2098: Magnetic Pole

Explain xkcd: It's 'cause you're dumb.
Jump to: navigation, search
Magnetic Pole
People keep trying to come up with reasons that we should worry about the magnetic field collapsing or reversing, but honestly I think it's fine. Whatever minor problems it causes will be made up for by the mid-latitude auroras.


Over the last couple of months, Earth's magnetic fields have been shifting rapidly. Although the magnetic fields do move regularly, the current shift has been unexpected and unprecedented. As many location systems are reliant on the magnetic fields to function, the accuracy of such tools is being shifted beyond the maximum acceptable error.

Locational and navigational systems use the magnetic field, combined with a model of field behavior, to do fancy math and pop out data. Because of the rapid shifts, a new model was scheduled to be created; however, the model has been considerably delayed by the US government shutdown,

As shifts occur, the error of geopositional data will increase until a new model is released. The effect is especially pronounced as you move toward the poles.

Cueball is saying that because of the currently published magnetic declination data being slightly incorrect, his schooners (old merchant sailing ships) may go off-course and crash on shoals. This is to illustrate how magnetic pole shift doesn't actually affect many people's daily lives. Modern ships' navigation systems do not rely on magnetic pole location – in contrast to old vessels which mostly used a compass.

Since the movement is only about two-fifths of a degree, it wouldn't cause much disruption for Cueball or require him to adjust anything about his lifestyle, but since the speed of the change has been steadily increasing over the past few years, it may mean we are heading for a geomagnetic reversal in the next few decades, something very exciting indeed. During a magnetic reversal, the poles wouldn't just switch places; several different poles would form and interact chaotically, and it's likely that one of them would end up close enough to where Randall lives to cause auroras to become more common at some point during the transition.

In the title text, Randall mentions that there are reasons people could be concerned, but says that they would be more than made up for by newly being able to experience mid latitude auroras.


[White Hat and Cueball are talking to each other. White Hat has a cellphone in his hand, while Cueball is raising his hands in the air in mock exasperation.]
White Hat: I just read that the Earth's North magnetic pole is drifting rapidly.
Cueball: Oh no! I must update our declination tables post haste, lest our merchant schooners run aground on the shoals!
[Caption below the panel:]
I like when the Earth's magnetic field does weird stuff, because it's a huge, cool, urgent-seeming science thing, but there's nothing I personally need to do about it.



GPS relies on satellites not the magnetic pole, so it wouldn't be affected.

I originally mentioned that modern GPS receivers like in smartphones may integrate the compass, gyro, and GPS to provide higher-quality location data using heuristics, which may get fouled-up if the pole moves too far, but I wrote it in too playful a manner and it has been deleted since. There was no citation anyway; it was just a vague memory. 06:08, 15 January 2019 (UTC)

So, GPS receivers don't need magnetic poles... but what about the GPS satellites? GPS works being them transmitting their exact location, so they need so way of knowing what that is. JamesCurran (talk) 22:58, 14 January 2019 (UTC)

I was wondering about that. Just added [citation needed] to that and a couple of other alleged facts that should really be cited if true, and removed if not. 20:35, 14 January 2019 (UTC)

It was speculated that reversals were linked to mass extinctions. This would make the alt-text appear to be a bit blase - but " Statistical analysis shows no evidence for a correlation between reversals and extinctions." so it seems we will probably be OK. It does seem odd that GPS wouldn't be calibrated against fixed ground positions. Baldrickk (talk) 22:06, 14 January 2019 (UTC)

I expect we'll be fine, but don't a lot of migratory critters use the Earth's magnetic field for navigation over very long distances? I mean, it's not as though they check a calendar and say, "Oh, hey, winter's coming, I guess I'd better head North." They just go in the direction they are 'programmed' to go when they start to feel the urge to do so. So... If the poles reverse (or whatever else) aren't they going to go the wrong direction? There are lots of other species that rely on those migratory species for their lunch. Yeah, I can imagine that there could be a lot of problems. Assuming, of course, that what I read about migratory species using the magnetic field of the Earth for navigation is true. 02:39, 15 January 2019 (UTC)

