Magnetic north is not where it used to be. Since 2015, the place to
which a compass points has been sprinting toward Siberia at a pace of more than
30 miles (48 kilometres) a year. And this week, after a delay caused by the
month-long partial government shutdown in the United States, humans have finally
caught up.
Scientists on Monday released an emergency update to the World Magnetic
Model, which cellphone GPS systems and military navigators use to orient
themselves. It's a minor change for most of us - noticeable only to people who
are attempting to navigate very precisely very close to the Arctic.
But the north magnetic pole's inexorable drift suggests that something
strange - and potentially powerful - is taking place deep within Earth. Only by
tracking it, said University of Leeds geophysicist Phil Livermore, can
scientists hope to understand what's going on.
The planet's magnetic field is generated nearly 2,000 miles (3,200
kilometres) beneath our feet, in the swirling, spinning ball of molten metal
that forms Earth's core. Changes in that underground flow can alter Earth's
magnetic field lines - and the poles where they converge.
Consequently, magnetic north doesn't align with geographic north (the end
point of Earth's rotational axis), and it's constantly on the move. Records of
ancient magnetic fields from extremely old rocks show that the poles can even
flip - an event that has occurred an average of three times every million
years.
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