Using Milankovitch Cycles to create high-resolution astrochronologies

Close-up of Petrified Wood in Petrified Forest National Park, Arizona

To quote (and H/T) Leif Svalgaard:

This is an interesting application.

From EGU Blogs

Lon Abbott November 20, 2020 Stratigraphy, Sedimentology and Palaeontology

This year marks the 100th anniversary of Milutin Milankovitch’s first paper about Earth’s climate. Milankovitch argued that the amount of solar radiation Earth receives, and hence its climate, varies cyclically as its orbit changes due to gravitational tugs from the other planets. His climate theory fell into disrepute during the 1950’s but was rehabilitated in the 1970’s.

Today, many people are aware that cyclic changes in Earth’s orbit, now known as Milankovitch Cycles, repeatedly plunged Earth into and out of glacial episodes during the last 2.7 million years. Less well known, however, is the control those same cycles have exerted to form rhythmically oscillating sedimentary sequences throughout Earth history, thanks to the changes in depositional conditions they induce. Stratigraphers “tune” the chronology of a rhythmic rock sequence to Milankovitch Cycle beats and then anchor those beats to the geologic time scale using radiometric and paleomagnetic dates to produce an astrochronology. Such astrochronologies, because of their unusually high temporal resolution, provide profound insights into the evolution of Earth, its inhabitants, and the Earth-Moon system.

Milankovitch orbital cycles have four primary periods. Earth’s rotation axis precesses on an approximately 20 thousand year cycle and changes its tilt (called obliquity) on an approximately 40 thousand year cycle. Changing gravitational tugs from Jupiter and the inner planets cause our orbit’s eccentricity (the elliptical nature of our orbit) to oscillate in two modes, one approximately 100 thousand years and the other a steady 405 thousand years. The remarkable stability of the 405 thousand year cycle, which is modulated by Jupiter and Venus, makes it the Milankovitch Cycle of choice to construct astrochronologies.

The stratigraphy of the eastern USA’s Newark Basin allowed scientists to construct one important early example. This Triassic rift basin hosts rhythmically alternating lake and fluvial sediments that reflect lake expansion and shrinkage as the climate changed. Scientists tuned the Newark Basin astrochronology to the 405 thousand year Milankovitch Cycle and then tied it to the geologic time scale using magnetic polarity reversals and high-resolution radiometric dates from basalt interbedded with the uppermost sediment layers. Although the chronology’s high temporal resolution appeared to represent a big leap forward, some scientists worried about missing cycles due to unrecognized sedimentary hiatuses; they didn’t trust the astrochronology because it lacked a radiometric date to anchor the sequence’s base.

Clearly, a test of the Newark astrochronology’s accuracy was needed.  The scientists had to find a comparably aged section that could be tied to radiometric dates at its top and bottom. In 2013, they found the ideal candidate: a 500-meter-long core drilled in the Chinle Formation of Arizona’s Petrified Forest National Park. This core possesses cyclic sequences deposited in rivers and lakes that drained a volcanically active area. The youngest detrital zircons in each sediment layer likely record that layer’s depositional age, so the scientists dated those zircons in key layers to provide radiometric pinpoints at the core’s top and bottom. The team then applied the same strategy to the Petrified Forest core as they had to the one from Newark Basin. By 2018, they had produced an identical astrochronology that confirms that no cycles are missing from the Newark Basin section and therefore “cements” its reliability.

The Petrified Forest/Newark Basin astrochronology has had many important implications. For example, paleontologists have long believed that the Late Triassic fossil record suggests dinosaurs achieved ecological dominance at mid-to-high latitudes millions of years before they achieved this in the tropics. This conclusion, however, has been controversial because of dating uncertainties. Application of the Petrified Forest/Newark Basin astrochronology to mid-latitude fossil sites in Argentina and Greenland, and to low-latitude sites in Canada’s Fundy Basin and Petrified Forest, now confirm the delay in tropical dinosaur dominance is real.

GeoLog | Using Milankovitch Cycles to create high-resolution astrochronologies – GeoLog (

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December 6, 2020 10:22 am

Maybe not exactly the same subject, but an interesting connection, nonetheless.

Clay Sanborn
Reply to  Kpar
December 6, 2020 11:59 am

This is very interesting. Did not know that we have a syzygy of Sun, Venice, Earth and Jupiter every, roughly, 11 years, coincident with the 11 year Solar Cycle. The application of the Rayleigh-Taylor Instability to explain how tidal forces of the above syzygy could influence the pinnacle/depth intensity of a given solar cycle is a fascinating idea indeed.

Reply to  Clay Sanborn
December 6, 2020 1:47 pm


John Tillman
Reply to  Jim
December 6, 2020 2:58 pm

Hey, Venice has some pretty mean tides!

Jim G
Reply to  John Tillman
December 6, 2020 6:55 pm

-> Hey, Venice has some pretty mean tides!

Are you suggesting that they are merely average?? 😉

December 6, 2020 10:22 am

Huh. Very cool.

Reply to  SMC
December 6, 2020 11:14 am

Except that the scientist’s name was Milutin Milankovic.


Rich Davis
Reply to  Vuk
December 6, 2020 12:42 pm

Hi Vuk,
As he was a Serbian, would it not be Милутин Миланковић?

Why would any particular transliteration be better than another? I guess you’re joking though.

John Tillman
Reply to  Rich Davis
December 6, 2020 1:35 pm

I guess Vuk is using the Croatian transliteration, but other languages don’t have to bound by Croatian conventions for rendering Serbian Cyrillic into Latin alphabets.

