The Homeric Minimum – climate change of the past

Posted: July 24, 2020 by oldbrew in climate, History, Natural Variation
Tags: , ,

World climate classification map [credit: Beck, H.E., Zimmermann, N. E., McVicar, T. R., Vergopolan, N., Berg, A., & Wood, E. F. @ Wikipedia]

The Homeric seems to have started about 2400 years before the Spörer (or Maunder?) Minimum, which may be its more recent equivalent. Researchers have found evidence of a ‘2400-year cycle in atmospheric radiocarbon concentration’ – for example, see here.

Much of the article below appears to have come from Wikipedia, but there it also says:
“Variations in the solar output have effects on climate, less through the usually quite small effects on insolation and more through the relatively large changes of UV radiation and potentially also indirectly through modulation of cosmic ray radiation. The 11-year solar cycle measurably alters the behaviour of weather and atmosphere, but decadal and centennial climate cycles are also attributed to solar variation.”

– – –
The Homeric Minimum is a grand solar minimum that took place between 2,800 and 2,550 years before present, says the Grand Solar Minimum website.

It appears to coincide with, and have been the cause of, a phase of climate change at that time, which involved a wetter western and drier eastern Europe.

This had far-reaching effects on human civilization, some of which may be recorded in Greek mythology and the Old Testament.

The Homeric Minimum is a persistent and deep solar minimum that took place between 2,800 and 2,550 years before present, starting around 830 BC and resembling the Spörer Minimum.

This minimum is sometimes considered to be part of a longer “Hallstattzeit” solar minimum between 705–200 BC, that also includes a second minimum between 460 and 260 BC. The Homeric Minimum however also coincided with a geomagnetic excursion named “Etrussia-Sterno”, which may have altered the climate response to the Homeric Minimum.

The Homeric Minimum has been linked with a phase of climate change, during which the Western United States, Europe and the North Atlantic became colder and wetter although the eastern parts of Europe appear to have become drier. This climate oscillation has been called the “Homeric Climate Oscillation”.

Human cultures at that time underwent changes, which also coincide with the transition from the Bronze Age to the Iron Age. The climate fallout of this prolonged solar minimum may have had substantial impact on human societies at that time.

A variety of phenomena have been linked to the Homeric Minimum:

Continued here.

  1. oldmanK says:

    What choice of dates!
    830bce is an Eddy cycle peak; between 460 and 260 ie circa 300bce is the Eddy cycle root.

    Archaeologically, Homer is a late-comer and his work is based on more ancient lore, from Mesopotamia via other routes.

  2. oldbrew says:

    oldmanK – 830 bce is about 2800 years ago, so subtracting 400 for a 2400 year span takes us back to about 1620. The Maunder Minimum was later that century, and the Spörer Minimum ended about 1550 according to Wikipedia:

    The Spörer Minimum is a hypothesized 90-year span of low solar activity, from about 1460 until 1550, which was identified and named by John A. Eddy in a landmark 1976 paper published in Science titled “The Maunder Minimum”.[1] It occurred before sunspots had been directly observed and was discovered instead by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity. It is named for the German astronomer Gustav Spörer.

    The 2400-year cycle is also based on carbon-14 data, as per the link at the top of the post (intro).

  3. oldbrew says:

    Btw that Wiki page on the Spörer Minimum also says the ‘Modern Maximum’ dates were 1950-2009 😎

    See also:

  4. oldmanK says:

    oldbrew: – 830bce, and particularly 300bce are the last two dates in the Eddy cycle series where the respective historical events – for me – were still somewhat unknown. Thus now we can place a series of Eddy cycles, roots in particular, from 8k2BP (6195bce) to today, that are all linked to events, some quite (very) cataclysmic.

    One can see these dates in this paper specifically fig4 B, C, D, in the spikes and abrupt changes.
    One in particular is the fig4 B North atlantic ice rafting at 7200BP. Then note same spike in the subject paper (link ) fig1 at same date.
    More: in same fig1, where it says 5400yr there are actually three spikes. The first is ~5200 which is an identical event to the 7200 in the ‘North atlantic ice rafting’. and a third at ~5500BP (3550bce) which is a spike in the C/N (the same time/date the Sahara changed to dry).

