Magnetic North Takes a Stroll

As liquid-hot magma boils and cascades beneath the surface of the Earth, the magnetic north pole seems to be following the whims of subterranean flows. This has potential implications for sailors, or for anyone who uses GPS on their phones, and is a head-scratcher for the scientific community.

“Unlike the static geographic north pole, the north magnetic pole is in constant flux, influenced by the movements of iron-rich fluids deep below the Earth’s crust,” read an article by Gizmodo. “Or at least that’s the theory — the whole thing is still somewhat of a scientific mystery.”

The article went on to say that over the last 30 years, the rate of distance that the magnetic north pole moves has increased from about 9 miles per year to around 35 miles per year.

The magnetic poles are used to determine the World Magnetic Model (WMM), a construct for navigation, attitude and heading referencing systems using the geomagnetic field. The WMM — which is created through a collaboration of several countries’ government agencies, including the National Oceanic and Atmospheric Administration — provides “a five-year forecast of the Earth’s magnetic field, which assists with navigation,” Gizmodo said. “But the rapid and irregular movements of the north magnetic pole over the past three years have made the 2015 WMM inaccurate.”

An update to the WMM wasn’t scheduled until 2020, “but ‘unplanned variations’ have degraded the quality of the WMM so greatly that NOAA published an out-of-cycle update on Monday,” according to NPR. The update was originally scheduled for January 15, but was pushed back because of the federal government shutdown.

So what, exactly, is happening? “The problem lies partly with the moving pole and partly with other shifts deep within the planet,” according to Nature. “Liquid churning in the Earth’s core generates most of the magnetic field, which varies over time as the deep flows change. In 2016, for instance, part of the magnetic field temporarily accelerated deep under northern South America and the eastern Pacific Ocean.”

The molten gurgling beneath the Earth’s surface was inconvenient for the WMM. “That 2016 geomagnetic pulse beneath South America came at the worst possible time, just after the 2015 update to the World Magnetic Model,” Nature said. “This meant that the magnetic field had lurched just after the latest update, in ways that planners had not anticipated.”

Early last year, scientists realized that the WMM was off. Way off. “Researchers from NOAA and the British Geological Survey in Edinburgh had been doing their annual check of how well the model was capturing all the variations in Earth’s magnetic field. They realized that it was so inaccurate that it was about to exceed the acceptable limit for navigational errors.”

This might all sound like scientific minutiae, but keep in mind that your smartphone contains a ‘magnetometer’, which measures the Earth’s magnetic field, according to Gizmodo. “In order to make sense of this information, a reference model like the WMM is needed to correct the measurements of magnetic north made by your phone to True North.”

“Let’s say you were on a boat at a distance of one mile from the north magnetic pole. The arrow on your phone’s compass will point directly at the magnetic north, but the corresponding map on your phone — because it’s referencing an inaccurate forecast of where the magnetic north should be — will likely give you a false impression of where you are on the planet. And given the degree to which the magnetic north pole is moving each year, the map could be really off.”

Gizmodo went on to say that the farther away from the north magnetic pole a navigator is, the less of an issue the variation becomes.

But still, for sailors, it’s a little disconcerting not to know where your True North lies.