“Smoking gun” on ice ages revisited

Paleoclimatologists Rock -Two million years of radical climate change is significant.

David C. Greene writes:

“The smoking gun of the ice ages” is the title of an article in the Dec. 9, 2016 issue of Science, the journal of the American Association for the Advancement of Science. The author, David A. Hodel, is listed with the Laboratory for Paleoclimate Research, Department of Earth Sciences, at Cambridge University in the UK.

Hodel cites a 40-year-old paper in Science, 194,1121 (1976). In that paper, Hays, Imbrie and Shackleton reported that their proxies for paleo sea surface temperatures and changing continental ice volumes exhibited periodicities of 42,000, 23,500 and 19,000 years, matching almost exactly the predicted orbital periods of planetary obliquity, precession and eccentricity. They also found that the dominant rhythm in the paleoclimate variations was 100,000 (±20,000) years.
Other climatologists have identified 20 glacial/interglacial oscillations over the past two million years with glacial parts of the cycles lasting about four times as long as the warm, interglacial parts. The last glacial maximum was about 18,000 years ago. We have been enjoying the present warm interglacial for about 12,000 years.

At glacial maxima, sea levels have been about 400 feet below present sea levels and sea surface temperatures about nine degrees C (14.4 degrees F) lower than present temperatures. The movement and conversion of 400 feet of ocean water to ice located in the higher latitudes required large and long-lasting influence from outside the Earth. The persistence and the magnitude of the above-described changes cannot logically be ascribed to mankind’s combustion of fossil fuels. Furthermore, in the terminations of the glacial eras, rising temperature preceded rises of CO2 by several centuries, absolving CO2 as the cause of the preceding temperature rise.

I cannot identify the cause(s) of the Earth’s quasi-repeatable climate excursions during the past two million years. However, the data provided by the paleoclimatologists makes sense to me as a physicist with three semester-hours of astronomy. My candidate for responsibility is an orbital influence on the amount of energy Earth received from the Sun as the Sun slowly danced around the center of mass of the entire solar system, with Jupiter being the weightiest of the Sun’s planetary dancing partners.

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208 thoughts on ““Smoking gun” on ice ages revisited

  1. “with glacial parts of the cycles lasting about four times as long as the warm, interglacial parts..”…

    well, you could say the set point is a lot lower than now…

    Knowing that…we should be pumping everything we’ve got into the air

    …or not

    “rising temperature preceded rises of CO2 by several centuries”

  2. orbital influence on the amount of energy Earth received from the Sun as the Sun slowly danced around the center of mass of the entire solar system
    No, that is not the reason.

      • Planetary perturbations [mainly Jupiter’s] alter the orbital parameters of the Earth leading to different regions receiving different amounts of TSI. This has been discussed ad nauseam here on WUWT. Go look and you’ll find.

      • Doc, I think these orbital parameters you talk about with Jupiter/Saturn applied to the Sun orbiting about the outer planets/Sun Barycenter centre of gravity, not directly implicating Earth except of course the well known Milankovitch Cycles which is a different set of ‘cycles’. Sorry for mentioning that. Yes, according to that hypothesis, Earth gets a differential amount of TSI as a result, supposedly the hypothesis stated that differential amounts of cosmic rays were based upon cycles of sunspot activity caused by these orbital fluctuations by the outer planets on the Sun orbiting that centre of mass in the solar system. Somehow, he made predictions of timing and varying intensities of sun spots and cosmic rays leading to more or less cloud cover, which he stated has a significant cause to climate change on a century basis. I don’t know if his hypothesis is correct or even close, but it changed my view on global warming that day.

        I recall the first day I got my first computer in 1992, this was the first scientific paper I ever downloaded and read. By some obscure German scientist I don’t remember or have the original paper anymore. Unfortunately he died many years ago, and I remember Wiki said 10 years ago the guy was an astrologer for the way he wrote his scientific paper. Of course Wiki also refers to this WUWT Blog as a site for dimwitted deni@rs, which is why I never visited this site until last year because of that writeup in Wiki about this blog. Since when, I found out only half the people or less, are dimwitted. So I cancelled leaving Wikipedia any of my inheritance, that ignorant beggar Jimmy Wales who is always begging for money.

      • Ron,

        You probably refer to Dr. Theodor Landscheidt. He had several articles at the late John Daly’s web site about the influence of solar cycles (induced by the larger planets) on e.g. El Niño episodes like here:
        http://www.john-daly.com/theodor/co2new.htm
        With several references to other articles by him.

        I suppose that Leif is right that the larger planets influence the orbits of the other planets, including the position of the sun in the centre. Thus a common cause, not the sun as cause.

        Thus I am agnostic about his findings, but if someone with more ambition can check if his findings still uphold in current times, I am always interested…

      • lsvalgaard May 23, 2017 at 1:57 pm

        Hi Doctor lsvalgaard I have a bit of a wild question. Alpha Centauri our neighbor, a three star system. Has anyone taken a look to see if the changing locations in that system influence our system?. Now please don’t jump all over me. I don’t think gravity from the thee stars is enough. I’m thinking Oort clouds and the movements of stuff way out on the system edges. We have been finding some good size non planets out there. In sum is it possible that the outer areas of our solar system and Alpha Centauri’s inter react ?

        Out of left field I know, but has it been looked at one way or the other.

        Michael

      • Thanks Ferdinand for that…yes I now recall that name. Hopefully I can retrieve that original scientific paper after 10-15 years and re-assess it in why it had such a significant effect on me 25 years ago changing me from a dyed in the wool ‘carbon’ convert, to a mild skeptic.

      • Leif, I don’t believe I’ve missed many of the ad nauseum discussions, and it strikes me you are selling out way below your usual standards on this. Sure, 41kyr is a fundamental beat, but there are way too many overrides for this to be a satisfying explanation for glacial/interglacial periodicity. Periodicity is only…period, and there is also amplitude to explain. Not only did the apparent period change at the mid Pleistocene transition, the amplitude increased considerably.

        There is no doubt that Shackleton’s plankton are Milankovitch canaries. Below is some sort of measurement of phytoplankton distribution.

        Your guess is as good as mine as to why this is so skewed to the northern hemisphere.

      • Has anyone taken a look to see if the changing locations in that system influence our system?

        Given they are lightyears away, and they don’t orbit our system, their effect is small (really really astronomically small), but believe me, if you got the idea, someone has calculated an estimate as soon as the distance was first measured. It probably (can’t remember any more) is something students of astronomy do as an exercise during the second year of their studies or something. Course named “planetary motions” and part of a lesson about perturbations caused by passing stars.

      • Oh, my, my, ….. now these two brash statements really have me confused, befuddled and aghast, …. To wit:

        lsvalgaard May 23, 2017 at 1:57 pm

        Planetary perturbations [mainly Jupiter’s] alter the orbital parameters of the Earth leading to different regions receiving different amounts of TSI.

        Ferdinand Engelbeen May 23, 2017 at 3:51 pm

        I suppose that Leif is right that the larger planets influence the orbits of the other planets, including the position of the sun in the centre.

        In order to lessen or eliminate my confusion, befuddlement and aghastment, ….. I need someone to explain to me how it is heavenly possible for the larger planets [mainly Jupiter] to alter the orbital parameters and/or influence the orbit of the Earth, …….. yet after all these thousands of thousands of years of “orbital adjustments” ……… the earth’s orbit is still pretty much the same as it has always been?

        Is it the gravitational attraction of Dark Matter that re-adjusts earth’s orbit, each and every time, ….. back to what it was before Jupiter adjusted it?

      • heavenly possible for the larger planets [mainly Jupiter] to alter the orbital parameters and/or influence the orbit of the Earth, …….. yet after all these thousands of thousands of years of “orbital adjustments” ……… the earth’s orbit is still pretty much the same as it has always been?
        Because all those perturbations are themselves cyclic, so things pretty much return to earlier values from time to time. This is not controversial, your incredulity notwithstanding.

      • >>Your guess is as good as mine as to why this
        >>is so skewed to the northern hemisphere.

        It is skewed to the northern hemisphere because the key to ice age modulation is albedo. And since all the major land masses (and ice sheets) are in the northern hemisphere, it is the northern hemisphere Milankovitch cycles that control ice age modulation.

        See my paper below.
        ralfellis May 25, 2017 at 2:12 am

        Ralph

      • Samuel C Cogar May 24, 2017 at 11:34 am

        A little physics would help. The basic fact is that every mass interacts with all other masses. They interact proportionately to their mass and inversely with distance. The barycenter of the earth-moon system falls inside the earth’s crust, but it results in the earth and moon having a secondary motion like a spinning, very lopsided dumbell that is in addition to the moons orbital motion around the earth. The individual interactions of the sun and all the masses in the solar system are the same.

        See this:
        https://en.wikipedia.org/wiki/N-body_problem

    • Who says its total tsi as the driving mechanism? It is the total energy that reaches the surface and its consequential effect that is the determinant. It has to pass through the atmosphere with the possibility of various interactions all the way down to the surface.

      The orbital wanderings also influence the amount of solar wind and such like which clearly affect the earth (the aurora’s being one effect). Effects on cloud formation and hence albedo is one mechanism I have heard mentioned. Not my field of expertise but I look at the temperature record and just want to do a Fourier analysis of the noise to see what might be there. After all we are talking about the surface temperature of a spinning planet with an orbiting moon in turn orbiting the sun in concert with a suite of other planets and a whole heap of other detritus from asteroids to dust particles with various periods and barycentres. I certainly don’t rule out CO2 as a component but nor does it seem there are no significant or even dominant cyclical inputs with the possibility of ‘beats’ and all the other interactive combinations.

      Experts were utterly convinced that stress and spicy food caused stomach ulcers until not that long ago and that tectonic plate theory was a bit whacko. I remain skeptical of scientific ‘concensus’.

      • Your quote is not what I said prof. read and quote the next sentence. Shallow smartypants rhetoric it seems to me and the sort of rhetorical shuffle that keeps me skeptical. The TSI is the total incoming energy sure but what is at issue is how much of that shows up as surface temperature, i.e as ‘global warming’, how much is reflected/radiated back into space, how much is absorbed into chemical bonds etc etc. All that coal/oil/gas in the earths strata represents absorbed solar radiation and a planet load of water cycle action with its cooling effect. Cloud albedo represents reflection into space, water vapour represents LHV absorbed plus a ‘greenhouse’ effect and so on.

      • You say you don’t rule out CO2 as a component. A component of what? Warming? If so, rule it out! It isn’t warming! Hasn’t for almost 20 years! It is in fact cooling at present. CO2 is still rising so I can’t rule out CO2 as a component of cooling!
        Since the weather appears identical to the 1970’s so far as I can tell, I can only conclude that natural variation must be a more powerful component than anything the 97% of a bogus sample of “climate fakirs” postulate.
        40 years of warming and we’re right back to 1977!

  3. Thanks for the post. You say:

    My candidate for responsibility is an orbital influence on the amount of energy Earth received from the Sun as the Sun slowly danced around the center of mass of the entire solar system, with Jupiter being the weightiest of the Sun’s planetary dancing partners.

    No, all of that makes almost no difference to the total energy received by the earth. The only influence is tidal, and that is tiny.

    w.

    • True, tilting the Earth from 22.1 deg to 24.5 deg may not matter as to the total annual energy received by Earth, but it does matter on how the Earth heats and cools during the seasons, especially above 65N and below 65S. Same with precession.

      Does less energy hitting the Arctic during summer put the lack of summer ice melt past the tipping point and ice starts accumulating setting off an ice age? Same amount of total energy hitting the Earth, but maybe a big difference in how the polar regions respond.

      • The amount of total solar energy received at Earth distance varies little throughout the ice age cycles and it never matches the ice ages at all. For example, the maximum total solar irradiance in the last ice age, actually reached its peak about 120,000 years ago, just as temperatures were crashing at the start of the ice age. Peak global TSI, ice age starting. So the more circular orbit plays no part at all really.

        But two things do vary a lot:

        – Summer solar irradiance at high northern latitudes (65N June 21 solar irradiance varies from a high of 540 W/m2 to a low of 430 W/m2); and,

        – the overall Albedo of the Earth based on how much ice builds up (which varies from about 29.7% non-ice age Eemian conditions to about 33.5% last glacial maximum conditions).

        So, drop solar irradiance at 75N down to 430 W/m2 which is not enough to melt the winter snow and sea ice over the summer AND then have the glaciers build up increasing the amount of sunlight reflected and that is what an ice age is about.

        Global Temp Non-ice Age = ([1361.5 W/m2 / 4 * (1-29.7%)]/5.67e-8)^0.25+33C= 287.8K = 14.7C

        Global Temp Ice Age = ([1361.0 W/m2 / 4 * (1-33.5%)]/5.67e-8)^0.25+31.5C= 283.3K = 10.1C

        Change is: -4.5C

        –> -0.02C from less total solar energy received by the Earth due to less circular orbit;
        –> -1.0C from lower GHGs because it is colder and the carbon cycle has absorbed CO2 out of the atmosphere (calculated at 1.5C per doubling); and,
        –> -3.5C from a higher global Albedo because of all the extra sunlight reflected by snow and ice.

        = Ice age does not START until ice builds up and reflects more sunlight and then it gets colder and GHGs drop but mainly more sunlight gets reflected and temps drop by -4.5C.

        = Ice age does not END until ice melts from the mid-latitudes first and ending in the high latitudes. It takes a lot of time to melt out 3 km high glaciers. I takes two or three good milankovitch up-turns to break the back of the ice ages.

        Albedo is the big make or break factor and that does not change until 75N summer solar irradiance falls below 440 W/m2 which is not enough the melt the winter snow during the summer high period.

      • Bill Illis

        How do you make the calculation that drops the insolation that much at those latitudes? (Average, I assume, per day TOA radiation based on the usual flat-earth plate model at a nominal earth orbit? But what is the rest of the math?)

      • Albedo is going to have just a tiny bit more influence than barycentres. Especially rapidly changing albedo.

      • With the current configuration of the continents on the surface of the planet, the tilt also changes the percentage of the TSI that is striking land areas versus the percentage that is striking open water. This results in a variation in the planet’s albedo.

      • Bill Illis May 23, 2017 at 6:12 pm

        Ice age does not END until ice melts from the mid-latitudes first and ending in the high latitudes. ….. I takes two or three good milankovitch up-turns to break the back of the ice ages.

        Here is a proxy graph that depicts the most recent of the aforesaid “break the back of an ice age” event but didn’t terminate it, …..which began at approximately 21,000 years BP, resulting in the current interglacial, ….. to wit:

        So, we have “terminations” of ice ages ….. and ….. we have “interglacials” within ice ages, … and what are the forces in nature that are responsible for the seeming two different types of events?

        Or are the forces the same that initiates both events, but one event is terminated before all the ice and snow is melted and glacial conditions return anew?

    • So the barycentre of the Jupiter-Sun system is actually outside the sun. link In that regard the sun could be said to dance around the Jupiter-Sun barycentre.

      However, the earth orbits the Sun and Jupiter has little effect on how far the Earth orbits from the Sun. link

      It’s a mistake to think everything orbits the same barycentre.

      • There is zero (none) mass in the barycenter. It does not attract anything. You could as well say that daily temperatures dance around an average temperature. They do, but not because the average temperature attracts them.

      • CB, that solar Jupiter barycenter is by calculation. The ‘correct’ barycenter is for all the planets together relative to the sun. That is well inside the sun, for simple reasons having to do with the accretion disk from the then inner Ortt cloud that eventually formed all the planets.

      • The barycentre is likely within the mass of the sun, but is constantly changing due to different planet orbital times and I presume that is part of the Milankovitch Cycles. What happens internally to the Sun? Are plasma masses sloshing around inside the Sun? Is this the cause, or at least a participant, in the 11 year (average) solar cycles? Look at the glacial/interglacial cycles for the last 2 million years, these are strong signals that significant forces have control of the thermostat here on Earth. SUV’s and Cow Farts are pushing us to a tipping point? Not possible.

      • Are plasma masses sloshing around inside the Sun?
        Of course not. The Sun is in free fall as are all the planets all well, thus feels no forces, except for absolutely negligible tidal forces.