    Comparing proxies is a case were the ‘whole’ is greater that the individual parts. It is also not just ‘solar cycles’. The effect on earth and humanity was ‘substantial’.

  5. oldbrew says:

    Somebody can’t count here…

    Evidence of 3,000 BC calamity
    Tim Radford
    Thu 16 Dec 2004

    Evidence from the Peruvian Andes, the snows of Kilimanjaro and tree rings in Britain all point to a calamitous episode of climate change 5,200 years ago.
    – – –
    That would be about 2400 years before the Homeric Minimum, i.e. near 3200 BC.

    Another quote:
    “Something happened back at this time and it was monumental,” Prof Thompson said. “But it didn’t seem monumental to humans then because there were only approximately 250 million people occupying the planet, compared to the 6.4 billion we now have.

    “The evidence clearly points… to similar changes occurring to today’s climate as well.”

    Climate is influenced by solar output and atmospheric chemistry, and small changes can have dramatic effects.

    Note this is, or was, the Guardian.

  6. oldmanK says:

    oldbrew; thank you for that piece. It is dated to 2004; it is near a decade before my coming to similar conclusions (ie not being fed my own stuff back).

    The tree ring date is nearer to 3195bce. It is referred as the 3200bce event. Climate wise as the Piora Oscillation. It is near enough to an Eddy cycle root.

    Was it ‘monumental’? Geologically it appears in an orientation change of some 47degrees in the horizon sunrise point on the equinox day of the megalithic calendar. Most calendar sites were abandoned then. That was also the start of large scale human abandonment. March 1st 3202bce was a Kepler Trigon ( ).

    There remains the question of what was the primary trigger; the state of the sun in its cycle?, planetary alignment? — ?

    All dates might have an error spread.

    Another curious case regards ‘Otzi the Iceman’. Most opinion on evidence say he was killed by an arrow. But there is no explanation for his being fast-frozen that prevents some decay. The find site flora included species that grew in warmer weather. The dating range from 3230 to 3100bce. An abrupt elevation change?

  7. oldbrew says:

    I have some ideas re. this, maybe a future post:

    Responses of the basic cycles of 178.7 and 2402 yr in solar–terrestrial phenomena during the Holocene

    I. Charvátová and P. Hejda

    Note the ‘2402 yr’. However, the actual dates cited don’t match the dates discussed above.

  8. ivan says:

    I find most articles found on Wikipedia to be suspect especially when they don’t fit the ‘settled science’ agenda.

    I have to question why anyone would put anything on there knowing that any idiot with an agenda can edit it out of all recognition.

  9. oldbrew says:

    This study was quoted in a WUWT article on the HM a few years ago

    Published: 06 May 2012
    Regional atmospheric circulation shifts induced by a grand solar minimum

    ‘We conclude that changes in atmospheric circulation amplified the solar signal and caused abrupt climate change about 2,800 years ago, coincident with a grand solar minimum.’

  10. oldmanK says:

    ivan says: July 24, 2020 at 9:16 pm
    “I find most articles found on Wikipedia to be suspect especially when they don’t fit the ‘settled science’ agenda”

    They are equally suspect when they do. Wiki is a good source for links for one to follow. But I don’t take it for granted. Go to the source; the Net is a very good vehicle for sourcing.

  11. oldbrew says:

    GWPF Xtra
    24 July 2020

    Roman Warm Period Was 2°C Warmer Than Today, New Study Shows

    For the first time, we can state the Roman period was the warmest period of time of the last 2,000 years, and these conditions lasted for 500 years,’ said Professor Isabel Cacho at the Department of Earth and Ocean Dynamics, University of Barcelona.
    – – –
    Were those Roman chariots fuel powered? 😆

  12. carol says:

