The compass always points north, that's for sure. But where exactly the North Magnetic Pole is is unclear, because every year it shifts by several kilometers, which has a serious impact on global navigation. And the slightest deviation in degrees can shift the target coordinates by hundreds of kilometers.
How does the North Magnetic Pole appear?
The Earth's magnetic field arises at great depths in the Earth, where huge flows of molten iron move at the boundary between the Earth's core and the mantle. They are in constant motion due to the Earth's rotation. This motion generates electric currents that create a magnetic field with two poles: the North and South magnetic poles.
However, since these processes in the Earth's interior are constantly changing, the Earth's magnetic field also changes. If these currents change or slow down due to the movement of tectonic plates, for example, the North Magnetic Pole also shifts.
What types of navigation are guided by the Earth's magnetic field?
The World Magnetic Model (WMM), which is updated every five years by the US weather agency NOAA and the British Geological Survey (BGS), is crucial for the accurate navigation of all military and civilian aircraft, ships, submarines, and GPS devices.
The WMM is used by NATO, the US Department of Defense, the US Federal Aviation Administration, the International Hydrographic Organization, and many others. Precise navigation is of great strategic importance for security, especially in today's times of confrontation, when individual countries such as Russia and China regularly jam navigation and localization systems.
The world magnetic model is also decisive for almost all map applications, compasses and GPS services for smartphones. All of them are updated accordingly. The latest calculations are now available: The world magnetic model for 2025 will probably be up to date until 2029. For the first time, a second high-resolution model is also being published, which offers significantly higher accuracy: While the standard WMM has a spatial resolution of around 3,300 km at the equator, the high-resolution one provides much more precise data – from about 300 kilometers at the equator.
Where is the North Magnetic Pole moving?
At the turn of the century, the North Magnetic Pole was near the Northeast Passage in Canada - one of the world's most important sea routes. Now it is much further north, near the geographic North Pole. In 2018, it crossed the International Date Line towards the Eastern Hemisphere.
For the past 20 years, it has been moving surprisingly quickly towards Siberia - at about 50 kilometers per year. But five years ago, the movement suddenly slowed to about 35 kilometers per year. "We have never seen the magnetic North Pole behave like this before," says William Brown of the British Geological Survey. “This is the largest delay we have ever measured.“
Why are strong magnetic fields important?
For life on Earth, it is not so much where the respective magnetic poles are located as how strong they are. For reasons that are still unknown, the Earth's magnetic field has weakened by ten percent since measurements began 175 years ago.
A weak geomagnetic field makes it difficult for animals such as whales, butterflies, sea turtles and many species of migratory birds to find their way. A strong geomagnetic field protects the Earth from aggressive cosmic radiation and solar storms. When the magnetic field is weak, the protective ozone layer is reduced and dangerous ultraviolet rays penetrate more easily, especially in the polar regions.
Geostationary satellites are also less protected when the Earth's magnetic field is weak. Radiation or cosmic particles can significantly affect them and severely limit communication.
Author: Alexander Freund