      • Something is causing the planets (and moons, asteroids, comets, etc.) to not continue moving in straight lines, as it seems to me their mass/momentum would tend to cause them to do, if they were not being acted upon by a force of some other kind, it seems to me, lsvalgaard. Are you calling the balance between inertial and gravitational forces “freefall” ?

      • John.

        The term “free fall” has a specific meaning in physics.

        In the Newtonian domain, free fall is any motion of a body in which gravity is the only force acting upon it.

        In the context of general relativity, in which gravitation results from a space-time curvature, a body in free fall has no force acting on it, but moves along a geodesic.

      • Chimp,

        “In the context of general relativity, in which gravitation results from a space-time curvature, a body in free fall has no force acting on it, but moves along a geodesic.”

        Yet, a heavier (or lighter) body will not follow the same geodesic, right? A balance of forces is definitely occuring therefore, don’t you figure?

      • Scratch that, I think the geodesic is independent of the mass of a given body . . but is dependent on the speed . .

      • Ron Long, the barycenter is quite often outside the Sun, more than one would imagine.

      • absolutely negligible tidal forces.
        =====================
        And yet Venus always presents the same face to Earth at closest approach. the tidal effect of Earth on Venus is negligible, but the odds of this happening by chance are also negligible. Somehow, as yet unexplained, the rotation of Venus is synchronized with the Earth’s orbit.

        And if it was not for the deep sea cores we would have discarded Milankovitch years ago, precisely because TSI doesn’t come close to predicting the past. All we can show is that there is correlation.
        The evidence strongly argues for a hidden variable.

      • Tidal Forces are mass interactions and are discernable where the mass has something less than absolute rigidity, ie, is somewhat viscous or plastic. If the barycentre is sometimes outside the mass of the Sun this means the mass interactions are even more likely to promote sloshing of plasma inside the Sun. I am in no way a Star expert, for instance I use the term “sloshing”, but the Sun certainly deforms as the planets align (reinforced net mass vector) or go their own way for awhile. Since the orbital periods of the planets are reasonably regular, there is certainly a cyclic nature to all of this.

      • lsvalgaard

        “The Sun is in free fall as are all the planets all well, thus feels no forces, except for absolutely negligible tidal forces.”

        What, if anything is not in “freefall”, as you use the term there?

        See, I am part of this planet, and I feel gravitational force (honest ; ) and I’m pretty sure the chair I’m sitting on does too (after a fashion ; ) and the house the chair and I are in, and the ground beneath, etc, etc. which to my mind means virtually the whole planet “feels forces” all the time, and, I suspect that all the material of the Sun similarly “feels forces” constantly. (And, I think those gravitational forces keep it from suddenly expanding rapidly and destroying the Earth and so on, for one thing…)

        And as I said earlier, I don’t think the planets would continue to travel around in circle like paths, if the did not “feel” the forces of gravity . . So, what did you mean?

      • free fall means that the only force you feel is gravity. Astronauts on the International Space Station are in free fall [around the Earth] and so is everything around them, so they don’t see any difference between them and their surroundings [“they are weightless” and can float around]. When you are sitting in your seat flying in an airplane there are two forces acting on you: gravity pulling you down and the electromagnetic forces in the seat pushing you up [“reaction” = “action”]. The two forces are equal and opposite so you stay put, and are not in free fall. If you get up and jump out of the plane, you remove the reaction from the seat and you fall ‘free’ [ignoring the air resistance] until you hit the ground and feel the upward electromagnetic force of the ground and you will again stay put [perhaps in not so good shape as before]. Solid bodies [the seat, the ground] are solid because of the extremely strong electrical attraction [and repulsion] between their atoms.

    • Willis: I’ve read your various analyses of this, and am unconvinced. It is mostly because I don’t believe your analyses take enough into account.

      However, your Fourier analysis may not be the right tool for parameter identification. You might try wavelet analysis. I’ve studied it, sort of, for a while. But until I ran across Bob McGinty’s amazing continuum mechanics website, I never really understood it. Check this out, and make sure you read to the end. http://www.continuummechanics.org/wavelets.html

      Also, read his explanation of Fourier analysis. It’s better than any I’ve ever seen. For that matter, so is his description of the Navier Stokes equations.

    • Willis – Eccentricity does affect total annual energy input from the sun.

      Total annual insolation goes like 1/(1-e^2) so when eccentricity is high, insolation is high. It is pretty obvious intuitively once you learn that the semi-major axis of the orbit is constant. Therefore higher eccentricity means that the semi-minor axis shrinks, and the planet gets closer to the sun on average.

      If you look at the charts in the root post, you can readily see how peaks in temperature tend to correspond to peaks in eccentricity, though the other orbital factors complicate the picture.

      • and here is an OLS curve fit using all orbital parameters to match temperature, explained in the document.

      • Where ‘all orbital parameters; means obliquity, precession, and eccentricity or the earth’s orbit…

      • RERT – remember that the planet moves fast when close to the Sun. It spends most time far from the Sun.

      • Russel.

        Look at the scale on your graph. The forcing due eccentricity is minuscule.


        Ralph

      • Ralfellis – I know, the implied sensitivity is very high. But I don’t have to be able to explain it for it to be valid data. I think its visually highly compelling that Eccentricity Forcing is a major contributor to climate.

        If you don’t trust my eyes and want a statistical test: there are 79 independent 10-thousand year intervals in the data. In 49 of them the direction of eccentricity forcing change matches the direction of temperature change. In 30 they differ. There is about a 2% chance of 30 or fewer heads in 79 tosses of a fair coin. In five minutes, doing nothing clever, that establishes a clear connection, at least until someone corrects my maths!

    • Willis, claiming the “only” influence is tidal is a rather dogmatic statement. I would also say it’s unproven. There have been plenty of papers discussing how the orbits of the planets of our solar system affect each other and how there are various resonant frequencies resulting from the orbits. Quite a few years ago, Ian Wilson suggested that planetary orbits affected the length of earth’s day, which in turn affected ocean currents. I thought then and think how that this mechanism makes a lot of sense. If you have a rotating planet, such as earth, that is significantly covered by water, and you change the speed of rotation, the currents will be effected. So the effect is not tidal, but inertial, and ocean currents clearly have a huge effect on climate. Also, there must be a reason for the approximately 22 year solar cycle. I agree that the tidal effect is minuscule, but the inertial effect could have a similar on the sun, which is a rotating mass of plasma. It makes a lot of sense that even if the tidal and inertial effects of the sun are minuscule, acting over the 4.6 billion year lifetime of the solar system, they could be the cause of the length of the solar cycle.

  4. Leif will be along here any minute now to tell us that TSI variations are much too small to account for the reconstructed temperature changes over geological time frames. That is true if the Earth is considered to respond to solar energy as a simple gray body. In fact, that was the initial obstacle to the acceptance Milankovitch’s thesis.

    One needs to consider, however, the very significant changes in the response characteristics produced by the manifold hydrological cycle, which alters not only the albedo of land and atmosphere, but strongly modulates the rate of evaporation from the oceans. It’s in that ADAPTIVE interaction that one should search for the “global thermostat.”

  5. Considering the “ice ages”; nowhere is Mark Twain’s observation more accurate: “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so“.

    Ice age researchers had to make repeatedly decisions about they thought that the geologic records and proxies told them, using a limited scope of logic, lacking the big picture. But all these decisions are inherent “affirming the consequent” fallacies.

    The big picture is that the 100ky cycle including the CO2 cycle is not a climate cycle, but an earth tectonic cycle, while the real climate cycle is only the 41k year obliquity cycle.

    It’s a long story.

  6. Here’s my off the wall idea: What if, the main control on average Earth Temperature is the temperature of the Oceans? What if, we have not accounted for heat flowing from the oceanic crust into the ocean and the variations that occur when there is a anomalous amount of tectonic activity. Consider that the stresses may build up in the plates in the oceans and have long periods of relatively non-tectonic periods. The Earth could gradually cool and sink into an ice age – that would be ended with an active tectonic period at every ~125,000 years or so?

      • How many orders of magnitude would solar energy influx be over terrestrial heating? Probably counts for a small fraction of oceanic heating, but no where close to the Sun shining 24/7 for ever.

        I heard another idea for ice ages was periodical influence of recurring comets crossing earths orbit. There is that possibility, but what if some miss every 100,000 years. There goes that hypothesis. Probably there is such a thing, but doesn’t cause ice ages. Maybe just wipes things out locally for a 1000 years if it is big enough…and hits an ice sheet 12,900 YBP.

      • Ron,

        There is no valid evidence of such an impact 12,900 YBP. The Younger Dryas is no different from the Older and Middle Dryas cooling events, and the dozens (at least) of similar events during prior deglaciations.

      • There is no valid evidence of such an impact 12,900 YBP.

        There is evidence. Whether valid or not is not for me to say:

        Petaev, Michail I., et al. “Large Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas.” Proceedings of the National Academy of Sciences 110.32 (2013): 12917-12920.
        http://www.pnas.org/content/110/32/12917.long

        Moore, Christopher R., et al. “Widespread platinum anomaly documented at the Younger Dryas onset in North American sedimentary sequences.” Scientific Reports 7 (2017): 44031.
        https://www.nature.com/articles/srep44031

      • Javier,

        The authors of the Greenland study concluded that such a small impact of an iron meteorite is “unlikely to result in an airburst or trigger wide wildfires”, as proposed by the YD bolide impact hypothesis.

        The later study attempting to piggyback on this discovery found traces of platinum at sites in North America poorly dated and generally no higher than background. That’s why, IMO, there is still no valid evidence for the conjectured impact of air burst at the YD.

        Maybe some of the sites are sufficiently elevated to have been caused by parts of the small meteorite en route to Greenland, but it’s clearly way too small and in the wrong place to fit the fantasists’ bill.

    • The plates mover faster or more slowly, but they have always been moving since tectonics got started on earth.

    • On the learning list you will also need to get up to speed on the time scales involved in tectonics. Think slow

    • There isn’t any 125 000 tectonic cyclicity. By the way the curren “long” glacial cycles vary from 80 000 to 120 000 yers.

    • It’s not a smoking gun, its a fuming volcano! IMSO. Most of the above is simpy looking in the wrong place, atmospheric energy. As with renewable enrgy, there isn’t enough of it at the rate erquired when it’s needed. I suggest the atmosphere is a conseqi uence of what the r core, rock and oceans of the planet are doing, bi ut primarily the core and rock, plus the Sun, but not it’s radiance.

      It appears to me, on the energy scale of things, that volcanic/tectonic activity is by far the most likely trigger for interglacials, and any move away from the stable albedo levels of the last few ice ages.

      But trendy climatologists, who canot easily measure the deep ocean activitiy anyway, simply look at the wrong thing because they want to account for everything with their bogus temperature tracking atmospheric models they tweak to track reality when it proves them wrong again, inside the noise. I suggest, for significant change, that the atmosphere simply responds to and is a function of much larger forces, it does not control them.

      Atmospheric forces are insignificant compared to the Volcanic Gorilla in the room. But climate scientists can only see their own cherished computer models of atmosphere, that are set within a miniscule fraction of an insignificant peak in climate time, an interglacial maximum, predicting the noise in an interglacial step function. But its how they make a living, through climate Science, not joined up science..

      Volcanic activity is never mentioned, yet is more powerful than they can possibly imagine, and a more likely cause for the rapid and sudden interglacial warmings than the atmosphere, which contains a tiny amount of energy relative to the oceans, which in turn contain a tiny amount of enrgy relative to Earth’s nuclear reactor iron and Heavy Metal core, also check out the enrgy involved in the pull of Solar gravity on Earth. in planetary.

      I was surprised to see a BBC documentary on the role of gravity in causing Volcanic activity and plate tectonics, and the impact of that on climate (Earth has plates, Venus doesn’t), which made me put these thoughts together.

      It is also now believed our CO2 and water levels levels, at the levels good for human and plant life, are controlled by volcanic release and re-absorbtion under tectonic activity. Have you seen how Io is a molten ball of volcanic rock kept that way by Jupiters gravity pulling it around.? Or the massive Volcanos of the tectonic plate free Venus, which may have led to a CO2 heat death for water/Carbon based life? Worth a watch.

      The gravtational force on the Earth from the Sun is 180 times greater than the moon at 3.6×10^22 Newtons. Check that force against yer climate models. Moon is 2.04×10^20.

      During Milankovtch cycles that varies from ZERO % per annum at minimum eccentricity, about now, to 30% pa at maximum, along with solar radiation, on the inverse square law – so in 50K years from now. I assume the precession and obv liquity and not significant on te gravitational effect? That’s a lot of push and pul, on core and mantle and crust. Plates may well move more, etc. Volcanoes erupt, lots more CO2 for a start, but MOST under the sea, into the sea.

      Someone should measure this, Plate bounday movement versus Milankotich cycle periodicities.

      Most of the plate boundaries and tectonic reated hot spots are under the ocean, so If the gravitational stresses at maximum eccentricity are enough to cause increased plate mobiity and resulting leaks, AKA vulcanism, then there is an easy way to account for the clearly rapid rise in Ocean temperature at an Interglacial, and then a more gradual decline back to the long term stable high albedo state as the leaks heal, the p[lant stops being ratteled around, ready for the next energy pulse in 100K years.

      Catt’s hypothesis, if you like. © Brian RL Catt 2017

      SUMMARY: Ice age cycles, or any serious climate change, are more likely to be caused by larger forces than atmospheric variations or solar radiance on that atmosphere, which are just too small relative to the actual chages observed.

      The energies involved within our planetary structure and its core are so much greater than atmospheric energies. A volcanically active period, triggered by the gravitational stress of a Milankovitch maximum eccentricity, releases a massive amount of heat by vulcanism, mostly into the seas where it can be held for several hundred years, which is passed to the glaciers by the sea directly, and by the the atmosphere on land, and the ice melts, simple. What is the causal effect? The gravitational drag on the planet’s mobile surfacet and molten core varies by 30% at maximum eccentricity, from around zero now, to create the necessary volcanic activity. The atmosphere follows. I may update this quick draft. E&OE, typos included.

      Brian RL Catt CEng, CPhys.

  7. We know from ice cores that CO2 lags delta T by about 800 years (a bit fuzzy, see essay Cause and Effect for more details). That makes sense, because the period of thermohaline circulation is also about 800 years and the oceans are a major CO2 sink based on Henry’s law in physical chemistry. The deep stuff doesn’t get to come in or out until the water re-emergs at the sirface mixed layer. Gore got it wrong. But that by itself says nothing about anthropogenic CO2 in the past century. See recent guest post ‘Is Salby Right’ for discussion of the past few decades.

    The Milankovitch theory for glaciation may or may not be right. There is much slop on the edges, and it most definitely does not explain the pleistocene shift from ~41ky glaciations to ~100ky glaciations about 1mya. The Pleistocene onset itself is explained by the tectonic closing of the isthmus of Panama ~2.2mya; major changes in ocean circulation resulted.

    The simplest disproof of the warmunist core belief is modeled on Lindzen 2012 testimony to UK Parliament. The warming ~1920-1945 is essentially (statistically as well as optically) indistinguishable from the warming ~1975-2000. Essay cAGw illustrates this. (It cooled ~1946-1974, and hasnt warmed since 2000 except by Karlization). But IPCC AR4 WG1 SPM figure 8.2 convincingly shows the earlier period was NOT mostly AGW; not enough increase in atmospheric CO2. Well, episodic natural warming did not miraculously stop in 1975, the hindcast period for CMIP5 model parameter tuning. Which is why they now run hot by 2 (Santer 2016 paper) to 4 (Christy 2017 congressional testimony) times in the tropical troposphere.

    Getting most skeptics re-iterating a few key irrefutable soundbites can be a powerful political counterforce to warmunism.

    • The apparent coincidence of the average lag of CO2 relative to T (sic!) in ice-core data and the “period of the thermohaline circulation” is quite illusory. Eminent oceanographers entirely dismiss the notion of any “great conveyor belt” that vertically transports water masses without turbulent mixing and attendant changes in temperature and salinity. In seeking an oceanic effect upon surface temperatures, one has to look elsewhere.