    Just a point to bear in mind. Dates have been changed by IntCal2013 and the 3200BC event is now something like 3500BC. The same goes for the low growth tree ring events in late third Millennium, raised to 2500 instead of 2345. The reason why is that it is a composite methodology that includes inexact methods such as speleology. One can see it is wrong as it does not fit into the tree ring data where extreme low growth events are captured for posterity.
    I have often thought the Oetzi ice man being frozen around 3200BC was evidence of a sudden cooling. The same goes for the mountain glaciers in the Andes at the same time, such as Quelcayya. Lonnie Thompson showed that warmer weather plants were frozen in situ, revealed when the ice melted. However, in both cases it is worth pointing out that glaciers move. Hence, Oetzi was graduall moving with the ice down the mountains from an original much higher location. That implies it was even more warmer and at a greater altitude. In the Roman period the mountain passes through the Alps were ice free. A matter of fact. Hannibal didn’t take his elephants across the Alps for nothing. At the same time a recent genetic study has shown that some of the mountain valleys in Switzerland harboured groups of novel DNA people suggesting the survival of some ancient tribes which can only be as a result of a general cool weather situation in the Alps. The warm periods appear to be exceptions.

  13. Paul Vaughan says:

    OB: Are you able to list the PRECISE (need ALL the decimal digits – DON’T leave any out) orbital periods Charvatova uses for J, S, U, & N to get 2402?

    Let’s get this RIGHT out in the open and burst some bubbles.

    (You may not be able to guess where I’m going with this.)

  14. oldbrew says:

    PV: It could be nearer to 2403y, sometimes at least.

    See Fig.4 here

    Click to access prp-2-21-2014.pdf

    E.g. 4647+159 or 4756+50 = 4806 = 2403*2
    Also see:

  15. Paul Vaughan says:

    Check the calculations OB.
    With Seidelmann’s (1992) numbers you’ll find something 30 years off Charvatova’s mark.

    Hiding the assumptions is for the UN and NOAA.

  16. oldbrew says:

    A post related to this should appear before long.

    S. S. Vasiliev and V. A. Dergachev: 2400-year cycle in atmospheric radiocarbon concentration

  17. Paul Vaughan says:

    Yes we studied that many years ago. 2300 years fits Halstatt better than 2400 years. I explored it firsthand years ago with advanced wavelets (the ones that subsume TC’s methods) after looking at TC’s work.

    I’m going to repeat this because it’s important:

    Can someone please list the PRECISE periods used in Charvatova’s 2400 year model? If someone can dig up those numbers (I have too many other things on my plate) I’m going to run a sensitivity analysis RIGHT AWAY.

    Does anyone remember Pierce Corbyn’s 132 year lookback cycle? Remember that I locked that to the Climate Casino (along with JEV). I didn’t point that out explicitly.

    And does anyone realize that we just hit a MAJOR celestial point this year? We haven’t even discussed that. Exactly 96 years ago something extreme happened between 9 year and 11 year sunspot area asymmetry. At the next critical point the stock market crashed. At the next: WWII started. At the next: the Korean War.

    Please: Someone find Charvatova’s PRECISE orbital periods (with ALL the decimal digits).

    Not seeing the forest for the trees is still a fatal obstacle in the discussions we have here. It’s why I usually boycott discussion of event series. There are already enough people obsessing over events, but there’s a shortage of people able to deduce the attractors that set the windows of opportunity for triggers.

  18. Paul Vaughan says:

    Orbital Periods Used in Charvatova’s “2400 year” papers:

    J: 11.__________ years
    S: 29.__________ years
    U: 8_.__________ years
    N: 16_.__________ years

    Someone fill in the blanks with ALL the decimal places please. I’ll make it worthwhile (“Climate Casino” extension) to go as far as contacting her for the precise info.

    If no one can fill in the blanks, that’s also delectably informative.

  19. oldbrew says:

    See Charvatova’s figure 4 here: SIM diagrams.

    Click to access prp-2-21-2014.pdf

  20. oldmanK says:

    Re carol says: July 25, 2020 at 6:38 pm

    A few comments:
    A common chronological datum is important. In my above post it was mainly tree-rings/C14 as in IntCal13. However, how that is tied down remains subject to review. Now that is where a different method of time measurement can be useful. The Eddy cycle can do that for it can be tied down to the past two millennia. As it happens, the Eddy cycle, particularly the roots, when extrapolated back in time, do corroborate certain dates. 3200bce is one, 2345bce is near another. So are 6200bce (the 8k2BP event), 5200bce and 4375-a near-. All dates are linked to events and can also be found indicated in proxies.
    Eddy cycle peaks are linked to warming. The MWP, the RWP, 2100bce is heading to warm.

