The North Pole is moving rapidly and  no one knows exactly why or where it’s  

going. That’s quite something. I’ve had a look.

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Strictly speaking, earth has two North poles. One  is defined by the Earth’s rotational axis. It’s  

called the geographic North Pole, is the thing  you find on your globe, and isn’t going anywhere.  

But we have a second North pole, that is the  North of Earth’s magnetic field. These two  

north poles used to be pretty much in the same  place, defining what we even mean by north. But  

in the past few decades, the magnetic north  pole has brought scientists some surprises.

For the past 400 years, the magnetic North Pole  wandered slowly around northern Canada with a  

speed of 5 to 10 kilometres per year. But then,  in the late nineteen nineties, its motion sped  

up. By the early two thousands, it was moving at  up to fifty kilometres per year towards Siberia.

Tracking in the North Pole is not some obscure  obsession of geophysicists, at least not only,  

it has practical consequences.  Because of this rapid motion,  

navigation systems that rely on the magnetic  north pole have to be frequently updated.  

“North” used to be a direction. Now it’s a  subscription service with regular updates.

Scientists keep track of this with the World  Magnetic Model. That is a data-based model  

maintained by the US-American NOAA and the British  Geological Survey. It is used by militaries,  

commercial airlines, shipping companies,  satellite systems, and oil and gas companies.

Why would oil and gas companies  care about the magnetic north  

pole? It’s because they need some way  to keep track of what direction they  

are drilling. If they get the angle  wrong even by a fraction of a degree,  

that will accumulate to a big offset as  they drill down. One of the ways they  

avoid this is by keeping track of the magnetic  field, so they need to know when it changes.

The magnetic north pole model used to  be updated every five years. But in  

twenty nineteen, researchers had to issue an  out-of-cycle update because the magnetic field  

was drifting too quickly for the old model  to remain reasonably accurate. The latest  

update of the model just appeared a few  months ago. The motion of the North Pole  

has slowed down a bit in the past few  years, but not a lot. The situation is  

becoming so complicated that the new version  of this includes a higher resolution option,  

and I expect that next year they’ll ask you  to upgrade for the premium pro North pole.

But that isn’t all that is going on. Scientists  have also found that the overall strength of  

Earth’s magnetic field has declined by roughly  ten percent over the past two centuries. And in  

some regions, the magnetic field is behaving  oddly. Over the South Atlantic, there is a  

region where the magnetic field is unusually  weak. It is called the South Atlantic Anomaly.

So what is happening? Well, scientists  don’t know for sure. The best current  

explanation is that things are shifting  around underground more than they used to. 

Earth’s magnetic field is generated in the  outer core, about two thousand kilometres  

beneath the surface. Down there is a  vast ocean of molten iron and nickel  

at several thousand degrees Celsius. The  stuff is electrically conducting and it  

moves. That generates electric currents  and those currents create magnetic fields.  

The process is powered by the rotation of  earth. Scientists call it the “geodynamo”.

So far so good, but the details are…  complicated. The field is produced by  

turbulent fluid motion in a spherical shell under  extreme conditions. And we cannot directly observe  

the flow. We can only indirectly infer it  from measurements of the magnetic field  

at the surface and from gravity measurements  and you know some earthquake data and so on.

What researchers have found from this is  that there is not one but TWO regions of  

bundled magnetic “north” fields. One is under  Canada and the other one under Siberia. Over  

the past few decades, the Canadian  one has weakened while the Siberian  

one has strengthened. This is why the  overall pole has moved towards Siberia.

But this is just a reconstruction from the  observations. Scientists don’t know why this  

is happening or what will happen next. One of  the big worries is that the magnetic field of  

Earth will reverse, and the magnetic south will  change with the North pole. We know that this has  

happened hundreds of times in the past. On the sun  it happens every 22 years. If it were to happen on  

earth, this would weaken our shield from cosmic  radiation, potentially for thousands of years.

There is no indication that our magnetic  field is indeed about to reverse. It is  

also somewhat unclear just how unusual  or normal the current observations are,  

because we don’t have data of Earth’s magnetic  field from the Pleistocene if you see the problem.

But maybe in a few decades we’ll no longer “head  north” but to the place formerly known as north.

Thanks for watching. See you tomorrow.