      • eminent oceanographers entirely dismiss the notion of any “great conveyor belt”
        =======================
        those must be the ones that sit in ivory towers and never get out on the water. cross the oceans in small boats and then tell us if there are rivers in the ocean. the equatorial counter current is a prime example. how can such a narrow river of water flow for thousands of miles just below the surface and not break down in turbulence.

        replace “eminent” with “ignorant” and you’ve hit the nail on the head.

      • fredberple:

        You’ve got it totally backwards. It’s precisely”the ones that sit in ivory towers and never get out on the water” that came up with the illusory notion of the “great conveyor belt” in the first place. And they’re not even oceanographers of any description, but rag-tag “climate scientists,” expressing their grossly unrealistic schematic view of very sluggish thermohaline circulation. Total oceanographic laymen tend to believe in picture-book depictions of coherent, turbulence-free transport; experienced oceanographers know that all ocean currents, including the ECC, develop tongues and narrow strands that promote mixing.

      • 1sky1: Horizontal layering in water masses has been known for nearly two centuries. These layers move in coherent and consistent ways without mixing until they are forced to rise (or lower) and mix by well-known mechanisms. This is demonstrated in many phenomena: the Humboldt current being one. The creep of deep, cold, nutrient-rich water, driven by the Antarctic ice cap melt, surfaces in the Northern Hemisphere resulting in the rich fisheries in that part of the globe. Even ancient Polynesians knew better – they used the consistency of wave and water directional movements as a current compass to assist in their long-distance navigation. They had many words and expressions for the angle that their craft could take in relation to these directional currents;.The boundary between these masses is amazingly sharp, as indicated by colour, temperature and salinity. So, how can you claim that such massive currents of seawater are not responsible for the transfer of heat? And the lag of CO2 fluctuations behind those of temperature seems to be very well established, and is thus better science than the poor correlations and even worse predictions used by uncritical proponents of anthropogenic climate change.

    • Isthmus of Panama formed closer to three million years ago than two. Assume the ~2.2 mya is a typo.

    • Ristvan – The Milankovitch theory for glaciation may or may not be right. There is much slop on the edges, and it most definitely does not explain the pleistocene shift from ~41ky glaciations to ~100ky glaciations about 1mya.

      Could this be they are using the current variance in ‘Net Polar Wander’, instead of what it really was.

      Polar wandering and the forced responses of a rotating, multilayered, viscoelastic planet
      Roberto SabadiniDavid A. YuenEnzo Boschi – http://onlinelibrary.wiley.com/doi/10.1029/JB087iB04p02885/abstract

      Sabadini and Peltier [1981] have constructed a physical model in which they found that a net polar wander could occur as a result of the periodic forcing by active glaciation and deglaciation. This phenomenon is illustrated in Figure 1. Previous work by McElhinny [1973] and Jurdy and van der Voo [1974] have concluded that the amount of true polar wander (TPW) during the last 55 m.y. has been quite small, about 2ø. However, recent reanalysis of paleomagnetic data by Jurdy [1981] and Morgan [1981], using a reference frame based on hot spots, have revealed that TPW of between 10ø to 15ø had occurred since the Cretaceous. Furthermore, Morgan has proposed boldly that, in fact, 5ø-10ø of this polar wander must have taken place in the last 10 m.y. Copyright¸ 1982 by the American Geophysical Union

      As to Peter Jones – “heat flowing from the oceanic crust into the ocean” & doesn’t work that way.

      What if you put a lid on a pot of water on the stove. Takes less heat to boil, Bit like Ice Caps on the ocean down to 45 degree. Slow heat in, less volume and not much out, will still warm the deep oceans.

  8. Ice Ages – he Cause
    We are circling the centre of the galaxy.

    As such we pass through the Dark Matter that makes up most of the Galaxy. It isn’t likely to be uniform in density – nothing is. And there is no reason to think it is revolving at the same speed as ourselves. We have more interactions and therefore different rotational energy, probably.

    Denser Dark Matter regions will accumulate more dust due to their gravity.
    Dust dims the Sun.
    Hence Ice Ages.

    This hypothesis is trademark me, completely unsubstantiated and as legitimate as any other explanation for the periodicity of Ice Ages.

    • well actually dark matter would only make sense if it was revolving at the same speed as the rest of
      matter in the galaxy. The standard assumption about dark matter is that it only interacts with ordinary matter through the gravitational force. Hence it obeys the same law of gravity as ordinary matter and so if the galaxy is stable then it must be rotating at the same rate as everything else.

      • Correct. But there may be no ‘dark matter’. Only more and more massive black holes made from ordinary matter than thought. Passes the Occam’s razor test.

      • Yes, it must rotate at the same rate as everything else, on average. But the density of Dark Matter need not.
        The oceans circle the Earth at the same rate as the land. But the Oceans have waves.

        Rotational energy (interactions that translate inertia into spinning matter) were mentioned because they can perturb the smooth mathematical average.

      • If everything in the galaxy is rotating at the same rate, then how do we pass through (in and out of) the spiral arms as described by Shaviv? He clearly describes our movement through the arms as different from our movements above and below the galactic plane.

        I’ve never understood this.

      • ristvan, I agree that it is a false conjecture to believe that ‘dark matter’ is an exotic and undiscovered force when we know that the universe is full of non-luminous bodies (mass) that could provide the ‘missing’ gravity. However, is it necessary for this ‘dark matter’ to be comprised of black holes or is it possible that ordinary matter is the source. I ask because it has been determined that our solar system is surrounded by the Oort Cloud of which the actual size and mass is unknown. Also, there is no reason to believe that our solar system is typical; might not other systems have greater non-luminous ordinary mass that contributes to the missing gravity? I ask not as a challenge to your assertion but as a sincere question. Thank you.

      • The big bang is still only a theory…hence the need for dark matter in first place. Or so I recall.

      • Read the Mcgaugh paper, university of Maryland. There may well be no dark matter as presently theorized.

      • Here’s a thought experiment about dark matter.

        Imagine you had a black hole with a large amount of only dark matter in it’s accretion disk. Would there be jets streaming from the poles? What would they “look” like? You run into theoretical trouble partly because of this. The idea of a black hole was derived completely from the properties of baryonic (“normal”) matter.

      • The other Mark W – I think Nir Shaviv’s ideas are based on the solar system being outside the galaxy’s spiral arms. Effectively we rotate within the galaxy in a plane parallel to the plane of the spiral arms, but at a different rate. That’s just my recollection, I suggest you go looking in Nir Shaviv’s work for confirmation.

      • Evidence of the existence of dark matter is even less than for global warming. Just a hypothetical fig leaf placed over an embarrassing ignorance.

    • Dark matter doesn’t really cluster on those scales, but you might consider looking up “dark matter caustics”.
      On the other hand, many years ago on this site there was a convincing argument made for the glacial periods corresponding to when the sun moved into the spiral arms of the galaxy and was exposed to more cosmic rays.

      • Dark matter doesn’t really cluster on those scales

        Like Ristvan above, I doubt we can be so sure of the nature of Dark Matter.
        All we know is that there is extra gravity from somewhere. That would be easier to see on large scales… measurement bias?

        But I do remember that cosmic ray article. It was excellent.
        Just thought I would try to give a new idea for the joy.

    • Cosmoclimatologists argue that the apparent 150 million year regularity in ice houses corresponds with the solar system bobbing below, then back above the plane of its orbit around the galactic barycenter.

      IMO, axial tilt adequately explains the 41,000 year glaciation cycle, as per Javier, affecting insolation at high northern latitudes (high southern latitudes having already been glaciated since ~34 mya). The mid-Pleistocene shift may have occurred simply because climate got colder the longer the NH glaciations lasted. This could have caused more of the incipient interglacials to be stillborn, producing glacial intervals of roughly 82,000 and 123,000 years, which averages to around 100 ky.

      • I thought that the ice age cycle had always been the 41,000 year cycle before about 1 million YBP. And then it started to change over to the 100,000 cycle about 800,000 YBP?

        I think the 41K Tilt cycle is the hammer when the eccentricity orbit is right for freeze -up, and to a lesser degree the Precision every 26,000 years. It sure looks like there is a lot of false starts and stops in the graphs, which show that everything has to line up perfectly. And maybe then even needs a volcanic trigger to really get it going.

      • Ron,

        Eccentricity will get a test in the next 10,000 years. If the Holocene lasts as long as proponents of eccentricity predict, then we’re in for the longest interglacial on record, ie up to 50,000 years. Much of Greenland’s Southern Dome will melt, hence natural “catastrophic” global warming.

        IMO precession (axial wobble) has little effect, but what do I know?

      • Chimp, I too am having troubles visualizing Precession as being very significant in the scheme of things, but then as I say I am having trouble trying to figure how that changes anything, except maybe for the difference in Earth/Sun distance on the equinoxes. My gut is telling me that since the earth precesses westward at 1 degree per 71.6 years, that possibly no given year is the same as the last until 26,000 years until the wobble returns to square 1. That is a human lifetime, and the distance of precession is equal to the width of two full moons. It is definitely a seasonal thing to when and where the background of the stars is in relation to the spring equinox. And that is always changing, but maybe it is only the view of the stars, and which star is the north or south pole star. Definitely a seasonal thing as per when your birthday was, at 72 years old the position of the Sun on your birthday will out by a full day as compared to your birth year where the background stars were. That will have moved one full degree westward.

        However, one thing we know for sure, is that the concept of modern day astrology can only be about 2300 years old since that was when constellation Aries was on the ecliptic March 21st, and now it is at the end of the constellation Pisces and soon regressing into Aquarius. So everything is off by one constellation for a literal interpretation of said subject.

      • Chimp
        The eccentricity low amplitude mode now is repeated every 400,000 years and is nothing new. So this 50,000 year Holocene is nonsense. In fact the opposite is true: when eccentricity has its nodes of minimum amplitude, that is when the interglacials are sharpest and most cleanly defined. By contrast at maxima of eccentricity amplitude you get ragged and double-headed interglacials, e.g. 200,000 and 600,000 years ago.

      • Here is a graphic from Clive Best showing TSI, eccentricity, and obliquity, with EPICA temps,co2 and dust. Ice volumes are from the delta O18 benthic stack. Its a bit busy, but worth a long look. There is a definite correlation of TSI with obliquity on the 41ky beat. Eccentricity is a bit more complex, but note the similarity of the present interglacial with -400,000 (name escapes me at present). Javier has has explained many of the details of these forcings on other threads here.

        http://clivebest.com/?attachment_id=7092

      • Yes Ralf, and I’m sorry I didn’t reference that. I think there is a lot of merit to idea that dust plays a role in ending the glacial intervals. I know you and Javier are in some disagreement on that point, but it seems to me that it takes a confluence of many factors to bring us back from the brink of icy CO2 death.

    • Ray in SC, your conjecture is as good as mine. Maybe both are true. Basic science point is simple. Lots of ordinary mass is not luminous on galactic scales.

      • There are plenty of other potential explanations for the data Dark Matter is conjectured to account for. Yilmaz postulated that gravity, like the other forces, created gravity, and thus disposed of singularities. De Broglie, Bohm, and current Pilot Wave theory also not only dispose of singularities, but Dark Matter, and Schrodinger’s Cat, as well as providing an ontological basis for the particle/wave duality (although I do not recall it accounting for observer effects).

        Regarding tectonic potential to affect climatic cycles, it is apparent that we are quite theoretical in our grasp of subcrustal fluid dynamics, and that seafloor volcanic events remain grossly indetectable (only recently a study that placed various instruments off the Oregon coast did not detect volcanic activity that actually buried some of the instruments, until researchers physically went there, and saw the fresh lava), and clearly the nature of episodic, constant, and cyclical seafloor vulcanism are very incompletely understood. The nature of potential turbulence in magma and what cycles might exist is hardly considerable as cast in stone, so to speak.

        It is certainly possible that cycles of subcrustal turbulence-caused seafloor vulcanism create episodes of accelerated evaporation of water, that then provides significant raw material for polar accumulation of snow, causing ice ages to begin.

        Frankly, there are so many potential contributors to climatic periodicity that are poorly understood, and probably several that aren’t known, or even hypothesized at present, that we can hardly characterize climate science as anything other than nascent, certainly not mature, and definitely not nailed down.

        I also want to say thanks to all contributing here for the best discussion of climatology I have read.

  9. The post records that Hays, Imbrie and Schackleton found three periods of 42,000, 23,000 and 19,000 years and that they are due to “obliquity, precession of the equinoxes, and eccentricity”. But in fact the last two periods of 23,000 and 19,000 years are two “shoulders” of the precession period. The eccentricity cycle is closer to 100,000 years. Since the latter was the cycle observed in the Vostok core, the authors had the problem of fitting their three cycles of 42k, 19k, and 23k into a 100k framework. (They felt that the eccentricity cycle alone was not sufficient to explain the 100k cycle.) So they came up with the idea of the pacemaker, which itself does not have a rhythym of the heartbeat but leads to that rhythym. Thus the name of their article. It was probably later that it was discovered that before the 100k period of the last 1.2 million years, there was indeed a 41k period for the previous 1 million years, which rather supported the authors’ feeling that eccentricity alone was not a sufficient cause and that obliquity and/or precession would be more likely to be linearly related.

    • Me thinks that the solution to the problem lies in the phase relationships of the three major periodicities. That is, they aren’t independent, but can constructively and destructively interfere to change the apparent periodicity of the resultants — glaciation and interglacials.

  10. So how does “consensus” climatology explain past variations ? Or does it even admit that colossal variations occur without CO2 being involved?

    • The only thing they admit is that “something” triggers a climate reversal, and then CO2 takes over. Weird science.

      • Bruce, CO2 takes over. Except when we are going down into the glacial time. Highest CO2 now starts the Ice Age? Must be short in the CO2 Control Knob for that to work.

    • CO2 was involved. Afterwards. Hundreds of years afterwards.

      But I agree with at least one contribuor above. I suggest most significant atmospheric variations AKA climate are a consequence of whatever actually causes the warming, an effect, not a primary cause. What the atmospheric cliamte models are predicting is Noise i ona ludicously short time sacle versus actaul periodicites. And attribting change to forces that are unlikely far too weak to produce them, without any real understanding of real atmospheric scieence from their numerical computer models. .No scientific laws are provable from such data about a unique planet..

      Just watched the BBC Horizon on Space Volcano’s, more episodes to come, so gravitationa variation now has top credibility as my go to serious climate change agent, just on the effect gravity has had on molten Io and massively volcanoed and gassed out Venus (with no plates on Venus either). I now prefer the serious science with relative cause and effect scale that needs no dodgy guesses about forcing, Also seems most of our water and CO2 comes from volcanoes (what happened to the meteor bombardment story?), and plate tectonics recyles it, or you end up like Venus without the tectonics.

      Io, in deep space, is a semi molten ball of volcanoes, created by gravitational stress from Jupiter alone. If you want to talk forcing, I propose the heating caused by increased volcanic releases from volcanic activity of the 30% gravitational variation of a MIlankovitch extreme. Most of that goes into the oceans. Gloabl climate is maninly a response to the amount of heat entering the system from volcanicity,, the noise if from solar variation, humans, unscheduled Super Volcanos. etc..

      Forcing is a randomly parametered massive gain assumed in the climate models to claim the atmosphere can do anything remotely significant due to CO2 variation leveraging water vapour content. Really?

      Why not look elsewhere, where there are serious forces conveniently to hand that can interact at a planetary scale and can do this directly? No gain required. The smoking crater/fumerole, as it were.

      I now much prefer this quite likely, and well big enough to do the job, volcanicity as a more likely major causal force of real climate change, versus the 5 minutes of noise within the hour or two of an interglacial peak currently classified as climate science for grant purposes.

      Thor’s hammer versus fan waving inadequates. Nuclear furnace versus wind and water power, literally. And the atmosphere not significant as a primay cause of its own change at all.

      That’s not a perturbation, THIS is a perturbation.

