Magnetic north on move

The Associated Press
Seth Borenstein

WASHINGTON–True north isn’t quite where it used to be.
Earth’s north magnetic pole has been drifting so fast in the last few decades that scientists say past estimates no longer are accurate enough for precise navigation.
Yesterday, they released an update of where true north really was–nearly a year ahead of schedule.
The magnetic north pole is wandering about 34 miles (55 km) a year. It crossed the international date line in 2017 and is leaving the Canadian Arctic on its way to Siberia.
The constant shift is a problem for compasses in smartphones and some consumer electronics.
Airplanes and boats also rely on magnetic north, usually as back-up navigation, said University of Colorado geophysicist Arnaud Chulliat, lead author of the newly-issued World Magnetic Model.
GPS isn’t affected because it’s satellite-based.
The military depends on where magnetic north is for navigation and parachute drops while NASA, the U.S. Federal Aviation Administration, and U.S. Forest Service also use it.
Airport runway names are based on their direction toward magnetic north and their names change when the poles moved.
The U.S. National Oceanic and Atmospheric Administration and United Kingdom tend to update the location of the magnetic north pole every five years in December, but this update came early because of the pole’s faster movement.
Since 1831 when it was first measured in the Canadian Arctic, it has moved about 1,400 miles (2,300 km) toward Siberia.
Its speed jumped from about nine m.p.h. (15 km/h) to 34 m.p.h. (55 km/h) since 2000.
The reason is turbulence in Earth’s liquid outer core,” said University of Maryland geophysicist Daniel Lathrop, who wasn’t part of the team monitoring the magnetic north pole.
“There is a hot liquid ocean of iron and nickel in the planet’s core where the motion generates an electric field,” he noted.
“It has changes akin to weather,” Lathrop added. “We might just call it magnetic weather.”
The magnetic south pole is moving far slower than the north.
In general, Earth’s magnetic field is getting weaker, leading scientists to say it eventually will flip, where north and south pole changes polarity, like a bar magnet flipping over.
It has happened numerous times in Earth’s past but not in the last 780,000 years.

“It’s not a question of if it’s going to reverse, the question is when it’s going to reverse,” Lathrop said.
When it reverses, it won’t be like a coin flip but take 1,000 or more years, experts noted.