Reply to  John Tillman
December 6, 2020 2:31 pm

John you are wrong, Latin alphabet is not Croatian, it is Latin! Both Latin and Cyrillic alphabets are in common use, but in the recent decades Latin is becoming more dominant. Here is link to the today’s issue of the most popular Serbian daily :

Reply to  John Tillman
December 6, 2020 2:47 pm

John, google ‘New York times Novak Djokovitch

John Tillman
Reply to  John Tillman
December 6, 2020 3:37 pm


That Serbian Novak Djokovic choses to transliterate his name in Croation convention doesn’t mean that the English transliteration of Milankovitch is wrong. Milankovitch himself never objected to this transliteration, which was common during his lifetime.

Because the sound of the Serbian letter “ћ” and Croatian letter “ć” is “ch” or “tch” in European languages using their own versions of the Latin or Roman alphabet, they’re free to transliterate it as close to native pronunciation as possible. The letter “c”, without superscript, is nowhere near to this pronunciation in most languages using the Latin alphabet. Similarly, French uses “ff” instead of “v” when transliterating the Romonov dynasty.

Speakers of other languages might pronounce his name as Milankovick without the phonetic transliteration.

Reply to  John Tillman
December 6, 2020 3:47 pm

“Latin alphabet is not Croatian”

John never said it was.

Reply to  John Tillman
December 7, 2020 2:21 am

John, there you go again, your superficial knowledge of languages there of the old and the invented is far more misleading than no knowledge at all. Adding your ch, tch or any other combinations will never get even close to right pronunciation of a numerous characters found in various versions of cyrillic used throughout number of countries and languages of the East Europe which have come or gone out of use in the last two centuries. Standard Latin alphabet with use of two types of ‘annotations’ on latin letters c, s,z etc only locals will get right. From age of five I written my name in both alphabets ( Vukčević & Вукчевић), you go and tell me what is my name, perhaps Vooktchcheveetch, nonsense my dear fellow, deprive me of – vic you deprive me of my origins. There I end this exchange.

Reply to  John Tillman
December 7, 2020 4:49 am

@ MarkW
John is fallen into the Google’s translation nonsense trap as he calls it ‘Croatian transliteration’ and ‘Croatian conventions’, there are no such things. Latin alphabet has been used in Balkans since the Roman times. Somewhat softer dialect of Serbian is spoken in Croatia, while in my parts is even softer (eg. white child = belo dete, bjelo djete & bijelo dijete, respectively), after WWII their common language was renamed Serbo-Croat, not as two but as a single language with two dialects. As Balkan nation’s became independent they renamed their dialects into languages. In the last decade or two the ‘Bosnjak’ and ‘Montenegrin’ languages appeared from nowhere ( google it for fun & entertainment). The USA has been independent nearly 250 years and Canada ( ? , you tell me how long) and so far they have dismally failed to ‘invent’ American or Canadian language, possibly gross lack of imagination, while the Balkan populace has excess of it, one would say, beyond what is for their own good.

John Tillman
Reply to  John Tillman
December 7, 2020 12:04 pm


Croatian is written in a version of the Latin alphabet, just as Serbian is in a variety of the Cyrillic alphabet.

I didn’t rely on Google Translate, but I grant you that the only Slavic language I know is Russian.

Few non-Croatian speakers are going to pronounce Croatian letter ć close enough for your liking. Those languages which transliterate it try to get as close as possible.

I’ll bet that Milankovitch would have preffered not to have his name pronounced so as to end in “ic” in English.

John Tillman
Reply to  John Tillman
December 7, 2020 12:25 pm

Besides which, Milankovitch was Serbian, not Croatian, so his name is transliterated from Cyrillic, hence as “tch”.

People of Serbian ancestry in the US spell their names to end with -ch rather than -c.

Reply to  John Tillman
December 7, 2020 4:16 pm

John you are at it again, Latin alphabet is not exclusive to territory of Croatia. For centuries when Serbs travelled to Austria or parts of their empire, or across Adriatic to Rome or Trieste and Venice, usually from port of Kotor (first Venice’s than A_H empire territory) and further on to France and other parts of Europe, their travel documents were written not in some kind of ‘Croatian’ transcript as you would have it, but in the proper Latin alphabet, often in Italian which was widely spoken along the Balkan side of the Adriatic coastline.
Standardisation of both Cyrillic alphabet, currently in use, and its equivalent with extra Latin characters was done by the Serb linguist Vuk Karadzic (as it happens a distant relative of the other well known Radovan Karadzic ) in the early 19th century. Vuk K. spent most of his working life in Vienna, was friend of Goethe for whom he translated some of the Serb folk songs, who apparently thought there were as good as ‘Songs of Songs’, a gross exaggeration on the Goethe’s part. Karadzic also published the first Serbo-German dictionary. FYI, the accentuation of c to get ć and č, as well as s for š and z for ž Karadzic copied/adapted from the linguist Jan Hus and his Czech alphabet. Vuk K. signed Vienna Literary Agreement with Austrian authorities around 1850 which laid foundations of what later was known as the Serbo-Croat language with the two alphabets of equal wight to be used in territories where the A-H empire ruled. As you can see it was a Serb who created what you falsely claim to be Croatian alphabet, perhaps wikipedia and or other sources might tell you more if you bother to find out. Serbian, Croat, and recently Bosnian and Montenegrin are the SAME and one language with dialects which are less distinct than those of the English spoken in London and Birmingham or London and Newcastle. So called Croat language became a new official language in Croatia with their recent independence.

