The Earth’s Magnetic Pole is Shifting

13 February 2019 By Laura Dunn

The Earth’s magnetic North Pole is moving. On average, it goes north about 30 miles each year, which is why the World Magnetic Model (WMM) finally got an update following the partial U.S. government shutdown in February. This means the magnetic north can once again be accurately located for everyone around the world.

But why is the magnetic north changing so fast? First off, it’s important to remember that the magnetic north is one of three “north poles” on our globe. “As you know, a compass needle generally does not point to true north — the axis of rotation of the Earth — but to the magnetic North Pole,” says Dr. Ciaran Beggan, geophysicist at the British Geological Survey (BGS). “Maps of the declination angle — the difference between True and Magnetic — are very complicated and because of the flow of the outer core, the position of magnetic North moves over time.”

Beggan further explains why the shifting is a big deal. “The Earth has a liquid outer core made of iron and nickel. The metal is very hot (3,000°C) and as runny as water at the Earth’s surface,” Beggan says. “It flows all the time, like the oceans. As it moves, it creates a magnetic field, which escapes the core through to the surface of the Earth. The magnetic field roughly aligns with the axis of rotation, but it deviates a bit for reasons that are not well understood.”

The updated World Magnetic Model was actually created by BGS and NOAA scientists back in September 2018. “The model coefficients, used to make the maps, were distributed to interested users (such as the U.S. Department of Defense) around that time,” Beggan says. “The official release was meant to be in January, when the coefficients were to be made available to general users, but delayed by a few weeks in the end. So, the users who needed the updated values did get them prior to the official launch.”

Beggan explains that the main differences between the 2015 release and the 2018 release are at the high latitudes (above 55N in particular), so most users at lower latitudes will not notice any change, as the differences are well below 0.25° in Declination. Only around the magnetic North Pole were the changes required, as the average error has exceeded 1° in grid angle.

While there’s plenty that humans can do about important matters like minimizing plastic waste, there’s nothing we can do to influence the magnetic field whatsoever. However, Beggan says it’s “good practice” to keep the compass navigation capability up to date, which we can do. “If GPS is lost for whatever reason, then the ship should be able to fall back to compass and waypoint navigation. Ship compasses are much better than standard consumer (e.g. smartphones) ones, so can make use of the updated WMM coefficients and maps.” Depending on the system they use on superyachts, Beggan presumes the manufacturers update the software whenever a new WMM becomes available. “From the manufacturer’s point of view, it should be case of replacing a single file with the model coefficients, so fairly trivial.”

Beggan adds that, “it would be good to make people aware of these efforts and support geophysical research!”