What is driving the movement of Earth’s magnetic north?

Earth’s magnetic north is shifting at an unprecedented rate, according to a new report from the European Space Agency (ESA). While scientists believe that this point has always wandered, exactly what is driving the recent acceleration remains unknown.

“While this has some practical implications, scientists believe that this sprint is being caused by tussling magnetic blobs deep below our feet,” explains the ESA.

The geographic North Pole is in a fixed location, but magnetic north has been known to shift since it was first measured in 1831. Since then, it has been drifting slowly from the Canadian Arctic towards Siberia.

As a result, the World Magnetic Model (WMM) has to be modified every few years with the pole’s current location so that navigation systems such as those used by ships, Google maps, and smartphones are up to date. Recently, the WMM had to be updated sooner than usual because of the pole’s accelerated speed.

Between 1990 and 2005, magnetic north shifted from a speed of 0-15 kilometers a year to its current speed of 50-60 kilometers a year. In 2017, it crossed the international date line within 390 kilometers of the geographic North Pole and continues to dive south.

“ESA’s Swarm mission is not only being used to keep track of magnetic north, but scientists are using its data to measure and untangle the different magnetic fields that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere,” states the ESA.

“Our magnetic field exists because of an ocean of superheated, swirling liquid iron that makes up the outer core. Like a spinning conductor in a bicycle dynamo, this moving iron creates electrical currents, which in turn generate our continuously changing magnetic field.”

This means that tracking changes in the magnetic field can give experts insight into how the iron in the core moves.

“Several theories have been proposed to explain this behaviour but, since they rely upon changes in the small-scale magnetic field, they cannot explain the recent trajectory of the pole,” explains Phil Livermore from the University of Leeds.

“Using data collected over two decades by satellites, including ESA’s Swarm trio, we can see that the position of the north magnetic pole is determined largely by a balance, or tug-of-war, between two large lobes of negative magnetic flux at the boundary between Earth’s core and mantle under Canada and Siberia.”

According to the ESA, changes in the pattern of core flow between 1970 and 1999 elongated the Canadian lobe and weakened its signature on Earth’s surface, causing the pole to move toward Siberia more quickly. Over the next decade, the north magnetic pole is predicted to wander 390-660 more kilometers in the direction of Siberia.

—

By Chrissy Sexton, Earth.com Staff Writer

Image Credit: ESA/ATG Medialab