Reply to  Rich Davis
December 6, 2020 2:19 pm

Hi Pич,
It is no matter if it was written in either of the two alphabets (Milanković), there is no requirement for extra t&h. Occasionally the French get it right « La théorie de Milanković suggère que les fins de glaciations …. », but Germans and Anglo-Saxons never do. The suffix -vic in all south Slavic languages is equivalent to the English -son. In the area where Milankovic was born colonial power was Austro-Hungarian empire, and authorities at the time tried to Germanise surnames, sort of ethnic assimilation. Russians did the same with non-Slavic population, someone with family name Ahmed would be known as Ahmedov, etc. while the British went to the extreme with the Afro-Caribbeans. Perhaps Gavin Schmidt should be anglicised and written as Gavin ‘Smith’.

John Tillman
Reply to  Vuk
December 6, 2020 3:41 pm

The cycles should be named for Scot James Croll, anyway.

Gordon A. Dressler
Reply to  SMC
December 6, 2020 12:40 pm

Except for the fact that than any given planetary alignment with respect to the Sun is extremely repeatable in the time domain over millennia, whereas the period of sunspot cycles is actually quite variable.

“The duration of the sunspot cycle is, on average, around eleven years. However, the length of the cycle does vary. Between 1700 and the present, the sunspot cycle (from one solar min to the next solar min) has varied in length from as short as nine years to as long as fourteen years. Note, however, that of the 26 solar cycles during that three-century span, 21 had a length between ten and twelve years.” —source:

A range of 9 to 14 years is a variation of +/- 22%, far beyond the percentage by which any alignment of the planets from Venus to Saturn could vary over a 320 year time span (< 2 degrees). Heck, even a +/- 1 year variation (as cited above for 21 of the last 26 solar cycles) is equivalent to a +/- 9% variation, which would be about an order-of-magnitude greater that that for any given alignment drift of planets from Saturn to Venus.

The video above fails the basic smell test based on scientific observation.

Reply to  Gordon A. Dressler
December 7, 2020 6:27 am

If there is any connection between solar cycles (solar surface magnetic events with average of 21 year magnetic polarity periodicity) and planetary system it is likely to be via closing of the magnetic and current circuits between heliospheric current and solar wind and the two major magnetospheres of Jupiter and Saturn (the Earth’s is too weak). Although two planets orbital movement is very precise, tails of their magnetosphere’s are bantered and spatially deviated by solar wind thus a triple magnetic reconnection can deviate by a + or – year or so. Also, heliosphere is not circular but elongated and the alignments shift by about 120 degrees (but not exactly so returns are shifted by 7-8 degrees) in respect of the heliosphere, the intensity and duration of the magnetic events may be affected. Even if so it can be only exist as a hypothesis since it can not be ever proven as correct.

William Astley
December 6, 2020 10:37 am

What you are quoting is a fake science press release about fake science. Fake science really is not science, it is just sneaky propaganda.

Blah, blah, 100 years of this great theory…. This stinky dead theory is what climate science is all about. Stinky dead theories. Like the theory that an interruption to the North Atlantic drift current AKA Gulf Stream caused the Younger Dryas abrupt cooling.

Cold Water Ocean Circulation Doesn’t Work As Expected

Sure, the climate changes when the earth sun distance changes. It is not solar insolation at 65N that is forcing the earth’s climate, though. A physical change to the sun is the real cause of ‘climate’ change and how that physical change to the sun affects the earth is dependent on the earth sun distance.

“A number of records commonly described as showing control of climate change by Milankovitch insolation forcing are re-examined. The fraction of the record variance attributable to orbital changes never exceeds 20%. In no case, including a tuned core, do these forcing bands explain the overall behavior of the records”

What is controlling the earth climate and causing cyclic abrupt climate change is not changes in solar insolation at 65N.
Climate ‘science’ is full of dead theories.
Currently summer insolation at 65N is the same as the coldest part of the last interglacial. Why no glacial phase?
Are at least 12 different observations and analysis results that support the assertion that insolation changes at 65N are physically not capable of causing the temperature changes observed in the paleo record and did not cause what is observed.
The following is a sample of the paradoxes which disproof the theory.

The Younger Dryas. The Younger Dryas is an abrupt cooling of the planet that occurred 12,900 years ago, at a time when summer solar insolation at 65N was maximum. The
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

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)(putative 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

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.

Reply to  William Astley
December 6, 2020 11:16 am

Sure, the climate changes when the earth sun distance changes […] A physical change to the sun is the real cause of ‘climate’ change and how that physical change to the sun affects the earth is dependent on the earth sun distance.
The sun-earth distance does not change. Neither does the sun.
On time scales that are of interest for the climate. On much longer time scales [millions and billions of years] the sun does get colder going back in time. What kept the earth warm way back then was a much higher concentration of CO2.

Gordon Lehman
Reply to  Leif Svalgaard
December 6, 2020 11:51 am

Of interest to CURRENT climate, perhaps? This is eccentricity, which by definition changes the earth’s distance from the sun.

Reply to  Gordon Lehman
December 6, 2020 12:03 pm

no, it does not when averaged over a year

Gordon Lehman
Reply to  Leif Svalgaard
December 7, 2020 10:52 am

Milankovitch cycles generally cancel when averaged over a year, including the ~40k that actually shows up in ice and sediment cores. Eccentricity is the only cycle that actually changes net insolation.

