ARI SHAPIRO, HOST:
There's some strange movement at the top of the globe right now. The north magnetic pole, which has been used for navigation for centuries, is shifting east - and it's shifting fast. Experts who map these magnetic fields are rushing to keep up as it heads away from Canada and towards Siberia. They've just announced they'll have to update the location of magnetic north a year ahead of schedule. To explain what's happening, Alexandra Witze of the scientific journal Nature joins us now. Hi there.
ALEXANDRA WITZE: Hi.
SHAPIRO: Shifting polls are not all that unusual, so explain what's different about this movement.
WITZE: Yeah. So we've known for centuries that the north magnetic pole kind of skitters around the Canadian arctic and is now sort of heading up and across the top of the world. What's new now is it's moving fast and in sort of unpredictable ways. And the scientists who use it to kind of build a model of how we navigate with that magnetic field, it's moving so fast that their models can't keep up with that.
SHAPIRO: That's wild. Remind listeners what the magnetic pole is. It's not the northernmost point on the globe, obviously. That doesn't move. What is the north magnetic pole, and why does it move around?
WITZE: It's basically the point at which Earth's magnetic field lines converge. So you think about the planet as a globe, and you think about magnetic field lines sort of coming out like a bar magnet connecting the north pole to the south pole. And these are magnetic poles. They're offset from the pole around which we spin. And it's different.
And it's created because deep in the Earth, in its core, there's liquid iron. And the liquid iron is sloshing around, and that generates this magnetic field. And it's what happens if you pull out an old-fashioned compass or the compass on your iPhone and look where that needle is pointing. That's the north magnetic pole. And it's a little bit off from the geographic pole all because of this sloshing of iron in the core.
SHAPIRO: Do scientists know why this rapid movement is suddenly happening?
WITZE: Not really. It's a bit of a mystery. The sloshing kind of changes from time to time in ways they don't quite understand. It's probably some kind of complex circulation deep down there in the core. But it's weird, right? So in the 1990s, the pole was moving along at a relatively sedate pace, and then it started to speed up. And it's been speeding up ever since. And what caused that speed up? They don't really know.
SHAPIRO: So I'm imagining scientists, like, tracking a beeping dot moving across a map. But what does it actually entail? How do scientists actually follow where the magnetic north pole is?
WITZE: Well, they used to actually go out and look for it. When it was in the Canadian arctic, when it was on land, when it was sort of among that archipelago up there, they could literally traipse to it and see the point where the north point of your compass pointed. Since it moved off shore and it's now in the Arctic Ocean, that's basically in water with some sea ice on top of it, so you can't really go out and check for it.
So what they do is they use models. There are satellites all around the planet, especially a European set of satellites called Swarm that measure the magnetic field at the surface. And from those measurements, the scientists create a model that shows basically where the magnetic field is, what's happening to it and how that Pole is moving.
SHAPIRO: Does the movement of the north magnetic pole matter for those of us who are not scientists? I mean we have GPS satellites to help with navigation. Do we really need magnetic north anymore?
WITZE: Yeah, we do because your iPhone has it in there. If you go and look in the credits for Google Maps in the iPhone, you'll see it's got the world magnetic model. So if the north magnetic pole is moving in a different direction or a different speed than it was a year or two ago and they haven't updated the model for a couple of years, you're going to be out of whack.
SHAPIRO: That's Alexandra Witze from the scientific journal Nature. Thanks for talking with us today.
WITZE: Thanks for having me. Transcript provided by NPR, Copyright NPR.