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News about the Geology of the Oceans

Winter 2007-2008

The Planet's Wandering Magnetic Poles

It may or may not come as a surprise to you to learn that the Earth's geographic north pole and its magnetic north pole aren't in exactly the same place. In 2007, the two poles were about 800 kilometers apart. Now located in the Arctic Ocean just north of Canada, the north magnetic pole is moving northwest toward Siberia by about 50 kilometers each year. The south magnetic pole is moving too, but at a much more leisurely 5 kilometers per year. These movements are a result of irregularities in the flow of the molten iron and lighter metals in the Earth's outer core. Eddies and swirling currents in the outer core lead to movement over time of the magnetic poles on the Earth's surface.

In the past few decades, stronger eddies and currents in the outer core actually have weakened the Earth's magnetic field. If the field's overall strength keeps weakening, it will reach zero in a few hundred years. It is not clear if this recent weakening trend is a routine variation that will reverse or whether it will lead to a full-blown reversal of the Earth's magnetic field—something that happens on the order of every 250,000 years (but that number is misleading because there is a great deal of variability in the amount of time that passes between reversals).

Reference

Perkins, Sid. 2007. North by Northwest. Science News, vol. 172, p. 392-394.

(photo source: Acute accent, http://acuteaccent.com/geographic-north-pole-and-north-magnetic-pole/)

movement of magnetic north pole

The dots denote the pole's movement since 1831. Blue dots are direct surface observations and red dots are from models using satellite data. The green dots indicate the pole's future location, if its current rate and direction of motion continue.

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