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Nick Danger
Ice climber
Arvada, CO
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A few years ago a geophysicist from (I think) Cal Tech had written software to model the dynamics of the Earth's magnetic field, including polar wandering and pole reversals. Over some holiday break he let is program run for a couple of weeks without checking up on it and it did model a polar reversal. Two of the phenomena accompanying the polar reversal was an increase in magnetic anomalies in non-polar regions, and an increase in the wandering of the magnetic pole. Subsequent detailed paleomag research at Steen's Mountain in Oregon confirms both of these trends occurred during the last polar reversal. Additional research has shown that both the wandering of the magnetic poles and an increase in magnetic anomalies in non-polar regions is very high at present. All of this points towards an impending polar reversal, although "impending" could mean several thousand years.
We are already witnessing a marine transgression and a mass extinction event. Observing a polar reversal would make this the trifecta geological phenomena. What a great time to be alive as an earth scientist!
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 5, 2019 - 08:19am PT
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Declination for compass use crossed my mind as soon as I read the article, and it is addressed in the article:
“South of 65 degrees north and away from Canada, the average user will notice very little difference to their daily life,” said Ciaran Beggan, a geophysicist at B.G.S."
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Nick Danger
Ice climber
Arvada, CO
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Randisi, The biggest effect at the Earth's surface during a polar reversal is a temporary weakening of the Earth's magnetosphere and a concomitant increase of cosmic radiation at the surface. This would result in the northern lights (Aurora borealis) being observed farther to the south and the southern lights (Aurora Australis) being observed farther north. There likely could be a statistically measurable increase in certain types of cancer, particularly skin cancer, although this could be mitigated by wearing hats, long pants, and long sleeved shirt outside.
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Nick Danger
Ice climber
Arvada, CO
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Extinction events are not associated with magnetic pole reversals. As far as the solar wind stripping away the atmosphere, this could only occur if the magnetosphere were to completely collapse, and it only weakens temporarily during a polar reversal. Numerous planetary astrophysicists have speculated that Mars had a much more robust atmosphere and hydrosphere when it was a tectonically active planet with it's own functioning magnetosphere. Once it lost sufficient internal heat to achieve tectonic quiescence and a suspension of internal circulation of its outer core (assuming that the interior of Mars was similar to our own planet), the magnestosphere collapsed completely and that is when Mars rather catastrophically lost much of its atmosphere and hydrosphere.
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Reilly
Mountain climber
The Other Monrovia- CA
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So what is the evidence of prior ‘reversals’, how did they find it, and what is the mechanism?
(I have a good sized bag of pop corn)
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skywalker1
Trad climber
co
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I believe the evidence of reversals is at the Mid-Atlantic Ridge (rift?). As it has expanded the polarity of the rock flips every 700,000 yrs or so or what ever it is. Rock closer = younger and vice versa. There is a pattern. We know the rate of expansion so we know roughly how long ago a certain location was created. I know magnetite rock can spin a compass one way then the other way by orientation. I think it's the same concept.
S...
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Reilly: answers to your questions can be found here... https://en.wikipedia.org/wiki/Paleomagnetism
The mechanism is thermal remnant magnetism. Basically the alignment of magnetic minerals (mainly magnetite (Fe3O4) in basalt lavas in response to the ambient magnetic field that is preserved when the lava cools below the Curie point temperature. The orientation of these magnetic minerals can be measured in oriented samples using a sensitive cryogenic magnetometer.
The 1963 Vine and Matthews paper in Nature "Magnetic Anomalies over Oceanic Ridges" demonstrated the symmetry of magnetic field anomalies (reversals) preserved in oceanic lavas across mid-oceanic ridges. The magnetic anomalies were measured using ship-towed magnetometers.
https://www.geolsoc.org.uk/Plate-Tectonics/Chap1-Pioneers-of-Plate-Tectonics/Vine-and-Matthews
A global Magnetic Polarity time scale (history of the earth's magnetic polarity reversals) has been determined for the last 500+ million years of earth history.
https://engineering.purdue.edu/Stratigraphy/charts/Magnetics_Tabloid_Feb2010.pdf
This time scale is based on paleomagnetic measurements of both oceanic and terrestrial volcanic rocks from all over the planet combined with radiometric age dating.
These references explain the theory behind what causes the earth's magnetic field to flip polarity...
https://www.scientificamerican.com/article/what-causes-the-periodic/
Glatzmaier G.A., and Coe R.S Magnetic Polarity Reversals in the Core. In: Gerald Schubert (editor-in-chief) Treatise on Geophysics, 2nd edition, Vol 8. Oxford: Elsevier; 2015. p. 279-295.
