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Magnetic north pole drifting fast

The Earth's north magnetic pole is drifting away from North America so fast that it could end up in Siberia within 50 years, scientists have said.

The Earth's north magnetic pole is drifting away from North America so fast that it could end up in Siberia within 50 years, scientists have said.

The shift could mean that Alaska will lose its northern lights, or auroras, which might then be more visible in areas of Siberia and Europe. The magnetic poles are different from geographic poles, the surface points marking the axis of Earth's rotation. Magnetic poles are known to migrate and, occasionally, swap places. "This may be part of a normal oscillation and it will eventually migrate back toward Canada," Joseph Stoner, a palaeomagnetist at Oregon State University, told a meeting of the American Geophysical Union (AGU) in San Francisco.

Wandering poles
Previous studies have shown that the strength of the Earth's magnetic shield has decreased 10% over the past 150 years. During the same period, the north magnetic pole wandered about 1,100km (685 miles) into the Arctic, according to the new analysis. The rate of the magnetic pole's movement has increased in the last century compared with fairly steady movement in the previous four centuries, the Oregon researchers said. The Oregon team examined the sediment record from several Arctic lakes. Since the sediments record the Earth's magnetic field at the time, scientists used carbon dating to track changes in the magnetic field. They found that the north magnetic field shifted significantly in the last thousand years. It generally migrated between northern Canada and Siberia, but has occasionally moved in other directions.

Rate of change
At the present rate, the north magnetic pole could swing out of northern Canada into Siberia. If that happens, Alaska could lose its northern lights, or auroras, which occur when charged particles streaming away from the Sun collide with gases in the ionosphere, causing them to glow.

The north magnetic pole was first discovered in 1831 and when it was revisited in 1904, explorers found it had moved by 50km (31 miles). For centuries, navigators using compasses had to learn to deal with the difference between magnetic and geographic north. A compass needle points to the north magnetic pole, not the geographic North Pole. http://news.bbc.co.uk/1/hi/sci/tech/4520982.stm

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Long term movement of the north magnetic pole

See also: In-depth

The figure shows the path of the north magnetic pole since its discovery in 1831 to the last observed position in 2001. During the last century the pole has moved a remarkable 1100 km. What is more, since about 1970 the NMP has accelerated and is now moving at more than 40 km per year. If the NMP maintains its present speed and direction it will reach Siberia in about 50 years. Such an extrapolation is, however, tenuous. It is quite possible that the pole will veer from its present course, and it is also possible that the pole will slow down sometime in the next half century.

The strength and direction of the Earth's magnetic field slowly change with time – a phenomenon referred to as secular change or secular variation. The cause of secular variation is related to the process by which the magnetic field is generated. Secular change occurs everywhere on Earth, but the magnitude of the change varies from place to place and also with time.

Daily movement of the north magnetic pole
It is important to realize that the position of the north magnetic pole given for a particular year is an average position. The magnetic pole wanders daily around this average position and, on days when the magnetic field is disturbed, may be displaced by 80 km or more. Although the north magnetic pole's motion on any given day is irregular, the average path forms a well-defined oval. The diagram shows the average path on disturbed days.

The cause of the north magnetic pole's diurnal motion is quite different than that of its secular motion. If we measure the Earth's magnetic field continually, such as is done at a magnetic observatory, we will see that it changes during the course of a day – sometimes slowly, sometime rapidly. The ultimate cause of these fluctuations is the Sun. The Sun constantly emits charged particles that, on encountering the Earth's magnetic field, cause electric currents to flow in the ionosphere and magnetosphere. These electric currents disturb the magnetic field, resulting in a temporary shift in the north magnetic pole's position. The size and direction of this shift varies with time, in step with the magnetic field fluctuations. Since such fluctuations occur constantly, the magnetic pole is seldom to be found at its "official" position, which is the position in the absence of magnetic field fluctuations.

http://gsc.nrcan.gc.ca/geomag/nmp/long_mvt_nmp_e.php http://obsfur.geophysik.unimuenchen.de/mag/news/e_nmpole.htm