North Magnetic Pole Moving East Due to rapidly changing Core Flux
Pastor Dale Morgan
North Magnetic Pole Moving East Due to rapidly changing Core Flux*
Richard A. Lovett in San Francisco
for National Geographic News
December 24, 2009
Earth's north magnetic pole is racing toward Russia at almost 40 miles
(64 kilometers) a year due to magnetic changes in the planet's core, new
research says.
The core is too deep for scientists to directly detect its magnetic
field. But researchers can infer the field's movements by tracking how
Earth's magnetic field has been changing at the surface and in space.
Now, newly analyzed data suggest that there's a region of rapidly
changing magnetism on the core's surface, possibly being created by a
mysterious "plume" of magnetism arising from deeper in the core.
And it's this region that could be pulling the magnetic pole away from
its long-time location in northern Canada, said Arnaud Chulliat, a
geophysicist at the Institut de Physique du Globe de Paris in France.
Finding North
Magnetic north, which is the place where compass needles actually point,
is near but not exactly in the same place as the geographic North Pole.
Right now, magnetic north is close to Canada's Ellesmere Island.
Navigators have used magnetic north for centuries to orient themselves
when they're far from recognizable landmarks.
Although global positioning systems have largely replaced such
traditional techniques, many people still find compasses useful for
getting around underwater and underground where GPS satellites can't
communicate.
The magnetic north pole had moved little from the time scientists first
located it in 1831. Then in 1904, the pole began shifting northeastward
at a steady pace of about 9 miles (15 kilometers) a year.
In 1989 it sped up again, and in 2007 scientists confirmed that the pole
is now galloping toward Siberia at 34 to 37 miles (55 to 60 kilometers)
a year.
A rapidly shifting magnetic pole means that magnetic-field maps need to
be updated more often to allow compass users to make the crucial
adjustment from magnetic north to true North.
Wandering Pole
Geologists think Earth has a magnetic field because the core is made up
of a solid iron center surrounded by rapidly spinning liquid rock. This
creates a "dynamo" that drives our magnetic field.
Scientists had long suspected that, since the molten core is constantly
moving, changes in its magnetism might be affecting the surface location
of magnetic north.
Although the new research seems to back up this idea, Chulliat is not
ready to say whether magnetic north will eventually cross into Russia.
"It's too difficult to forecast," Chulliat said.
Also, nobody knows when another change in the core might pop up
elsewhere, sending magnetic north wandering in a new direction.
Chulliat presented his work this week at a meeting of the American
Geophysical Union in San Francisco.