The earth's magnetic field is simulated as a self-generating dynamo that arises from convection currents in the outer Fe-Ni liquid core. When you look at the behavior of the field over 10^5-10^6 year time scales, the temporally-averaged geomagnetic field is that of a geo-centric axial dipole.
[Click to View YouTube Video]
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 6, 2019 - 02:19am PT
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Randisi, thanks for pointing out the typo.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Not all those who wander are lost ;-)
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 10, 2019 - 10:18am PT
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Looks easy: where along the "0" declination line are you located?
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looks easy from here
climber
Santa Cruzish
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Feb 10, 2019 - 10:29am PT
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Is that map you posted up to date? Its title says 2010 and still has me at about 12°, which was my old declination.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 10, 2019 - 04:11pm PT
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Easy: the map I posted above is current. At my location in Concord, the declination is +13.4 which is consistent with the 2016 map shown below.
2016 Magnetic Declination map...Note the green line is the "0" declination line; red lines are positive declination and blue lines are negative in increments of 2 degrees...
The declination is not changing that quickly. For example, this 1934 historical declination map from the NOAA website showing the declination in central California at ~ +18 degrees...
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looks easy from here
climber
Santa Cruzish
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Feb 10, 2019 - 05:12pm PT
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Aw, man. Now I'm bummed. I'm just a bit (relatively) south of you. Not sure why NOAA lied to me. But it's still showing me 0° when I go back to that site.
Oh well. If this is the biggest problem in my life right now I guess I'm living pretty well.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 10, 2019 - 05:17pm PT
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Did the NOAA website prompt you to enter your current location?
I thought maybe you were stuck in Missouri or Arkansas and was thinking you probably miss Santa Cruz ;-)
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looks easy from here
climber
Santa Cruzish
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Feb 10, 2019 - 07:03pm PT
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No. I figured Big Brother was watching and just tapped into my phone's gps. But you're right that I would be missing the Best Coast if I were on the actual 0° line. I much prefer being here and 13° off (having lived in Texas for 3 years, gig 'em!)
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 11, 2019 - 06:31am PT
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tuolumne_tradster,
The line of declination doesn't move fast as you stated, but that is relative to your location.
What has moved drastically is the 0° line of declination. If you compare where the was on your 1934 map you can see it was off the East Coast of Fla on the 30° line of Latitude in North America.
The map below, the most current (February 2019) puts it west of the Mississippi River, a change of 700 +- miles.
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brotherbbock
climber
So-Cal
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Feb 11, 2019 - 08:08am PT
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It's the nephilim.
They are trying to confuse us on purpose because we are too close to the entrance to the hollow earth.
We need to stop diddling around the north pole.
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TwistedCrank
climber
Released into general population, Idaho
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Feb 11, 2019 - 08:18am PT
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I miss the flat earth.
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looks easy from here
climber
Santa Cruzish
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Feb 11, 2019 - 09:17am PT
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Well, turns out I'm the dummy, not NOAA. I had my phone's location turned off, so it just defaulted to 0°. Oops.
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Nick Danger
Ice climber
Arvada, CO
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Feb 11, 2019 - 09:43am PT
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Tuolumne tradster, your posts are exceptionally well informed and documented - thanks dude. I very much appreciate your posted references.
-Nick
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 11, 2019 - 12:27pm PT
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Thanks man. I appreciate it. I was a Paleomagician in a former life, so this thread caught my eye.
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neebee
Social climber
calif/texas
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Feb 11, 2019 - 03:36pm PT
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hey there say, tobia... nice to hear from you...
say, thanks for the share...
and, to everyone... will go read all this, soon as i can...
:)
interesting, :O
:)
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 13, 2019 - 04:47am PT
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Tuolumne tradster,
I appreciate your thorough explanation of why the shifting occurs and agree with Nick about your writing.
I have long been interested in navigation, since navigating seismic vessels in the Gulf of Mexico and working in a nautical instrument repair shop and Chart House in New Orleans.
Hi, Neebee!
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 13, 2019 - 12:58pm PT
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Ahh, another "duddle bugger"!
The air cannons, firing every 8 seconds are still ringing in my ears.
