‘True polar wander’ may have caused ice age

From Phys.org

 

November 19, 2018, Rice University
truepolarwan

Illustration depicting the minimum (interglacial, black) and maximum (glacial, grey) glaciation of the northern hemisphere during the ice age that began about 3.2 million years ago. Credit: Hannes Grobe/AWI/Wikimedia Commons

Earth’s latest ice age may have been caused by changes deep inside the planet. Based on evidence from the Pacific Ocean, including the position of the Hawaiian Islands, Rice University geophysicists have determined Earth shifted relative to its spin axis within the past 12 million years, which caused Greenland to move far enough toward the north pole to kick off the ice age that began about 3.2 million years ago.

Their study in the journal Geophysical Research Letters is based on an analysis of fossil signatures from deep ocean sediments, the magnetic signature of oceanic crust and the position of the mantle “hot spot” that created the Hawaiian Islands. Co-authors Richard Gordon and Daniel Woodworth said the evidence suggests Earth spun steadily for millions of years before shifting relative to its spin axis, an effect geophysicists refer to as “true polar wander.”

“The Hawaiian hot spot was fixed, relative to the spin axis, from about 48 million years ago to about 12 million years ago, but it was fixed at a latitude farther north than we find it today,” said Woodworth, a graduate student in Rice’s Department of Earth, Environmental and Planetary Sciences. “By comparing the Hawaiian hot spot to the rest of the Earth, we can see that that shift in location was reflected in the rest of the Earth and is superimposed on the motion of tectonic plates. That tells us that the entire Earth moved, relative to the spin axis, which we interpret to be true polar wander.”

By volume, Earth is mostly mantle, a thick layer of solid rock that flows under intense pressure and heat. The mantle is covered by an interlocking puzzle of rocky tectonic plates that ride atop it, bumping and slipping against one another at seismically active boundaries. Hot spots, like the one beneath Hawaii, are plumes of hot solid rock that rise from deep within the mantle.

Gordon, the W.M. Keck Professor of Earth, Environmental and Planetary Science, said the new findings build on two 2017 studies: one from his lab that showed how to use hot spots as a global frame of reference for tracking the movement of tectonic plates and another from Harvard University that first tied true polar wander to the onset of the ice age.

“We’re taking these hot spots as marked trackers of plumes that come from the deep mantle, and we’re using that as our reference frame,” he said. “We think the whole global network of hotspots was fixed, relative to the Earth’s spin axis, for at least 36 million years before this shift.”

1-truepolarwan

True polar wander occurs when the entire Earth shifts relative to its spin axis. Credit: Victor C. Tsai/Wikimedia Commons

Like any spinning object, Earth is subject to centrifugal force, which tugs on the planet’s fluid interior. At the equator, where this force is strongest, Earth is more than 26 miles larger in diameter than at the poles. Gordon said true polar wander may occur when dense, highly viscous bumps of mantle build up at latitudes away from the equator.

“Imagine you have really, really cold syrup, and you’re putting it on hot pancakes,” Gordon said. “As you pour it, you temporarily have a little pile in the center, where it doesn’t instantly flatten out because of the viscosity of the cold syrup. We think the dense anomalies in the mantle are like that little temporary pile, only the viscosities are much higher in the lower mantle. Like the syrup, it will eventually deform, but it takes a really, really long time to do so.”

If the mantle anomalies are massive enough, they can unbalance the planet, and the equator will gradually shift to bring the excess mass closer to the equator. The planet still spins once every 24 hours and true polar wander does not affect the tilt of the Earth’s spin axis relative to the sun. The redistribution of mass to a new equator does change Earth’s poles, the points on the planet’s surface where the spin axis emerges.

Woodworth said the hot spot data from Hawaii provides some of the best evidence that true polar wander was what caused Earth’s poles to start moving 12 million years ago. Islands chains like the Hawaiians are formed when a tectonic plate moves across a hot spot.

“True polar wander shouldn’t change hot spot tracks because the hot spot track is the record of the motion of the plate relative to the hot spot,” Woodworth said.

Gordon said, “It was only about a 3 degree shift, but it had the effect of taking the mantle under the tropical Pacific and moving it to the south, and at the same time, it was shifting Greenland and parts of Europe and North America to the north. That may have triggered what we call the ice age.”

2-truepolarwan

The movement of the Pacific plate across a mantle hotspot created the Hawaiian islands over millions of years. Credit: National Geophysical Data Center/USGS/Wikimedia Commons

Earth is still in an ice age that began about 3.2 million years ago. Earth’s poles have been covered with ice throughout the age, and thick ice sheets periodically grow and recede from poles in cycles that have occurred more than 100 times. During these glacial cycles, ice has extended as far south as New York and Yellowstone National Park. Earth today is in an interglacial period in which ice has receded toward the poles.

……………

More information: Daniel Woodworth et al, Paleolatitude of the Hawaiian Hot Spot Since 48 Ma: Evidence for a Mid-Cenozoic True Polar Stillstand Followed by Late Cenozoic True Polar Wander Coincident With Northern Hemisphere Glaciation, Geophysical Research Letters (2018). DOI: 10.1029/2018GL080787

Journal reference: Geophysical Research Letters search and more info

Read more at: https://phys.org/news/2018-11-true-polar-ice-age.html

 

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121 thoughts on “‘True polar wander’ may have caused ice age

      • Their hypothesis is that true polar wander initiated the Pleistocene glacial cycles, not each individual cycle.

        • They leap to quite a few claims from scant evidence.

          Perhaps their polar wander theory can explain why India broke off of Australia, crossed the equator, where all mantle lumps are supposed to migrate and slammed into the Eurasian plate.

          And you’ve gotta love claims like: “Hot spots, like the one beneath Hawaii, are plumes of hot solid rock that rise from deep within the mantle”. Solid doesn’t mean what they think it means.

      • Maybe, Plate tectonics have diluted the evidence for claims of a very tall Appalachian chain considerably by providing alternative explanations for many of the features that supported the claims. It’s also something of a mystery how they survive at all since they seem to have been around a lot longer than most other mountain ranges. It’s hard to explain why they didn’t erode away completely 100 million years ago.

