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SkS Analogy 20 - The Tides of Earth

Posted on 5 September 2019 by Evan, jg

Tag Line

Heavenly bodies regularly cause sea level to change by 0.5 to 120 m (2 to 400 ft).
Human bodies can cause sea level to change by 60 m (200 ft).

Elevator Statement

You’ve heard it said, “The climate is always changing.” What does that mean?

If someone said, “Mr. Smith is always falling down”, you would assume that Mr. Smith is unstable.

When you hear the phrase “The climate is always changing,” you might think, “I wonder why the climate is so unstable and always changing?” On 100,000-year cycles the global average temperature varies by 5°C, which causes variation in sea level of 120 m (400 ft). That is a lot!

These massive, 120-m glacial tides are caused by heavenly bodies that are hundreds of millions of miles away, tugging on what appears to be a very sensitive environmental system, causing regular, massive changes.

Is it possible that 8,000,000,000 human bodies pushing hard on this same, sensitive environmental system could cause a similar effect?

Jupiter and Saturn cause 100,000-year glacial tides

Climate Science

The tides of Earth include …

  • Daily tides: Controlled by daily changes in the alignment of the Earth, Moon, and the Sun.
  • Spring tides: Higher than daily tides, and occurring every 14 days when the gravitational forces of the Sun and the Moon are aligned.
  • King tides: Higher than Spring tides, and occurring once a year when the Earth is at perihelion (orbit of Earth closest to the Sun) and the moon is at perigee (orbit of Moon closest to the Earth).
  • Glacial “tides”1: Fluctuating sea level up to 120 m (400 ft), occurring over 100,000-year cycles and primarily influenced by the effects of Jupiter and Saturn on the orbital dynamics of the Earth.

The Sun and Moon pull on the oceans, causing bulges in their shape that cause local fluctuations of sea level.

Jupiter and Saturn pull on the Earth, causing bulges and wobbles in Earth’s orbit around the Sun. The influence on Earth’s orbital dynamics caused by Jupiter and Saturn are called Milankovitch cycles, named after a Serbian mathematician, Milutin Milankovitch.2  Because the orbits of planets are very regular, the Milankovitch cycles cause bulges and wobbles in Earth’s orbit that operate over 20,000, 40,000, and 100,000 years. The Milankovitch cycles drive the current ice-age variations.3

Changes in the orbital dynamics caused by Milankovitch cycles affect the distribution of sunlight between the northern and southern hemispheres. When the northern hemisphere receives less sunlight, large glaciers form over North America and Europe. The water used to form the large glaciers comes from the oceans, causing sea level to drop globally by up to 120 m. When the northern hemisphere receives more sunlight the glaciers melt, and sea level rises. The driver of these massive changes is not the orbits of Jupiter and Saturn, but rather feedbacks that are triggered by Jupiter and Saturn.

What are feedbacks? Speak into a microphone connected to an amplifier set on high-gain. Your voice into the microphone triggers a set of feedbacks that repeatedly amplify your original words until a loud squeal comes out of the speakers. Your voice does not cause the squeal, but triggers a set of feedbacks, which in turn cause the squeal.4 A similar process occurs during Milankovitch cycles where a small change in the orbit of the Earth causes a small amount of warming, which triggers feedbacks that eventually lead to large changes in CO2, temperature, and sea level.5

The sequence of events of how Jupiter and Saturn trigger 120-m sea-level change is6

  • Jupiter and Saturn affect Earth’s orbital dynamics, changing the energy distribution between the Southern and Northern Hemispheres, which causes a small temperature change in the Northern Hemisphere.
  • This small temperature change in the Northern Hemisphere causes about a 10-ppm increase in atmospheric CO2 concentration
  • Feedbacks cause the 10-ppm CO2 increase to further increase the temperature, which causes a further increase in CO2, which causes a further increase of temperature, …

This cycle goes on until the initial, direct effects combined with the feedbacks cause …

•    CO2 to change by 100 ppm …
•    Which changes global, average temperature by 5°C …
•    Which causes sea level to change by 120 m

The direct effect of Jupiter and Saturn is to cause a 10-ppm change in CO2. The feedbacks in Earth’s climate do the rest to cause the 100-ppm CO2 change.