Reply to  Gordon Lehman
December 6, 2020 12:18 pm

As the earth’s orbit eccentricity changes its semi-major (long) axis doesn’t change. Its semi-minor axis changes. The distance at aphelion is the same, but the time spent at that distance changes. Kepler’s third law- equal areas swept in equal times.

John Tillman
Reply to  Leif Svalgaard
December 6, 2020 12:08 pm

Alternative or additional solutions to the faint young Sun paradox exist besides probably higher concentrations of H2O, CO2, CH4 and other GHGs in Earth’s early atmospheres.

Covering them all would require a long post. Suffice it to say that one source of Hadean and Archean surface warmth was Earth’s own then higher internal heat, blanketed by denser air. Also, with the Moon much closer, our young planet spun faster, so length of day has to be factored in.

Reply to  John Tillman
December 6, 2020 12:14 pm

The point was that the solution does not lie with a changing distance to the sun.
The internal heat was still minute compared to the composition of the atmosphere.

John Tillman
Reply to  Leif Svalgaard
December 6, 2020 12:30 pm

Of course you’re right about distance to the Sun.

Heat flow to the surface during the Hadean and Archean was much higher than now. Even after the crust cooled in the later Hadean, heat flow was at least thre times greater than now, to which must be added tidal heating from the much closer Moon.

But, as noted, other explanations for liquid water on the surface have also been offered.

John Tillman
Reply to  Leif Svalgaard
December 6, 2020 12:43 pm

Earlier in the Hadean, naturally, heat flow was around 700 times greater than now.

Reply to  Leif Svalgaard
December 6, 2020 3:26 pm

Obliquity is the major factor out of the three cycles.

Reply to  Leif Svalgaard
December 6, 2020 4:22 pm

Earlier in the Hadean, naturally, heat flow was around 700 times greater than now.
But we would not go that far back. Reasonable would be 2 to 3 billion at the most and then the heat flow was minute.
No need to drag irrelevant things into it. And one has to keep the perspective. 700 times the present heat flow is only 55 W/m2. Not nearly enough to compensate for a 20% cooler sun (280 W/m2 down).

John Tillman
Reply to  Leif Svalgaard
December 7, 2020 12:06 pm

I must have been using the wrong figure for present heat flow, which in the Hadean is estimated to have been 140 W/m^2.

Reply to  Leif Svalgaard
December 6, 2020 12:23 pm

Too bad the historical record shows that there is no correlation between CO2 levels and temperature.
Add to the fact that above 400ppm, CO2 is so close to being saturated that adding more CO2 to the atmosphere has little to any influence.
Reply to  MarkW
December 6, 2020 1:59 pm

“to being saturated that adding more CO2 to the atmosphere has little to any influence.”
This is wrong, because more CO2 raises the EFL.

Reply to
December 6, 2020 3:49 pm

B, so what?

William Astley
Reply to  Leif Svalgaard
December 6, 2020 3:19 pm


What are you talking about? Abrupt cyclic, Climate change is not caused by the sun getting warmer or colder.

Leif anyway you are not interested in any of the paradoxes that have been found in the earth data.

The unexplained physical cyclic changes to the geomagnetic field are on observational fact not a theory. An in your face paradox.

The earth data, temperature, geomagnetic field changes that are correlated and that are changing for no known physical reason.

Everything that is observed must have a physical explanation. When there is no physical explanation there is a breakthrough waiting to be found.

It is a fact that the sun earth distance and the timing of in the seasons when the closest and farthest distance from the sun occurs, changes with time.

And the orbital changes does change the amount of summer insolation at 65N. That does not however cause the abrupt changes. It is too small. The abrupt changes occur before the change insolation. The abrupt changes occur when there is no insolation changes.

So there must be something besides the sun getting warmer or colder to cause cyclic abrupt climate change and there is.

In the last 15 years, it has been found that, the cyclic changes in temperature, correlate with abrupt, cyclic changes to the geomagnetic field and the geomagnetic field intensity and orientation absolutely effects planetary cloud cover and temperature.

What geologists have found is the geomagnetic field intensity is also changing cyclically by a factor of three to four. Higher in intensity during the interglacial period and lower in the glacial period. And the geomagnetic field is changing cyclically abruptly in orientation.

And in addition, it has been found there are smaller fast changes to the geomagnetic field that correlate with cyclic no physical explanation climate change. Just like the Younger Dryas abrupt climate change at which time there is the largest geomagnetic excursion in the geomagnetic record in the last 2000 years.

So it is a fact observationally that the geomagnetic field strength and geomagnetic field orientation is changing cyclically and rapidly, driven by something.

The geomagnetic paleo data indicates that geomagnetic field is changing abruptly, just like I said above. The problem there is no physical explanation to cause cyclic abrupt changes to the geomagnetic field.
Is the geodynamo process intrinsically unstable?

Recent palaeomagnetic studies suggest that excursions of the geomagnetic field, during which the intensity drops suddenly by a factor of 5 to 10 and the local direction changes dramatically, are more common than previously expected. The `normal’ state of the geomagnetic field, dominated by an axial dipole, seems to be interrupted every 30 to 100 kyr; it may not therefore be as stable as we thought.

We have investigated a possible mechanism for the instability of the geodynamo by calculating the critical Rayleigh number (Rc) for the onset of convection in a rotating spherical shell permeated by an imposed magnetic field with both toroidal and poloidal components.

