The North Pole moves as ice sheets melt (Greenland is losing mass)

[NickB79]

http://science.nbcnews.com/_news/2013/05/15/18280341-the-north-pole-moves-as-ice-sheets-melt?lite

The North Pole’s surprise trip toward Greenland is due to Earth's rapidly melting ice sheets, a new study finds.

The distribution of mass across the planet determines the position of Earth's poles. Because Earth is a bit egg-shaped, the North Pole is always slightly off-center. It's also been slowly drifting south, responding to long-term changes since the last Ice Age, as the enormous ice sheets that once covered large swaths of the planet melted and parts of the Earth rebounded from the lost weight.
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But in 2005, the pole suddenly started making a beeline east for Greenland, moving a few centimeters eastward each year. The cause? Rapid melting of the Greenland Ice Sheet, finds a study published Monday in the journal Geophysical Research Letters. Ice loss and the associated sea-level rise account for more than 90 percent of the polar shift, Nature News reported.

Oh fuck......

[limpyhobbler]

1. ....

[freshwest]

2. 'It's always something...'

[corkhead]

3. And Greenland will be green again!!11!1!!1

at least while it's still above water.

[DCKit]

16. It's going to rise as the weight of the ice comes off.

Too rocky for agriculture, but a great base for north seas fishing... if there are any fish left.

[jimlup]

4. There exist many ominious warnings

that all is worse than even the most pessimistic models ...

yeah, it will be an interesting ride into the next 40 years

[longship]

5. Let me know when my 2000.0 star charts and Astro computers will be out of date.

I hate searching by hand with a Dobsonian mounted scope.

[defacto7]

6. Pole shift... They mean geographical North?

There are 2 poles, geographical and magnetic. Every couple hundred thousand years or so the magnetic pole turns completely around; south switches with north. Ice melt can shift the geographical pole I guess since the crust is basically floating.

Edit: I goofed up my info.... From NASA:

Earth has settled in the last 20 million years into a pattern of a pole reversal about every 200,000 to 300,000 years, although it has been more than twice that long since the last reversal.

[truedelphi]

7. Thanks for pointing that out.

Of course, why blame myself for not keeping all of this straightened out in my head, when Mother Earth can't keep a handle on it either!

[HooptieWagon]

8. This is going to fuck navigation all up.

Are lines of latitude and longitude going to be redrawn?

[defacto7]

9. Lines are lines. Probably not.

But navigation has to be altered all the time due to the changing nature of magnetic North. Pilots have to make slight changes to the charts every once in a while since it's the magnetic pole they set course to. Geographical poles makes little difference to navigation.

edit: Maybe if the geo. shift was 5 or 10 degrees someone in the far future might decide to change the map. Who knows.

[HooptieWagon]

10. No, magnetic pole is only used to keep course.

Its change is noted on charts, as is the magnetic variation at different parts of the globe. This is only used when steering a course, or taking a bearing on a landmark, using a magnetic compass. Position location, whether by GPS or celestial navigation, uses the geographical pole, which is the axis of rotation. If that axis of rotation is changing, as the article indicates, then by necessity charts and tables will have to be recalculated to correct for a new geographical pole.

[defacto7]

12. Interesting...

Yes, but that magnetic variation is a moving target. Not by much but changes happen and the global variation just increases the calculated differences. So pilots are using celestial navigation? That messes up my whole pilot training. (Which ain't all that much really) But talking to commercial pilots in the 90s, they were complaining about a 2 percent movement of the magnetic pole in a couple days which caused them to shift their charts to accommodate. The only celestial navigation I am acquainted with deals with the celestial or the ecliptic equators. Would charts actually have to define new coordinates simply because there is a .05 to .1 shift in the geo. axis? Why wouldn't the change be sufficient with a slight calculation alteration? We are not talking about the earth sliding 30 degrees, at least not in the next half millennium. And why would that effect the celestial coordinates? Is that directly connected to the earths lat/long grid? I'm rusty on this. Glad to hear input.

[HooptieWagon]

13. OK, a brief rundown.

Magnetic variation is the differrence between the magnetic north pole, and the geographic north pole. It varies widely, in some locations its zero, I've seen it be 30 deg in my sailing...possible its even more in higher latitudes. Depending on location, it either decreases or increases by a small annual amount...usually a few minutes annual change (average 5). Most small boats use magnetic compasses, ships use gyro-compasses because the large amount of steel causes excessive deviation (compass innaccuracy)...I would assume large aircraft do too. Small aircraft might use either. I would assume that the magnetic pole would continue its shifts in the current fairly predictable manner. However, longitude and latitude are NOT based on magnetic north, but on geographic north...the axis of rotation....and it is the geographical pole that concerns us in navigation.
The article seems to be saying that its the geographical pole that is starting to change. In that case, bodies used for navigation (be they sun, stars, or GPS satelltes) no longer have the same orientation to the earth's axis of rotation as previously. This throws off charts, navigation tables, and the computers in your GPS unit. Since 1 minute of latitude is 1 natical mile, even a slight shift in the geographic pole would create a large error in calculating your position.

[muriel_volestrangler]

19. For a change of a few centimetres a year? No.

It's pretty amazing that they can measure it that accurately, if you ask me. But the article points out there are seasonal and a 14 month variation that dwarf this, and it's only when you remove those that you can see this. So if this does affect GPS positioning which has to be accurate to centimetres, then they must already have a system that can take into account the seasonal adjustment, so they'd just reprogram to include the long-term drift, now they've discovered it.

[HooptieWagon]

20. Yeah, you're right.

A few cm per year won't make a diff. GPS only has a several meter accuracy. Article said it was taking off in a beeline for Greenland, which implied a larger and faster change. I suppose when a few cm accumulate to a few meters, something will have to be done.

[Major Nikon]

11. In Thule, Greenland north is more west than north

The last time I was there the magnetic deviation was 75 degrees.

[HooptieWagon]

14. Variation. Deviation is a compass error caused by proximity to iron.

There is also dip, which normally isn't a concern. The magnetic north pole moves around a point NW of Hudson Bay, and is several miles beneath the surface. If you sailed over that spot, a magnetic compass would point straight down, and be useless. That is dip.
And yes, variation can be large...it increases the farther north, and farther east (from US) you go.

[trof]

15. True Virgins Make Dull Companions

Learned that in pilot training.
True heading +/- Variation = Magnetic heading +/- Deviation = Compass heading.

[HooptieWagon]

17. +1

Good one.
I wasn't trying to be a vocabulary nazi to the poster, but learning the proper terminology increases ones understanding of a subject.

[trof]

18. I understand. It matters.

On my polar flights we sometimes crossed over both mag north and geographic north.
The lines of variation become a swirl on the chart and all mag headings become due south for a while. The 'whiskey' compass just twirls for several minutes.

[HooptieWagon]

21. Damn, that must have been a confusing several minutes.

Your story reminded me of the first time I was navigating in pea-soup fog using radar. This was a couple miles up the Damariscotta River in Maine, before GPS was common. We had a bouy located on radar, and were trying to get a visual ID on it before steering a compass course to a mooring cove. There was about 30' of visibility. We would near the bouy, and lose it in the clutter at center of radar, shut down engine and listen for the bell. After a minute or so, bouy would reappear on radar astern or to the side of us. We would restart motor, idle that direction until bouy was lost in radar clutter again, and again stop motor and listen. Did this several more times. Finally, while we were stopped and listening, a crusty old lobsterman in an aluminum skiff rowed up to us and demanded to know why we were chasing him! He told us the direction to the bouy we were looking for, along with where we could go, so to speak.