I worked for ONI, who also owned PHI, Petroleum Helicopter Services. I worked out of LA mainly but sometimes down to Miami and west to Corpus Christi. Once Lorain C was developed and later GPS, there was no need for ONI. In 1980-1981 it was good money. Trying to keep the kinks out of the cables with course changes was a pain. The shrimp boats cutting the cables in half, made for excitement as well. Some were not so bad, they would trade
bushels and bushels of shrimp for diesel fuel.
Working at Baker Lyman & Co. in New Orleans repairing compasses, sextants, and the like is what built my interest. That was 1976. All those chronometers on the shelf and the little Dutchman working on them was golden. I am not sure when the Quartz chronometers ended the day of the spring type, but it was it was after I left.
Riding around in the Gulf of Mexico from oil rig to oil rig was fun. Those
Vietnam Veteran pilots were crazy, most navigated by the oil rig numbers.
I started out looking for a job as a crane operator on a rig, but the ONI job was a lot better paying and I went straight to navigation, no roustabout or rough necking for me.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 13, 2019 - 05:04pm PT
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Thanks for sharing those photos Tobia...brought back memories for me. Ya PHI, that was the outfit that ran the heli service out to the rigs. You mentioned crane operators...I remember one night one of the crane operators was killed on the Key Drill jackup when he brought a load right down on top of himself.
I was a rig Geo back then. I'd go out to the rigs for a week at a time to QA/QC and interpret geophysical logs run by Schlumberger or one of the other logging contractors in the early 80s.
Here's a merging of those two data sets, geophysical logs and reflection seismic...
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Kligfield
Mountain climber
Boulder, CO
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Feb 13, 2019 - 07:26pm PT
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Here are some additional observations and facts regarding magnetic field reversals. Scientific peer-reviewed journal articles to back up these assertions can be provided upon request.
(1) The duration of a magnetic field reversal is about 10,000 years. The transition begins with an increased polar wandering of 4,000 years, followed by a 2,000 year "flip" of N to S, or S to N, followed by another 4,000 years of unstable polar wandering.
(2) The mathematical description of the earth's magnetic field as a dipole is only a portion of the complete mathematical description. In the oblate spheroidal coordinate system used for the earth, the actual field is composed of a "dipole" component [which most people have heard about] and additional higher frequency components such as the quadrapole and higher order components. These latter characterizations are referred to as the "non-dipole" field component of the total earth magnetic field.
(3) during a magnetic field reversal, the polar wander path does not "FLIP" but instead what happens is that the dipole portion of the field decreases towards zero, and then increases the other way with a reversed polarity. Effectively the dipole portion of the N pole shrinks from positive to zero and then grows out in the opposite polarity, i.e., from zero to negative.
(4) During the 2,000 year period in which the dipole component shrinks towards zero, the non-dipole portion of the field is still active. However, being a quadrapole, or even octupole field, it is not only in the northern and southern hemispheres but exists in smaller N-S pole combinations in different portions of the earth. So the apparent polar wander that is talked about in earlier posts on this site is the result of the dying out of the main field and the concurrent taking over of the higher order dipole field portions--producing the apparent polar wander.
(5) Speculation that we are entering into a new field reversal is not supported by any modern evidence. Thus it would not be appropriate to claim that global warming and or climate change is related at this moment in time to a field reversal. that connection appears incorrect by the data.
(6) During field reversals, mass extinctions do indeed and have been shown to occur--just not in the large species fossil record. Obviously not with Dinosaurs and other mammals. Rather, the single celled organsisms such as foraminifera and other critters exposed to higher doses of cosmic rays have suffered declines in their populations during periods of magnetic field reversals. The scientific record on this is complicated and it is not reasonable to arrive at sweeping conlcusions about this topic without additional research.
Finally, it is indeed remarkable, that such a discussion thread as this one would occur on SuperTopo! It's rewarding to know that climbers have some interest in this type of topic.
One more--there is an earlier thread somewhere on Supertopo about "what are those holes on El Capitan" that possited that the holes were paleomagnetic sample cores drilled into the granite facies on the side of El Cap and elsewhere in the valley. Although not directly related to this current discussion of polar wandering and magnetic field reversals, some of the basic principals of paleomagetism were discussed by this earlier thread.
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Kligfield
Mountain climber
Boulder, CO
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Feb 14, 2019 - 04:36pm PT
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The AF demagnetization data provided above is an example of establishing the stable remanence direction (declination and inclination) of a sedimentary rock. The term "viscous" remanent magnetization refers to the "time dependent" change in the remanence vector subsequent to acquisition of the depositional remanent magnetization (DRM). The case shown only illustrates a particular state of the magnetic field, in this case a reversed state.