Recent studies suggest that the Earth’s magnetic field has fallen dramatically in magnitude and changed direction repeatedly since the last reversal 700 kyr ago (Langereis et al. 1997; Lund et al. 1998).

These important results paint a rather different picture of the long-term behaviour of the field from the conventional one of a steady dipole reversing at random intervals: instead, the field appears to spend up to 20 per cent of its time in a weak, non-dipole state (Lund et al. 1998).

One of us (Gubbins 1999) has suggested that this is evidence of a rapid natural timescale (500 yr) in the outer core, and that the magnetic field is usually prevented from reversing completely by the longer diffusion time of the inner core (2 to 5 kyr).

This raises a number of important but difficult questions for geodynamo theory. How can the geomagnetic field change so rapidly and dramatically? Can slight variations of the geomagnetic field affect the dynamics of core convection significantly?

If so, is the geodynamo process intrinsically unstable?

What Caused Recent Acceleration of the North Magnetic Pole Drift?
The north magnetic pole (NMP) is the point at the Earth’s surface where the geomagnetic field is directed vertically downward. It drifts in time as a result of core convection, which sustains the Earth’s main magnetic field through the geodynamo process.

During the 1990s the NMP drift speed suddenly increased from 15 kilometers per year at the start of the decade to 55 kilometers per year by the decade’s end. This acceleration was all the more surprising given that the NMP drift speed had remained less than 15 kilometers per year over the previous 150 years of observation. Why did NMP drift accelerate in the 1990s?

Response to Comment on “Are there connections between Earth’s magnetic field and climate?, Earth Planet. Sci. Lett., 253, 328–339, 2007” by Bard, E., and Delaygue, M., Earth Planet. Sci. Lett., in press, 2007

Also, we wish to recall that evidence of a correlation between archeomagnetic jerks and
cooling events (in a region extending from the eastern North Atlantic to the Middle East) now covers a period of 5 millenia and involves 10 events (see f.i. Figure 1 of Gallet and Genevey, 2007).

The climatic record uses a combination of results from Bond et al (2001), history of Swiss glaciers (Holzhauser et al, 2005) and historical accounts reviewed by Le Roy Ladurie (2004).

Recent high-resolution paleomagnetic records (e.g. Snowball and Sandgren, 2004; St-Onge et al., 2003) and global geomagnetic field modeling (Korte and Constable, 2006) support the idea that part of the centennial-scale fluctuations in 14C production may have been influenced by previously unmodeled rapid dipole field variations.

Hatter Eggburn
Reply to  William Astley
December 6, 2020 12:25 pm

Hi William
What’s my horoscope looking like for the rest of the year?

William Astley
Reply to  Hatter Eggburn
December 6, 2020 4:25 pm

Great, Hatter Eggburn.

The future is super clear now. I see a great deal of excitement for you and everyone else, in your immediate future. Early next year.

Something that is really going to change everything. I heard, it is going to make the climate emergency go away. Shake things up in a good way. A real paradigm change.

Reply to  William Astley
December 6, 2020 1:50 pm

Ellis and Palmer (claim to have) solved the 100,000 year problem.

December 6, 2020 10:39 am

Precession striping in rock is old news.

Gordon Lehman
Reply to  Phil Salmon
December 6, 2020 11:53 am

This is eccentricity striping.

Reply to  Phil Salmon
December 6, 2020 12:25 pm

They aren’t claiming to have discovered precession layering. What they are claiming to have done is more accurately date it.

December 6, 2020 11:11 am

I am surprised that the various permutations of the Milankovitch Cycles are so reliable. For more than three objects the n-body problem is intractable.

How do they know the Milankovitch Cycle is so darn regular?

Reply to  commieBob
December 6, 2020 11:50 am

but numeric integration works very well. Currently, the orbits are determined using more than 500,000 objects [planets, asteroids, comets, etc]

Reply to  Leif Svalgaard
December 6, 2020 12:13 pm

Really? How wide does your data bus have to be to give you any accuracy at all?

John Tillman
Reply to  commieBob
December 6, 2020 12:25 pm

Milankovitch and shorter solar cycles are evident in layers at least back to the Eocene, for example:

Studies abound from nay paleoproxies around the world, as for instance on varves in Miocene lacustrine cores.

Earth’s axial tilt and the other rotational and orbital insolation cycles can surely change over time, as of course does the length of day.

Reply to  commieBob
December 6, 2020 12:26 pm

“The existence of resonances and small denominators led to the important question of stability in the planetary problem: do planets, in nearly circular orbits around a star, remain in stable or bounded orbits over time? In 1963, Vladimir Arnold proved using Kolmogorov-Arnold-Moser (KAM) theory a kind of stability of the planetary problem: there exists a set of positive measure of quasiperiodic orbits in the case of the planetary problem restricted to the plane. In the KAM theory, chaotic planetary orbits would be bounded by quasiperiodic KAM tori. Arnold’s result was extended to a more general theorem by Féjoz and Herman in 2004.” n-body problem, Wikipedia

Reply to  noaaprogrammer
December 6, 2020 12:49 pm

… quasiperiodic …

That’s the magic word.

Joel O'Bryan
Reply to  noaaprogrammer
December 6, 2020 12:56 pm

The large scale, long-term stability of our solar-planetary system has been controlled by the gravitational resonance between Jupiter and Saturn. Without a Saturn in resonance with Jupiter to keep Jupiter’s location stable, Jupiter would almost certainly have moved inwards to Mercury’s orbital location, and gravitationally crushed or kicked out the inner planets. We would NOT have been around to see it as it would have happened in the first 1-2 billion years (or less). Such a hot Jupiter scenario would have stopped any further biological evolutionary processes that created this planet and biosphere we have today.