If planets 100’s of millions of miles away can trigger 120-m tides, is there anything that human civilization is doing today that could trigger feedbacks in our sensitive, unstable environment?

By burning fossil fuels we’ve increased CO2 by 130 ppm in 200 years, 13 times the initial CO2 pulse during an ice-age cycle.

We live in an era of Earth’s history with very sensitive climate-feedback dynamics.

CO2 is currently increasing about 2.5 ppm/year. This represents a continuous, hard push on the environment.

What kind of feedbacks will we trigger if we keep pushing hard on our sensitive climate system?

Footnotes

1. “Glacial tide” is a term we define for this analogy. It does not refer to direct, tidal influences such as the Sun and the Moon exert on the oceans, but simply refers to the fact that in the same way that the relative orbital dynamics of the Sun, Moon, and the Earth cause periodic sea-level fluctuations, the relative orbital dynamics of Jupiter, Saturn, Sun, and Earth cause periodic sea-level fluctuations. The Sun and Moon cause tidal fluctuations with a period of about 12 hours and simply cause a local redistribution of water up and down a local shoreline, whereas Jupiter and Saturn cause fluctuations with a period of about 20,000, 40,000, and 100,000 years, and which redistribute water between the oceans and the land.

2. https://www.skepticalscience.com/Milankovitch.html

3. Read here for information about ice ages and glaciation cycles.

4. The feedback process is something like: small soundwave (trigger) into microphone -> electrical signal -> amplified electrical signal -> louder sound wave out of speaker and back into microphone -> stronger electrical signal -> amplified stronger electrical signal -> really big sound wave out of speaker and back into microphone -> …

5. https://skepticalscience.com/co2-lags-temperature.htm

6. The dynamics of how the distribution of sunlight between the northern and southern hemispheres causes the complex feedback between CO2 and temperature leading to large-scale glacial formation/retreat is beyond the scope of this analogy. For a summary of the link between Milankovitch cycles and ice sheet growth please read here. The scientific paper referenced in this summary article is available in this Nature article. Also read here for additional information about the effects of positive and negative feedbacks that control glaciation.

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Comments

Comments 1 to 46:

  1. "On 100,000-year cycles the global average temperature varies by 5°C... That is a lot!"  Is it 'a lot'?  5C in 50,000 years is 0.01C per century.  The temperature change over the last century is seventy times higher, i.e. 0.7C per century.  I got tired of hearing the phrase 'climate changes naturally' (implying the current change is also natural) so I did some digging.  Looking at the global average temperature over the last 22,000 years, I calculated the temperature change per century for each of the last 220 centuries (further back in time these were estimates).  The plot of those 220 centuries is a normal distribution with an average change of 0.014C per century, and a standard deviation of 0.077C per century.  By ordinary 3-sigma statistics, the claim that last centuries 0.7C change is 'natural' is easily disproven (3-sigma is 0.24C per century).  Since 1993 the atmosphere has warmed at a rate of 2.24C per century, approximately ten times the rate at which it no longer could be considered 'natural', using that 220-century bell curve as a guide.  Climate indeed changes naturally.  Ordinary statistics proves the current change is not even remotely natural.

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  2. ubrew12, the complete statement that you partially quoted is

    "On 100,000-year cycles the global average temperature varies by 5°C, which causes variation in sea level of 120 m (400 ft). That is a lot!"

    "That is a lot" refers to a change of sea level of 120 m, not to the temperature change alone. I think many people are unaware that the Earth, through regular, normal, recent cycles, experiences sea level changes of 120 m.

