The Earth has a magnetic field that, like a magnet, goes from the north pole to the
south pole.
This field is caused by complex processes inside of the Earth’s molten core.
This magnetic field is much more important than you think.
Not only does it help us find north with a compass, it also protects us and all our technology
from dangerous cosmic radiation.
Many animals depend on it for their migrations and dogs apparently align themselves along
a north south angle when they poop.
Like all magnets, the Earth’s magnetic field has a north and south pole, so what would
happen if they would flip?
First, let’s lay down some definitions.
The Earth rotates around its geographic north Pole, this pole would take massive amounts
of energy, akin to a giant asteroid, to move and generally stays where it is.
In a globe, the geographic north pole is marked by the top part of the stick that connects
the globe to the mount.
The bottom part is the south pole of course.
The magnetic poles are the two places where the magnetic field is vertical to the Earth’s
surface.
Near the geometric north pole the field will point vertically down, and near the geometric
south pole the field will point vertically up.
This means that your compass needle would not point forward on the north pole, but downwards
toward the ground.
On the south pole it would point straight up into the sky.
Due to historical shenanigans the magnetic south pole is actually at the geographical
north pole and vice versa.
This is because we once decided that the north-part of a magnet on a compass, points to the geographic
north pole.
Since opposite sides attract, that means that the magnetic south pole is at the geographical
south pole.
Unlike their geometric counterparts, the magnetic poles are wandering points.
This has to do with the fact that our Earth’s core is not a solid bar magnet, but rather
a very dense magnetic liquid.
Changes in this liquid affect the shape, strength and orientation of the magnetic field, which
can have some major effects for us.
Direct measurements of the magnetic field have been ongoing for over 4 centuries now,
and in this time we have mapped the path of the magnetic north pole very accurately.
It wanders around a lot, but it has always stayed close to the geographic north pole.
A flip would require the magnetic pole it to move down past the equator, towards the
other pole, so that a compass would now point south instead of north.
However, if we go back much further in time then we can see that the magnetic field has
flipped 183 times in the last 83 million years.
That means that we should have one flip roughly each 450000 years.
However, these same measurements indicate that the last flip happened around 780000
years ago.
That is almost twice as long as the average, which implies that we are long overdue for
the next flip.
Perhaps it is already happening!
How do scientists know this, you might ask.
For the last 400 years we could measure it the location of the magnetic poles directly.
The rough process is to compare compasses on different locations and triangulate the
location of the poles.
But before that we did not have the technology nor the knowledge to measure these things.
The way that we managed to find out the location of the magnetic poles further back is by observing
particles that were somehow ‘frozen’ into place during a certain time and point to the
position that the poles had when they were still mobile.
If we find a 1000 year old magnetic particle that has not moved since then, we can tell
where the poles are based on its orientation.
The scientists basically look for very old compasses.
The most popular source for these particles are cooled volcanic flows, which have very
accurate measurements but of course do not happen on a continuous basis.
Alternatively scientists look for these frozen particles in sedimentary deposits on ocean
floors.
These stack in a continuous process, but the problem there is that it is very hard to date
the layers of sediment accurately.
A new and very promising method of determining the past magnetic field is based on the observation
of stalagmites.
These are rock structures that are formed over the course of thousands of years by a
constant dripping in a cave.
Magnetic particles that float around in the cave get caught by the drop and become part
of the structure.
This method is very promising because stalagmites form in a very controlled manner and are easy
to date, it is a destructive process however and we have a limited amount of them.
Scientists study these and other methods to go back millions of years and get very accurate
measurements of the strength of the magnetic field and the location of the poles.
From this research we found that a flip is not necessarily a fast thing, it takes between
two hundred and twelve thousand years.
This is bad news for us, as the Earth and all of its life are most venerable during
a flip.
This is mostly due to the fact that the magnetic field serves as a shield for any and all ionizing,
radioactive and generally highly energetic particles from the Sun that bombard us on
a constant basis.
These particles cause cancer, sterilize life and in general kill everything in high enough
doses.
Besides that, the particles also disrupt any and all technology that they come across.
Currently, most of these particles get deflected by our magnetic field, and sent up around
the poles.
Some particles still get through around the poles, where the field points inwards.
These particles are what cause the Aurora Borealis in the North and Aurora Australis
in the south.