Additionally, the fortuitous endowment of Earth with a large moon has stabilized obliquity transitions to a narrow range. With their no large moon, compare that to Venus’s crazy rotation, and to Mar’s geologic history of obliquity upsets to >45º to understand how important our Moon has been in keeping Earth’s spin alignment stable.

Our is a rare Earth indeed.

John Tillman
Reply to  noaaprogrammer
December 6, 2020 1:45 pm

An early planet between Saturn and Jupiter was voted off the system:

“New work reveals the likely original locations of Saturn and Jupiter. These findings refine our understanding of the forces that determined our Solar System’s unusual architecture, including the ejection of an additional planet between Saturn and Uranus, ensuring that only small, rocky planets, like Earth, formed inward of Jupiter.”

Hence setting up the Jupiter-Saturn resonance, and maybe contributing to the formation of Jupiter and Saturn’s big moons, ie the four Galilean satellites and Saturn’s Titan. Earth’s Moon is #5, beating out Europa.

John Tillman
Reply to  noaaprogrammer
December 6, 2020 2:43 pm

Sorry. Meant Saturn and Uranus.

Reply to  commieBob
December 6, 2020 12:53 pm

accuracy is good several million years back. And more objects have been included since I last looked:
“The JPL HORIZONS on-line solar system data and ephemeris computation service provides access to key solar system data and flexible production of highly accurate ephemerides for solar system objects ( 1036884 asteroids, 3695 comets, 209 planetary satellites, 8 planets, the Sun, L1, L2, select spacecraft, and system barycenters ). HORIZONS is provided by the Solar System Dynamics Group of the Jet Propulsion Laboratory.”
Currently, the orbits are good to one meter accuracy. Going back in time, the accuracy gets worse,, but still good enough for M Cycles some million years back AFAIK.

Janice Moore
Reply to  Leif Svalgaard
December 6, 2020 1:13 pm

… the orbits are good to one meter accuracy.


Thank you, Dr. Svalgaard, for all your helpful, patient, instruction here.

I hope your granddaughter’s college experience went (or still is?) very well. Can you believe it is already 6 years ago (IIRC) that you shared that she was about to attend the university? My theory about time speeding up (it really does! lol): each year becomes a smaller percentage of the time we have lived.

Take care.

Glædelig Jul!


Reply to  Leif Svalgaard
December 6, 2020 2:38 pm

She got her masters last year.
We are proud of her!

Reply to  Leif Svalgaard
December 6, 2020 2:43 pm

One meter accuracy is needed if you want to land an un-crewed spacecraft on Mars or on an asteroid or comet [as we can now do]

Janice Moore
Reply to  Leif Svalgaard
December 6, 2020 5:00 pm

CONGRATULATIONS!! Oh, that is, indeed, something to be proud of. 🙂

Thank you for letting me know. I did pray for her several times throughout the years…

Reply to  Leif Svalgaard
December 6, 2020 5:33 pm

Knowing the precise location of Mars over a short period of time is not the same as knowing the precise period of any particular Milankovitch cycle millions of years ago.

The limit of the precision of the data going into the numerical integration produce large variations in the output over various times scales. This results in a chaotic drift in the values of the g and s frequencies over tens to hundreds of millions of years within a specifiable chaotic region (see Laskar, this report). This chaotic behavior makes it impossible to produce an insolation curve for more than about 20 million years into the past (or future), and indeed makes it impossible to predict the value for the longest period modulators of precession and obliquity. In fact, for 200 million years ago there can be as much as a 40% difference between extreme possibilities in the periods of the beats between some of the combinations of g frequencies within their chaotic zones. link

Reply to  Leif Svalgaard
December 7, 2020 4:38 am

Janice Moore,
Though I share your observation that “each year becomes a smaller percentage of the time we have lived”, a good professor has pointed out the error in my thinking. He calls it the “Toilet Paper Roll ” effect. The thickness of the roll simply decreases ever more quickly as you near the end!

Reply to  Leif Svalgaard
December 7, 2020 8:38 am

@ Janice
” each year becomes a smaller percentage of the time we have lived.”
… but regretfully on the down side, each year becomes a greater percentage of the time left. I’ve just plotted it and it looks horrible curve form about 10 year down.
All the best and keep safe.

Janice Moore
Reply to  Leif Svalgaard
December 7, 2020 4:10 pm

Dear Tom,
Dear Vuk (good to “see” you :)),

Lol. Well…

I’d prefer to look at the metaphor and Vuk’s curve this way:

Our lives are a skein of beautiful, silk, kite string (my kite is garnet red silk), swiftly unrolling and

as the skein nears its end, the kite dances ever closer to the stars…

when the string is out, the kite is free, free to sail up, up, up, to…


Those who lose the kite are sad.

But, the kite is happy.

Or, another thought:

As the skein whirls round and dwindles down, the weary traveller holding onto it smiles, for the end of the klew is attached to


“… and one by one the stars will all go out and you and I would simply



(can’t recall artist/author, it starts, “If a picture paints a thousand words, then why can’t I paint you…”)

Yes. As George Carlin said (but meant differently), “We’re going away. ”

And we get to choose where we will go! 🙂

Choose heaven!

Take care, over there in the U.K, Vuk,


P.S. I give the mod permission to give my email address to anyone who wants to talk with me about this.

