One day
in 1905, the French geophysicist Bernard Brunhes brought back to his
lab some rocks he’d unearthed from a freshly cut road near the village
of Pont Farin. When he analyzed their magnetic properties, he was
astonished at what they showed: Millions of years ago, the Earth’s
magnetic poles had been on the opposite sides of the planet. North was
south and south was north. The discovery spoke of planetary anarchy.
Scientists had no way to explain it.
This
essay is adapted from “The Spinning Magnet: The Electromagnetic Force
That Created the Modern World — and Could Destroy It,” by Alanna
Mitchell, to be published on January 30 by Dutton, an imprint of Penguin
Publishing Group, a division of Penguin Random House LLC.
When
next the poles change places, the consequences for the electrical and
electronic infrastructure that runs civilization will be dire. The
question is when that will happen.
Today, we know that the poles have changed places hundreds of times,
most recently 780,000 years ago. (Sometimes, the poles try to reverse
positions but then snap back into place, in what is called an excursion.
The last time was about 40,000 years ago.) We also know that when they
flip next time, the consequences for the electrical and electronic
infrastructure that runs modern civilization will be dire. The question
is when that will happen.
In the past few decades, geophysicists have tried to answer that
question through satellite imagery and math. They have figured out how
to peer deep inside the Earth, to the edge of the molten, metallic core
where the magnetic field is continually being generated. It turns out
that the dipole — the orderly two-pole magnetic field our compasses
respond to — is under attack from within.
The latest satellite data, from the
European Space Agency’s Swarm trio,
which began reporting in 2014, show that a battle is raging at the edge
of the core. Like factions planning a coup, swirling clusters of molten
iron and nickel are gathering strength and draining energy from the
dipole. The north magnetic pole is on the run, a sign of enhanced
turbulence and unpredictability. A cabal in the Southern Hemisphere has
already gained the upper hand over about a fifth of the Earth’s surface.
A revolution is shaping up.
If these magnetic blocs gain enough strength and weaken the dipole
even more, they will force the north and south poles to switch places as
they strive to regain supremacy. Scientists can’t say for sure that is
happening now — the dipole could beat back the interlopers. But they can
say that the phenomenon is intensifying and that they can’t rule out
the possibility that a reversal is beginning.
It’s time to wake up to the dangers and start preparing.
-
This animation shows the
movement of the north magnetic pole at 10-year intervals from 1970 to
2020. The red and blue lines indicate “declination,” the difference
between magnetic north and true north depending on where one is
standing; on the green line, a compass would point to true north.
The Earth’s magnetic field protects our planet from dangerous solar
and cosmic rays, like a giant shield. As the poles switch places (or try
to), that shield is weakened; scientists estimate that it could waste
away to as little as a tenth of its usual force. The shield could be
compromised for centuries while the poles move, allowing malevolent
radiation closer to the surface of the planet for that whole time.
Already, changes within the Earth have weakened the field over the South
Atlantic so much that satellites exposed to the resulting radiation
have experienced memory failure.
That radiation isn’t hitting the surface yet. But at some point, when
the magnetic field has dwindled enough, it could be a different story.
Daniel Baker, director of the Laboratory for Atmospheric and Space
Physics at the University of Colorado, Boulder, one of the world’s
experts on how cosmic radiation affects the Earth, fears that parts of
the planet will become uninhabitable during a reversal. The dangers:
devastating streams of particles from the sun, galactic cosmic rays, and
enhanced ultraviolet B rays from a radiation-damaged ozone layer, to
name just a few of the invisible forces that could harm or kill living
creatures.
How bad could it be? Scientists have never established a link between
previous pole reversals and catastrophes like mass extinctions. But the
world of today is not the world of 780,000 years ago, when the poles
last reversed, or even 40,000 years ago, when they tried to. Today,
there are nearly 7.6 billion people on Earth, twice as many as in 1970.
We have drastically changed the chemistry of the atmosphere and the
ocean with our activities, impairing the life support system of the
planet. Humans have built huge cities, industries and networks of roads,
slicing up access to safer living spaces for many other creatures. We
have pushed perhaps a third of all known species toward
extinction
and have imperiled the habitats of many more. Add cosmic and
ultraviolet radiation to this mix, and the consequences for life on
Earth could be ruinous.
And the perils are not just biological. The vast cyber-electric cocoon
that has become the central processing system of modern civilization is
in grave danger. Solar energetic particles can rip through the
sensitive miniature electronics of the growing number of satellites
circling the Earth, badly damaging them. The
satellite timing systems that
govern electric grids
would be likely to fail. The grid’s transformers could be torched en
masse. Because grids are so tightly coupled with each other, failure
would race across the globe, causing a domino run of blackouts that
could last for decades.
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In this animation, the
blue lines indicate a weaker magnetic field, the red lines a stronger
one, and the green line the boundary between them, at 10-year intervals
from 1910 to 2020. The field is weakening over South America, and the
red area over North America is losing strength.
No lights. No
computers. No cellphones. Even flushing a toilet or filling a car’s gas
tank would be impossible. And that’s just for starters.
But these dangers are rarely considered by those whose job it is to
protect the electronic pulse of civilization. More satellites are being
put into orbit with more highly miniaturized (and therefore more
vulnerable) electronics. The electrical grid becomes more interconnected
every day, despite the greater risks from solar storms.
No
lights. No computers. No cellphones. Even flushing a toilet or filling a
car’s gas tank would be impossible. And that’s just for starters.
One of the best ways of protecting satellites and grids from space
weather is to predict precisely where the most damaging force will hit.
Operators could temporarily shut down a satellite or disconnect part of
the grid. But progress on learning how to track damaging space weather
has not kept pace with the exponential increase in technologies that
could be damaged by it. And private satellite operators aren’t collating
and sharing information about how their electronics are withstanding
space radiation, a practice that could help everyone protect their gear.
We have blithely built our civilization’s critical infrastructure
during a time when the planet’s magnetic field was relatively strong,
not accounting for the field’s bent for anarchy. Not only is the field
turbulent and ungovernable, but, at this point, it is unpredictable. It
will have its way with us, no matter what we do. Our task is to figure
out how to make it hurt as little as possible.
Alanna Mitchell is an award-winning
science journalist and author. She is also a playwright who performs her
one-woman play, “Sea Sick,” based on her book of the same name, around
the world.
