Models Can't Keep Up With Migrating Magnetic North Pole, And The US Government Shutdown Just Made It Worse

A view of Earth’s north polar regions (Image: NASA/GSFC/Suomi NPP)

Rapid and erratic movements of Earth’s north magnetic pole have prompted an early update to a model that assists with navigation. The scheduled fix was supposed to happen on January 15, but the US government shutdown has forced an unwelcome delay.

The magnetic north pole is shifting at an unprecedented rate. Over the last 30 years, the rate of distance that the magnetic north pole moves per year has sped up, around 15km per year to around 55km per year, according to Nature.

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. Or at least that’s the theory — the whole thing is still somewhat of a scientific mystery.

The World Magnetic Model (WMM) provides a five-year forecast of the Earth’s magnetic field, which assists with navigation. But the rapid and irregular movements of the north magnetic pole over the past three years have made the 2015 WMM inaccurate. An unprecedented early update was supposed to happen on 15 January 2019, but that’s been bumped to January 30 owing to the ongoing US government shutdown, reports Nature.

The WMM forecasts are produced by the US National Oceanic and Atmospheric Administration (NOAA) and the British Geological Survey (BGS) on behalf of the US National Geospatial-Intelligence Agency and the UK Defence Geographic Centre.

The WMM describes the primary engine responsible for magnetic pole movement: The Earth’s core. Beginning in late 2014, however, the core geomagnetic field started to shift in a way that hadn’t been predicted, wrote BGS scientist Will Brown at his blog.

In addition to this abrupt change, scientists started to observe accelerations of flow in the core in the northern hemisphere. And in 2016, a particularly powerful geomagnetic pulse under South America complicated matters even further, the Nature article explained.

By March 2018, the 2015 WMM had become woefully out of date, with the BGS saying it was “no longer meeting its accuracy requirements.” Hence the need to update the map a year earlier than usual. For the fix, scientists will add three years of scientific data to the model, taking the 2016 pulse into account.

Obviously, we’re no longer solely dependent on compasses for navigation, so it’s unlikely that ships will run aground or planes will smash into mountains as a result of the government shutdown. But as Brown explains, an inaccurate WMM is not without implications.

The WMM is the standard magnetic model used for navigation by organisations such as NATO, the Ministry of Defence, and the U.S. Department of Defence, and also by smartphone operating systems such as Android and iOS. When you open your smartphone’s map app, you may see an arrow pointing which way you’re facing, and there’s something quite clever going on underneath.

Your phone contains a magnetometer that is measuring the Earth’s magnetic field. 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.

Indeed, the accuracy of a phone’s compass is only as good as the WMM. For example, let’s say you were on a boat at a distance of 2km 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.

It’s important to point out that, the farther you are from the north magnetic pole, the less of an issue this becomes. Arnaud Chulliat, a geomagnetist at the University of Colorado and NOAA, told Nature that the rapid movements of the north magnetic pole makes navigational systems in the Arctic “more prone to large errors”. Unless you live way up north or work for any of the defence agencies listed above, you likely have nothing to worry about. As BGS scientist Ciaran Beggan told Reuters, the compasses in our smartphones will only be “fractionally wrong", and “within errors allowed in the five-year models”.

Regardless, it’ll be good to get an accurate WMM in place as soon as possible. The north magnetic pole shifts around 3 to 5km each month in the general direction of Siberia. Ah, nothing like a government shutdown to remind us of the wide net cast by our public institutions.

[British Geological Survey, Reuters via Global News, Nature]

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