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  3. Thanks for bringing up Milankovitch Cycles. We talk about this in my climate class: Climate Change: Impact of an Outlaw Species. I'll just throw in the calculations we did to compare the current Sixth Extinction with the end Permian along with the effects of the M-cycles. Our best guess was that the Sixth is motoring along some 43 times faster than the End Permian. Anyone out there have a better number?

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  4. Of course, we made a number of assumptions about how long it took for Earth to proceed from general "goldilocks" conditions to the climate hell of the End Permian, selected 120,000 years, then applied the current rate of GGEs and fudged to get our Sixth Extinction to mature to a 90/97% die off by the year 4880.

    How far off are we???

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  5. swampfoxh @3 and 4. My only caution would be that you are using linear logic. That is, you are dividing 120,000 by 43 to estimate how long the 6th mass extinction will take. I would expect that extinction-level processes are highly non-linear. I would also expect that proceeding 43 times faster than a "well-understood" event means that it will likely happen much, much faster than 120,000/43 years. I am not an expert in this area, so I will stop here and hope that an expert will chime in.

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  6. There is a very believable theory that the highly unusual stability of our present interglacial, up to recently, was due to our output of Greenhouse gasses from the use of the plow, forest clearing and Rice cultivation.  Previous interglacials have begun to slide back into a glacial period almost as soon as the interglacial begins.  See the book Plows Plagues and Petroleum by Ruddiman.

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  7. Evan...agreed. It was a sloppy estimate not really intended to say much except to point to the possibility that the Sixth is going to take "awhile" to become a global catastrophe regarding species extinction. And to William...yes, Bill Ruddiman is a "neighbor" of mine here in Virginia. I know his work well and consider it of great value in the literature. I thought that some dialog on predicting the GGE trends might be interesting in the Big Picture of the Big Five.

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  8. swampfoxh@7, pull on a branch and it bends a certain amount. Now pull on it 40 times as hard. Will it bend 40 times the distance, or will it simply break?

    Fast cars can acclerate from 0 to 60 in about 2 seconds. Some people might feel a little sick under those high acceleration. Acclerate 40 times that fast an you may die.

    Natural systems have limits of how much they can absorb before they no longer react, but simply break. I know you know this, so just making a point about the dangers of extrapolating by a factor of 40.

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  9. SkS’s ditty on Milankovitch cycles is better than most at explaining the mechanics involved given the difficult subject, yet I did notice a possible rough spot there: the Earth’s orbital plane, or ecliptic (Fig. 5 on that page). Shouldn’t this remain nearly fixed in space over as short a time as 41000 years, so that changes in its orientation can be ignored when discussing changes in the obliquity of Earth’s axis? The Earth possesses much more angular momentum about the sun in its orbit than it does about its axis in rotating daily, and any out-of-plane component of Jupiter’s torques on Earth (measured with sun at pivot point) should be quite small because Jupiter’s always close to the ecliptic and pulling on us from a direction nearly in-plane.

    My suspicion is reinforced by Figs. 4 and 5 in Souami & Souchay below, who show that the inclination and North node of the solar system’s invariable plane, with respect to the International Celestial Reference Frame (based on the stars), vary by a mere ~0.01 arcsecond over 6000 years, a time lapse comparable to that of the nodding obliquity cycle, yet an amplitude quite tiny compared to 2½˚, the arc through which the axial obliquity swings. Therefore, it shouldn’t matter in Fig. 5 of SkS’s Milankovitch page, and if so, then SkS can omit the diagram altogether. (The other orbital oscillations discussed on the page, advance of apsides and change of eccentricity, remain the same as before since they’re confined to the ecliptic itself.)

    As I lack a degree in this stuff, you may wish to run it by someone in the field who contributes to your site.