Now looking at the drawing of our magnetic field, it does not take much imagination to
realize that if one of the poles would turn to face the Sun, we would lose all of the
protection that the Earth’s magnetic field gives us, as the particles would no longer
get deflected, and we would end up microwaved and ready to serve.
Especially if this continues for thousands of years.
Humanities only hope would be to move underground and start a new civilization there, with thick
layers of rock protecting us from the radiation.
Going to the surface would only be possible for short whiles and most probably a special
suit would be needed.
To a large extent this would be the end of life as we know it.
But a flip of the magnetic poles is not the only thing that could cause problems for us.
A simple weakening would also do the trick.
We have not yet measured anything that could indicate a polar flip, but we have been measuring
a growing area where the magnetic field is weakening.
This area is called the ‘South Atlantic Anomaly’, where the magnetic field has weakened
by over 20% in this century and a half and its area has grown by over 3 times to a massive
105 million square km.
Which is equal to roughly 70% of all the worlds landmass and about one fifth of the total
surface of the Earth.
The magnetic field in this area is so weak that many satellites suffer problems when
flying over it.
Their systems malfunction, they lose communication, some break altogether.
The Hubble space telescope stops observing and shuts down sensitive equipment when flying
through this zone.
And NASA astronauts have reported seeing a large amount of ‘shooting stars’ when
passing the region, which in reality are cosmic particles hitting their retinas.
It has also been reported that a flyby through this region once fried several modern laptops
on the International Space Station.
If the weakening of the field in this region continues, it might become impossible to fly
airplanes though it, both due to the risk of failing electronics and due to a higher
risk of cancer for the passengers and airplane staff.
Satellites could stop working completely in this region, severely crippling its technology.
If the region grows large enough, them it can even influence our global network.
Currently the anomaly is mostly above the ocean but it is already over a large part
of South America and Afrika.
However, at the rate that this anomaly is growing, it will envelop the United States
in roughly 100 years, and the field will have weakened by another 15%.
The entire world will be enveloped in roughly 350 years by which time the field will have
only 50% of the strength of today.
A small consolidation is that we would be seeing auroras at all latitudes and quite
regularly.
History shows us that during a polar flip many things can happen.
The field can shift like we described before, but it can also just weaken and nearly turn
off for a while.
There are also recorded cases of the magnetic poles breaking up into 4, 6 and even 8 due
to instabilities in the Earth’s core.
All of these fields will be much weaker than our current one and point in random directions.
The fields will be very messy and much less capable of defending us from the harsh conditions
of space.
For this reason it is very important that we study the Earth’s magnetic field and
do our best to predict what will be happening.
The forerunners of this are the European Space Agency with their Swarm satellites.
These spacecrafts form a constellation and scan the Earth for over 6 years now, making
very accurate maps of the Earth’s magnetic field.
Knowing how and when the field is changing, will allow us to predict the required level
of protection for our satellites and plan ahead for how to minimize this influence on
the planet.
Now, even if we manage to find a way to get around the radiation, there would still be
the large amount of species that rely on the magnetic field for orientation and navigation.
For ourselves this would mostly be a technological distortion, as humans do not seem to be sensitive
to magnetic fields.
Our navigational equipment would get disoriented and compasses would point to the wrong part
of the world, but we would be able to fix this with relative ease.
Especially because these instruments get recalibrated every few years anyway.
Depending on how slowly it flips, the blow on the animal kingdom could be much worse.
If it moves too fast, this could cause mass extinctions of thousands of species that rely
on the magnetic field to find their migration grounds or their spawning grounds.
Research suggests that many of them rely on the magnetic field for finding their way.
Birds migrate by following a certain field gradient, homing pigeons find their way home
by using the magnetic field and it is theorized that many migrating fish, like salmon use
the magnetic field to find their way.
Some predators, like foxes prefer to attack from a North-Eastern direction and large grazing
animals tend to align north south while grazing.
We do not think that the cows or foxes would mind much if the field changed, or that dogs
would refuse to do their business if the field orientation changed.
But any animal that uses the magnetic field for navigation would surely get lost and probably
die on the way.
Therefore the ideal scenario for a potential flip of the Earth’s magnetic field would
be for it to do so quickly, but not so fast as to disorient migrating animals.
So it should not change too much within their lifetime.
The hope is that at this point humanity found a way to hold back the radiation and everything
else survives also.
Perhaps some kind of futuristic satellite shield?
Or will we all live under ground in a few decades?
Tell us what you think in the comments.