      The more I think about it as an engineer, the dafter climate science gets as a primary factor, considered in isolation from the much larger forces involved. I prefer to believe, on the energy physics, that the atmosphere is a consequence of other things more powerful, kept warmish by the Sun once there. Balanced by natural effects of vegetation, oceans and albedo, which we can do without altogether (the ice that is) , that vary to correct imbalances and extremes in one or another, but whose effects tail off asymptoticallly, don’t run away at all, negative not positive feedback in this system, which is stble inside a tight range of absolute temperature, +/- 12 degrees on the -273 in deep space between intergalcials and ice age minima. That’s pretty stable. Not running away. anywhere.

      All the evidence is for a self regulating planet between two temperatures for the last 1 milion years or so, and not a lot of variation outside that. Gaia.

      Real climate change must deliver a huge amount of heat to the high capacity oceans that can directly deliver the step function required to resuscitate us from an ice age every main Milankovitch cycle or so. It needn’t be precise, plenty of other factors on a planetary scale are involved.Not even sure how the effect of what season it is in which hemisphere when closest/futhest from the Sun matters. Same energy overall but more extreme seasons in one hemisphere, less the other, etc.?.. But solar radiation’s effect on the atmosphere, even at 30% pa variation it shares with gravitation in Milankovitch extremes, is inadequate to trigger major change such as climagedddon or the end of an ice age, compared to core leakage of heat from our on board nuclear reactor into the oceans that the gravitational changes could cause, now that’s a forcing.. Probably. Watch that programme on Space volcanoes before you comment that gravitational stress is unimportant.

  11. Whenever the discussion of Milankovich cycles comes up I wonder why glaciation didn’t happen (or didn’t happen often) after the Carboniferous period… until the Pleistocene? Did the earth’s orbit change? Solar output change? Planet got hit with more cosmic rays causing clouds and global cooling?

    • It is thought that the closing of the Isthmus of Panama is principally responsible for a major reorganization of ocean currents, principally the Japan Current and the Gulf Stream, which probably redirected the massive atmospheric flows of moisture towards North America and Europe which had then grown cooler because of the closing.

      The Quaternary glaciation, also known as the Pleistocene glaciation or the current ice age, is a series of glacial events separated by interglacial events during the Quaternary period from 2.58 million years ago to present. Which is about the same time as Panama closed up.

    • The Cenozoic Ice House actually started in the Oligocene Epoch, ~34 Ma, when Antarctic ice sheets rapidly built up, following the formation of deep oceanic channels between that continent and South America and Australia. Then ~3 Ma, the Americas joined, interrupting tropical ocean circulation and strengthening the Gulf Stream, initiating the Pleistocene Northern Hemisphere glaciation.

    • Here is full set:

      “Impact of the ~ 2400 yr solar cycle on climate and human societies” *by Javier Posted on September 20, 2016
      https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/

      “Nature Unbound I: The Glacial Cycle” by Javier Posted on October 24, 2016 | 269 Comments

      –https://judithcurry.com/2016/10/24/nature-unbound-i-the-glacial-cycle/

      Insights into the debate on whether the Holocene will be long or short.

      Summary: Milankovitch Theory on the effects of Earth’s orbital variations on insolation remains the most popular explanation for the glacial cycle since the early 1970’s. According to its defenders, the main determinant of a glacial period termination is high 65° N summer insolation, and a 100 kyr cycle in eccentricity induces a non-linear response that determines the pacing of interglacials. Based on this theory some authors propose that the current interglacial is going to be a very long one due to a favorable evolution of 65° N summer insolation. Available evidence, however, supports that the pacing of interglacials is determined by obliquity, that the 100 kyr spacing of interglacials is not real, and that the orbital configuration and thermal evolution of the Holocene does not significantly depart from the average interglacial of the past 800,000 years, so there is no orbital support for a long Holocene.

      “Nature Unbound II: The Dansgaard- Oeschger Cycle” by Javier Posted on February 17, 2017
      https://judithcurry.com/2017/02/17/nature-unbound-ii-the-dansgaard-oeschger-cycle/

      Dansgaard-Oeschger (D-O) events are the most dramatic and frequent abrupt climate change events in the geological record. They are usually explained as the result of an Atlantic Ocean salinity oscillation paced by internal variability. Available evidence however supports that they are the result of an externally paced oceanic-sea ice interaction in the Norwegian Sea. A lunisolar tidal cycle provides an unsupported hypothesis that explains all of the known evidence for the 1470-year pacing and the triggering mechanism for D-O oscillations.

      “Nature Unbound III: Holocene climate variability (Part A)” by Javier Posted on April 30, 2017
      https://judithcurry.com/2017/04/30/nature-unbound-iii-holocene-climate-variability-part-a/

      First in a two part series on Holocene climate variability.

      Summary: Holocene climate is characterized by two initial millennia of fast warming followed by four millennia of higher temperatures and humidity, and a progressively accelerating cooling and drying for the past six millennia. These changes are driven by variations in the obliquity of the Earth’s axis. The four millennia of warmer temperatures are called the Holocene Climatic Optimum which was 1-2°C warmer than the Little Ice Age. This climatic optimum was when global glaciers reached their minimum extent. The Mid-Holocene Transition, caused by orbital variations, brought a change in climatic mode, from solar to oceanic dominated forcing. This transition displaced the climatic equator, ended the African Humid Period and increased El Niño activity.

      • +1
        This was all put to bed by Javier, but here we are having yet another “50-blind-dates” discussion of the Milankovich cycles.

  12. “… proxies for paleo sea surface temperatures and changing continental ice volumes exhibited periodicities of 42,000, 23,500 and 19,000 years, ”

    All I can say is duh. The first thing I looked at when deciding whether to jump on the CAGW bandwagon or determine that it is complete garbage was the periodicity in the ice cores. Even the RMS rate of change in long term averages is about the same as the change in short term averages observed today, even ignoring all the data manipulation.

  13. Beside the strong 40 & 100 Ky ice ages cycles, we often hear about a (much weaker) 1000 year climate cycle.
    Spectral analysis of two apparently unrelated sets of (both 7000 years long) data shows presence of a strong component with periodicity just below 1Ky.

    which could be but unlikely a coincidence.
    Existence of 1Ky cycle apparently is not present within solar activity, but it may be that the source is another less pronounced wobble in the earth’s axis of rotation.
    …. “the fluid nature of the Earth’s core and oceans” are two factors contributing to the “Chandler wobble or variation of latitude is a small deviation in the Earth’s axis of rotation relative to the solid earth”
    Two global fluids (oceans and the molten core) from time to time hit the natural resonance in the region of 1Ky, via angular momenta ‘crosstalk’ resulting in:
    – increase in the oceans currents strength (volume and / or velocity) and by doing so enhancing transfer of the equatorial heat energy polewards
    – increase in the the molten core circulation boosting magnetic field’s strength.

  14. I find it extremely optimistic that here (and on other sites) the ideas relating to the effects of gravity on climate are getting greater recognition every day. These ideas about cyclic effects in the solar system causing climate fluctuations on Earth are just the same as those discussed by the WUWT antichrist (Do*g Cott*n). Can it be simply a matter of time before Anthony allows these ideas to be discussed in more detail i.e. NOT just the gravity that makes the planets move but the gravity that keeps the atmospheres of all planets in place?

  15. “I cannot identify the cause(s) of the Earth’s quasi-repeatable climate excursions during the past two million years.” Well then it is CO2 wut dunnit. The science is settled. QED.

  16. The start of long periods of no pole reversal roughly coincides with large changes, 2.6, 1.78 and 0.78 M years ago. Could it be that it coincided with large changes in the crust (not as big as Drake Passage opening or Panama Isthmus closing) and ocean currents, which themselves were the result of changes deeper in the Earth. Now the science. What to look for to test it.

  17. How do we know the eccentricity of the Earth 1,000,000 years ago? Is there a decent proxy for this? Or do we just have “faith” in the computer simulations? I really do not know – I am asking.

    Also, how do we know the wobble of the Earth around it’s axis from 1,000,000 years ago? If there is an ice age, wouldn’t that effect the wobble, and maybe slow down or sped up rotation a bit? All that water (in ice form) would have to have an impact, and what if the weight is not distributed at all evenly.

    And how do we know the albedo in an ice age? Is that just another estimate? I would assume it would have to be. So if the northern hemisphere were covered in significant ice and the southern hemisphere had significant water, then the southern hemisphere would be warming more, right?

    If cosmic rays do increase cloudiness, how do we account for those 1,000,000 years ago. I assume their might be some decent proxies for this – isotopes created by cosmic ray collisions. But is that the only reaction creating the isotope? (I really distrust proxies, its hard to know just how accurate they are).

    I don’t see how anyone sorts these estimates out with any degree of certainty, so how can you make predictions from it? The best one can do is look for a combination that MIGHT explain the ice ages. And then how do you test it?

    Meanwhile the climate scientists just make up whatever they want.

    • How do we know the eccentricity of the Earth 1,000,000 years ago? Is there a decent proxy for this? Or do we just have “faith” in the computer simulations? I really do not know – I am asking.

      We can calculate the relative positions of the solar system planets with extraordinary precision. This is what allows our satellites reach other planets, comets, and so on. We can then project them back even 200 million years ago. The accumulated error will still be relatively small. Every test done so far indicates the back projection is quite correct. For example matching past interglacials from 2 million years ago to extrapolated obliquity cycles. Within dating error they match.

  18. The Hays, Imbrie, and Shackleton article is a classic that anybody interested in the glacial cycle should read. In a way it solved the mystery of glacial periods by matching the until then discredited Milankovitch glacial cycle theory of changes in insolation due to orbital variations, to the then recently found evidence on multiple glacial/interglacial periods dated at about 100 kyr intervals. At the same time it is also a classic example on how a myth can reach the status of consensus and then become almost impossible to dispel despite blocking the advance to a better understanding. This is the 100 kyr cycle myth.

    In a way this was the final triumph of those that defended that climate was not operating in an unpredictable manner (chaotic we say), but according to cycles that could be predicted to a certain extent. Until then the people that talked about climatic cycles beyond the seasonal cycle were laughed at. Yet it is a pity that at that moment of triumph the community would accept quasi religiously the 100 kyr cycle for which there was some evidence but no proper mechanism. The eccentricity forcing, by itself, is very small. The 100 kyr cycle created far more problems that it solved.

    Scientific consensus still has not gotten around the 100 kyr myth despite being already solved. I did it on my own by first correctly identifying all interglacials. Unknown to me at the time a group of Pleistocene experts had already got to the same task and reached the same conclusion: There are 11 interglacials in the past 800 kyr (do the math, there is no room for a 100 kyr cycle).

    Past Interglacial Working Group of PAGES. Interglacials of the last 800,000
    years. Rev. Geophys. 54, 162–219 (2016).
    https://www.repository.cam.ac.uk/bitstream/handle/1810/252679/Berger_et_al-2016-Reviews_of_Geophysics-VoR.pdf?sequence=5&isAllowed=y

    Afterwards is very easy to determine that interglacials have always responded and still respond to the 41 kyr obliquity cycle as a first order factor. Since the world got so cold at the Mid-Pleistocene Transition, obliquity is no longer enough by itself, and requires the participation of second order factors. One of them is the 23 kyr precessional insolation cycle, and the other a group of feedbacks that create ice sheet instability as the ice sheets become bigger with the passing of glacial time.

    After posting this at Judith Curry’s blog last October:

    https://judithcurry.com/2016/10/24/nature-unbound-i-the-glacial-cycle/

    I had the satisfaction of seeing P. Tzedakis et al. publish the same findings in Nature last February:

    Tzedakis, P. C., et al. “A simple rule to determine which insolation cycles lead to interglacials.” Nature 542.7642 (2017): 427-432.
    http://eprints.esc.cam.ac.uk/3856/1/nature21364.pdf

    You would think that after showing that the consensus is wrong, and the 100 kyr cycle is actually an artifact of mathematical averaging and does not exist, the consensus would change. However changing a consensus view is difficult even when you show it is incorrect. A lot of people that have read my article and know about Tzedakis et al., 2017 paper still believe in the 100 kyr cycle. Eventually the scientific community will come around, but it will take many years before the 100 kyr cycle disappears from textbooks, if it ever does. Don’t underestimate the power of consensus.

    And by the way, cycles do exist in climate. From the daily cycle to the 150 myr ice-ages cycle. Cyclophobics had to swallow the Milankovitch cycles and they will have to swallow several more as the evidence becomes better and better. But not all cycles are real. The 100 kyr interglacial cycle is not.

    • Javier is much too modest. Here are links 4 of his lengthy posts at Judith Curry’s site:

      “Impact of the ~ 2400 yr solar cycle on climate and human societies” *by Javier Posted on September 20, 2016
      https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/

      “Nature Unbound I: The Glacial Cycle” by Javier Posted on October 24, 2016 | 269 Comments
      https://judithcurry.com/2016/10/24/nature-unbound-i-the-glacial-cycle/

      Insights into the debate on whether the Holocene will be long or short.

      Summary: Milankovitch Theory on the effects of Earth’s orbital variations on insolation remains the most popular explanation for the glacial cycle since the early 1970’s. According to its defenders, the main determinant of a glacial period termination is high 65° N summer insolation, and a 100 kyr cycle in eccentricity induces a non-linear response that determines the pacing of interglacials. Based on this theory some authors propose that the current interglacial is going to be a very long one due to a favorable evolution of 65° N summer insolation. Available evidence, however, supports that the pacing of interglacials is determined by obliquity, that the 100 kyr spacing of interglacials is not real, and that the orbital configuration and thermal evolution of the Holocene does not significantly depart from the average interglacial of the past 800,000 years, so there is no orbital support for a long Holocene.

      “Nature Unbound II: The Dansgaard- Oeschger Cycle” by Javier Posted on February 17, 2017
      https://judithcurry.com/2017/02/17/nature-unbound-ii-the-dansgaard-oeschger-cycle/

      Dansgaard-Oeschger (D-O) events are the most dramatic and frequent abrupt climate change events in the geological record. They are usually explained as the result of an Atlantic Ocean salinity oscillation paced by internal variability. Available evidence however supports that they are the result of an externally paced oceanic-sea ice interaction in the Norwegian Sea. A lunisolar tidal cycle provides an unsupported hypothesis that explains all of the known evidence for the 1470-year pacing and the triggering mechanism for D-O oscillations.

      “Nature Unbound III: Holocene climate variability (Part A)” by Javier Posted on April 30, 2017
      https://judithcurry.com/2017/04/30/nature-unbound-iii-holocene-climate-variability-part-a/

      First in a two part series on Holocene climate variability.

      Summary: Holocene climate is characterized by two initial millennia of fast warming followed by four millennia of higher temperatures and humidity, and a progressively accelerating cooling and drying for the past six millennia. These changes are driven by variations in the obliquity of the Earth’s axis. The four millennia of warmer temperatures are called the Holocene Climatic Optimum which was 1-2°C warmer than the Little Ice Age. This climatic optimum was when global glaciers reached their minimum extent. The Mid-Holocene Transition, caused by orbital variations, brought a change in climatic mode, from solar to oceanic dominated forcing. This transition displaced the climatic equator, ended the African Humid Period and increased El Niño activity.

  19. I think everyone has been looking in the wtong direction to explain the ice ages and interglacial periods. I agree with thevauthor that the energy change required to end an ice age iis difficukt to explain with orbital variations. Why cannot large scale periodic sub-oceanic magmatism be the explanation ? The earths natural temperature balance is glaciated, and every 120k years there is a massive pulse of mid ocean ridge magmatism that forces us into an interglacial, from which we decline back towards the glaciated state as the magmatism dies away.

  20. “Smoking gun” on ice ages revisited
    Anthony Watts / 6 hours ago May 23, 2017

    Thanks Anthony and all those who posted above.

    You’all left out one thing (or more) about our solar systems free fall through its galaxy.
    The interstellar background changes, it is not consistent. Above the galactic plane in galaxy’s forward direction, (inter-galactic cosmics) will be different than below the plane. And changes at the crossings would be different..
    The galaxy is a Messy place. Much progress on the subject below is currently being made.