    Souami & Souchay (2012), “The solar system’s invariable plane,” Astronomy & Astrophysics 543
    DOI: 10.1051/0004-6361/201219011

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  10. I can't stand sloppy unscientific sentences such as "The sun and moon pull on the oceans" as described in the beginning of this topic. They do NOT! It's their gravitational interaction across the entire body of Mother Earth which changes the shape of the planet. It's this bulge which flexes the lithosphere. The bulge of the ocean floor pushes the ocean from beneath to create our daily tides. The person who wrote the intro doesn't understand the very basic nature of how our tides work.

     

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    Moderator Response:

    [DB] You are certainly welcome to your own opinions, but this venue is science-based and to be taken seriously here you will need to up your game and start providing citations to the peer-reviewed published evidence that you feel supports your contentions.  Otherwise it will be assumed that you are simply making things up, AKA, sloganeering.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Moderating this site is a tiresome chore, particularly when commentators repeatedly submit off-topic posts or make things up. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.
     
    Finally, please understand that moderation policies are not open for discussion.  If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  11. Alao Liwry

    Are you suggesting that the floor of the ocean flexes several feet every day?  How come no one else has noticed this movement?  Please provide a citation for this astonishung claim.

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  12.  

    Alan Lowey at 10,your post suggests that the combined gravitational pull of the Moon and Sun could pull the lithosphere but not the ocean on top of it. That makes no sense. There is plenty of info here:

    https://en.wikipedia.org/wiki/Tide 

    No mention whatsoever of the lithosphere pushing the oceans anywhere.

    The lithospere does move but that is not what makes the oceans move, they both move due to the same causes.

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  13. Alan , the regular readers of this website often encounter "unorthodox" ideas (to put it politely).

    The readers must then decide whether such ideas come under the category of Troll or Crackpot (of course, those categories are not mutually exclusive).

    You are now suggesting that [peace, O Archimedes!] the atmospheric H2O is treated very differently from the non-H2O portion of the atmosphere, regarding its susceptibility to the gravitic connection with the Moon.  And I dare not ask about the Solar tides  ;-)

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  14. Phillip Chantreau

    Please consider this thought experiment:

    The only easily observed gravitational effect of the Moon is the regular ebb and flow of the ocean tides. If the commonly held belief that the Moon acts directly on the water itself, why don't we observe the water vapour of the clouds being influenced by the Moon?

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  15. Alan Lowey at 14,

    This is the most inept thing I have heard in quite a while, and we see some pretty heavy ones on this site. Considering how eager you were to lecture others on the history of tidal science, you should have bothered to read the wiki that I linked.

    Let's first clarify that clouds are not made of water vapor, but of liquid or solid water. Then we can clarify your question/thought experiment and even generalize it under the following form: "if the combined gravitational pull of the Sun and Moon makes the Oceans move, should we not also observe a similar movement in the atmosphere (where, by the way, water vapor is a well mixed gas)?

    Well, it is painfully obvious that you have zero familiarity with the very stuff you lectured everyone about, and if you had bothered to read the wiki article I linked earlier, you would have found this other one about atmospheric tides:

    https://en.wikipedia.org/wiki/Atmospheric_tide

     

    So the answer to you ill formulated thought experiment is that, indeed, there are tidal movement of the atmosphere. They include other infuences than Sun and Moon, but they exist nonetheless, and you would have known that if you had done the least bit of digging on the subject. You should stop pontificating on matters you don't know anything about. 

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  16. The point I'm making is that we don't easily observe the supposed direct gravitational effect upon the clouds as we do the oceans. There's no real reason why the effect shouldn't be observed with the naked eye.

    The fact that the Moon orbits ahead of the ocean tide and not directly in-line lends itself to the notion of new physics.

    See: Land Info NZ, The Nature and Cause Of The Tides.

    The atmospheric tides are even more delayed. This kind of detail which contradicts the basics of gravity gets harder and harder to find using a web search.

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  17. Word salad in the "not even wrong" category. The basics of gravity are laughing.