    Otzi the ice-man has been linked to 3200bce (see pg2 ). The find place -pg3- is a sediment trap, ie no movement, as also said elsewhere .However there are details to consider. Site is at latitude ~47degree.

    Quelccaya is inter-tropics. Soft bodied plants found, were fast frozen, but dating is variable. There are several different materials/dates.

    There is evidence of a sudden cooling event. But when and where? GF Dodwell, the first to risk his reputation (and I support him) said 2345bce was an earth tilt change from low the >23.5deg. That means an abrupt temp decrease inter-tropic, as per what happened to Quelccaya; a surge in ice cover.

    Otzi’s case is different. Comparison of ice-cores from polar and equatorial do correlate to the Eddy cycle, but show different events. While at 2345bce they show a spike in polar temps and a downward trend in equatorial, at 3200bce they show a global downward trend. However other proxies and geological/archaeological evidence also show great upheaval at 3200bce, thus the temp variation was likely a resulting effect. It appears there are trigger point near the Eddy cycle inflection points.

  21. oldbrew says:

    More on the ~2300 BC Abrupt Climate Change: Tree Rings, Hekla 4 & the Irish Annals
    from: Prof Mike Baillie

    However, irrespective of the pine issue, it is clear that some interesting things took place in the 24th century BC. The evidence is indelible and is not going to go away. I would suggest that this is a classic “marker date” i.e. a date which will show up on a regular basis in studies of various kinds.,extremely%20narrow%20band%20of%20rings%2C%20beginning%20in%2023

  22. oldmanK says:

    oldbrew: Prof M Baillie’s paper is relatively old, from 1995. Dodwell’s work then was still unknown; he also picked the 2345bce date from a completely different perspective (note: Dodwell applied maths to existent data, not to create a speculative model). Baillie was right, that date did turn up in many proxies. He also came up with a later date, 4375bce which at that time was completely unconnected with any events. This paper below link, in the C/N ratio fig 4 C, of 20 years later, gives the full range of corroborations. The 3200bce – and ~5200 can be seen in B (% HSG) as very large abrupt swings. See

  23. Paul Vaughan says:

    OK: No one can fill in the blanks …so let me just assert: There is no “2402”.

  24. Geoff Sharp says:

    Evidence of a possible solar downturn at 3200 BC is very interesting. To my knowledge no intcal record from any period suggests this. The planetary positions suggest there should be a LIA type cluster at 3200BC ( 4627 years before the Sporer Minimum)

  25. oldmanK says:

    Geoff Sharp: IntCal13 has a major disturbance at 3200bce. This was also one of Prof Baillie’s identified tree-ring – at 3195bce – . In the link in my earlier post it is an abrupt change in the %HSG record. That particular record I associate with geologic events more that anything else in a direct manner. To which there is evidence from roughly dated man-made structures. The %HSG has an earlier similar abrupt change at 5200bce, which is again seen in the man-made structures. However here it is used it to date the structures. (The archaeological side seem to agree).

    The interesting point is that 5200, 4375, 3200, 2345 occur near to Eddy cycle roots (as extrapolated back from the past two millennia). The 5200 and 3200 appear quite precise, the others as somewhat earlier trigger points for major events.

  26. oldbrew says:

    Charvatova’s three ’50-year’ trefoils do repeat every 2402-2403 years, according to Arnholm’s solar simulator software. Whether they appear anywhere else is another question. Presumably not or she would have found them?