    Cloud Tripping Through the Milky Way
    https://jila.colorado.edu/news-highlights/cloud-tripping-through-milky-way

    Our solar system is currently sprinting around the center of the Milky Way at a speed of 26 km/sec. But, we’re not just hurtling through empty space, according to Fellow Jeff Linsky and former graduate student Seth Redfield (now assistant professor of astronomy at Wesleyan University). We’re surrounded by 15 “nearby” clouds of warm gas, all within 50 light years of the Sun. Three of the nearest ones are shown in the figure. Together, the Local Interstellar Cloud (LIC) and G clouds cover 70% of the sky. Linsky says that a collision between the two massive clouds is likely responsible for the filamentary shape of the Mic cloud, which is being squished between them.

    These turbulent clouds were formed several million years ago by the winds from young, massive stars and supernova explosions in the Scorpio-Centaurus Association. Earth has already flown through at least one of these clouds — and countless others like them during our solar system’s cosmic journey around the Galaxy during the past four billion years.

    For instance, a dense enough cloud could push in on the solar wind and pollute the interplanetary medium, decreasing the Sun’s intensity and cooling the Earth. A very dense cloud could even produce an ice age on the Earth. Luckily, the G cloud isn’t dense enough to cause an ice age. It would only cool the earth a little relative to the environment we’re in now. Still, Linsky says, it’s only a matter of time until we encounter a cloud that is dense enough to radically alter our climate.


    The solar system is currently in between the LIC and G clouds, which cover about 70% of the sky around the Earth. A collision between these two clouds is producing the filamentary Mic cloud, as shown here in an all-sky map. The map is in galactic coordinates with the center of the Milky Way at the center and the north galactic pole at the top. Credit: Seth Redfield

    An oldie but goody Dr. S…

    • An oldie but goody Dr. S…
      No, no goody. The solar wind keeps the interstellar clouds at bay, unless they are extraordinarily thick. And there are none such in the solar neighborhood.

  21. This post brings back good memories. I read the Hays, Imbrie, and Shackleton paper when it came out when I was a graduate student. Quite by extraordinary coincidence I was working with them two years later on the groundbreaking projects – CLIMAP and SPECMAP – that elaborated on their original work. They were excellent scientists. Imbrie brought mathematical techniques (factor analysis) to geological research. Shackleton did much of the isotopic analysis. Hays led the collaboration.

  22. Just found this article from Dr. Linsky and Seth Redfield…
    Open access article too, HB to me..

    Visualizing the three-dimensional structure of the
    local interstellar medium and possible physical
    causes for this structure
    J.L. Linsky, Redfield, S., and Schwarz, M.,
    Journal Of Physics: Conference Series 767, (2016).
    http://iopscience.iop.org/article/10.1088/1742-6596/767/1/012016/pdf

    …Understanding the structure and properties of the LISM clouds is important, because the
    LISM serves as an interface between the heliosphere and the Galactic interstellar medium,
    providing physical insights concerning both. The Sun is located barely inside the Local
    Interstellar Cloud (LIC) (see Figure 1), and the motion of the Sun through space will take
    the heliosphere outside of the LIC and into either: (a) the adjacent G cloud, (b) an interface
    between the LIC and G clouds, or (c) the highly ionized gas that may lie between the LISM
    clouds. This transition will occur in less than 4000 years [8], perhaps far less.

    M¨uller et al. (2006) [8] calculated the location of the termination shock, heliopause,
    and bow shock for a wide range of interstellar densities, temperatures, and flow velocities that the heliosphere would see during its past and future trajectory through the inhomogeneous LISM.
    For example, the passage of the heliosphere through a cloud with a neutral hydrogen density of 11 cm−3
    rather than the present value of about 0.2 cm−3 would shrink the termination shock from about 90
    AU in the upwind direction to only 14 AU
    . ……………

      • “The answer my friend, is blowing in the wind, the answer is blowing in the wind.”

        Density is only one factor.

        Interstellar Wind Velocity and Direction(s) (more then one? arrival direction)

        Interstellar Magnetic Field strength

        Interstellar Temperature

        Interstellar Density and composition at time

        ETC….

      • There also would be other types of Interstellar Scale Type interactions.

        Visualize Interstellar Scale Size Co Rotating Interaction regions or Counter Rotating Interaction regions. CIR’s located within and at boundaries and cloud collisions regions of Interstellar clouds. Whew, sounds breezy to me.

        We encounter the small scale CIR’s on Earth from our Sun and is proportional to our Sun’s output. Galactic scale is significantly larger.

      • Density is only one factor.
        It is the only factor as the distance to the heliopause is determined by the pressure balance between the solar wind and the interstellar medium which in turn depends on the density.

    • The hypothesis that the solar system displacement through the galaxy, both through the spiral arms in its rotation around the center of the galaxy, and through the plane of the galaxy, can explain both the apparent 150 Myr ice-age cycle and the apparent 27 Myr cycle in biological diversity is quite interesting, even if far from having strong support.

      This is the essence of the 150 Myr ice-age cycle, according to Shaviv:


      “Two extraterrestrial signals have the same periodicity and phase as two independent terrestrial records. Plotted are the period and phase (of expected peak coldness) of two extraterrestrial signals (astronomical determinations of the spiral arm pattern speed and cosmic ray flux reconstruction using Iron meteorites) and two paleoclimate reconstruction (based on sedimentation and geochemical records). All four signals are consistent with each other, demonstrating the robustness of the link. If any data set is excluded, a link should still exist.”

    • The paper you link also has an interesting conclusion:

      “Using this model, we have tested whether ram pressure, magnetic fields, or EUV radiation are the most likely physical process that shapes these clouds. We find that EUV radiation from the brightest nonsolar source, ǫ CMa, is the most likely source for shaping the LIC and four other LISM clouds”

      Differences in UV radiation have also been proposed as causative agents mediating the solar variability effect on climate.

      • …”””For example, the passage of the heliosphere through a cloud with a neutral hydrogen density of 11 cm−3
        rather than the present value of about 0.2 cm−3 would shrink the termination shock from about 90
        AU in the upwind direction to only 14 AU”””…

        14 AU would put the solar systems, “”termination shock, heliopause, and bow shock,”” between the Jupiter/Saturn system and the Neptune/Uranus system. What a mess that would/did create, sounds like the perfect, hail and brimstone scenario, mentioned by antiquities.

      • Except for two things:
        There are no such dense clouds in the solar neighborhood and because the solar wind is supersonic the Earth would not know it.

  23. It seems to me I keep seeing attempts to simplify causes for climate variations. This would appear to be a futile task given the volatile and chaotic nature of climate, atmosphere and oceans.

    As far as I can see from the work of much smarter and more dedicated researchers than I, there are many factors involved in changes.

    Some notes: (feel free to comment on any of them or tell my my arse has replaced my mouth… :D

    1. The Sun orbits the solar system barycenter which can be outside the solar surface when the gas giants congregate on one side.

    2. The Earth of all the planets, specifically does NOT orbit either the Sun or the barycenter; instead the CoG of the earth Moon system is what orbits the solar system barycenter.
    This means even on a small scale there are variations in distance to the Sun and thus incoming radiation/solar wind, especially when the Moon gets closer to the Sun that Earth.

    3. Svensmark et al’s CLOUD effects magnify the changes in incoming energy by changing the lower cloud cover (from GCR’s) and thus the albedo. Thus a minor alteration in solar TSI can multiply the apparent effect for the planet.

    4. The Earth is NOT a flat disk as used to simplify calcs for albedo etc. This causes AGW types no end of trouble as they claim ice at the poles has significant effects on albedo in relation to solar input, but seems to me, as soon as you use a globe instead of a flat disk, the albedo from the poles becomes close to irrelevant. This is because the incoming energy is at an angle-to-surface of 70º or more. i.e. most of it is going to ‘bounce’ from the surface rather than reflect directly back out..
    You can sort of see this effect with false dawn at lower latitudes – the light from the approaching Sun reflects into areas before the Sun actually approaches the horizon as the true dawn.

    5. Herndon’s georeactor seems to have come well beyond the ‘outlandish’ idea it was greeted as and is moving into mainstream. Thus we have an ongoing and renewing source of internal heat for Earth rather than a fading ’ember’ of a core steadily losing heat over the millennia.

    9. There appears to be movement of heat regions internal to Earth that can bring more heat closer or further to various regions under the crust.

    10. There are gravity ‘pulses’ that perturb the Earth as the larger planets (or nearer ones) approach and recede – these must have an effect and there are quite a few people linking earthquakes/vulcanism events to astro causes.

    11. There is a magnetic ‘reconnection’ event occurring between Earth and Sun at what seems a weirdly significant timing – every 8 and a bit minutes. Given the Earth to Sun light time, this seems strangely synced – strange because it SHOULD be 16 and a bit to account for a dual trip effect. Just what this event does I don’t know but it is a strong indicator (IMO) that we cannot exclude either electrical or magnetic additions to the climate causes.

    12. The solar system is awash in electrical energy from the solar plasma. So we live IN an electrical field so solar changes will have significant effects right throughout the system in an electrical and magnetic sense.

    13. There are the longer term astronomical cycles such as Precession, Obliquity and Eccentricity. I have yet to see a refutation of the idea that Precession is a whole-of-system effect rather than a simple Luni/solar effect causing the Earth to wobble. It seems to me the reliability of certain meteor showers and the precision of Venus Transits argues the Precession cannot be only an Earth phenomenon.
    If this is so, then the calculated effects of Milankovitch cycles are going to have a built in error.

    With all of these and probably lots I haven’t thought of, it seems premature to say the least to be arguing Milankovitch and other cycles as if they are solely significant.

    I guess it comes back to what I keep telling the true believers of the Church of AGW – you cannot model chaotic systems on binary computers. And just as they fail constantly in their prophesies from computer models, any attempt to define what is really causing climate change will have the same issues.

    • MarkMcD May 23, 2017 at 9:12 pm
      …rather than a simple Luni/solar effect causing the Earth to wobble…

      Just a comment on your wobble comment.

      As Earth rotates there is a compressional effect at the N. Pole and an extensional effect at the S. Pole.

      Because the mass at the S. Pole is greater, land, ice, water, and the Earth is ‘somewhat’ pear shaped, this contributes to Earth wobble.

  24. The rotary lie detector disproves all of the above comments and theories. About 1 million years BP there was no ice anywhere on the planet. How to we know that? Vostok 3 stops about 850,000 yrs BP while still in solid ice yet Greenland is known to have a temperate climate (Ancient Biomolecules from Deep Ice Cores Reveal a Forested Southern Greenland Science, Eske Willerslev et al., 2007 July 6; 317(5834): 111–114. doi:10.1126/science.1141758). Vostok, by extrapolation, has about 150,000 years BP of time still to drill to reach bottom. Now that would be interesting in the core that could be recovered near the ice/basement interface. It would show spores of the day such as in Dye 3. Since ice formed in both locations there has been more or less constant build up of ice. In both locations, there has been no evidence of interference in the build up by any of the oscillations covered in the “Smoking Gun” article. There has of course been temporary build up of glaciers etc and that is where the article has some substance. These are quite separate events to what has taken place around Dye 3 and around Vostok 3. Perhaps the readers could consider the expanding and contracting earth theory to further explain these oscillations remembering that sea level rises and falls are of themselves anything but uniform events.

    • “About 1 million years BP there was no ice anywhere on the planet.” Now IRFM, would you be willing to take a rotary lie detector test about that statement you just made?

      • Over to you – and where was the ice of that age and the core evidence to support your claim. I just happen to be part of a profession which drills on good imagination (aka modelling) and has a success rate on greenfield projects of about 1:100. Call me a positive sceptic!

    • >>About 1 million years BP there was no ice anywhere on the planet.

      Complete nonsense.

      Prior to the MPT a million years ago, there were many ice ages, but they were smaller.
      And Antarctica has been covered in ice for millions of years. It is just that the maximum lifetime of the deep ice is about a million years – anything older than that is crushed, pressure-melted, and flows out to the sea.

      R

  25. hallelujah – at last thank you Anthony – I have to admit I was extremely upset when a common contributor to your blog – rubbished Milutin Milanković theory – he is my favourite climate scientist of the previous century. John Christy is my fav for this century.
    Milutin Milanković took about 30 years to do the maths (astronomical calculations) before the advent of computers for such purposes and his theory has been backed up not only by ice core day but by deep sea sediment data – a few decades ago and since then – more current evidence strongly suggests obliquity is the biggest player of the orbital cycles and guess what folks?? obliquity is on the decrease at the moment – many science text books have it still at 23. 5 degrees – it is now without question at 23.4 degrees and decreasing – which means the seasons will become less severe and all research is suggesting – another ice age is coming but not for many thousands of years yet!! so I suggest enjoy the warming because there will be hell on Earth as land that is used at present to grow crops becomes covered in up to 1.5 and some kilometres thick of ice as was the case (lots of sci evidence for this) during the last ice age!!

  26. The persistence and the magnitude of the above-described changes cannot logically be ascribed to mankind’s combustion of fossil fuels.

    Not aware of anyone claiming otherwise.

    Furthermore, in the terminations of the glacial eras, rising temperature preceded rises of CO2 by several centuries, absolving CO2 as the cause of the preceding temperature rise.

    Again, this is not disputed by the climate science community. CO2 didn’t cause the termination of the glacial maximums. CO2 only became important as a warm forcing on climate once thawing and ocean out-gassing allowed sufficient quantities of it to re-enter the atmosphere. The initial cause of the thawing is generally believed to be the very orbital cycles discussed in the article.

  27. My report at:
    https://wattsupwiththat.com/2016/12/16/climate-change-debate-latest-results/
    described the application of advanced statistical analysis to the relationship between the monthly atmospheric CO2 concentration from the Mauna Loa Observatory and UAH satellite lower troposphere temperature for the Tropics Land zone. There was a positive correlation between the temperature and the annual rate of change of CO2 concentration with very high statistical significance. However, for the temperature relative to the CO2 concentration time series, there was a minute correlation coefficient with significant probability that the coefficient was zero.

    The result was supported by the same analysis applied to the atmospheric CO2 data from Macquarie Island in the Southern Ocean. To these results I can now add the analysis the CO2 concentration time series for the Mount Waliguan Observatory on the Tibetan Plateau. Relative to the Northern Extension satellite temperature zone, the Land component gave a correlation coefficient of -0.12 with a 3% probability that the coefficient was zero and, for the Ocean component, the coefficient was -0.13 with a 2.1% probability that the coefficient was zero. Once again this result is the complete opposite to the IPCC claim. For the temperature relative to the annual rate of change of CO2 concentration, the maximum correlation of 0.14 arose with respect to the Tropics Land temperature zone with 1.3% probability of a zero coefficient for a two month lag of the CO2 annual rate of change relative to the annual average Tropics Land temperature.

    Additional confirmation has been found in the auto-regression function for the Tropics Land and Ocean satellite lower troposphere temperature series and the same function for the Mauna Loa annual rate of change of CO2. All have identical auto-correlation functions showing that they have arisen from the same cause. The first maximum in the periodicities was at 45 months which is the period for the El Nino maxima. Another was at 135 months corresponding to the Sun cycle driven by the 11.86 year orbital period for Jupiter. The source of other periodicities, for example 90, 180 and 270 months, remain to be discovered.

    In conclusion, increased atmospheric CO2 concentration does not cause an increase in temperature. It is the level of temperature that controls the rate of change of CO2 concentration. As the Equatorial zone has the highest average temperature, it must produce a major portion of the atmospheric CO2. That concentration will continue to increase until the temperature reaches a critical level where the rate falls to zero. This could be zero degrees Centigrade at which point water freezes and is no longer available to life forms. That explains the 700 year lag between the temperature maximum preceding an ice age and the consequent maximum in the CO2 concentration. The auto- correlation function indicates that it is the Sun’s radiance, modulated by the tidal effect of the rotating planets, that drives the change in the Earth’s atmospheric temperature.

    • ” In conclusion, increased atmospheric CO2 concentration does not cause an increase in temperature. It is the level of temperature that controls the rate of change of CO2 concentration. …. ”

      I fully agree and support that statement.

      • Thank you rishrac. At least I now know that there is one other person that agrees with my findings.
        Of equal importance is my statement that the Tropics temperature and the rate of change of CO2 concentration have the same auto-correlation function. That means that neither parameter responds to human activity as human activity has not altered with the periodicities revealed by the auto-correlation function, at least, not to my knowledge.
        It is also pertinent to the comment by Frederick Michiels May 24, 2017 at 5:35 pm in that the auto-correlation function has revealed the periodicities that he suggests combine together to bring about ice ages.