Janice Moore
Reply to  Leif Svalgaard
December 7, 2020 5:51 pm

*blush *


As the weary traveller gathers MORE thread on the skein, she or he smiles,
for the end of the klew is attached to Home.

Reply to  Leif Svalgaard
December 9, 2020 2:39 am

Janice, thanks.

Janice Moore
Reply to  Leif Svalgaard
December 9, 2020 10:44 am

Vuk 🙂

Joel O'Bryan
December 6, 2020 12:27 pm

“repeatedly plunged Earth into and out of glacial episodes during the last 2.7 million years.”

Last I heard, the quaternary period dates back to ~2.6 mya (2.588 ± 0.005 million years ago). Any geologists care to comment?

The Petrified Forest is a pretty cool place to visit if you’ve never been.
225 mya is ‘deep time” as you look at (petrified) pine tree logs that really are that old. Geological “deep” time is so hard for us to even fathom how much time that is and the changes that happened since then. It is basically why the late, great scientific-communicator George Carlin observed, “The planet has been through a lot worse than us. …we’re going away, pack your s#!& folks, we’re going away… the planet will shake us off like a bad case of fleas.”

Reply to  Joel O'Bryan
December 6, 2020 1:03 pm

The Ginkgo Petrified Forest in Washington State is another fascinating place to visit. I still have large pieces of petrified wood that I picked up there in 1952. (Nowadays, it is illegal to take any petrified wood from there.)

John Tillman
Reply to  noaaprogrammer
December 6, 2020 3:08 pm

Very cool, but a lot younger, from the Miocene Epoch, ~15.5 Ma.

John Tillman
Reply to  noaaprogrammer
December 6, 2020 3:12 pm

I also like this guy (or girl) from around the same time:

Janice Moore
Reply to  Joel O'Bryan
December 6, 2020 1:07 pm

Heh. I LOVE that George Carlin routine. 😄 It is accurate, thorough, and scintillatingly witty (except for his unfortunate habit of using the F word — that doesn’t ruin it, just makes one cringe from time to time).

Your quote, Joel O’B., is at about 3:55 in the below video (I no longer am allowed to post videos here — at least, every time I have asked how, the mod never answers…..).☹
George Carlin “Save the Planet” (youtube)

December 6, 2020 2:50 pm

I have read that the future is difficult to predict. It seems that the past is just as hard. No one seems to allow for any catastrophic events in the past that could change everything.

December 6, 2020 3:35 pm

“This core possesses cyclic sequences deposited in rivers and lakes that drained a volcanically active area. The youngest detrital zircons in each sediment layer likely record that layer’s depositional age, so the scientists dated those zircons in key layers to provide radiometric pinpoints at the core’s top and bottom.”

The one thing that makes me nervous about this quote is that in the radiometric dating world, it is known that “zircons are forever”. Now they are guessing that just because the core was in a volcanically active area, the zircons are themselves volcanic. The first problem with this is that if there are any zircons that are not volcanic, they will give a very erroneous age, much older than the depositional age.

Even if the zircons are volcanic, they can still be too old, often by an amount of 100s of kyr or even millions of years. Volcanic eruptions frequently disgorge material from the last eruption, or even from several previous eruptions. This phenomenon is even seen with the K-Ar clock in sanidines, which is a system much more easily reset than is the U-Pb zircon clock. So even with purely volcanic zircons, it’s possible to miss a few 405 kyr cycles. One must always be careful with zircons. The precision is great, but you need to know what exactly you are dating. Zircon ages must always be approached as being maximal ages.

December 6, 2020 4:29 pm

i was shocked to hear that the astrological calendars, and they paid detailed attention to these matters, of every ancient culture had 360 day calendars: Aztecs, Mayans, Caldeans, Hebrews, Chinese, Egyptians, Hindus, Entruscans, Phoenicians, Cathoginians (Greece), Totens (Rome), Babylonians….until @ 701 B.C. Something happened. And they all try to deal with it in different ways…the need to add 5 and bit days to the year. True???
(H/T Emmanuel Velikovky R.I.P.)

William Astley
December 6, 2020 4:39 pm

Hey someone above tried to insult me by asking for a horoscope because I said it is fact that the earth’s geomagnetic field is changing abruptly and cyclically correlating with the planetary temperature changes.

If we had not spent 20 years in the climate war, this scientific paradox would be solved.

More real data. Independent authors. Same conclusion,

Orbital Influence on Earth’s Magnetic Field: 100,000-Year Periodicity in Inclination

A continuous record of the inclination and intensity of Earth’s magnetic field, during the past 2.25 million years, was obtained from a marine sediment core of 42 meters in length.

This record reveals the presence of 100,000-year periodicity in inclination and intensity (William: Of the earth’s geomagnetic field_, which suggests that the magnetic field is modulated by orbital eccentricity.

The correlation between inclination and intensity shifted from antiphase to in-phase, corresponding to a magnetic polarity change from reversed to normal. To explain the observation, we propose a model in which the strength of the geocentric axial dipole field varies with 100,000-year periodicity, whereas persistent nondipole components do not.

The Gothenburg magnetic excursion is an unexplained large region of the earth’s surface where the geomagnetic field polarity reversed suddenly, reversed at the same time the planet abruptly cooled for 1200 years.
The Gothenburg Magnetic Excursion
Manifestation of the gothenburg geomagnetic field excursion in sediments on the northwestern Central Russian Upland

The Gothenburg Magnetic Excursion in a broad sense ranges from 13,750 to 12,350 years BP and ends with the Gothenburg Magnetic Flip at 12,400−12,350 years BP (= the Fjärås Stadial in southern Scandinavia) with an equatorial VGP position in the central Pacific.