        • It’s hard to explain why they didn’t erode away completely 100 million years ago.

          From what I’ve read, they did — flat as a pancake & near sea level. Then the mirror-like “underside”, which was protruding down into the denser mantle, was unloaded & caused that area to rise again and then erosion carved out the previous sedimentary features (layered soft and hard rocks).

          • Mountain chains can have a complex history. Take the Ozark plateau in northern AR and southern MO. Many hundreds of Ma ago, these were a part of a giant Mt. chain that stretched from west TX to the Appalachians. They were then eroded to sea level and below. A few hundred Ma ago marine sediments were deposited on top of the metamorphosed basement rocks. The whole area was uplifted with minimal tilting. Most sediments in MO were eroded away, exposing part of the old crystalline basement — the Saint Francis Mts. In AR thick layers of flat-lying sediments remain (including the highest Boston Mts.) Although having a older common history, the two areas now possess very different characteristics — poorer soils & metal ores and many old mines in MO, more fertile soils and abundant marine fossils in AR.
            One more reason why geology is interesting.

        • “It’s hard to explain why they didn’t erode away completely 100 million years ago.”

          They did. What is seen today is resurgent uplift exposing the roots of the original Taconic orogeny.

        • The Andean Mountains in South America are an example of geologically young mountains.
          The tallest is not quite 7 kilometers high.

          Plate tectonics, in shoving the continents around, sometime open or closes off polar water to currents from the equator. One theory is that this is a necessary condition for ice ages, Milankovitch cycles and possibly solar variability, provide the rest.

    • WX,

      They’re a lot older than that, if you date their origin to the time at which the collision of the Indian and Eurasian plates closed the Tethys Sea and began the continental crumpling which has thrust up the mountains.

      • As you may know, the top of Mt. Everest consists of limestone from the bottom of the Tethys Sea. The upthrust began some 65 Ma, before the submerged shelves of the Indo-Australian and Eurasian Plates even made direct contact.

        In its passage of the Indian Ocean from Antartica to Eurasia, the (now separated) Indo-Australian Plate set a world tectonic speed record.

  1. Earlier this year, I read articles about Canadian Indian tribes who have witnessed the shift of sunrise/sunset position with respect to their forebears.
    How very observant, given their supposed lack of technology. Just a pedestrian opinion.

    • Humans as a species are only a few hundred thousand years old, the events being described here are millions of years ago. Whatever they observed, it wasn’t this.

    • They didn’t observe anything. Milankovich changes are to small and to slow to be detectable without instruments.

      • TTY – not entirely true.

        If you had a Stonehenge-type monument, that looked between two large standing stones and down a 1 km causeway towards the midsummer sunrise, you would certainly be able to see a shift in the obliquity of the Earth’s axis. (Which moves a couple of degrees and back, every 40 ky).

        In fact, you could easily detect a shift of 1/10th a degree, which would happen in just 1,000 years. So ancient man could quite easily monitor the obliquity of the Earth.

        Incidentally, if the Earth’s obliquity was 22.5 degrees, Stonehenge would sit on the only latitude that is the same as the midsummer sunrise angle (measured from true north). That last happend 20 ky ago.

        R

    • for me it is very simple. with the orientation of my house is almost perfectly south facing. The sun used to rise almost perfectly to shine on the front with no shadows from the house. Now there is a shadow of possibly 3 feet into the front garden. It is not a big change but noticeable to me.

    • Yes this whole ocean heat absorption from the atmosphere because of CO2 increase is so bogus. Heat is lost from the oceans to the atmosphere by evaporation. It doesnt go the other way around. Since 70% of the earth’s surface is water, the solar radiation that finally makes it to the ocean surface has to find a way out of our geosystem. The way out is by evaporation. Even NASA says that ocean heat lost though evaporation is more than 50% of the solar radiation reaching the ocean surface. IR does not penetrate more than a few microns deep in the ocean surface. The oceans are heated mainly by underground volcanos. Since 1850 CO2 ppm in atmosphere has only increased by 46%. So if there is heat hiding in the ocean now because of 410 ppm CO2 there was heat hiding in the ocean when the CO2 ppm was 280. So if the transfer of heat was from atmosphere to ocean the oceans would have boiled over long ago. The reality of evaporation of sea water makes the transfer of heat one way from ocean to atmosphere. Alarmists will stop at nothing to try to explain global warming.

      You may want to look at this paper from 1996. It represents one of the last non fraudulent papers that came out of the Goddard Institute for Space Studies. I am astounded that Hansen let it be published. The only explanation is that around that time Hansen had a change of heart and had concluded that there wasnt any global warming. A couple of years later he again changed back to his original fraudulent thinking and the rest is history.

      https://journals.ametsoc.org/doi/full/10.1175/1520-0442%281998%29011%3C3069%3ACFBCSR%3E2.0.CO%3B2
      In the abstract they say this:
      “Extending this correlation to the present suggests that solar forcing may have contributed about half of the observed 0.55°C surface warming since 1900 and one-third of the warming since 1970. ”
      At the end of the abstract they say this:
      “But attributing a significant fraction of recent climate warming to solar forcing presents serious ambiguities about the impact of increasing greenhouse gas concentrations whose radiative forcing has been significantly larger than solar forcing over this time period. Present inability to adequately specify climate forcing by changing solar radiation has implications for policy making regarding anthropogenic global change, which must be detected against natural climate variability.”

      In the Summary at the end of their paper they say this:

      “Response of the climate system to radiative forcing, including by the variable sun, is not yet understood with sufficient certainty to unambiguously interpret the earth’s surface warming over the past 140 yr. Presently specified climate sensitivity overpredicts the magnitude, and cannot replicate the shape of the surface warming expected from radiative forcing by greenhouse gases alone.”

      Theses days, saying such things would harm a climate scientist’s funding.

      Finally they say this:

      “Unless (until) the reality of longer-term solar irradiance variations is established it will be difficult to evaluate whether the correlations among solar and climate parameters are coincident or causal,”

      Climate science as yet has not provided an answer to the above. And yet we are now stuck with carbon taxes. Absolute madness.

