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What Will Happen When Earth's North And South Pole Flip?

- [Narrator] Did you know that Earth has two north poles?

There's the geographic north pole,

which never changes,

and there's the magnetic north pole,

which is always on the move.

And right now it's moving faster than usual.

Over the last 150 years,

the magnetic north pole

has casually wandered 685 miles across northern Canada.

But right now, it's racing 25 miles a year

to the northwest.

This could be a sign

that we're about to experience something humans

have never witnessed before:

a magnetic polar flip.

When this happens, it could effect much more

than just your compass.

- Right now on the surface of the planet,

it looks like it's just a bar magnet.

Our compasses are just pointing toward one pole at a time.

There's a dominant two pole, dipole system.

- [Narrator] But sometimes, Earth doesn't always

just have a single magnetic north and south pole.

Evidence suggests that for hundreds to thousands

of years at a time,

our planet has had four, six

and even eight poles at a time.

This is what has happened

when the magnetic poles flipped in the past.

And when it happens again, it won't be good news for humans.

Now you might think that eight poles

must be better than two,

but the reality is that multiple magnetic fields

would fight each other.

This can weaken Earth's protective magnetic field

by up to 90% during a polar flip.

Earth's magnetic field is what shields us

from harmful space radiation

which can damage cells, cause cancer

and fry electronic circuits and electrical grids.

With a weaker field in place,

some scientists think this could expose planes

to higher levels of radiation making flights less safe.

This could also disrupt the internal compass

in many animals which use the magnetic field for navigation.

Even more extreme, it could make certain places

on the planet too dangerous to live.

But what exactly will take place on the surface

is less clear than what will undoubtedly happen in space.

Satellites and crude space missions

will need extra shielding

that we'll have to provide ourselves.

Without it, intense cosmic and solar radiation

will fry circuit boards

and increase the risk of cancer in astronauts.

Our modern way of life could cease to exist.

We know this because we're already seeing a glimpse of this

in an area called the South Atlantic Anomaly.

Turns out, the direction of a portion

of the magnetic field deep beneath this area

has already flipped.

Scientists say that's one reason why the field

has been steadily weakening since 1840.

As a result, the Hubble Space Telescope

and other satellites

often shut down their sensitive electronics

as they pass over the area.

And astronauts on the international space station

report seeing a higher number of bright flashes of light

in their vision, thought to be caused

by high energy cosmic rays

that the weaker field can't hold back.

Since experts started measuring

the anomaly a few decades ago,

it has grown in size.

It now covers a fifth of Earth's surface

with no signs of shrinking anytime soon.

This is so extreme that it could be a sign

we're on the brink of a polar flip

or we may already be in the midst of one.

But scientists remain skeptical, mainly because...

- The last time the poles reversed was 780,000 years ago

so we don't have a record of this.

- [Narrator] Turns out, 780,000 years

is over double the time Earth usually takes between flips.

- Since the last mass extinction,

there have been reversals roughly every 300,000 years.

- [Narrator] So, what gives?

Well, scientists haven't figured it out, yet.

It's unnerving to think that our modern way of life,

banking, the stock exchange, missile tracking, GPS,

relies on the outcome

of something we can neither predict nor control.

One study went so far as to estimate

that a single, giant solar storm today

could cost the U.S. up to

41.5 billion dollars a day in damages,

and that's with the Earth's magnetic field

at it's current strength.

It's frightening to even imagine

the devastation a storm would bring to an Earth

with a magnetic field only 10% as strong as it is now.

We may not be able to stop a polar flip,

but we can at least start to take measures

to minimize the damage.

The first step, figure out what's going on

with this wacky field.

On the hunt are the European space agency's

Swarm satellites

that are currently collecting the most precise data

on the strength of Earth's magnetic field.

Right now they could be our greatest hope

for solving this riddle.