Global Warming Shifts the Earth's Poles 482
ananyo writes "Global warming is changing the location of Earth's geographic poles, according to a study published this week. Researchers at the University of Texas, Austin, report that increased melting of the Greenland ice sheet — and to a lesser degree, ice loss in other parts of the globe — helped to shift the North Pole several centimeters east each year since 2005. From 1982 to 2005, the pole drifted southeast towards northern Labrador, Canada, at a rate of about 2 milliarcseconds — or roughly 6 centimetres — per year. But in 2005, the pole changed course and began galloping east towards Greenland at a rate of more than 7 milliarcseconds per year (abstract). The results suggest that tracking polar shifts can serve as a check on current estimates of ice loss. Scientists can locate the north and south poles to within 0.03 milliarcseconds by using Global Positioning System measurements to determine the angle of Earth's spin. When mass is lost in one part of a spinning sphere, its spin axis will tilt directly towards the position of the loss — exactly as the team observed for Greenland."
It's another check on the measurements. (Score:3, Informative)
Just like the age of something can be measured by multiple decay products, layer depth, and many other measures of archeological assessment, and when they are in agreement, you know your results are robust, this is another way to measure the loss of ice which, if it agrees with GRACE, land measurements and predictions from models, will indicate that the model results are robust.
It's even in the FS:
"The results suggest that tracking polar shifts can serve as a check on current estimates of ice loss."
WTF? has been happening for years (Score:3, Informative)
i first read about this a decade ago and it has been happening for hundreds of years. scientists are studying ships' logs from the 1700's and earlier and this process started 300 years ago.
Re:The opposite might also be true (Score:5, Informative)
Re:it all goes south from here... (Score:2, Informative)
Counterclockwise.
Re:Three Gorges Dam (Score:5, Informative)
With that said, why did they change from "centimeters" to "milliarc"? What the hell is the ratio?
A Nautical Mile [wikipedia.org] is one minute of arc. Since a NM is 1852 meters, an arc second would be 1852/60 = 30.87m, so a milliarcsecond would be 3.087. So the ratio is about 3.
Re:Three Gorges Dam (Score:5, Informative)
Something about this article just feels wrong. http://en.wikipedia.org/wiki/True_polar_wander [wikipedia.org] feels more right - just sits better in my gut. ;)
Re: Spinny-Chair (Score:4, Informative)
You seem to be talking about the magnetic poles, which are indeed caused by the spin of the core and move a lot every year, in the magnitude of 50 km/year. This is so much that navigating using a compass requires compensating for the specific declination of that year. You can even observe it if you have a good bearing compass: take the bearing from a fixed position to a relatively far away object, such as a broadcast tower. A couple years later, take the bearing again, and (depending on your location) it may have changed by one or even several degrees.
TFA talks about the geographic north, e.g. the intersection of the surface and the axes around which the earth spins. This does not generally move around much, as it is affected by the distribution of mass around the earth causing the axis to shift. According to TFS, it can be measured using GPS, and moves in the magnitude of centimeters per year.
Re:Only if you make money out of polluting. (Score:3, Informative)
Re:The opposite might also be true (Score:2, Informative)
There is pretty clear causality here - melting ice results in a shift of mass on the surface of the Earth, which causes a change in the moments of inertia and products of inertia of the planet - due to conservation of angular momentum this results in the axis of rotation shifting.
Re:In Other News! (Score:3, Informative)
I know you're being ironic, but I'd like to point out he's also completely wrong.
The effect of continental drift, ice melting, ocean temps, etc is a quite long studied subject (see ref below which mentions George Darwin already looked at polar wobbling). I admit not everything about the wobbling is fully understood, but at least since 2002 [1] we are quite confident that the Greenland ice melting is significant enough to cause an effect on polar motion.
The fact that random people here often think they did a better job at the science in a 20 sec post (especially if that science is related to a politically sensitive topic) is something interesting I have been observing on /. for the last 2-3 years, and is quite a disappointing trend imho.
[1] http://www.pnas.org/content/99/10/6550.full
Re:Simple question (Score:4, Informative)
You're confusing the drift and inversion in the planet's magnetic pole with the drift in the planet's rotational pole. This article is about the latter.
Re:All Just a SWAG (Score:4, Informative)
Not at all. It's a method that's proven itself repeatedly in studies on other subjects, such as the inner structure of the Earth and the measurement of earthquakes. If you'd rather believe that geophysicists studying the earth's mantle who've never written a climate science paper in their lives are also part of The Conspiracy you're welcome to, but you're rapidly going to find yourself as the only one who isn't In On It.
Re:Three Gorges Dam (Score:5, Informative)
. Meters and kilometers are strait-line measures, and can only approximate distance on Earth (unless you want to bore through the earth).
Which is bollocks. The one is not more "curved" than the other. Both can be used to measure distance on either flat ( Euclidean ) or curved surfaces.