  2. I read this whole thing and it’s just time wasted! Incredible, there was no mention of man’s effect on the mantle or rotation of the earth or that man has been ruining everything ! Where do we get crack-pot articles like this that seems to infer that the earth has mechanisms that are really old, and we have zero affect on, and evidently are so epic that really, it’s as if man has no effect at all! And we all know this just can’t be. Nope. /s

    • Cheer up! Anthropocentric CO2 caused the temperature in up state New York to fall to -27 degrees C today.

      The green house effect takes awhile to kick in, but it’s here with a vengeance now, and spare a thought for the pathetic sods at the IPCC, who may lose extremities to frost bite today. Like cutting-off your nose to spite your face.

      • Ya the headlines here in Ontario are

        Cities across Ontario smash low temperature records for November 22 . In all, 25 different cities in Ontario set low temperature records. At the Ottawa airport the old record was -14.4 C Last nite’s temperature went to -18.7 C A DIFFERENCE OF 4.3 C That must be a record in itself , breaking the old record by 4.3C Amazing. I wonder how Trudeau will explain this to his kids. Probably something like : Global warming causes climate change and climate change causes everything to go wacky.

        Yes Virginia , things sure are wacky in the country of Canada , probably wacky in the state of Kansas as well. Well truth be told the whole world has gone wacky except Sky News in Australia and the Barzilian foreign minister. Of course the 3% climate scientist skeptics are not wacky but they dont have access to the media.

          • Alan, the Barzilian Foreign Minister is offended that you now include him among those who have gone w*cky. BTW, do you know what w*cky means in Potruguese, the native language of Barzil? It is very bad word.

        • Sault St. Marie broke their record for Nov 22 by 4.8 C and
          North Bay broke their record for Nov 22 by 7.7 C

          and Lansdowne House went to -33C

          Absolutely amazing

          • As I am writing this the temperature in Ottawa has dropped to -20C at 4am on November 23, 2018. We havent even hit winter yet officially.

            I thought we were promised GLOBAL WARMING.

        • “I wonder how Trudeau will explain this to his kids. Probably something like : ”

          November is the WARMEST MONTH EVER, LIKE WE MEAN IT, IT’S SUPER WARM! SUPER WARM! SUPER……*hang on need to put on my ski mask, dang it feels like January already”…where was I? Oh YES. NOVEMBER HAS BEEN DECLARED WARM, WARMEST MONTH ON RECORD…well since we threw out this other data anyway.

        • And you actually believe that despite all the actual land based evidence?
          As for Lapland snow, try looking at all the places that do have snow now much earlier than normal, or later in the case of Australia & New Zealand.

          • The evidence lies in anomalies …. the difference from a base.
            An extreme (warm or cold) is not evidence of climate unless reffered to that base line.
            And only averages can reveal that.
            Extremes happen and a warming climate will still produce cold ones … just less and less frequently.
            I chose the Lapland example because it was just as cherry-picked as the one Wxcycles presented – presumably as evidence that global warming isn’t happening or at least not because of increasing GHGs. Many more could be found.
            And that people here invent their own facts does not change that the Earth is warming (or do you refute that?).
            The “evidence” that is referred to lies only in the eyes of those who read it in ideologically biased Blogs. Is that map of NH anomalies wrong then ? A lie?
            And then, if in the affirmative, we get the ultimate get-out with “one-bound” coming to the rescue …”it’s all a scam” … or else incompetence.
            That thosuasands of scientists in multidisciplinary Earth fields are frauds/incompetents comes from deep-down the rabbit-hole.
            And ultimately there is no “talking” to that mentality.
            That you get your “science” from here and other naysaying blogs will never reveal it, as is proved by the occasional posts by people such as me that can be bothered to counter the echoes here.
            Well, well done.
            Those like me are the only ones that are hearing you different from the denizen community who bounce the usual myths and denial back and forth.
            As if slapping each other on the back alters things.
            No ones listening but yourselves.
            It’s a Blog and matters not a jot.
            It’s just a hobby for me to brush up on my past professional field and an insight into the psychology of naysaying when reading the expected replies burying deeper down the rabbit-hole.
            To see how far you can go in refuting logic, observation and empirical physics known of for ~120years, with doubt, ridicle and conspiracy theory.
            Over to you ….
            See how many exhoes can be created to alter the reality you dont like.

          • Anthony Banton

            Further to your little rant, no one I know of here ‘denies’ the planet is warming what we don’t accept is either:

            1) The purported alarmist claim of the cause (atmospheric CO2), and;

            2) That warming is anything but beneficial.

            There has never been a successful, empirically derived field study which demonstrates atmospheric CO2 causes the planet to warm. The last one attempted by Berkely was demonstrable nonsense.

            It has been demonstrated that during both the Roman and Medieval warm periods mankind flourished. Nothing went insanely wrong with the planet so what’s the problem now if the planet gets warmer?

            And whilst we’re not absolutely certain what a warmer planet might hold for us, we are 100% certain that a colder planet will bring with it an awful lot of human misery.

            But these simple facts just seem to pass you alarmists by.

            You might also have a look at the disaster causes by the US government mandating that a small amount of bio fuel be mixed with petrol and diesel because of irresponsible, ignorant, ideological pressure from the green lobby: https://www.nytimes.com/2018/11/20/magazine/palm-oil-borneo-climate-catastrophe.html

          • Cherry picked? You keep using that word. I do not think it means what you think it means.

            My parents once had their own cherry trees; these days I go to the neighbors and pay for pick-your-own. Harvesting is done by picking the tree clean, dropping the odd spoiled cherry on the ground.

            This summer in the Great Lakes region was warm and wet. The cherries were as abundant and sweet as I have ever experienced.

          • Fake news, yes. Non sequitur is also what one could use. The news is accurate in some sense, but the what follows is not what is assumed.

            It’s like the classic “Trump denies affair”;the assumed affair is fake news, and denying affair is not following an affair.