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  18. The Moon orbits in the same direction as the Earth rotates, prograde. Because the Earth rotates at a faster rate than the Moon's orbit, the tidal bulge appears to be ahead.

    I'm saying that if the Earth didn't rotate, the Moon would be ahead of the tidal bulge.

    The image I have in my head is a strong gravitational interaction between the innermost cores of the two bodies. In this scenario, there is a delay for the initial inner bulge to reach the surface. 

    Because every single schoolchild is taught that "the Moon pulls on the oceans" it's extremely difficult for the average person to comprehend any alternative explanation.

    Incidentally, in a book about the science within the Koran, they say that the tides are "Waves upon Waves upon Waves". This just happens to fit the alternative suggestion I'm trying to explain.

     

     

     

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  19. There's a logical error given in the intro text of this topic. The author states that 'Glacial tides', referring to the advance and retreat of glaciation on the 100,000yr cycle, is due to the 'orbital influence' of Jupiter and Saturn.

    The explanation given in the LINZ The Cause and Nature of Tides, states that Jupiter and Saturn have a negligible influence on the tides (with respect to 'the standard version of' gravity).

    How can these two opposing views be reconciled without the new physics I'm suggesting?

     

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  20. The new physics explanation is that a strong gravitational attraction exists between the inner cores of planetary bodies and the Sun, when they are on the same 'plane of angular momentum'.

    This new physics scenario can then be applied to the Moon orbiting the Earth. The King tides, referred to in the intro text, would therefore be due to the Earth and Moon aligned on the 'local plane of angular momentum'.

    Another way of describing the Glacial tides would be to say that they are caused by King tides due to the alignment of the Earth, Sun and planets on the plane of angular momentum.

    The language makes it sound much more complicated than it really is. A visual simulation model would convey this new physics idea without any problem at all.

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  21. Alan @20 ,

    the "glacial tides" being influenced by the gravity of Jupiter & Saturn . . . is explained within the text of the OP article.

    It is also explained a second time, in Footnote 1.

    And explained again in Footnote 2.   And also explained in Footnote 6.

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  22. Correction : that should be Alan @19 

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  23. The author states:

    "Jupiter and Saturn affect Earth's orbital dynamics"

    This is in complete contrast to the professional article "The Cause and Nature of the Tides" by the Land Information of New Zealand (LINZ). This states quite clearly:

    "What about the planets? Venus exerts the greatest gravitational pull on the Earth of all the planets but, at just 0.0054% of the effect of the Moon, makes no real impression. Despite being the largest planet, Jupiter's greater distance means that it's influence is ten times smaller than Venus. So the Moon and Sun are the only celestial bodies that have any significant gravitational impact on the Earth."

    I'm guessing that your reply will be something like:

    "Jupiter's gravity, despite being just 0.00054% of the effect of the Moon, has feedback loops which amplifies this near invisible influence, to create sea level changes of 120m."

    The numbers just don't stack up. Even if they were anyway near close, there's still another logical error. Jupiter's gravitational influence would be acting all the time, not just on a 100,000yr cycle.

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  24. Alan , it is there in the OP article, and in the footnotes.  In plain English. Please read through again, with understanding, about the planetary gravities and "glacial tides" connection.

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  25. Eclectic 

    I have read the OP article thoroughly, many times. It isn't just about reading, it's also about taking time and deep thinking. These subjects aren't easy.

    Could please read my post #23 in the same manner.

    The gravitational influence of Jupiter is 0.00054% of the effect of the Moon. It therefore cannot alter the Earth's orbital dynamics, as claimed.

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  26. Correction: in post#20, I should have said "Spring tide" instead of "King tide".

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  27. Alan,

    These subects indeed are not easy and that's why you should not meddle with them, since it is painfully obvious that you are unable to comprehend any of it.

    First of all if you are going to use quotation marks, like you did in post # 23, do not include an imaginary statement in them, especially after you really quoted actual words by others. That is a very suspect way of operating, suggesting an intent to deceive.

