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Earth’s magnetic field seems to be weakening and potentially migrating

Earth’s magnetic field is weakening, and may be getting set to flip—in just a few thousand years north will become south and south will become north, LiveScience reports. But before it can do that, the magnetic field may wander around a bit. Right now, say scientists with the European Space Agency, the Earth’s magnetic north pole seems to be wandering over to Siberia.

The strength of the Earth’s magnetic field is always changing, with patches of stronger or weaker shielding found across the planet. Right now, the weakest spots hover above the Western Hemisphere, whereas places around the Indian Ocean have been growing stronger. The wobbles in magnetic field strength, says LiveScience, could mean that the planet’s magnetic field is entering a period of flux that will last up to a few thousand years and may ultimately end in a flipping of Earth’s magnetic poles.

Researchers with the European Space Agency noticed the abnormalities in the Earth’s magnetic field strength while analyzing data collected by magnetometers attached to a new three-satellite system called Swarm. Here’s LiveScience:

Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner.

Illustration of the difference between geomagnetic poles (Nm and Sm) and geographical poles (Ng and Sg)

The geomagnetic poles are antipodal points where the axis of a best-fitting dipole intersects the Earth's surface. This dipole is equivalent to a powerful bar magnet at the center of the Earth, and it is this theoretical dipole that comes closer than any other to accounting for the magnetic field observed at the Earth's surface. In contrast, the actual Earth's magnetic poles are not antipodal—that is, they do not lie on a line passing through the center of the Earth.

Owing to motion of fluid in the Earth's outer core, the actual magnetic poles are constantly moving. However, over thousands of years their direction averages to the Earth's rotation axis. On the order of once every half a million years, the poles reverse (north changes place with south).