            But more importantly, global warming is so bad an excuse they call snow and the lack of snow with a common term called climate change. Just try to remind them it’s weather, won’t work. The met (ours and yours) are fully into it.

        • Anthony Banton

          Colours on a globe are meaningless other than they are designed to scare people.

          Note Greenland compared to the East Coast of the US. Greenland currently between -6°C & -14°C showing as bright red. North Carolina (or thereabouts) between 10°C and 1°C shown as bright blue.

          A lot of hysterical nonsense.

        • Every year we go through this. That blob of cold air sitting at the North Pole sloshes on to Eurasia one year, and on to North America in another year. Each time, the unlucky area gets frozen, and they cry “What global warming?”. The lucky area enjoys a mild winter. Nothing new here.
          There is on thing of interest this year, however. The climate people predict a warm winter in the NE USA because of El Nino. The sunspot people are predicting a cold winter, although I am not sure if they are predicting a global or regional cold winter. Should be fun.

          • The same thing can be said of those who proclaim that every heat wave is proof of global warming.
            Sauce. Goose. Gander.

        • Yes indeed, and meanwhile…..
          Lapland has no snow.

          The least snowy winter in Sodankylä, Finnish Lapland since 1911 has been 1931-1932. The max snow depth then was 54 cm. (source: met office as of today)

          The maximum has been 119cm in year 2000.

          The shortest and longest snowcovers since 1961 have been 159 and 229 days. So in all, there is a lot of snow there, but variation is also large.

          I can assure you people like some snow, but for example last year, when my daughter was bleeding and taxi got stuck in loose wet snow at our driveway I wasn’t quite willing to take more.

          I can also assure you I know my hundred words on snow, as do my children.

        • It is a good job that Santa relocated this summer from Lapland to Canada. He is pretty good at knowing where it’s gonna be naughty or nice and cool.

          https://www.therecord.com/news-story/9046006-thursday-s-cold-weather-breaks-records-in-waterloo-region/

          Previous low record was in the year 2000. Broke that by 1.8 deg C.

          Other cities:
          https://globalnews.ca/news/4688507/ontario-break-temperature-records-november-22/

          “I don’t remember the last time so many record lows were set by so much on a single day.”

          North Bay broke their previous record by 7.7 C: -26.6 and not yet winter! Yeowch!

  3. Motion of the crust relative to the spin axis is what continentl drift is all about. Paleomagnetic reconstructions presume the magnetic poles approximate the spin axis, even though magnetic north is currently away from the north pole.

    Having the entire planet , core, mantle, and crust move relative to the spin axis should also move the magnetic field relative to the crust, upsetting paleomagnetic reconstructions.

    True polar wander seems independent of the motion of the Hawaiian/Emporer chain. Studies of different hotspot chains show different trajectories relative to plate motion above, indicating that the hotspots themselves are not fixed relative to the spin axis.

    Both hotspots and spreading ridges are shallow melt features in the upper mantle, not deeply rooted. We know spreading ridges move relative to the spin axis. It is no surprise that hotspots do too.

    • Good comments, Gordon. The other problem in utilizing the trace of hotspots as changing axis spin indicators is that the motion of the plates changes over time. For instance the convergent motion along much of western North America changed to mixtures of strike-slip and oblique convergence, where we are now. With direct versus oblique convergence margins all around the earth the geometry of the plate interaction is constantly changing. The current magnetic north pole is wandering and weakening, perhaps getting ready for a reversal?, and introduces another variable due to changing in the magnetic poles imprinted into rocks as they cool below the Curie Point. I think a dedicated group of Geologists/Geophysicists could work out a lot of this variable geometry, but more accurate than the three degrees of claimed wander? No way.

  4. The earths axis at the poles are wandering around and moving as I write this, is this real climate change a new idea?
    Been going on for ………ever. Stability after our release from our galixy billions of yrs going around our star building our atmosphere and seeding of life began , microbiol. Life/nature takes hold. Through big swings of environmental chaos on earths rotation from a young sun,extinction after extinction , volcanism after volcanism.
    Our vessel of life is the sun, a moving crust on earth can help us or kill us . But we are here now, we started somewhere hundreds of millions years age, maybe a billion. We didn’t just pop out of the no where, we got a genetic advantage as mammals when things got cold.

    Co2 or a meteorite did not kill the dinosaurs , yeah it took thousands of years (if not a million) to kill them off(some of them)The interglacial was a part of earths/suns evolution and our position spinning around our galaxy. We are very stable now and we circle around a aging star that some time will lose grip on us and the sun goes super nova and we get recycled back into the center and bits of microbiol matter and elements seed another evolving planet….star permitting.

  5. And it’s something of that order and magnitude that would be necessary to cause catastrophic climate change. I can see why glaciers were as far south as Iowa. I thought perhaps a polar shift of some kind would have been necessary. I want to see where Antarctica ended up. It was once a tropical paradise….this would explain so much.

    • It is a very long time since Antarctica was tropical. It was near the south pole and cool to temperate even back in the Cretaceous. And you are mixing up continental drift and true polar wander. They are two entirely different things.

    • True polar wander, the mantle moves relative to the spin axis, but what if the spin axis changed from eg. about zero to now opprox 23 deg, followed by the mantle? – What term should be used for that? and could it possibly have happened?
      With a zero deg spin axis, there would be no seasons.

      • It could happen, but requires an external force, i e perturbation from other planets. Very unlikely to impossible for the Earth which is stabilized by the presence of the Moon.

        There is very good evidence that not only seasons, but even the Milankovich effects on them have been very similar for at least the last 250 million years, and less definitive evidence back to 500 million years ago. The day-length has increased a bit though, due to tidal braking.

        Mars is thought to be much less stable due to the absence of a large Moon and closeness to Jupiter.

        • Thanks tty. I was thinking much the same thing. I’m a lousy physicist but it seems to me that either an external force or something quite exotic within the Earth would be required to suddenly shift the spin axis. “Dense anomalies within the Earth’s Mantle”? I’ll give them that we don’t seem to know a lot about the mantle. But how would those anomalies form? and why? Is there any evidence other than this hypothetical spin axis shift that those anomalies exist? Or ever have existed? Are there any other effects that we would expect to see that can be checked to add some credibility to this concept?