The Gothenburg Magnetic Flip is recorded in five closely dated and mutually correlated cores in Sweden. In all five cores, the inclination is completely reversed in the layer representing the Fjärås Stadial dated at 12,400−12,350 years BP. The cores were taken 160 km apart and represent both marine and lacustrine environments.

The Gothenburg Magnetic Flip represents the shortest excursion and the most rapid polar change known at present. It is also hitherto the far best-dated paleomagnetic event.

The Gothenburg Magnetic Excursion and Flip are proposed as a standard magnetostatigraphic unit. (William: i.e. What causes the abrupt climate changes are abrupt changes to the geomagnetic field and this one that correlates in time with the Younger Dryas abrupt cooling period, 12,900 years ago when the planet went from interglacial warm to glacial cold for 1200 years.

The physical explanation for the YD abrupt climate change is the abrupt change to the geomagnetic field that takes 1200 years to return to undisturbed.

A paleomagnetic study of sediments at the Baranova Gora and Podol III/1 archaeological sites, located near Lake Volgo on the northwestern Central Russian Upland (56.9°N, 33.2°E), was performed. The paleomagnetic studies at both sites for the first time revealed the development of the Gothenburg geomagnetic excursion (dated 13000-12350 BP) in this region. This made it possible to specify the time interval when the Alleroed climatic phase started developing on the Central Russian Upland.
The Earth Palaeoclimate Response to Cosmic Rays Exposure During Geomagnetic Field Excursions

Steve Z
December 7, 2020 4:41 pm

It would seem that the 20,000-year precession cycle and the 40,000-year tilt cycle would have significant impacts on the climate.

For example, at present, the perihelion (closest approach to the sun) occurs in mid-January, which is summer in the Southern Hemisphere and winter in the Northern Hemisphere. This means that the seasonal variation of total insolation (a function of both solar distance and sun angle due to the tilt) is greater in the Southern Hemisphere than in the Northern Hemisphere. But the Southern Hemisphere is mostly covered by oceans, whose large heat capacity tends to damp out fluctuations in temperature. The Northern Hemisphere, which has much more land area, has a smaller seasonal variation in total insolation, although temperature variations are sharper over land than over the oceans.

Ten thousand years from now, the perihelion will probably occur in July, meaning that seasonal variation of insolation will be greater over the Northern Hemisphere than over the Southern Hemisphere. This would result in hotter summers (with the sun at both a smaller distance and a higher angle above the horizon) and colder winters (with the sun at a larger distance and a lower angle above the horizon). Due to the tendency of continental areas to cool off rapidly, there may be a period of glaciation in the far northern areas of Russia, Scandinavia, and Canada, which the summer sun may not be able to melt completely.

If a perihelion in summer coincided with a higher tilt of the Earth’s axis, then Northern Hemisphere winters would be even colder, due to a faraway sun at an even lower angle. This would accentuate the tendency toward glaciation in the far north. Glaciation would also tend to lower sea levels, which could result in a land bridge across the Bering Strait, which would prevent Pacific water from mixing with Arctic water. This could result in even further cooling of the northern coasts of Alaska and Siberia, while the southern coasts could actually become warmer, since Pacific water would not be mixed with Arctic water.

Of course, this assumes there are no other changes to the sun or volcanic activity on earth, which is extremely difficult to predict over thousands of years!

December 7, 2020 7:16 pm

So long as the sun is up in the morning. I have this theory it will be but it’s only based on supposition.

December 8, 2020 9:09 pm

I’m mostly interested in the connection between Earth’s climate and Milankovitch cycles over the past 420,000 years (as recorded at Vostok). Very long term climates over millions of years, as in this article, are less significant in this respect because continental drift changes the relative positions of the land masses adding another variable – which we don’t need!

1. I’ve often seen the various curves comprising Milankovitch but never the equations that produce the numerical results. Anybody help?

2. Solar cycles seem to vary Earth’s temperature by maybe +/- 0.2 C, but average over several cycles at close to zero, and so would appear to be insignificant.

December 8, 2020 9:14 pm

Dr Leif Svalgaard
No-one has shown that CO2 has any influence on temperatures; “should err on the safe side!” gives the game away. The reason it can’t be shown is that ALL gases are so-called “Greenhouse Gases” – they all absorb heat, regardless of whether they can also absorb IR – and so, at very minor CO2 levels, it is a very minor absorber of heat.

December 8, 2020 11:46 pm

A very nice piece of exact science, solving a difficult problem in palaeontology and geological dating.
I didn’t know that the Triassic dinosaurs first gained a foothold at high latitudes, before conquering the tropics also.
Their warm-bloodedness, bird-like one-way efficient breathing and fur or feather like coats no doubt helped in cooler regions.
I wonder which creatures held out in the tropics before the mid-late Triassic?
Maybe the Permian mammal-like Therapsids, together with fellow Thecondont crocodilians?
As always the closer you look the more interesting stories you find.
Like a world 15 degrees C hotter than today and life flourishing from pole to pole.
Gotta stop that 1.5 degrees at all cost!
A sad day indeed when political puritanism strips science of all its childlike curiosity and innocence.

December 9, 2020 2:33 pm

What are the references to the influence of past climate on today climate.
How much the last glacial era influences climate today; The question is in short: if it did not existed how it would be today’s climate?

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