In many ways, the world may seem to be turning on its head. In one way, in particular, it might be literally true: The Earth’s north and south magnetic poles are due for a dramatic switch in positions, according to geophysics research at the University of Leeds.
The Earth’s satellites, power lines, ocean currents, and animal migration patterns are all dependent on the stability of the magnetic field, which envelops the planet and shields it from harmful cosmic rays like a pair of polarized sunglasses. Modern humans have been lucky to take that stability for granted; the Earth hasn’t experienced a full magnetic pole switcheroo for 780,000 years (though it experienced a temporary one 41,000 years ago). But after looking at evidence of magnetic field reversals in the Earth’s rocks, Phil Livermore, Ph.D., and John Mound, Ph.D., suggest it could happen sooner rather than later.
In a new article in The Conversation, they noted that reversals are hard to predict, but scientists have a rough idea of when a celestial body is “overdue” for one:
Geomagnetic reversals occur a few times every million years on average. However, the interval between reversals is very irregular and can range up to tens of millions of years.
While Earth’s magnetic field appears relatively stable to us, on a grand time scale it is actually quite changeable. Written in the rocks is evidence of “several hundred” reversals in the history of our planet — other bodies in space, like the Sun, experience them too — which sometimes led to the movement of the north and south poles toward the equator or the existence of multiple poles in addition to pole reversal.
The biggest concern that a pole reversal event poses is that it would weaken our planet’s greatest shield: In particular, fluctuations in the stability of the magnetic shield opens up the Earth to threats from geomagnetic storms, which take place when the Sun’s eruptions of energy (like coronal mass ejections) reach our field 3 to 5 days after they leave the Sun. According to NASA, it’s our high-orbit communications satellites that are in most danger — they’re located at the center of the storm — but our power lines can also be affected. In 1989, the entire Canadian province of Quebec lost power just as a massive geomagnetic storm took place.
Because of the field’s variability, however, Livermore and Mound say that pinpointing the exact date of the next reversal will be “difficult,” but research like theirs, which tracks the flow of molten iron in the Earth’s core that gives rise to the magnetic field, is improving our prediction abilities. In the meantime, however, we probably shouldn’t worry too much: In an article in Nature in 2008, another University of Leeds researcher, David Gibbons, Ph.D., said we “could be” headed toward another reversal but assured readers that the “human race has survived many excursions and a few reversals already: so we are likely to come through the next one unscathed.”