    Second, you are so obviously out of your depth that not one of your comments is worth bothering with. Your claims about education and training made early in you first comments appear highly dubious in light of all the following: your unability to do even the most basic fact checking before spouting nonsense, comments about gravity that reveal a profound ignorance of the subject, comments about tides shown to be wildly nonsensical, followed by others that do nothing but distract from how inept the original comments were, and an overall lack of scientific literacy, demonstrated by more comments so inane as "water vapor in clouds." 

    You persist in not educating yourself about tides and invoke "new physics" that are unnecessary and that you do not bother to try to explain. 

    Third, just because you do not understand something and are unable to reproduce it does not make it impossible. That logical fallacy is called argument from incredulity. Milankovitch cycles are very real, and astonomical calculations are very precise. Back in the 19th century, Urbain le Verrier caculated the existence of Neptune from variations in the orbit of Uranus, even though they are over 10 AUs apart and Uranus has 27 moons, including some fairly massive ones. Neptune is smaller than Jupiter, Uranus a lot larger than Earth, and they are much farther apart than Earth and Jupiter are from each other.

    Just as you were shown to be completely off on Dansgaard-Oeschger events, you are now revealing yourself too incompetent on this subject to produce any interesting reflection. Fess up and learn. You have a lot of that to do before you can lecture others.

    Your continued persistance in trying to appear as knowing better, combined with comments that can only be possible with a combination of ignorance and incomprehension, make you appear like a complete fool. Every new comment digs your hole deeper. You should stop.

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  28. In case anyone is wondering, the LINZ quote cited by Alan in post 23 figures in the section of the LINZ web site titled "The cause and nature of tides"; it treats exclusively of oceanic tides and the comment about gravity of other planets pertains to oceanic tides, not orbital alterations of the Earth.

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  29. Philippe Chantreau

    I understand that the SkS policy is to try to debunk claims made by others which contradict what their bloggers have stated in the articles.

    The LINZ article states that only the Sun and Moon have significant gravitational effects on the Earth. The OP article above, tries to state that the gravitational effect of Jupiter causes "bulges and wobbles in the Earth's orbit around the Sun". This is an incorrect statement based on the information given by LINZ.

    A five year old could tell you that. 

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    Moderator Response:

    [DB] The LINZ article is clearly dealing with the effects of the various bodies in the solar system on oceanic tides (liquid bodies of water) on Earth and on short timescales only.  Try reading the article for actual context.

  30. Multi-body gravitational system are complex and well studied, and the influence of other bodies most certainly affected the orbital parameters of earth when accumulated over billions of years. There is a massive literature of this going back to Poincare if not further. Jupiter and Saturn have no significant effect ocean tides.

    See for instance this paper or this one.

    The wobbles in earth orbit affect climate through the distribution of sun on continents, not via any direct affect on climate.

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  31. I suggest you try to read beyond the level of a 5 year old. Then again,m you seem rather refractory to advice, and keep digging...

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    Moderator Response:

    [PS] Inflammatory remarks dont help, violate comments policy. Try again (though I know how you feel).

  32. For the reader wandering here who is interested and willing to read beyond the 5 year old level:

    https://www.universetoday.com/39012/milankovitch-cycle/

     

    Venus and Jupiter's effect:

    https://www.universetoday.com/139198/jupiter-and-venus-change-earths-orbit-every-405000-years/

     

    Brings to this paper:

    https://www.pnas.org/content/115/24/6153

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    Moderator Response:

    [DB] Inflammatory snipped.

  33. In the circumstance, the LINZ webpage being cited @23. 25 & 29 may be worth quoting from.

    "What about the planets? Venus exerts the greatest gravitational pull on the Earth of all the planets but, at just 0.0054% of the effect of the Moon, makes no real impression. Despite being the largest planet, Jupiter's greater distance means that its influence is ten times smaller than Venus. So the Moon and Sun are the only celestial bodies that have any significant gravitational impact on the Earth."