Other studies that span the period of a magnetic field reversal show how the declination and inclination vary at different stratigraphic levels starting at the lower (older) strata, continuing through the intermediate levels which sample the time of the magnetic pole reversal transition zone, and end in the upper (younger) strata.
The time frames involved in all these studies average about 10,000 years with the most rate of change in field direction within a 2,000 year period. Given that we don't have historical records greater than these time spans, the evidence is obtained from geological records and absolute age dating. But NONE of these studies indicates that anything serious (such as a full field reversal) will occur in time frames that coincide with modern effects of humans on the planet. In any case it's still an active area of research.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 14, 2019 - 05:09pm PT
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Yes, the example I showed above was only 1 out of 79 samples that were collected over a stratigraphic interval of ~ 250 meters of the Purisima Fm in Santa Cruz. Several normal and reverse polarity magneto zones were determined from these samples. The objective was to define the sequence of normal and reverse polarity magneto-zones and combine the magnetic stratigraphy with other data, including K/Ar age date and diatom biostratigraphy to develop a chronostratigraphy (i.e., absolute ages) for this stratigraphic section. As shown in Figure 2 in this paper,
https://www.arlis.org/docs/vol1/164589542.pdf
the stratigraphic section spans the interval from Chron 5 to the Matuyama (~6 to 2.8 mya).
I did go back and sample continuously across one of the normal to reverse transitions to see if I could detect any anomalous paleomagnetic directions associated with the transition but I found that the reversal occurred across an erosional bedding boundary as shown in this photo.
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Tobia
Social climber
Denial
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Topic Author's Reply - Feb 15, 2019 - 06:17am PT
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Toulumne tradster,
I remember PHI was losing one helicopter a month in the oil of the early 80's. I never verified that and at the time didn't want to.
Thanks for the in depth information you have provided.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 15, 2019 - 08:05am PT
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I recall 2 helicopters going down during the 5 years that I did that work. Both went into the water at night in poor visibility. Fortunately I wasn't on either one.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 15, 2019 - 08:22am PT
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Not sure when the last time USGS updated this page...
https://www.usgs.gov/faqs/are-we-about-have-a-magnetic-reversal?qt-news_science_products=3#qt-news_science_products
Are we about to have a magnetic reversal?
Almost certainly not.
Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those same paleomagnetic records also show that the field intensity can vary significantly without resulting in a reversal.
So a reduced intensity in the magnetic field does not necessarily mean that a reversal is about to occur. Moreover, the decrease in intensity is not a dramatic departure from normal. For all we know, the field may actually get stronger at some point in the not-so-distant future.
Predicting the occurrence of a reversal based on the current state of the magnetic field is extremely difficult. Reversals are not instantaneous--they take place over a period of hundreds to thousands of years. We wouldn’t know that a reversal is happening until it was half over.
Consistent with #5 that Kligfield posted ^^^
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Reilly
Mountain climber
The Other Monrovia- CA
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Feb 15, 2019 - 08:27am PT
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TT, now yer scaring me. That picture was hoisted from a Monty Python show! I’m certain!
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 15, 2019 - 08:47am PT
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Pass the popcorn Reilly...
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 22, 2019 - 09:45pm PT
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Using this NOAA Magnetic Field Calculator...
https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml#igrfwmm
...you can determine all 7 components (Declination, Inclination, Horizontal Intensity, North Component, East Component, Vertical Component, and Total Intensity) of the geomagnetic field going back to 1590 for any location by entering the Lat & Long. E.g., here is the historical declination for Concord, CA. 37.98N / 122.03W from 1840 to 2019...
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ionlyski
Trad climber
Polebridge, Montana
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Feb 23, 2019 - 11:57am PT
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Moosedrool, what do you make of all these wandering poles?
That was pretty good Dingus. Took me a second to get it.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 23, 2019 - 12:32pm PT
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as was said ^^^ "Not all who wander are lost..."
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ionlyski
Trad climber
Polebridge, Montana
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Feb 24, 2019 - 08:53am PT
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I don't know if I will make that this year but next year yes. Actually pure sandstone crack climbing tends to torque or sprain my ankles by turning them sideways all day long and standing on them that way.
But, I will meet you in COR in June, in fact have already committed with the family to do so. And if we need the rope gun, my son, living in Seattle will be meeting there as well.
See you then Moosie!
edit-and we can tell Norwegian jokes around the campfire:)
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