11 years. Even our Milky Way galaxy is magnetized, and experts say it probably reverses its polarity as well. Moreover, while a severe weakening or disappearance of the magnetic field would lay us open to harmful radiation from the sun, there's little evidence to date that "flips" per se inflict any lasting damage (see Impact on Animals).
Our Earth is an amazing place full of happenings we do not understand, but which are completely normal. In another million years our Earth may not look the same as it does today. Change, it seems is eternal.