      • If you look back at some of my earlier posts concerning topics of co2, I have clearly stated that co2 follows temperature. The reason is that, at least up until March 2015, ( and it was in response to a poster that said something about the rate of increase after 1998 ) I downloaded the co2 ppm per year and the the temperature change per year from NOAA right into a spread sheet. I was really surprised that even with this very simplistic method, nowhere near the level which you have done, the co2 levels per year varied with temperature. NOAA has been hard at work revising those numbers since. Also, one of the other things I also discovered was that co2 levels from peak ppm to peak ppm follow solar activity. It also follows cosmic ray activity as well. It is very clear from the record that it does so. there was a blip in cosmic ray activity in 1962/1963 and co2 ppm per year followed. Which one followed which, temperature or cosmic ray affecting temperature or something else, or a combination remains unknown. Since I let this be known, NOAA has adjusted the co2 ppm per year, 2005 is a good example of refuting findings by changing the data. 2005 the ppm for that year was 2.52 in 2015, the last time I looked it was 3.10 for 2005 and the temperature data set had changed as well.
        There has been some excellent work done on the periodicity. I gave someone here a +1 on saying three when combination are either constructive or destructive in bring about an ice age. There is also evidence that supports close encounters with comets ( Malaga bay) for rapid cooling. They’ve also alluded to a property that I’ve seen physically in that ( and I didn’t know that it was written in ancient Greece) that the earth’s way of rotating around the sun changes. One pole faces in and the other out, so that there are 2 springs and 2 winters in one hemisphere, and 2 summers and 2 falls in the other.

        Thank you for publishing your research. It really helps an argument when researchers determine the same thing by 2 different methods and independently.

  28. If sea level is 120m lower and we have a landbridge from Australia to Asia and between America and Russia doesn’t that change ocean circulation? Tropical oceans oceans must get warmer also because of increasing atmospheric pressure.

  29. This is a slightly off topic comment, but this seems the proper forum. In looking at the contribution of volcanos to CO2 it seems that the contribution is in the range of 0.6 billion metric tons of CO2 per year. This is in the range of 2% of the current human contribution. A significant and uncertain portion of that comes from undersea volcanos.

    The thought is how does this contribution function during the ice ages. In the cold ocean water is the CO2 and methane (as methane hydrate) retained (accumulated) in the ocean (deep ocean) until some level of warming occurs. I could then be released as a surge (over hundreds of years) when the saturation pressure equalizes with the increases ocean temperature.

    A way to check would be to calculate the quantity of CO2 added to the atmosphere during the end of ice age warming (presumably from the oceans); and see if this sort of balances with the contribution of undersea volcanos over the course of a couple 100,000 years. I would think that significant methane volumes would also be released.

  30. Dr. Isvalgaard, Good day sir and thank you for all that you do. Regarding this (orbital influence on the amount of energy Earth received from the Sun as the Sun slowly danced around the center of mass of the entire solar system. No, that is not the reason), you said the following, above. “Planetary perturbations [mainly Jupiter’s] alter the orbital parameters of the Earth leading to different regions receiving different amounts of TSI. This has been discussed ad nauseam here on WUWT. Go look and you’ll find.” I once read a quote that said “the problem with the world is that ignorance is cock sure and intelligence is full of doubt.” While I respect your research and what you have brought to the table of knowledge on the subject, I can’t help but ask if you are closed to the idea that perhaps both theories have a part in Earth’s Climate?

    • if you are closed to the idea that perhaps both theories have a part in Earth’s Climate?
      The first one will not work as the sun [like the earth] is in free fall. You don’t feel you are moving, so neither does the sun. The second one has observational support although there is debate about the details.

  31. On Tue, May 23, 2017 at 1:29 PM Watts Up With That? wrote:

    > Anthony Watts posted: “Paleoclimatologists Rock -Two million years of > radical climate change is significant. David C. Greene writes: “The smoking > gun of the ice ages” is the title of an article in the Dec. 9, 2016 issue > of Science, the journal of the American Association” >

  32. Milankovitch Theory is a Zombie Theory

    Come on man. I am bored to tears talking endlessly about zombie theories. We likely need a thread per Zombie theory to explain why the Zombie theory is a Zombie theory which can be referred to.

    The smoking gun, is solar cycle changes cause the cyclic changes to the earth (geomagnetic field changes that correlate with climate change, volcanic changes that correlate with solar cycle changes, cyclic abrupt climate changes, and sea level).

    The problem is not if the sun causes what is observed but how the sun causes what is observed.

    P.S. There are more than 200 astronomical anomalies and paradoxes that are directly connected to how the sun is causing the weird cycle changes on the earth.

    First Milankovitch’s Zombie Theory

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

    Milankovitch cycle Problems (How many ‘problems’ are required to stop a Zombie theory?)

    1) 100,000 year problem

    The 100,000-year problem is that the eccentricity variations have a significantly smaller impact on solar forcing than precession or obliquity – according to theory- and hence might be expected to produce the weakest effects. However, the greatest observed response in regard to the ice ages is at the 100,000-year timescale, even though the theoretical forcing is smaller at this scale.[10] During the last 1 million years, the strongest climate signal is the 100,000-year cycle. In addition, despite the relatively great 100,000-year cycle, some have argued that the length of the climate record is insufficient to establish a statistically significant relationship between climate and eccentricity variations.

    2) Southern Hemisphere cools cyclically at the same time as the Northern Hemisphere

    https://www.sciencedaily.com/releases/2004/03/040319071426.htm

    Glacial records depict ice age climate in synch worldwide
    “During the last two times in Earth’s history when glaciation occurred in North America, the Andes also had major glacial periods,” says Kaplan.

    The results address a major debate in the scientific community, according to Singer and Kaplan, because they seem to undermine a widely held idea that global redistribution of heat through the oceans is the primary mechanism that drove major climate shifts of the past.

    “Because the Earth is oriented in space in such a way that the hemispheres are out of phase in terms of the amount of solar radiation they receive, it is surprising to find that the climate in the Southern Hemisphere cooled off repeatedly during a period when it received its largest dose of solar radiation,” says Singer. “Moreover, this rapid synchronization of atmospheric temperature between the polar hemispheres appears to have occurred during both of the last major ice ages that gripped the Earth.”

    3) Stage 5 problem (Causality Problem)

    The stage 5 problem refers to the timing of the penultimate interglacial (in marine isotopic stage 5) that appears to have begun ten thousand years in advance of the solar forcing hypothesized to have caused it (also known as the causality problem) effect precedes cause).

    4) Effect exceeds cause

    The effects of these variations are primarily believed to be due to variations in the intensity of solar radiation upon various parts of the globe. Observations show climate behavior is much more intense than the calculated variations.

    5) The unsplit peak problem

    The unsplit peak problem refers to the fact that eccentricity has cleanly resolved variations at both the 95 and 125 ka periods. A sufficiently long, well-dated record of climate change should be able to resolve both frequencies.[15] However, some researchers[who?] interpret climate records of the last million years as showing only a single spectral peak at 100 ka periodicity.

    6) The transition problem

    The transition problem refers to the switch in the frequency of climate variations 1 million years ago. From 1–3 million years, climate had a dominant mode matching the 41 ka cycle in obliquity. After 1 million years ago, this switched to a 100 ka variation matching eccentricity, for which no reason has been established

    http://en.wikipedia.org/wiki/Milankovitch_cycles#/media/File:Five_Myr_Climate_Change.svg

    7) Identifying dominant factor

    Milankovitch believed that decreased summer insolation in northern high latitudes was the dominant factor leading to glaciation, which led him to (incorrectly) deduce an approximate 41 ka period for ice ages.[16] Subsequent research[17][18][19] has shown that ice age cycles of the Quaternary glaciation over the last million years have been at a 100,000-year period, leading to identification of the 100 ka eccentricity cycle as more important, although the exact mechanism remains obscure.

    The Earth’s orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The shape of the Earth’s orbit varies in time between nearly circular (low eccentricity of 0.000055) and mildly elliptical (high eccentricity of 0.0679)[3] with the mean eccentricity of 0.0019 as geometric or logarithmic mean and 0.034 as arithmetic mean, the latter useless. The major component of these variations occurs on a period of 413,000 years (eccentricity variation of ±0.012). A number of other terms vary between components 95,000 and 125,000 years (with a beat period 400,000 years), and loosely combine into a 100,000-year cycle (variation of −0.03 to +0.02). The present eccentricity is 0.017 and decreasing.

    8) The Younger Dryas Problem
    The planet when from interglacial warm to glacial cold at the time of the Younger Dryas abrupt cooling event 11,900 years BP, at a time when summer solar insolation at 65N was maximum (the YD is another observation that supports the assertion that Milankovich’s theory is pure Zombie) 70% of the cooling occurring in less than a decade.

    The Younger Dryas abrupt cooling event lasted for 1200 years. An impact or a volcanic eruption will cool the planet for a few years, not 1200 years.

    9) Periodicity Paradox. The small, large, and super large climate events all have the same periodicity (1400 years with a beat frequency of plus or minus 400 years) which points to the same cause.

    Another hint to the cause is there is solar cycle change evidence in the proxy which correlate with each and every climate change event.

    The periodicity paradox rules out internal earth mechanisms which are ‘chaotic’ (William: Volcanic eruptions for example or changes to ocean currents) as the cause of massive cycle climate changes.

    http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml

    Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
    Many paleoclimatic data reveal a approx. 1,500 year cyclicity of unknown origin. A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles. This highly precise clock points to an origin outside the Earth system (William: Solar magnetic cycle changes cause the warming and cooling); oscillatory modes within the Earth system can be expected to be far more irregular in period.

    10) And so on.

    This is what we are trying to explain.

    Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper. William: The Greenland Ice data shows that have been 9 warming and cooling periods in the last 11,000 years. There was abrupt cooling 11,900 years ago (Younger Dryas abrupt cooling period when the planet went from interglacial warm to glacial cold with 75% of the cooling occurring in less than a decade and there was abrupt cooling 8200 years ago during the 8200 BP climate ‘event’).


    • Another hint to the cause is there is solar cycle change
      There is no evidence [or physical explanation] for your “solar cycle change”. And the influence of solar activity is so minute anyway that it barely rises over the noise.

      • the whole issue is it’s not the milankovich cycle, it’s not the sun cycle, it’s not obliquity,…. each on their own are not able to drive enough to explain the ice age

        however when you take all these drivers together as a timed harmonic event (just as how you look at a sound that’s just a resulting wave formed by a combination of sinus waves of varying phases amplitudes, intensities and frequencies) then it becomes interesting….

        to me ice age/interglacials always resembled a lot like this basic “sawtooth sound”

        Of course sound is a static set of variables that repeat with very static known “drivers” while climate also has a noise and dynamic aspect (no sawtooth wave of the interglagial/glacial cycle is the same), however something is producing a 100Kyr main “driver wave”. unlike with sound in climate this can be a combination of climate drivers that “join and then diverge to join then again together.

        what does sound and climate have then in common? Well just add a strong random noise to that sound drawing and it will become pretty similar to the temp graph. add a random slight “pitch change” and you even get near to the iregularity of the temp graph.

        so add it all up: Milankovich cycles, solar cycles, obliquity, precession,… (do we even know them all? i’m sure we don’t) and add the noise of volcanic eruptions, iregularities in these cycles,……

        See this as looking at it from a totally different angle, but something is driving this and the “shape” of the wave is referring to what order and in which way these drivers do amplify/converge with each other and subtract/diverge with each other to create the ice age cycle with it’s Oescher Dansgaerd events etc….

        to me it’s not “just the sun, or just the Milankovich cycle or just (fill in what applies) but a combination of how they “work together as a dynamic system”

        imho we even don’t know how these work we just start to scratch the surface of it but thats why i find these discussions here so fascinating….

      • If you scratch the surface enough, you ruin the sculpture.
        Sharp cycles have sharp drivers and restoring forces. Those seem to be missing in the climate.

    • >>100,000 year problem.

      There is no 100,000 year problem, because thre is NO 100,000 year cycle. The recent cycle is 90 ky and 115 ky, and it is comprised of multiple precessionary cycles.

      .

      >>Southern Hemisphere cools cyclically at the
      >>same time as the Northern Hemisphere.

      Because the climate is controlled by albedo, not CO2. And the large land masses and therefore ice sheets (and therefore most of the albedo) are all in the northern hemisphere.

      .

      >>Stage 5 problem (Causality Problem).

      Not sure what you mean. The Eemian appears to be coincident with a NH precessionary increase.

      .

      >>Effect exceeds cause.

      Because there are feedback effects. The feedback-forcing provided by albedo is in the order of 200 w/m2, when measured regionally, which is much greater than orbital forcing on its own. So albedo trumps Milankovitch, and it trumps CO2.

      .

      >>The unsplit peak problem.

      Because albedo trumps orbital insolation variation. The albedo feedback effect is so intense that some precessional (and obliquity) peaks have no effect whatsoever (all the increased insolation is reflected back to space). Orbital forcing (Milankovitch) can only have an effect when the ice sheets are impregnated with dust, and have a lower albedo.

      .

      >> The transition problem.

      The MPT was caused by the steady cooling of the climate passing a threshold, and allowing albedo effects to become dominant. Thus obliquity was superceded by precession as a modulating factor. The reason for the continuous cooling of the climate over the last 50 odd million years is not entirely understood. Possibilities include the slow cooling of the oceans, or the rise of the Himalaya (and its albedo) reducing total absorbed insolation.

      .

      >>Identifying dominant factor.

      The dominant orbiting factor was obliquity, but is now precession (except when eccentricity is low, and then obliquity becomes dominant again).

      .

      >The Younger Dryas Problem

      The YD may well have been due a meteor impact, and so is anomalous. Please see this short article:

      The YD, the Carolina Bays, and the Destruction of North America.
      https://www.academia.edu/20051868/The_Carolina_Bays_and_the_destruction_of_North_America

      .

      See my paper on the modulation of ice ages via albedo and dust, which explains everything:

      Modulation of ice ages via precession and dust-albedo feedbacks.
      http://www.sciencedirect.com/science/article/pii/S1674987116300305

      Ralph

    • You are asking the right questions IMHumbleO. The unintended red herring is obliquity – that it is restricted to ~22-24deg. NO. Its mean floats. Ask why both poles change temps at the same time, but opposite to equator. At ~2345bce there is an abrupt increase at Gisp2/Vostok but a drop at Kilimanjaro (remember the fast frozen weeds at Quelccaya). There are other issues also.

  33. Why are we still asking the question “how can such a weak forcing as obliquity be responsible for pacing the interglacials”, over the last million years following the mid Pleistocene revolution (MPR)? The answer is obvious from the above figure which shows in parallel all the Milankovich cycles. Two important Milankovich drivers, both much stronger than eccentricity per se as climate forcers – the summer insolation at 65degN and precession, both directly correlate with eccentricity in their amplitude modulation. By this I mean the way that their respective wavetrains get fatter and thinner, i.e. alternate between smaller and larger amplitude. High amplitude eccentricity peaks coincide with high amplitude oscillations of both the above mentioned cycles, and ditto for the low amplitude eccentricity peaks.

    Now as Javier made clear in his recent post at Judith Curry, especially in figure 35:

    https://judithcurry.com/2017/04/30/nature-unbound-iii-holocene-climate-variability-part-a/

    the proximal driver of the timing of interglacials, but with a 6,500 year delay. In figure 35 of Javier’s article, there is a temperature peak at every single one of the (6,500 year lagged) obliquity peaks. No exceptions. However, of course, not all those peaks are interglacials.

    Only the obliquity peaks which come close to eccentricity peaks result in a full interglacial.

    And no – O ye of the 7-second-goldfish-memory – before you start replying that eccentricity can’t be strong enough to force the interglacial, remember what I just pointed out: every eccentricity peak coincides with peak amplitude in both 65N summer insolation and precession. (Those two are of course directly related to each other, I get that).

    It isis when a 6,500-year-lagged obliquity peak comes closest to the combined eccentricity / 65N summer insolation / precession amplitude peak, that you get an interglacial.