I don't believe any "location systems" depend on magnetic field for their accuracy, other than a magnetic compass. As noted above, GPS is calculated numerically from signals received from satellites, so the only effect the magnetic field could have on that is if it somehow disrupts the broadcast of the satellite radio signals. Similarly, LORAN calculates location based on radio signal, from towers on land. There are others as well, and I'm pretty sure none that depend on the location of the magnetic pole. GPS in general is not calibrated to fixed ground positions, but there are enhancements to GPS that do. But those still use radio broadcasts from towers whose locations are known, and don't need to take into account the location of magnetic north. Lnthomp (talk) 22:28, 14 January 2019 (UTC)

I agree that the way it is currently phrased is misleading (to the point of being wrong), but some "location systems" use multiple factors to increase their accuracy. A good smartphone will use GPS together with signal strengths to wifi routers with known locations together with its compass to increase accuracy above that which it could obtain from GPS alone. I've only taken little glimpses into the issue professionally but if I were making an algorithm for such a thing I'd also use input from the accelerometers. In any event, I'd most certainly use the built-in compass. Cheap estimation of direction of travel. Of course I'm just being pedantic with all of that. The difference in accuracy for such a scenario would most likely be minor to the point that nobody would notice. I just kind of think the algorithms that try to combine all that sensor data are cool. -- 01:24, 15 January 2019 (UTC)

It's navigation systems rather than location/positioning systems that rely on magnetic field (although both are often combined). You need a compass to know which direction your are facing and how to go to your destination. 11:32, 15 January 2019 (UTC)

Granted no one has ever experienced and documented a magnetic reversal event, however, would it be possible for the magnetic flux to cause errors on magnetic media? (eg HDD, credit cards, floppies, cassette, VHS, etc) If it were a cause for alarm, would a faraday cage be useful in protecting against the effects? 23:05, 14 January 2019 (UTC)

Faraday cages attenuate electric, not magnetic, fields. I think magnetic shielding involves thick, rounded material with high permeability such as iron, steel, mu-metal, often placed inside a faraday cage to prevent RF signals from saturating the permeability; never done it myself though. 06:13, 15 January 2019 (UTC)

No. Magnetic media would not be affected. Geomagnetic field strengths are orders of magnitude weaker than those used to write to magnetic media. -- 01:27, 15 January 2019 (UTC)

The biggest issue during a magnetic pole reversal will be the loss of the Van Allen belt, frying all of us. RandalSchwartz (talk) 02:39, 15 January 2019 (UTC)

Unlikely to literally fry us, but there could definitely be damages on the electrical grids around the world as the magnetic field is weakened during the transition. Probably also a rise in radiation-induced cancers. 11:32, 15 January 2019 (UTC).

GPS and Solar weather citation - worth a read. Basically, the ionosphere disturbance from a changing Earth field (analogous to a changing solar wind) leads to notable inaccuracy and service disruption. 23:12, 14 January 2019 (UTC)

We'll have to renumber all our runways, which will be annoying. 04:27, 15 January 2019 (UTC)

actually, several runways have already had to have been renumbered because of change in the magnetic poles. 05:19, 15 January 2019 (UTC)

Wait, "geomagnetic reversal in the next few decades"? Last I checked, it was scheduled to happen in the next few millennia. Have there been new data? 09:00, 15 January 2019 (UTC)

Reversals appear to happen randomly, so there's no way to know when the next one will happen. Even if the last one happened about 800 000 years ago, there have been periods of tens of millions of years without reversal. 11:32, 15 January 2019 (UTC)
800 000 = 0. Lysdexia (talk) 16:08, 15 January 2019 (UTC)
Not when the fields can reverse as often as 5 times in a million years. 16:37, 15 January 2019 (UTC)
https://www.sciencedaily.com/releases/2012/10/121016084936.htm might shed some light on things. In any case, “scheduled” is definitely the wrong word. 13:49, 15 January 2019 (UTC)

What about the SOUTH magnetic pole? 15:29, 15 January 2019 (UTC)

We should mention the other comic with similar reaction: https://xkcd.com/2029/ 11:45, 16 January 2019 (UTC)

I'm glad we decided to work on that. Now a lot of geography-students will be a lot less confused when the magnetic field comes up.