Something strange is happening at the top of the planet: the north magnetic pole is moving so fast that world experts in geomagnetism will be forced to update the magnetic declination model ahead of schedule , which must be applied in the calculations of bearing on nautical charts to facilitate navigation, not only on ships but also in modern positioning systems such as Google Maps. But let’s go in parts.
We know that the magnetic poles are not fully aligned with the Earth’s geographic poles, and that their position changes slightly over time. This is mainly due to the movements of the liquid materials that make up the Earth’s core (molten iron and nickel), which are what originate the magnetic field of our planet. Currently the magnetic north pole moves from Canada to Russia at a rate of several tens of kilometers per year.
Because of this, experts from the US National Oceanic and Atmospheric Agency (NOAA) and the British Geological Survey (Edinburgh) meet every five years to update the World Magnetic Model .
© Nature; fuente: World Data Center for Geomagnetism/Kyoto Univ.
The most recent version of this model was published in 2015 and is supposed to be valid until 2020, the date of the next revision. The problem is that the magnetic field is changing so fast that researchers are going to have to make corrections ahead of time. And it is that this latest model has not had a very lucky life to say. In the brand new year 2016, part of the magnetic field temporarily accelerated deep in northern South America and the eastern Pacific Ocean. This change was tracked by satellites such as the European Space Agency’s Swarm mission.
At the beginning of 2018 the alarm was raised: when doing its annual verification, the experts realized that the current model is so inaccurate that it is exceeding the acceptable limit of errors in navigation. Although the appointment to extraordinarily update the magnetic declination model was set for January 15, 2019, it has had to be delayed to the 30th due to the partial shutdown of the US Government.
What’s going on?
Why is the magnetic field changing so rapidly? The causes are not known, but experts believe that geomagnetic pulses, such as the one that took place in 2016, can be traced back to hydromagnetic waves that arise from the depths of the Earth’s core.
On the other hand, the movement of the magnetic north pole is a source of problems, and it is that it wanders in totally unpredictable ways. In the mid-1990s, the pole increased its speed from 15 kilometers per year to 55, and in 2001 it had already entered the Arctic Ocean. In 2018 it crossed the international date line and is currently on a straight line to Siberia.
The problem is that the geometry of the Earth’s magnetic field magnifies the errors of the model in places where the field changes rapidly (the north pole). “The fact that the pole is going fast makes this region more prone to big errors,” explains Arnaud Chulliat, a geomagnetist at the University of Colorado and NOAA.
This accelerated movement of the north magnetic pole could be linked to a jet of liquid iron propagating just below Canada. “The location of the north magnetic pole appears to be defined by two large-scale magnetic field ‘patches’, one below Canada and one below Siberia, and the Siberian patch is winning the competition,” explained Phil Livermore, a geomagnetist at the University. from Leeds (UK).
The erratic movements of the magnetic field have fascinated scientists and explorers since James Clark Ross first measured them in 1831, and discovering their causes in order to predict future behavior is challenging. A challenge that, in addition, is of great relevance to guarantee the correct functioning of our modern navigation systems . What is clear is that, for the moment, the world’s geomagnetics experts have reason to be entertained for a long time.
This article is a version of the one published by Alexandra Witze in Nature 565, 143-144 (2019)