    What would you expect to happen when the lagged obliquity peak falls halfway between the amplitude peaks of eccentricity / 65N insolation / precession? A double-headed interglacial. And that is exactly what happens. At 200,000 and 600,000 years ago, such double-headed interglacials occured.

    The above relationship completely and sufficiently explains when interglacials occur. It also helps understand why the MPR happened, when the pacing of interglacials changed from 41,000 years – i.e. directly following lagged obliquity, to an apparent, approximate 100,000 year pacing. Prior to the MPR, lagged obliquity alone was strong enough to initiate an interglacial every time. However as the Pleistocene glaciation deepens, there appears to be a declining sensitivity of the climate’s glacial-interglacial system to Milankovich forcing (which itself remains essentially unchanging). Thus after the MPR, an obliquity peak (lagged) alone was no longer sufficient to initiate an interglacial. It needed the added impetus of amplitude peaks of 65N insolation and precession – both of which are in step with eccentricity.

    It is also obvious why 65N insolation and precession amplitude peaks should coincide with eccentricity peaks, since eccentricity directly affects both these cycles. High eccentricity will amplify the insolation effect of precession as the earth is brought closer to the sun at perihelion.

    Finally, why the 6,500 year lag in the dominant interglacial forcing of obliquity which Javier showed incontrovertibly? The reason for this is important. It takes 6,500 (not 800) years of increased solar heat input to the oceans before the oceans themselves, by their dynamics of circulation and heat transport, bring about climate warming and interglacial inception.

    Climate change comes from the ocean, and follows the ocean’s rhythm. It’s a slow one, and can’t be rushed.

    • Another correction in the opening sentence:

      “Why are we still asking the question “how can such a weak forcing as obliquity eccentricity be responsible for pacing the interglacials”

    • What has been overlooked in all of the discussion is that we have an example of what has caused glaciation and recovery in the past, and that is the Little Ice Age. This began with a VEI7 eruption in 1258, followed by an “unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60Tg” (Miller, et al, 2012).

      This quantity of sulfate aerosols would have caused global cooling for more than 5 years each (based upon the cooling resulting from the 1815 VEI7 Mount Tambora eruption, with about 50Tg of sulfate emissions). Other eruptions also occurred during the LIA, maintaining the cooling through “sea-ice/ocean feedbacks”, and glaciers advanced.

      With demonstrated cooling from volcanic sulfate aerosols, periods of extensive volcanism in the past would NECESSARILY have had the same effect, and, when extensive enough, would have triggered the various Ice Ages, regardless of any solar cycles.

      Cessation of eruptive periods would explain the observed rapid warming at the end of an Ice Age, with the suddenly less polluted air allowing sunshine to strike the earth’s surface with greater intensity.

      William Astley, above, states that “an impact or a volcanic eruption would cool the planet for a few years, not 1200 years”, but periods of multiple eruptions could easily do so. Volcanism that formed the Deccan and Siberian traps, for example, reportedly lasted for thousands of years.

    • FWIW here is the corrected version:

      Why are we still asking the question “how can such a weak forcing as eccentricity be responsible for pacing the interglacials”, over the last million years following the mid Pleistocene revolution (MPR)? The answer is obvious from the above figure which shows in parallel all the Milankovich cycles. Two important Milankovich drivers, both much stronger than eccentricity per se as climate forcers – the summer insolation at 65degN and precession, both directly correlate with eccentricity in their amplitude modulation. By this I mean the way that their respective wavetrains get fatter and thinner, i.e. alternate between smaller and larger amplitude. High amplitude eccentricity peaks coincide with high amplitude oscillations of both the above mentioned cycles, and ditto for the low amplitude eccentricity peaks.

      Now as Javier made clear in his recent post at Judith Curry, especially in figure 35:

      https://judithcurry.com/2017/04/30/nature-unbound-iii-holocene-climate-variability-part-a/

      the proximal driver of the timing of interglacials, but with a 6,500 year delay, is obliquity. In figure 35 of Javier’s article, there is a high temperature peak at every single one of the (6,500 year lagged) obliquity peaks. No exceptions. However, of course, not all those peaks are interglacials.

      Only the obliquity peaks which come close to eccentricity peaks result in a full interglacial.

      And no – O ye of the 7-second-goldfish-memory – before you start replying that eccentricity can’t be strong enough to force the interglacial, remember what I just pointed out: every eccentricity peak coincides with peak amplitude in both 65N summer insolation and precession. (Those two are of course directly related to each other, I get that).

      It is when a 6,500-year-lagged obliquity peak comes closest to a combined eccentricity / 65N summer insolation / precession amplitude peak that you get an interglacial. Every time.

      What would you expect to happen when an amplitude peak of eccentricity / 65N insolation / precession falls halfway between two obliquity peaks? A double-headed interglacial. And that is exactly what happens. At 200,000 and 600,000 years ago, such double-headed interglacials occured.

      The above relationship completely and sufficiently explains when interglacials occur. It also helps understand why the MPR happened, when the pacing of interglacials changed from 41,000 years – i.e. directly following lagged obliquity, to an apparent, approximate 100,000 year pacing. Prior to the MPR, lagged obliquity alone was strong enough to initiate an interglacial every time, regardless of where the other Milankovich cycles were at. However as the Pleistocene glaciation deepens, there appears to be a declining sensitivity of the climate’s glacial-interglacial system to Milankovich forcing (which itself remains essentially unchanging). Thus after the MPR, an obliquity peak (lagged) alone was no longer sufficient to initiate an interglacial. It needed the added impetus of amplitude peaks of 65N insolation and precession – both of which are in step with eccentricity.

      It is also obvious why 65N insolation and precession amplitude peaks should coincide with eccentricity peaks, since eccentricity directly affects both these cycles. High eccentricity will amplify the insolation effect of precession as the earth is brought closer to the sun at perihelion.

      Finally, why the 6,500 year lag in the dominant interglacial forcing of obliquity which Javier showed incontrovertibly? The reason for this is important. It takes 6,500 (not 800) years of increased solar heat input to the oceans before the oceans themselves, by their dynamics of circulation and heat transport, bring about climate warming and interglacial inception.

      Climate change comes from the ocean, and follows the ocean’s rhythm. It’s a slow one, and can’t be rushed.

  34. Slightly off-topic but I have a question for the physicists here

    Please go to : http://www.remss.com/measurements/upper-air-temperature

    Scroll down to temperature records since 1980 and observe charts showing:

    Lower troposphere: 0.135 K/decade
    Lower Tropospheric Stratosphere: – 0.258 K/decade

    What is going on guys?

    I am a Seeker (of truth) , not a skeptic

    Regards

    M

  35. It seems to me that precession, obliquity and eccentricity will have an affect upon ocean currents, wind patterns, El Niño, la Nino, and jet stream patterns. Would this not also affect weather and thus, to some degree, climate?

  36. Figure 10 in Trenberth et al 2011jcli24 is typical of the so called atmospheric heat or energy balances which show 342 +/- W/m^2 entering perpendicular to the entire surface of the ToA, Top of Atmosphere. This models the earth as a ball suspended in warm fluid evenly heated in all directions. There is no consideration of day or night, aphelion or perihelion, tropospheric thickness, or the oblique incidence on a spherical surface. This value begins with the TSI, total solar irradiance, delivered by the expanding solar photosphere (3.847 E26 W) to the spherical surface of an average orbital distance of 1.496 E8 km yielding a value of 1,368 +/- W/m^2. A sphere of radius r has four times the area of a disc of radius r so 1,368 / 4 = 342 W/m^2.

    As pointed out above the earth’s orbit is not circular, but elliptical and the difference in TSI between perihelion, closest and 1,423 +/- W/m^2, and aphelion, farthest and 1,323 +/- W/m^2, a total annual fluctuation of 90 W/m^2. But there is a second consideration, the 23.5 degree tilt of the earth’s vertical axis which drives the seasons. When the tilt is away from the sun it is winter in the northern hemisphere, summer in the southern hemisphere. When the tilt is towards the sun it is summer in the NH and winter in the SH. At this point in the Malinkovitch cycle the NH winter occurs near perihelion. So the coldness of the away tilt is balanced by the hotness of the closer orbit. This will change.

    When the sun is directly overhead TSI at ToA delivers its full amount, but because of the oblique angle at other locations the TSI on a horizontal surface is reduced. Those who design and install solar panels are well aware of this.

    At 40° N latitude and winter solstice the sun is 26.5° above the horizon and the TSI on a ToA horizontal surface is 630.5 +/- W/m^2.

    At 40° N latitude and summer solstice the sun is 73.5° above the horizon the TSI on a ToA horizontal surface is 1,268.5 +/- W/m^2.

    The total TSI variation on a ToA horizontal surface from winter solstice to summer solstice is 638 +/- W/m^2.

    A TSI fluctuation of 638 W/m^2 and the only difference is summer and winter which the earth and mankind have survived every year for millions of years. The 2 W/m^2 and even the RCP 8.5 W/m^2 of IPCC models don’t seem all that significant.

    And the notion that this 2.0 or 8.5 W/m^2 is disturbing some marvelous Zen balance maintained for millennia is religious dogma, not science.

  37. The problem with the straight Milankovitch theory, is the missing ice ages over the last million years.

    The periodicity of recent ice ages varies from 90 kyr to 115 kyr, which means that whether you champion obliquity or precession there are missing ice ages. No theory of ice age modulation can be complete, if those missing ice ages are not accounted for.

    I accounted for this strange periodicity via albedo and dust. It is a theory that has stood up to questioning and has not been falsified.

    Modulation of ice ages via precession and dust-albedo feedbacks.
    http://www.sciencedirect.com/science/article/pii/S1674987116300305

    .

    Abstract

    We present here a simple and novel proposal for the modulation and rhythm of ice-ages and interglacials during the late Pleistocene. While the standard Milankovitch-precession theory fails to explain the long intervals between interglacials, these can be accounted for by a novel forcing and feedback system involving CO2, dust and albedo. During the glacial period, the high albedo of the northern ice sheets drives down global temperatures and CO2 concentrations, despite subsequent precessional forcing maxima. Over the following millennia more CO2 is sequestered in the oceans and atmospheric concentrations eventually reach a critical minima of about 200 ppm, which combined with arid conditions, causes a die-back of temperate and boreal forests and grasslands, especially at high altitude. The ensuing soil erosion generates dust storms, resulting in increased dust deposition and lower albedo on the northern ice sheets. As northern hemisphere insolation increases during the next Milankovitch cycle, the dust-laden ice-sheets absorb considerably more insolation and undergo rapid melting, which forces the climate into an interglacial period. The proposed mechanism is simple, robust, and comprehensive in its scope, and its key elements are well supported by empirical evidence.

    1. Introduction

    Since the discovery of ice-age cycles almost two centuries ago, a large amount of geological evidence has been assembled from a variety of sources, and many different hypotheses have been advanced to account for their approximate 100 kyr periodicity and asymmetric, saw-tooth temperature response. Improved calculations of Milankovitch insolation cycles and greater precision of Antarctic ice-core records demonstrate that each major deglaciation coincides with maximum summer insolation in the northern hemisphere. And yet many of the other insolation maxima only trigger minor warming events, and so interglacials only occur after four or five insolation cycles. No generally accepted explanation exists for this peculiar intermittent climate response, and any comprehensive explanation for ice-age modulation and periodicity has to be able to explain this anomaly.

    The answer to this conundrum can be found in a novel reanalysis of the effects of decreasing atmospheric CO2 concentrations during an ice-age. Ice age CO2 reductions coincide with an increase in ice sheet extent and therefore an increase in global albedo, and this should result in further cooling of the climate. But what actually happens is that when CO2 reaches a minimum and albedo reaches a maximum, the world rapidly warms into an interglacial. A similar effect can be seen at the peak of an interglacial, where high CO2 and low albedo results in cooling. This counterintuitive response of the climate system also remains unexplained, and so a hitherto unaccounted for agent must exist that is strong enough to counter and reverse the classical feedback mechanisms.

    The answer to both of these conundrums lies in glacial dust, which was deposited upon the ice sheets towards the end of each glacial maximum. Previous research has considered two effects of this aeolian dust on the glacial climate: the increased albedo of atmospheric dust cooling the climate, and the mineral fertilization of marine life reducing atmospheric CO2. But both of these effects would result in a cooling feedback, and therefore provide no explanation for the interglacial warming that appears to result from dust deposition. In great contrast to these explanations it is proposed here that during the glacial maximum, CO2 depletion starves terrestrial plant life of a vital nutrient and causes a die-back of upland forests and savannahs, resulting in widespread desertification and soil erosion. The resulting dust storms deposit large amounts of dust upon the ice sheets and thereby reduce their albedo, allowing a much greater absorption of insolation. Up to 180 W/m2 of increased absorption can be provided to the northern ice sheets, when calculated seasonally and regionally instead of annually and globally.

    This dramatic increase in insolation and absorption results in melting and dissipation of the northern ice sheets, and the establishment of a short interglacial period. Ice ages are therefore forced by orbital cycles and Milankovitch insolation, but regulated by ice-albedo and dust-albedo feedbacks. And the warming effects of dust-ice albedo are counterintuitively caused by a reduction in global temperatures and a corresponding reduction in CO2 concentrations. And while this proposal represents a reversal of conventional thinking it does explain each and every facet of the glacial cycle, and all of the many underlying mechanisms that control its periodicity and temperature excursions and limitations.

    • Ralf
      What do you mean by “ice age”? The whole Quaternary? Or just an interval between interglacials?

      There are no “missing ice ages”. I return to the figure 35 of Javier’s recent Holocene post at JC (it didn’t have 35 figure btw – just a number):

      With the 6,500 year lag, every single temperature peak correlates with an obliquity peak. And why are some tall and some short? The tall ones which are called interglacials were the ones coinciding with the eccentricity / 65N max summer insolation / precession. Resonance, if you like.

      I do think your glacial maximum dust findings are important and valid, especially insofar as they point to CO2 starvation.

      But glacial-interglacial timing needs no atmospheric deus-ex-machina (dust, volcanos, cosmic magnets, CO2, bolides, etc…). It’s the oceans.

      The 6,500 year delay which Javier showed is incredibly important. Think about what it means. What else other than ocean heat dynamics could account for it?

      • >>There are no “missing ice ages”.

        The obliquity maxima 450, 370, 170, and 50 kyr ago did not produce interglacials. Javier has never explained the missing interglacials, and until he can do that the theory of obliquity influence is wrong.

        And the obliquity maximum 250 ky ago is completely misaligned with the interglacial. Again, there is a failure here to acknowledge the role of precession, because this interglacial is aligned with precession, not obliquity.

        Javier also has a habit of using Huyber’s marine sediment ice-age chronology, which is pure guessworks and should not be used in Palaeoclimatology.

        R

      • Ralf
        The obliquity maxima 450, 370, 170, and 50 kyr ago did not produce interglacials. Javier has never explained the missing interglacials, and until he can do that the theory of obliquity influence is wrong.

        The whole point of my post was that precession and 65N summer insolation modulate the response of the glacial oscillator to obliquity. I don’t think you read more than a few words of it.

        I’ll say it for the 4th time. With the 6,500 year lag, every single temperature peak correlates with an obliquity peak. And why are some tall and some short, some almost nonexistent ? The tall ones which are called interglacials were the ones coinciding with the eccentricity / 65N max summer insolation / precession peaks. Resonance, if you like.

        Again, there is a failure here to acknowledge the role of precession

        No there isn’t. In my post I write the word precession lots and lots of times. Alongside 65N summer insolation and eccentricity. My posts are not excessively long, please read them if you wish to comment.

        Precession modulating obliquity with. 6500 year lag, explains perfectly all thr glacial-interglacial oscillation of the last million years and probably further back as well.

        Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession. Precession.

  38. Or It’s the increased volcanic activity from the Suns graviational oscillations you don’t consider, not the atmosphere, as the main effect, solar irradiance may also play a part as the radiation variation is the same as the graviational, +/- 30% or so pa.

