Everyone knows that the Earth has two magnetic poles, the North and the South Pole. But what everyone doesn't know is that the North Magnetic Pole is on the move, and this movement could disrupt aviation and navigation systems and GPS systems.
News of the pole's meanderings was released by The World Magnetic Model (WMM), a joint endeavor of the U.S. National Geospatial-Intelligence Agency (NGA) and the UK Defence Geographic Centre (DGC). The WMM produces an updated model of Earth's magnetic field every 5 years.
The World Magnetic Model is used by GPS services, telecommunications transmission systems, smartphone compass apps, maps and the navigation tools used by various agencies, including the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), the U.S. Department of Defense and NATO.
Currently, the North Magnetic Pole is moving at an unprecedented rate of 31 miles (50 km) per year, and its speed is only increasing as it moves away from Canada toward Siberia. In comparison, in 2000 the North Magnetic Pole was moving at a rate of just 6.2 miles (10 km) per year.
This speed is the fastest recorded since the mid-16th century. Between 1590 and 1990, the North Magnetic Pole moved slowly around northern Canada, covering around 1,400 miles until its sudden shift towards Siberia.
As it has moved, the North Magnetic Pole has passed within 390 km, or 3°, of the Geographic North Pole. Then it crossed the Greenwich Meridian, or point of zero longitude on Earth.
What's causing this change?
Earth’s magnetic field extends from its interior out into space, where it interacts with the solar wind, a stream of charged particles that emanate from the Sun, and cosmic rays. Without the magnetic field, they would strip Earth's ozone layer, which protects us from harmful ultraviolet radiation.
The magnetic field is generated by what's called the dynamo effect, which is the movement of liquid iron and nickel within the Earth’s outer core, around 1,800 miles down from the surface. This movement generates electric currents, which in return create the magnetic field.
Furthermore, since the liquid iron is incredibly hot, over 5,432° Fahrenheit, it flows very easily, dragging the magnetic field along with it. At its surface, Earth's magnetic field ranges between 25 and 65 microteslas (0.25 to 0.65 gauss). Currently, the field is tilted at an angle of approximately 11 degrees with respect to Earth's rotational axis.
Consequences of the pole's movement
Airport runways get their names from WMM data. By FAA rules, runways are numbered from 1 to 36 according to the points on a compass, reflecting magnetic compass readings to the nearest 10 degrees, and dropping the last digit. Runway numbers also convey the direction in which a plane is traveling. On a handheld compass, south is 180 degrees, which is 18 in runway designations, but if a plane is heading north, it is on runway 18–36.
Large airports that have parallel runways include other designators, such as L or R for the left or right runway. At Denver's International Airport (DIA), runway 17L–35R is currently magnetically oriented at 172.5°. However, when the magnetic pole's movement shifts another 4 degrees to 176°, that runway will become 18L–36R.
Denver airport spokesman, Heath Montgomery, told NCEI that "The declination has changed just over 2.5 degrees over the past 22 years since Denver opened. Declination is changing by 0.1 degrees per year, so about another 30 years or more until the next change at the current rate." Declination is the measurement of the distance from the magnetic equator.
Magnetic shifts happen faster as you get closer to the poles. For the Fairbanks International Airport, its runway designations must be updated every 24 years. In 2009, runway 1L-19R had to be renamed to 2L-20R due to the shift in the magnetic north.
Over the next several months, Google and Apple will change the magnetic field maps in Android and iPhones as part of their general software updates. Another consequence of the North Magnetic Pole's movement is it will be harder to see the northern lights in Canada.
A weakening or reversing magnetic field
Besides moving, the Earth’s magnetic field is also weakening at a rate of about 5% every century. A big disruption of Earth's magnetic field would have a catastrophic effect on life on Earth, leaving it vulnerable to solar and cosmic radiation.
It is also possible the magnetic field may reverse, and that the North and South Poles would switch places. This actually happens every 500,000 years or so, but the last time it happened was about 780,000 years ago. That means we're overdue for another reversal.
Before a reversal, the North and South Magnetic Poles would vanish, and it would take between 5,000 and 10,000 years for them to re-establish themselves in their reversed positions.
The magnetic weather at your place
If you're curious what the magnetic field looks like in your neck of the woods, NCEI has a really nifty online magnetic field calculator that shows the magnetic orientation, and the rate of change, for any location during the years 1750 and 2024.
All you have to do is enter an address, and the app will tell you that location's latitude and longitude. Press "Calculate" and the app will display the magnetic orientation and rate of change. For example, 40° 30' 51" N, 112° 2' 0" W on December 13, 2019 is shown below.