          • Any “dense anomalies” if they were capable of forming at all, would quickly sink back to the center of the earth.

        • Thank you, I ask the question because 55 million years ago, very north (80 deg) in Canada on Ellesmere Island there was subtropical ecosystem with “lush lowland forests and swamps inhabited by alligators, giant tortoises, snakes, lizards, and a host of mammals that included primates, tapirs, hippo-like Coryphodon, and large, rhino-like brontotheres. In the nearby ocean, clams and snails thrived.” [Canadian Encyclopedia] Lots af fossiles found. How could such a system survive with winters without light for several months? It might have been warmer, yes, but the important factor is light every day. At that time Ellesmere Island was almost as northern as it is today. An explanation could be a differnt angle for the spin axis. I wonder if someone could explain how such an ecosystem could exist so far north.

          • The (sub)tropical climates in the early Cenozoic seem to have occurred when the Earth overall was considerably warmer than today and when the North American interior seaway was possibly still open and still pumping warm water into the Arctic. Alligators and such can handle a bit of cold. Modern alligators, for example, live as far North as North Carolina. Many species of snakes and turtles live as far North as Quebec and survive annual freeze ups that last for several months. I don’t think the Paleocene-Early Eocene Arctic climate was that cold although it was probably uncomfortably cold and damp in mid-Winter.

            The Paleomap project has geographic and climate maps. The one you’d want is probably at http://www.scotese.com/paleocen.htm It shows Canada and all but the NorthEasternmost part of Greenland as being “Warm Temperate” — think Carolinas or Australia.

      • Actually the Earth has three spin axes. The lithosphere, the mantle and the liquid core with the solid core inside.

        The lithosphere can slide over the mantle quite easily forced either by the precession as described above, a cometary impact, one of which is suspected to have struck at high latitude and high speed about 3100 BC, or by a shift in the mass, for example the loss of ice from W Antarctica and a gain in the east.

        It is reported that Einstein believed this ice mass was a danger. Once a slip starts it will ripple around the lithosphere. This day-long realignment then transfers momentum to the mantle which settles down relatively quickly – a few decades – then it is transferred to the core slowly.

        The poles wobble for a long time. At present the approx 1/2 degree shift in 3100 BC (some say 3300 BC) is still visible as a ten ft diameter wobble traced by the north pole. That event pretty much wiped out agriculture in Great Britain for several centuries. Ireland moved South and the local sea level rose about 1000 ft to flood ‘the Irish Sea’ in a single day. Remember that the oceans shift as well so the ‘bulge’ moves. The worst effect is at 45 degrees latitude. That’s why ancient Welsh stone fences run down the hills, into the sea and out across the sea floor. Stone-fenced fields are visible from the air far offshore.

  6. Coment lost in the ether, damn smart phone!

    This is not some new science discovery, the earth/sun/galaxy is always evolving .

  7. This is way overblown.

    For one thing the result in itself is shaky. It is only a matter of 3 degrees movement since the Miocene. It is doubtful if either the hotspot coordinate system the geomagnetic field or the equatorial sedimentary belt can really detect such small changes. True, hotspots seem to be fairly fixed in relative position, true the geomagnetic poles are on average close to the rotational poles and true, the equatorial belt is at the Equator, but all three are known to be only approximately true.

    Also a move of three degrees since the Miocene equates to only about 28 mm per year. Three million years ago when extensive northern hemisphere glaciation started the pole would have been about 80 km from its current position. It is dubious that this would have had much of an influence on Greenland. Eastern Greenland is known to have been partially glaciated long before the Miocene in any case. The blocking of the Panama strait is much more likely to have been the crucial factor.

  8. A more likely reason, suggested back in 1988 by Matthias Kuhle, is that the slow rise of the Himalaya caused the cooling into the ice ages.

    His paper suggest that as India hit Asia, causeing the uplift of the Himalaya, a large ice sheet grew on its surface. Since this ice sheet was so close to the tropics, and so large, its ice-albedo effect reflected and rejected a substantial amount of insolation.

    It was this reduction in surface insolation absoption, that caused the world to gently cool into an ice age.

    Ralph

    • There has never been a large ice-sheet in Tibet. The climate is too dry. The Tibetan high plateau has however certainly had some albedo effect, but not more than any similar desert area. The effect on the asian monsoon was probably much more important.

      There is another more politically-correct way to blame Tibet, i e that increased silicate weathering due to mountain-building drew down CO2, thus causing global cooling. This ignores two things 1. A draw-down of atmospheric CO2 also requires ocean cooling for any long-term effect since the amount of CO2 in the atmosphere is minimal compared to the ocean. And 2. As shown by sedimentological studies of the Bengal fan the rise of Himalaya actually caused a shift from chemical (CO2-consuming) to mechanical (CO2-neutral) weathering.

      • Last time I went up the Himalaya, I can assure you it was still covered in snow and glaciers. And that was in September. If the majority of Himalayan winter snows last through to the end of June, that is a very large reduction in insolation absorption.

        And you forget that ice ages are only initiated by a deep Northern Hemisphere Great Winter (a NH Milankovitch minimum). During a NG Great Winter, NH temperatures would be lower than now, and the high Himalayan glaciers would extend to lower levels. During the LGM, the Himalaya had a sizeable ice sheet on it.

        R

        • “Ice sheet” has a specific definition.

          ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles). The two ice sheets on Earth today cover most of Greenland and Antarctica. During the last ice age, ice sheets also covered much of North America and Scandinavia.

          https://nsidc.org/cryosphere/quickfacts/icesheets.html

          A recent publication, Quaternary Glaciations – Extent and chronology, a closer look, edited by Ehlers, Gibbard and Hughes[10], provides detailed information on each of these ice sheets at their maxima. It even provides GIS shapefiles that you can download to examine the LGM of each ice sheet yourself:

          http://booksite.elsevier.com/9780444534477/digital_maps.php

          In the map above, you can see the extent of the world’s ice sheets outlined in blue. Mountain glaciers are shown as green dots. The continental shelf edges around the world are visible in paler blue, and in many places would have been dry land due to the global sea level lowering at the Last Glacial Maximum, but close to the ice it would depend on how much each individual landmass was lowered by the weight of the overlying ice sheets.

          https://nsidc.org/cryosphere/quickfacts/icesheets.html

          While the timing of Himalayan glacial maxima during the LGM are poorly constrained, the maximum extent was nowhere close to being an ice sheet.

          https://serc.carleton.edu/vignettes/collection/58523.html

          • The whole point of the paper, if you had bothered to read it, is that the Himalaya ice sheet has a much greater albedo effect than the polar ice sheets – per unit area.

            The Himalaya sits at high altitude, and in the tropics, so it is subject to much greater insolation than the high latitude ice sheets, and it is subject to insolation the whole year round.

            I think the estimate was that the Himalayan ice sheet had four times the albedo effect, of the equivalent surface area up in the Arctic.

            R

        • I’ve been up on the plateau, and there are no glaciers up there and no traces of former glacial activity except on the highest ranges, particularly in the south. I’ve only been there in summer, but I understand there is little snow even in winter. The plateau is mostly snowless now (though there is actually more snow than usual):

          https://worldview.earthdata.nasa.gov/?p=geographic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2018-11-23-T00%3A00%3A00Z&z=3&v=62.444190528515406,20.446455790655982,110.4676280285154,43.54411204065598

          You can change the dates, and you will see that the plateau is almost almost snowless. It is the mountain rim to the west/south/southeast that is snow-covered and has glaciers.

          Nor was it ice-covered during the Pliocene. Google “Zanda basin” for some interesting data on Pliocene conditions in Tibet, and how the high plateau seems to have been an evolutionary centre for cold-adapted biota.

          • Well I walked the whole way up the Baltero Glacier to Concordia and beyond.
            It is called a glacier for a reason. Because it is a glacier.

            And you cannot see it is a glacier, in the summer, because it is covered in rocks.
            But I can assure you it is a thick glacier that is snow white, up until June.

            R

          • Well, I’ve walked a few glaciers too in my days, from Nordaustlandet to Antarctica. And not just valley glaciers either. And a valley glacier is not an ice sheet. It isn’t even an ice cap.

          • Ralf, In the grand scheme of things, the Himalaya’s are relatively small, & even with 4 times the albedo because of their latitude, I don’t think that would be sufficient to start an ice-age.

          • Boorman.

            The whole point of the paper, is that the Himalaya ice sheet has a much greater albedo effect than the polar ice sheets – per unit area.

            The Himalaya sits at high altitude, and in the tropics, so it is subject to much greater insolation than the high latitude ice sheets, and it is subject to insolation the whole year round.

            I think the estimate was that the Himalayan ice sheet had four times the albedo effect, of the equivalent surface area up in the Arctic. And it does not take much of an energy decrease, to lower a temperature below a tipping-point.

            R

      • (Silicates and CO2).
        You have the cause and effect the wrong way around. The world only cools into an ice age, when CO2 levels are high. And the world only warms into an interglacial when CO2 levels are very low. And CO2 responses follow temperature.

        So silicates and CO2 have nothing to do with global cooling. Ice age cooling is caused by a NH Great Winter, and albedo effects.

        And we know that CO2 is not involved, because it is a global feedback mechanism. But ice ages and interglacials only occur during NH Great Winters and Great Summers (Milankovitch minima and maxima). Therefore the feedback mechanism mypust be regional, not global. So we can be sure that the true feedback is regional ice-albedo, and not global CO2.

        R

      • tty,
        You said, “There has never been a large ice-sheet in Tibet.”

        How can you be sure that ‘Tibet’ was as dry as it currently is, before it reached its current elevation?

  9. There is no mention of timing here. Shifting mass to or from the equator large enough for true polar wander would probably also influence the rotational speed of the Earth. This should be possible to investigate in the number of days per year.

    • It would not be nearly enough for that, more like a second or two in day-length.

      Actually the absence of this effect is a big headache for the CAGW crowd since any substantial melting of polar ice and transfer to the ocean, mostly closer to the Equator, must inevitably affect the day-length, for which we have very precise astronomical data, some of it stretching back to late Babylonian times.

      • You might be right, although I feel that the size of a mass distribution capable of shifting the Earth axis 3 degrees would be so large that it would also influence day length. As most of the momentum is in the outer parts of the planet close to the equator, relatively small changes here would make a considerable contribution. I do not know how you calculate the 1 to 2 seconds change. Could you give the details of that estimate?

          • Interesting article though it does not in any detail discuss change in Length of Day due to Earths internal changes. It covers Length of Day increase during the last 2500 years. This thread is about the paper that describe a considerable change in the weight distribution of the earth that is large enough to shift the axis of the Earth 3 degrees. If this shifting of mass is not perfectly symmetric it will also have an effect on Length of day.
            Your 1-2 seconds is about 1/60000 of the LOD. A 3 degree shift of the axis represent a 1/30 of the angular momentum of the entire Earth moved to another axis. I do not think this is possibe.

            Kai

  10. I find the idea that rising hot spot masses causing the planet to go into a corrective wobble to bring the dense mass closer to equatorial equilibrium very interesting. Watching gyroscopes one of the things that has always intrigued me is that when they are spinning around happily showing the slight precession wobble as they rotate is that – every now and then – the gyroscope will suddenly lie over at almost 90 degrees and spin around for a while before recovering its normal, more or less upright, rotation.

    This has made me wonder if planets might occasionally be prone to doing this. Uranus is basically lying over on its side in exactly this way. (Yes I do know this is held to be because something large knocked it over). I wonder if the possibility of such a gyroscopic effect has ever been seriously investigated?

  11. The author has things backwards.

    Without a change to the tilt of the equatorial bulge, the rotational axis is not going to change.

    That requires the external force such as the gravitational pull of the sun and moon.