  39. It’s so obviously the oceans that hold the majority of the heat. How does solar variation affect that heat content during a an ice age cycle, and, in particular how does an eccentric orbit create such rapid, geological time step function, as oceanic warming, if it isn’t gravity working on the viscoelastic tectonics and our nuclear reactor core that cooks up the magma for redistribution? I suspect that is far more powerful than solar irradiance variation as an effect. Especially now I know about IO and Venus, and the role of tectonics in recycling CO2 from volcanoes, w/o which tectonics it is now said we would be Venus..

    Also the solar radiation effects when closer and futher away must largely cancel each other out on total irradiance pa, whereas the gravitationally induced rock movements must increase, doesn’t net out. Because this such an obviously more powerful effect in term of heat content and gross energy in molten rock, delivered mostly directly to the high capacity long term ocean heat sinks for delivery to land by weather and directly by sea. Model that! Evidence would help such a hypothesis.

    FIrst of all: Has anyone done a study of the movement of tectonic plates across ice ages, to see if movement varies cyclicy and in a correlated manner?. Is there a study of volcanic activity on land before an interglacial, at the end of an ice age?

    I’m going to do the David MacKay back of the envelope maths on the incremental ice formation and melting involved in a typical ice age and compare to the magma flow required into the oceans to cause that, compared to what we think leaks out the various holes now.

    Basically how much magma at 1200 degrees and the known thermal capacity of the rock will melt that much ice at the latent heat of ice plus a bit, Not that hard. Does the answer seem credible as an ibcrease in magma flow to the surface? Obviously weather can affect whether there is enough heat to complete the process to the temperature we expect of an interglacial, if the whole process is a bit marginal. But this is a hammer blw, as already suggested elsewhere. Just not binary on the return to long term stable ice age, sawtooth with noise.

    But I’m not that clever. What I do see are relative energy levels between the various supposed cause and effect, and the simple facts that the effects that end ice ages are sudden, massive and must come from warmer oceans. How? – peak of MIlankovitch cycle is a good smoking volcano, doesn’t have to be precise.

    Just the scale of relative effects and the new science on space volcanoes in the solar system means I now think looking at the atmosphere suffers from a serious failure to “organdise” a search. “Organdise”, said Christoper Robin, “is when you have a search, but you don’t all look in thsame place”. For me, it seems climate science is doing just that, looking at the relatively weak symptoms of the atmosphere as causes, modelling the noise using almost meaningless numerical models as “science” that they can force to correspond to the old dat at and forecest a tiny bit into the future, badly.

    Yet the real cause may be left mainly unstudied, as it doesn’t fit the rhetoric, the tunnel vision climate atmospheric model led agenda, the subsidies for renewables that fund all this but make CO2 emissions worse in fact, etc., or simply the narrow speciaisation of the scientists turned priestsfor money and fame, and their unknowing but faithful believers. Just IMO. Your climate may vary.

    Need to do some numbers. Where is that envelope?

  40. Climate science is chock full of urban legends. Urban legend theories are theories (typically connected to a Zombie mechanism) which are repeated when there is obvious data and logic that supports the assertion that the theories in question are completely incorrect, not part of the solution.

    Zombie theories block the solution to the problem.

    notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth

    1. The discrete thermal halone ocean conveyor theory has been proven incorrect by ocean float data. The discrete thermal halone conveyor started with a picture that Wally Broeker included in a paper without proof. Wally later in an interview stated that he was only presenting a hypothesis. Ocean float data shows only 8% of the flow in the North Atlantic follows the Broeker conveyor path. Therefore changes in the fresh water flow cannot interrupt the North Atlantic drift current and changes in the North Atlantic drift current do not affect ocean current flow in the Southern Hemisphere.

    2. Basic analysis shows the heat transferred by the North Atlantic drift current is three times less than the heat that is transfer from summer warming of the North Atlantic ocean. A complete interruption to the North Atlantic drift current therefore cannot cause the cyclic warming and cooling of Europe and Greenland Ice sheet.

    3. There is in the paleo record warming and cooling in the Southern Hemisphere that is simultaneous with the warming and cooling in the North hemisphere. If ocean currents where the cause of the warming there would be roughly a 1000 year lag.

    4. When the Southern hemisphere, the Greenland Ice Sheet, and the Northern hemisphere warm, the Antarctic ice cools. This phenomenon is called confusingly the Polar see-saw (see Svensmark’s attached paper). The Antarctic ice sheet cools as the albedo of that ice sheet is greater than the albedo of clouds. Therefore, an increase in cloud cover over the Antarctic causes warming of that ice sheet rather than cooling. The albedo of the Greenland ice sheet is less than the Antarctic ice sheet and the Greenland ice sheet is not isolated by a polar vortex and hence unlike the Antarctic ice sheet follows the temperature of the surround ocean.

    http://www.sciencedaily.com/releases/2009/05/090513130942.htm

    Cold Water Ocean Circulation Doesn’t Work As Expected

    The familiar model of Atlantic ocean currents that shows a discrete “conveyor belt” of deep, cold water flowing southward from the Labrador Sea is probably all wet.

    A 50-year-old model of ocean currents had shown this southbound subsurface flow of cold water forming a continuous loop with the familiar northbound flow of warm water on the surface, called the Gulf Stream.
    “Everybody always thought this deep flow operated like a conveyor belt, but what we are saying is that concept doesn’t hold anymore,” said Duke oceanographer Susan Lozier. “So it’s going to be more difficult to measure these climate change signals in the deep ocean.”

    The question is how do these climate change signals get spread further south? Oceanographers long thought all this Labrador seawater moved south along what is called the Deep Western Boundary Current (DWBC), which hugs the eastern North American continental shelf all the way to near Florida and then continues further south.

    But studies in the 1990s using submersible floats that followed underwater currents “showed little evidence of southbound export of Labrador sea water within the Deep Western Boundary Current (DWBC),” said the new Nature report.

    Scientists challenged those earlier studies, however, in part because the floats had to return to the surface to report their positions and observations to satellite receivers. That meant the floats’ data could have been “biased by upper ocean currents when they periodically ascended,” the report added.

    To address those criticisms, Lozier and Bower launched 76 special Range and Fixing of Sound floats into the current south of the Labrador Sea between 2003 and 2006. Those “RAFOS” floats could stay submerged at 700 or 1,500 meters depth and still communicate their data for a range of about 1,000 kilometers using a network of special low frequency and amplitude seismic signals.

    But only 8 percent of the RAFOS floats’ followed the conveyor belt of the Deep Western Boundary Current, according to the Nature report. About 75 percent of them “escaped” that coast-hugging deep underwater pathway and instead drifted into the open ocean by the time they rounded the southern tail of the Grand Banks.

    Eight percent “is a remarkably low number in light of the expectation that the DWBC is the dominant pathway for Labrador Sea Water,” the researchers wrote.

    Studies led by Lozier and other researchers had previously suggested cold northern waters might follow such “interior pathways” rather than the conveyor belt in route to subtropical regions of the North Atlantic. But “these float tracks offer the first evidence of the dominance of this pathway compared to the DWBC.”

    http://www.americanscientist.org/issues/pub/the-source-of-europes-mild-climate

    The Source of Europe’s Mild Climate
    The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth

    If you grow up in England, as I did, a few items of unquestioned wisdom are passed down to you from the preceding generation. Along with stories of a plucky island race with a glorious past and the benefits of drinking unbelievable quantities of milky tea, you will be told that England is blessed with its pleasant climate courtesy of the Gulf Stream, that huge current of warm water that flows northeast across the Atlantic from its source in the Gulf of Mexico. That the Gulf Stream is responsible for Europe’s mild winters is widely known and accepted, but, as I will show, it is nothing more than the earth-science equivalent of an urban legend.

    Recently, however, evidence has emerged that the Younger Dryas began long before the breach that allowed freshwater to flood the North Atlantic. What is more, the temperature changes induced by a shutdown in the conveyor are too small to explain what went on during the Younger Dryas.  Some climatologists appeal to a large expansion in sea ice to explain the severe winter cooling.  I agree that something of this sort probably happened, but it’s not at all clear to me how stopping the Atlantic conveyor could cause a sufficient redistribution of heat to bring on this vast a change.

    http://www.atmos.washington.edu/~david/Gulf.pdf

    Is the Gulf Stream responsible for Europe’s mild winters?
    By R. SEAGER, D. S. BATTISTI, J. YIN, N. GORDON, N. NAIK, A. C. CLEMENT and M. A. CANE

    It is widely believed by scientists and lay people alike that the transport of warm
    water north in the Gulf Stream and North Atlantic Drift, and its release to the atmosphere, is a major reason why western Europe’s winters are so much milder (as much as 15–20 degC) than those of eastern North America (Fig. 1). The idea appears to have been popularized by M. F. Maury in his book The physical geography of the sea and its meteorology (1855) which went through many printings in the United States and the British Isles and was translated into three languages.

    In summary, the east–west asymmetry of winter climates on the seaboards of the North Atlantic is created by north-westerly advection over eastern North America and by zonal advection into Europe. The Pacific Ocean has an analogous arrangement with meridional advection being an especially strong cooling over Asia. Since western Europe is indeed warmed by westerly advection off the Atlantic, we next assess how the
    surface fluxes over the Atlantic are maintained.

    In conclusion, while OHT warms winters on both sides of the North Atlantic Ocean by a few degC, the much larger temperature difference across the ocean, and that between the maritime areas of north-western Europe and western North America, are explained by the interaction between the atmospheric circulation and seasonal storage and release of heat by the ocean. Stationary waves greatly strengthen the temperature contrast across the North Atlantic and are themselves heavily influenced by the net effect of orography. In contrast, transport of heat by the ocean has a minor influence on the wintertime zonal asymmetries of temperature. Even in the zonal mean, OHT has a small effect compared to those of seasonal heat storage and release by the ocean and atmospheric heat transport. In retrospect these conclusions may seem obvious, but we are unaware of any published explanation of why winters in western Europe are mild that does not invoke poleward heat transport by the ocean as an important influence that augments its maritime climate.

    This paper by Svensmark provides data and analysis to support the assertion that changes to the solar cycle causes the weird phenomena which is called the polar see-saw.

    As I noted above the earth’s climate is cyclically changing with a periodicity of 1470 years plus/minus 500 years. Svensmark shows through the analysis of ice sheet bore hole temperature, that the cyclic change is effecting both hemispheres simultaneously.

    http://arxiv.org/abs/physics/0612145v1

    The Antarctic climate anomaly and galactic cosmic rays

    Borehole temperatures in the ice sheets spanning the past 6000 years show Antarctica repeatedly warming when Greenland cooled, and vice versa (Fig. 1) [13, 14]. North-south oscillations of greater amplitude associated with Dansgaard-Oeschger events are evident in oxygen isotope data from the Wurm-Wisconsin glaciation [15]. The phenomenon has been called the polar see-saw [15, 16], but that implies a north-south symmetry that is absent. Greenland is better coupled to global temperatures than Antarctica is, and the fulcrum of the temperature swings is near the Antarctic Circle. A more apt term for the effect is the Antarctic climate anomaly.

    Attempts to account for it have included the hypothesis of a south-flowing warm ocean current crossing the Equator [17] with a built-in time lag supposedly intended to match paleoclimatic data. That there is no significant delay in the Antarctic climate anomaly is already apparent at the high-frequency end of Fig. (1). While mechanisms involving ocean currents might help to intensify or reverse the effects of climate changes, they are too slow to explain the almost instantaneous operation of the Antarctic climate anomaly.

    Figure (2a) also shows that the polar warming effect of clouds is not symmetrical, being most pronounced beyond 75◦S. In the Arctic, it does no more than offset the cooling effect, despite the fact that the Arctic is much cloudier than the Antarctic (Fig. (2b)). The main reason for the difference seems to be the exceptionally high albedo of Antarctica in the absence of clouds.

  41. Ptolemy2:

    You asked me to look carefully at Figure 35 in a cited Judith Curry post by Javier.

    What is most obvious to me is that warming during maximum periods of obliquity is poorly correlated with these periods, Sometimes there is a large response, but most times, just a minor blip of decreased cooling.

    If obliquity were a significant factor, there would be strong warming during each peak, and that does NOT happen.

    Even the legend of the graph, that the drop of obliquity always terminates interglacials is not completely correct, such as for the MIS17, MIS13, and MIS7c peaks–close, but no cigar.

    Historically, cooling due to large volcanic eruptions always occurs, and any effort to explain pre-historic temperatures MUST include their effects.

    • A friendly reminder, while every ice age does not end when obliquity reaches it’s peak of around 24.5 degrees, EVERY ice age begins when obliquity drops below 23.5 degrees on it’s way to the minimum of around 22 degrees. There are NO EXCEPTIONS to this, zero, none…

      Whatever the prime driver of ice ages are, whatever the combination of factors are, we know with 100% certainty they begin when obliquity drops below 23.5 degrees. No amount of arguing the details changes the outcome.

      You all have been warned, act accordingly and stop rearranging the deck chairs on the Titanic.

      Migrate below the Wisconsin Ice Age line and you should be fine.

      • dscott:

        You state that “EVERY ice age begins when obliquity drops below 23.5 degrees on its way to the minimum of around 22 degrees. There are NO EXCEPTIONS TO THIS”

        Assuming that we are looking at the same graph, MIS17 began dropping before obliquity reached 23.5 deg, as did MIS13, the first drop in MIS7c, and the deepening of the ice age in the first unlabeled peak after MIS7c.

        Fine points, but not quite what you had stated.

        Another friendly reminder: Correlation does not always prove causation.

    • Burl
      Ptolemy2:

      You asked me to look carefully at Figure 35 in a cited Judith Curry post by Javier.

      What is most obvious to me is that warming during maximum periods of obliquity is poorly correlated with these periods, Sometimes there is a large response, but most times, just a minor blip of decreased cooling.

      If obliquity were a significant factor, there would be strong warming during each peak, and that does NOT happen.

      Like Ralf you very obviously did not read more than one or two words of my post.

      It’s not obliquity alone, but modulated by precession-eccentricity.

      The whole point of my post was that precession and 65N summer insolation modulate the response of the glacial oscillator to obliquity. I’ll say it for the 4th time. With the 6,500 year lag, every single temperature peak correlates with an obliquity peak. And why are some tall and some short, some almost nonexistent ? The tall ones which are called interglacials were the ones coinciding with the eccentricity / 65N max summer insolation / precession peaks. Resonance, if you like.

      dscott is right, obliquity is obviously the prime Milankovich forcer of the interglacials. Those who persist in opposing Milankovich pacing of glacial cycles do so for religious reasons and employ the tactics of creationists in their argument, like the “Gish gallop” – an apparently impressive plethora of irrelevant arguments, and inflating the importance of non-zero error in experimental measurements.

      Precession modulating obliquity with. 6500 year lag, explains perfectly all the glacial-interglacial oscillation of the last million years and probably further back as well.

      • ptolemy2:

        I am in a quandry. Your analysis appears to be “right on”, but episodes of volcanic cooling, (and warming when they cease) are inescapable,

        It seems far-fetched that they would be in sync with your alignments, but perhaps they are.
        What is your view?

      • This was actually Javier’s analysis – obliquity and the 6,500 year lag – not mine.

        Volcanism is clearly influenced by the glacial – interglacial cycle, as shown by papers such as this (if one filters out the CO2 worship):

        http://www.cam.ac.uk/research/news/increase-in-volcanic-eruptions-at-the-end-of-the-ice-age-caused-by-melting-ice-caps-and-glacial

        For instance the melting of glacial ice caps releases pressure on underlying rock, causing an increase in volcanoes 🌋. Glacial erosion also appears to play a role in this.

      • The authors of the link cannot be right. More volcanism will cause cooling due to sulfurous emissions, negating any warming trend.

        And CO2 from volcanic eruptions is a fiction–none has ever been observed from any of the major eruptions during historical times, just cooling.

  42. Sun’s graviatational foce is 180 times the moon, and varies 30% during a year at maximum Milanovitch eccentricity, when the sudden warming to interglacials occurs. I have already written what this could , and does on other planets and Moons we recently learnt about, Check out Io and what’s under the Venusian clouds due to no plate etctonocs, probably. If toides matter, they wil also be part of the picture of substantial variatio durinf Milankovitch extremes.

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