    There is a difference between a planet having a "significant gravitational impact on the Earth" (with respect to tides) and a planet having a significant gravitational impact in the Earth's orbit. It is the tidal influence of Jupiter that is "ten times smaller" than Venus's. A tidal influence is an inverse cube relationship. The orbital gravitational influence is the better-known inverse square relationship. And thus the orbital influence of Jupiter is greater than that of Venus.

    Of course, the complex interaction between the orbiting planets is such that all are part of an orbiting system of significant stability. Moving one of them in its orbit can have unexpected results. Thus you can, for instance, find papers (see article here) describing the eccentricity of the Earth's orbit being most sensitive to the orbit of Saturn even though for Earth, Saturn's gravity varies perhaps 8-times less than Venus's, 13-times less than Jupiter's.

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  34. Philippe Chantreau, MA Rodger

    We all need to keep thinking logically for ourselves and not just quote research paper conclusions as if they are fact set-in-stone. All theories are work-in-progress until a Theory of Everything has been established.

    The two UniverseToday articles can't be directly compared as 'evidence'. Let me explain why.

    The Precession cause is given as "by the tidal forces from the Sun and Moon". This agrees with the information from LINZ.

    The Tilt cause is not mentioned.

    The Eccentricity, 100,000yr cycle, cause is given as the planetary influence of Jupiter and Saturn. This doesn't agree with LINZ.

    The second article refers to a 405,000yr cycle, via the gravitational effects of Venus and Jupiter. This doesn't agree with LINZ but at least they have some evidence in rocks that the cycle does exist.

    ...

    The logical conclusion is that LINZ is both correct/incorrect and that the causes of the 100,000yr and 405,000yr cycles are both correct/incorrect.

    This does take some mental agility. The basic law of Newtons gravitational attraction doesn't reconcile with the amount of perturbation required to create such significant orbital changes.

    The only logical conclusion is a new physics with regard to gravity. The issue is solved by the notion of a strong gravitational interaction between the cores of the planetary bodies when on the same plane. We tend to think of planetary motions in two dimensions but it's the third dimension, the inclination, which has been omitted from deep thought.

    I know this sounds as if I must be insane to doubt the entire scientific community but my position is one of logic. 

    I don't expect anyone to leap to my side and accept that I'm making a valid logical point. It takes a lot of time to be able to comprehend the issues I'm raising.

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  35. Alan Lowey @34,

    If you can accept that tidal effects are a product of the inverse-cubed relationship and the orbital wobbles the product of the inverse-squared relationship, doesn't then your correct/incorrect convert to correct/correct? There is no need for "a new physics with regard to gravity."

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  36. MA Rodger

    Can you provide a link or quote please to justify your assertions.

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  37. Also note that Earth has an inclination cycle of exactly 100,000yrs as opposed to two eccentricity cycles which can be averaged to 108,000yrs.

    The inclination cycle is therefore, on the face of it, a better fit of the data.

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  38. Alan Lowey @34,

    I'm not totally sure what you are asking of me but the fact that tidal forces are inverse-cube is plainly set out in the Tidal Force Wikipedia page:-

    "The tidal force acting on an astronomical body, such as the Earth, is directly proportional to the diameter of that astronomical body [which for the Earth remains constant] and inversely proportional to the cube of the distance from another body producing a gravitational attraction, such as the Moon or the Sun."

    Is that the sort of justification you were after?

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  39. MA Rodger

    As I've said before, just quoting without deep thought isn't sufficient.

    The effect your referring to is only relevant when two astronomical bodies are relatively close together. The example of the Earth and Moon is relevant because the scale can be compared to your eye being the size of the Earth and the Moon being a pea held at arm's length. 

    ...

