The magnetic north pole is moving...

RichardS said:
50km is 50km wherever you are, surely. :)

Richard
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Not at the moment in the UK. “Experts” have been “debunked” by Tabloids and taken over by “enlightened” beings and numbers and statistics also debunked as sorcery. Apparently, these days you can pull 350 million out of any magical hat and Unicorns are real.
So 50km in the UK mean nothing because it’s an EVIL EU measurement Unit designed solely to oppress the masses.
 
ghostlymoron said:
The figures on charts say something like"variation 5°W reducing by x minutes per year.
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Such predictions on older maps and charts will be way off. The speed of movement of the N magnetic pole was quite small (on average around 10km p.a.) for most of the 20th century. It speeded up considerably in the 1990s, and for the past 20 years has been around 50km per year (part of the point of the article, which isn't exactly news).

Having not sailed in the SE of England for many years, I was quite startled to notice a year or two ago that True and Mag N were identical just off Deal. That point (although actually a line, of course) seems now to be somewhere around Junction 5 on the M2. Never expected to witness that when I was getting my first OS maps soggy in the Peak District all those years ago...
 
macd said:
Such predictions on older maps and charts will be way off. The speed of movement of the N magnetic pole was quite small (on average around 10km p.a.) for most of the 20th century. It speeded up considerably in the 1990s, and for the past 20 years has been around 50km per year (part of the point of the article, which isn't exactly news).

Having not sailed in the SE of England for many years, I was quite startled to notice a year or two ago that True and Mag N were identical just off Deal. That point (although actually a line, of course) seems now to be somewhere around Junction 5 on the M2. Never expected to witness that when I was getting my first OS maps soggy in the Peak District all those years ago...
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I haven't sailed around that corner recently but from memory I would say that the depth of water at junction 5 is insufficient for most cruising boats.
 
cpedw said:
How long does a flip take? Do the poles move steadily and stay at the same longitude(s) during the flip?

I will accept "Nobody knows" as an answer.

Derek
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Good question! Unfortunately, the last time it happened was when our ancestors were learning to bang rocks together, so the answer is "we don't know". There isn't a good, finely datable sequence through a change, so we don't know how long it takes - rapidly by geological standards, but that's between 100 and 1000 years. We know that the field doesn't collapse to nothing( the effects of solar radiation would be obvious) and we know that it doesn't affect life on earth (it doesn't correlate with extinctions). But most geologists would quite like one to happen so we can observe it! The next one is a bit overdue..
 
I have an old Admiralty Chart of the Sound of Harris, on which Variation is given as 27°25'. OK, that chart is dated 1857, but with Variation like that, you couldn't just ignore it.:D (I do have more modern charts):D
 
cpedw said:
How long does a flip take? Do the poles move steadily and stay at the same longitude(s) during the flip?

I will accept "Nobody knows" as an answer.

Derek
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AntarcticPilot said:
Good question! Unfortunately, the last time it happened was when our ancestors were learning to bang rocks together, so the answer is "we don't know". There isn't a good, finely datable sequence through a change, so we don't know how long it takes - rapidly by geological standards, but that's between 100 and 1000 years. We know that the field doesn't collapse to nothing( the effects of solar radiation would be obvious) and we know that it doesn't affect life on earth (it doesn't correlate with extinctions). But most geologists would quite like one to happen so we can observe it! The next one is a bit overdue..
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Last I heard its going to be very messy...
At the moment the magnetic field pattern at the Earth's surface isnt uniform, there are hot spots, some so strong they are tending towards being a separate pole.
These variations are set to increase, leading to a rather mottled pattern of N and S poles all over the place. Over time this pattern evens out with, potentially, a N S swap.

Forget all the problems of navigation and pigeons getting lost, the effect on the magnetosphere which stops us being fried in a microwave oven is somewhat more significant.

Hers a fun page to gander:
http://www.geomag.bgs.ac.uk/education/earthmag.html#_Toc2075563
and this
https://www.livescience.com/18426-earth-magnetic-poles-flip.html
where it states that a flip can take 1,000 to 10,000 years!
 
This thread reminds me strongly of a time when I was an undergraduate on an expedition to Spitzbergen. Six of the party were geologists, and four weren't. Our camp had an excellent view of some highly deformed rocks, and one evening we were discussing the processes that had given rise to the deformation. This was when plate tectonics was a new and exciting idea, and we were speaking of continents colliding and rocks being squeezed and crushed. One of the non-geologists listened with big, round eyes, and eventually remarked ".Gee, it must have been real exciting round here when all that was happening!"

We geologists looked at each other, and then one of us quietly asked "How long do you think it all took?" - of course, the events we had been discussing took tens or hundreds of millions of years, with the change even over a lifetime being imperceptible!

Yes, we expect the magnetic pole to flip from the present polarity to the opposite sometime, but the change will happen at rates comparable to the existing rates of change. There may be a period when the magnetic field is weak, but it won't be nothing. And the change will be slow enough that we will simply adapt, just as we adapt to the variation of the compass at present.

Certainly it is nothing to worry about!
 
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