North isn't quite where it was after the Earth's north geomagnetic pole made an unexpected sprint across arctic Canada. According to the US National Oceanic and Atmospheric Administration (NOAA), scientists at the agency's National Centers for Environmental Information (NCEI) bureau have had to update its World Magnetic Model (WMM) almost a year early because the magnetic pole is moving faster than predicted, which could affect global navigation.
"I am as constant as the northern star," said Julius Caesar in Shakespeare's play of the same name, and it seems obvious that north must be an unchangeable fact in our lives. But is it?
In one sense, yes it is. The North Pole, which is the point marking the Earth's axis is constant within a reasonable degree. It may wobble a few inches a year due to tidal effects of the Sun, Moon, and planets, but it tends to stay put. The direction to the North Pole is what's known as true north.
However, the magnetic poles are another matter and it is to these poles that magnetic compasses point. What draws the needle of a compass to point north are the lines of the Earth's magnetic field, which is generated by the liquid iron core of the planet, turning it into a gigantic dynamo.
The problem is that this magnetic field is very uneven due to the effects of the Sun, the interior dynamics of the Earth, and the uneven nature of the crust. It's a phenomenon that's been known almost as long as compasses have been commonly used and it's the reason why navigational charts have notations indicating how to calculate the difference between magnetic north and true north in a particular area, which can vary by several degrees.
In an age of GPS, old fashioned compasses may seem redundant, but magnetic navigation is still vital in the 21st century. GPS hasn't replaced the compass, merely enhanced it and a functioning compass is necessary for smartphone navigation apps, military operations, air traffic control, and satellite tracking, to name a few examples.
In fact, ships and aircraft, no matter how sophisticated their navigation systems, must still carry a magnetic compass by law. Even something as simple as airport runways are affected. The designations you see at the end of the runway when coming into land are abbreviations of its alignment to magnetic north and must be changed as the pole shifts, which is why Fairbanks International Airport in Alaska had to get out the paint brushes in 2009 to change 1L-19R to 2L-20R.
Because the compass is so important, NCEI and the British Geological Survey produce an updated model of the WMM every five years. Based on satellite observations, a global network of 120 magnetic observatories, and data from geological surveys of changes in the magnetic field over the centuries, scientists have been able to produce an accurate map of the field going back to the year 1590.
According to NOAA, the WMM was scheduled to be updated at the end of 2019 and released as WMM2020, but the magnetic pole has shifted so far in the direction of Siberia so quickly that it reached a speed of over 34 mi (55 km) per year. Therefore, an unusual early update was required to ensure safe navigation – especially in the polar regions where magnetic compasses become unreliable.
As to why this sudden shift is occurring, National Geographic reports that the north magnetic pole is being pulled by two patches of magnetic field – one under Canada and another Siberia – and that the Canadian one appears to be weakening.
Source: NOAA