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  40. With reference to my post#37:

    Please refer to: Origin of the 100kyr Glacial Cycle: Eccentricity or Orbital Inclination (Muller, MacDonald).

    ...

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  41. A quote from the paper referenced in post#40:

    "We will also show that a previously ignored astronomical cycle, that of the orbital inclination, passes the spectral tests failed by the eccentricity. In addition the cycles precede the effects, and thus have no causality problem. Although the orbital inclination does not affect the insolation and therefore was ignored by previous analysts, the match to the spectrum and bispectrum is excellent, and so a linking mechanism to climate should be sought."

    ....

     

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  42. Alan Lowey @39,

    I'm not too sure it takes much thought to grasp the message I present @38. It is true that an inverse-cube effect will reduce with distance quicker than a lower order relationship but the diameter of the moon or the sun is an irrelevance. Thus your eyeball and pea visualisation is irrelevant. Do note that the relative effect of sun & moon on the Earth's tides can be calculated. Relative to the moon, the sun is 389-times more distant but 27-million-times heavier. Thus if, as your LINZ reference notes:-

    "The Earth-Sun system is also subject to similar gravitational and centrifugal forces but due to the Sun's greater distance they have less than half the strength of the lunar-related forces. As a consequence, the solar-related residual forces and resulting bulges are correspondingly smaller."

    If this LINZ statement is correct (and I have no reason to doubt it), it would require an inverse-cube relationship to reduce the sun's tidal influence on Earth to "less than half the strength of the lunar-related forces," indeed down to 45% of that of the moon.

    On a quite seperate matter, the paper referenced @40, Muller & MacDonald (1997), is linked here.

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  43. MA Rodger

    You're missing the point. The issue we're talking about is the gravitational effect of Jupiter on the Earth. LINZ correctly calculates that the gravitational effect is 0.00054% of the effect of the Moon. They correctly state that this is negligible.

    If you think that this is wrong, then you'll need to show your workings.

    ...

    Thank you for the putting the link. It would be great if we could move on to discuss it in more detail.

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  44. Post#41

    See this paper: A Causality Problem For Milankovitch (Karner, Muller)

    Summary

    According to the Milankovitch theory, changes in the incident solar radiation, called insolation, in the Northern Hemisphere provide the driving force for global glacial cycles. In their Perspective, Karner and Muller discuss recent studies of corals from around the world that shed doubt on the applicability of the theory to the termination of the penultimate glaciation. The authors argue that a fresh, unbiased look at the data is warranted.

    .....

     

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  45. Alan Lowey @43,

    This is all very simple. Normally I would not expect to have to show the arithmetic.

    Jupiter is 25,800-times the mass of the moon. Its closest approach to Earth is 1,636 further away than the moon is. (Note that your 0.00054% for the ratio of Jupiter's influence on Earth's tides is an approximate value deriving from your LINZ quote [see @33] which said Venus had 0.0054% the influence of the moon and that Jupiter was "ten times smaller than Venus.") If you calcuate 25,800/(1,636^3) the result yields 0.00059%. So it is indeed ten times smaller than Venus.

    So the LINZ value bears out.

    But importantly, this is the effect of Jupiter on Earth's tides. The influence of Jupiter on Earth's orbit and thus its impact on the ice age cycles and the 'glacial tides' that result is an inverse-square relationship not an inverse-cube. The impact is thus greater and thus significant.

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  46. Alan Lowey,

    You have this wrong. There is a large, well established body of litterature in astronomy and mathematics, going back well over a hundred years, that shows how planets influence each other's orbits. This body of litterature is full of precise calculations that you have not shown to be wrong. It is incumbent on you to show how all these scientists and mathematicians before you were wrong, not the other way around. You are the one who needs to show some work because you are the one making wild incoherent claims.

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    Moderator Response:

    [DB]  That user has recused himself from further participation here, finding the onus of the burden of proof and adherence to the Comments Policy too onerous.

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