    Tectonic plates and hot spots move without regard to the earth precession which occurs every 26KA. See Secular trend of the Earth’s rotation pole: Consideration of motion of the latitude observatories by S. R. Dickman; Geophysical Journal International, Volume 51, Issue 1, 1 October 1977, Pages 229–244, https://doi.org/10.1111/j.1365-246X.1977.tb04198.x

  12. FTA:

    “Earth is still in an ice age that began about 3.2 million years ago.”

    Is not the “ice age” considered to be the Pleistocene, which began 2.588 MYA?

    • In geology, an “ice age” is a period in which there is year-round polar ice in at least one hemisphere and episodic glacial advances and retreats.

      Earth has been in an ice age since the beginning of the Oligocene (~37 Ma) with the possible exception of the Middle Miocene.

      The nature of the ice age changed significantly about 2.6 Ma, at the Pliocene-Pleistocene boundary. Their hypothesis is that true polar wander about 3 Ma triggered this.

      It’s an interesting hypothesis, worth further study.

      https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080787

  13. I do not see how any of the evidence they cite supports the conclusion they have reached.
    We already know that the pole wanders. We have observed it in out lifespans. No need for the crust to shift to account for that.
    We already know that the crust moves, plate techtonics, we have observed that within our lifespans as well.

    Sounds more like a fanciful idea desperately searching for confirming evidence.

    • The author suggests that internal structures alter the rotational axis, such as viscous molten magma or plumes.

      However, the earth is much like a gyroscope with the central mass of its equatorial bulge spinning around an axis. The earth’s presession is governed by the gravitational pull of the sun and moon. Disturbance of earth’s internal structures is not possible by these gravitational forces to which the earth only experiences a constant free-fall. Internal earth structures, such as tectonic plates and hot spots, can not experience the earth’s 26KA presession.

      The author mistakenly conflates the magnetic poles and the rotational axis.

      • “Disturbance of earth’s internal structures is not possible by these gravitational forces to which the earth only experiences a constant free-fall.”

        This is not quite correct. The Earth experiences gravitational tidal effects on top of the “free fall” of the Earth’s center-of-mass from the gravitational attraction of the Moon and Sun.

        One estimate puts Earth’s internal heat generation from tidal-induced friction at 3.2 TW. However, this is only about .0018% of the 176,000 TW of the solar radiation input at Earth top-of-atmosphere.

        Beyond this, the Earth will spin about a principal moment of inertia and that is currently the axis of rotation of an oblate spheroid that closely approximates the Earth’s shape. The Earth is actually quite close to being a sphere, since the minimum radius to either pole is no more than 13 miles smaller than the maximum radius to any equatorial point (a difference of about 0.3%). Therefore, it is credible that an unequal redistribution of a large amount of mass on Earth’s surface (from mass changes in large glacial sheets and/or from crustal plate tectonics causing areas of substantial uplift or subsidence) could change the orientation of the principal moment of inertia relative to surface features at a given point in time, thereby resulting in true polar (spin axis) wander.

        Note that this can occur as the result of Earth’s internal heat energy and corresponding unbalanced internal forces causing movement of mass, as well as the result of atmospheric climate patterns causing non-uniform redistribution of water/ice on Earth’s surface. Changes to Earth’s principal moment-of-inertia do not require an external-to-Earth forcing.

        • The Earth is actually quite close to being a sphere, since the minimum radius to either pole is no more than 13 miles smaller than the maximum radius to any equatorial point…

          A configuration in which were the reverse was true, a 0.3% bulge circumscribing the poles rather than the equator, would be unstable, and therefore, could be only be temporary.

      • Therefore, it is credible that an unequal redistribution of a large amount of mass on Earth’s surface…

        However, in a molten environment, gravity would only allow such an unequal distribution, once present, to be only temporary.

      • Note that this can occur as the result of Earth’s internal heat energy and corresponding unbalanced internal forces causing movement of mass, as well as the result of atmospheric climate patterns causing non-uniform redistribution of water/ice on Earth’s surface. Changes to Earth’s principal moment-of-inertia do not require an external-to-Earth forcing.

        These are but minuscule, transient examples. The formation of glaciers causes deformation of the crust. The movement of mass forces the molten mantle to an equilibrium constrained by gravity.

        The magnetic poles are influenced by these motions, not the rotational axis.

        • I’m waiting for you to explain how your asserted compliant molten environment inside Earth has allowed large mountain ranges, such as the Himalayan range and Karkorum range with many mountain peaks more than 4 miles above sea-level, to exist as such for millions of years (or is this consistent with your phrase “only temporary’?)

          Beyond this, redistribution of mass around the Earth does affect the vector of the axis of its principal moment of inertia, and therefore where its spin axis is relative to a theoretically-fixed surface feature. This has nothing to due with directly affecting the magnetic poles, which are normally significantly offset from the spin poles and which independently (north versus south) wander to a much higher degree than the amount of true polar wander.

          Finally, for clarification, the average vector orientation of Earth’s spin axis (averaged over time to cancel out precession and nutation motions) remains essential fixed in an inertial frame encompassing Earth (under the rules of conservation of angular momentum in the absence of external torques). However, this does not preclude the surface of the Earth rotating relative to this vector orientation in response to changes in Earth’s principal axis of moment-of-inertia, a result separate altogether from continental drift.

  14. Find a copy of “The Coming Ice Age” – originally published in Harpers in the mid-1950’s. Written for a general audience, but with enough ‘meat’ to make it interesting. “Maurice Ewing” and “William Donn” were the researches involved. The recent research just confirms what they stated back then.

  15. This would be a plausible model since the Earth’s mantle and core rotate independently of each other. But the problem is that it doesn’t account for the consecutive ice ages broken by the interglacials, today being one such interglacial. So we’re in the era of ice ages *now* with the north pole where it is and not where the authors suppose it was. Yes, an ugly fact to break the beautiful theory, yet again.

  16. The elephant in the room concerning the most recent rise of northern hemisphere glaciation since the start of the Pleistocene circa 2.6 YBP is the closing up of the Isthmus of Panama, which was also a done deed about 3 million YBP. This was one of the most geological significant events, along with the Himalaya uplift to affect the good Earth in the last 60 million years. Previous to that, the Pacific Ocean currents had a direct flow into the Atlantic near the Equator and on around to Africa/Asia.

    Combined with the now well established Milankovitch cycles, I think the Isthmus closure is currently the best explanations of what is going on in the long term scheme of things regarding the the start of the Pleistocene ice age. While the ‘True polar wander’ might be an interesting hypothesis deserving of more study, we shouldn’t abandon what we already have a good idea about for another hypothesis in its infancy. We don’t know a lot about how Earth’s internal processes might alter climate globally over long time frames, so at the end of the day we really need to let the best evidence surface that fills in all the blanks. Thank goodness that the various geological disciplines don’t suffer the excesses so prevalent to climate science.

  17. Getting back to the height of the Appalachians, one current theory is that they are being pushed up at about the same rate that they are wearing down. This is why they didn’t disappear long ago.

  18. For those looking for something different but not completely irrelevant to read there’s Allan Eckhart’s novel, The Hab Theory. It’s based loosely on the pole shift ideas of Charles Hapgood (2 volume book on the subject in the 60s) and Hugh Auchincloss Brown’s Cataclysms Of The Earth IIRC.

    Anthony Banton: great to see an alternative point of view. We need more like yours, to mute the mutual reinforcement, echo chamber effect here.

  19. so rice u has discovered centrifugal force,how long till sth oz can build a pipeline to carry the heavy water from 80 deg south to 38 deg sth where it will have accumulated some of this force and use it for water turbines to back up our wind turbines?

  20. Why did the last ice age glaciers melt so quickly? An atmospheric river causing rain for 40 days?

    iron brian

    • The end of the ice age was mainly A Grand Precessional Spring and Summer (Milankovitch Cycles) lasting the better part of 13,000 years that wound up from about 1000 years after the LGM 20,000 YBP to basically completed by 6000 YBP. During that time, it would have slowed from snowing and accumulating on the ice caps to rain, which would have really accelerated the melt, so you are thinking in the right direction about an atmospheric river from time to time with that much heat going into the oceans raising the average ocean temps from .9C to an an average 3.5C now.

      I believe this is the obvious Flood Myth in actual long held collective memory, where globally the oceans rose 400+ feet over 13,000 years or less, and many local floods like the Black Sea breach of the Bosporus Straight and the Missoula Floods and countless other smaller floods would have made a deep impression on our ancestors. Tens of millions of square Km would have been flooded, at about an average rate of SLR of 1 Meter per century.

  21. If you please … for the curious layman, please provide a bit more description from the sentence fragments extracted from your paragraph: “By volume, Earth is mostly mantle, a thick layer of solid rock that flows under intense pressure and heat. The mantle is covered by an interlocking puzzle of rocky tectonic plates that ride atop it, bumping and slipping against one another at seismically active boundaries. Hot spots, like the one beneath Hawaii, are plumes of hot solid rock that rise from deep within the mantle.”

    [1] “… mantle, a thick layer of solid rock that flows under intense pressure and heat.” How does this solid rock flow — it is relatively plastic? — and, are the heat and pressure primarily from the underlying core or from within the mantle itself … or both?

    [2] ” … of rocky tectonic plates that ride atop it …” Are there “detachment surfaces” between the base of the tectonic plates — that is, of these crustal plates as seen at the surface — and its contact with the underlying mantle? If yes, generally, what is the thickness variability of these plates? Is there a name for such detachment surfaces? And, if yes, is this detachment surface observable … via some means [such as indirect reflection or refraction seismic technique]?

    [3] “Hot spots, like the one beneath Hawaii, are plumes of hot solid rock that rise from deep within the mantle.” Are these plumes — that is, the hot solid rock — sourced in any way, ultimately, from some molten volume of rock “leaking” out from the underlying molten core, or, are they hot because of some mechanism internal to the mantle?

    Note: I saw co-author Gordon’s “maple syrup and pancakes” metaphor, but, I needed to get a more precise understanding of the notions described in the above-cited paragraph before visualizing and understanding these other parts of this article.

    Note: I did note this portion from that comment, above, of Gordon Lehman: “Both hotspots and spreading ridges are shallow melt features in the upper mantle, not deeply rooted. We know spreading ridges move relative to the spin axis. It is no surprise that hotspots do too.” If true — the not deeply rooted part — this would seem to rule out the source of heat and pressure resulting from molten rock from the core, yes?

    TIA.

    PS: regarding the above crust, mantle and core matters, if more convenient for you, perhaps you can reference a text or paper — latest and/or greatest earth model interpretation of components — by some author who you may trust.

  22. If the mantle anomalies are massive enough, they can unbalance the planet, and the equator will gradually shift to bring the excess mass closer to the equator. –>

    If the mantle + newly built ice sheet MASS imbalances

    [anomalies] are massive enough, they can unbalance the planet, and the equator will gradually shift to bring the excess mass closer to the equator.
    _________________________________________________

    sounds reasonable. Could explain ongoing glaciation / deglaciation cycles.

    Anyway interesting.

  23. and the mass balance / equilication is not gliding but jerky by stick / slip effect:

    Otherwise we would not notice any glaciation / deglaciation expiration.

    https://www.google.at/search?client=ms-android-samsung&ei=d9sDXJPhM4GdsgGIs7LQBw&q=stick+slip+effect&oq=stick+slip+effect&gs_l=mobile-gws-wiz-serp.

    Said stick / slip effect is propagatet by / due to

    – first build up the new mass imbalances by adding new ices heels

    – then let them tectonic plates rock again

  24. Damned spell check: ices heels –> iceshields

    and the mass balance / equilication is not gliding but jerky by stick / slip effect:

    Otherwise we would not notice any glaciation / deglaciation expiration.

    https://www.google.at/search?client=ms-android-samsung&ei=d9sDXJPhM4GdsgGIs7LQBw&q=stick+slip+effect&oq=stick+slip+effect&gs_l=mobile-gws-wiz-serp.

    Said stick / slip effect is propagatet by / due to

    – first build up the new mass imbalances by adding new iceshields

    – then let them tectonic plates rock again

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