    The very long, regular cycle of 2402 yr represents a repetition of the exceptional, nearly 370 yr-long interval of
    trefoil solar motion.
    – from the PRP paper

    Click to access prp-2-21-2014.pdf

    Btw if we call the ’50-year’ periods 2.5 J-S each (3 loops, 2 arcs as per the graphics), then the two disordered between them are 5.5 J-S each (5 loops, 6 arcs) and the sum is 18.5 J-S (3*2.5 plus 2*5.5) = 1/4 of a Dansgaard-Oeschger cycle (74/4 = 18.5), or 367.5 anomalistic years.

  27. Geoff Sharp says:

    OldmanK, can’t see the 3200BC dip in any of the INTCAL series…please post a plot/graph to support your statement.

  28. Geoff Sharp says:

    Oldbrew, there is no repeating 2400yr etc pattern that repeats across the Holocene…FFT type analysis might suggest this pattern but is not complete. Think about it, if the pattern repeats it must mean the outer 4 planets must align again in the same position every 2400 doesn’t happen.

  29. oldbrew says:

    GS — Well, for something that’s not supposed to exist it gets a fair amount of attention.

    Impact of the ~ 2400 yr solar cycle on climate and human societies
    Posted on September 20, 2016 by curryja
    *by Javier

    What Charvatova shows is the solar motion repetition. Let me put another post up with perhaps a new way of looking at it.

    Some call it a quasi-cycle as it can go +/- 200 years or so from the 2400 year figure, but the 14C data is there to see, or so we’re told.

    A Probable Approx. 2400 Year Solar Quasi-cycle in Atmospheric Delta C-14

  30. Geoff Sharp says:

    Chavatova’s work is ground breaking but simplistic. Instead of observing circle drawings the detail of the circles needs to be understood. The exact outer planet angles need to be plotted to see the underlying detail.

  31. Geoff Sharp says:

    Oldbrew…the planets do not repeat their positions every 2400 years…show me the evidence.

  32. Geoff Sharp says:

    Oldbrew, your +/-200 year statement holds the key…the 4 outer planets repeat their positions every 4627 years…BUT a similar but not as strong alignment does occur at around 2100 years from the start of the cycle. This leaves a 2400 year gap to the start of the next cycle….you find many papers stating 2100 and 2400 year cycles but the real cycle is 4627 years with a player not quite in the centre

  33. oldbrew says:

    This one starts from 208 AD as mentioned in the PRP paper (2611 – 208 = 2403)
    The planet orientations are about 120 degrees different.

  34. oldbrew says:

    Bear with me as a related new post is in the pipeline.

  35. oldmanK says:

    Geoff Sharp: First link below is IntCal13 from pdf put next to each other in sequence. Used to high-light ‘disturbance’ points.

    Next is same used to correlate chronologically with other proxies:
    At bottom is a test – not explained and never quite finished- to indicate that certain proxy chronologies are out of step with others (another Gisp2 trace). For the present matter it shows that IntCal13 disturbances match chronologically with other proxies.

  36. Paul Vaughan says:

    OB: Get the EXACT periods Charvatova uses for J & S (ALL decimal places). Nothing else will do.

    GS: The math is simple. OB’s avoiding my request for the model parameters. I already have the algebra worked out. All I need is Charvatova’s model parameters for comparison with Siedelmann (1992). Maybe you can beat OB to it. Do you see anywhere in the 2000 &/or 2014 articles a statement of what model she used? I have model parameters for one of her much older papers and the parameters are nowhere near the parameters OB uses (which are based on Seidlemann (1992)).

    Gentelmen: Let’s not turn this into a game. Just get me the exact parameters and you’re going so see QUICK action.

    GS: “2400” isn’t about 4-way conjunction — it’s about nested slip cycles. Here’s a scenario: Imagine you have a block of cheese. You make multiple equally spaced perpendicular cuts with a sharp knife on 2 perpendicular axes (perpendicular to the edges of the block). Then someone accupunctures through the block obliquely. HOW MANY LITTLE CUBES ARE ON THE NEEDLE?

    This is DISCRETE math. There’s NOTHING controversial about the methods. It’s all strict logic.

    But just imagine Seidelmann & Charvatova cut the cheese by a different model. Then the thing to do is put the 2 sets of calculations side-by-side. Decisions don’t even have to be made. There’s just this thing sitting beside that thing. People can simply observe how they differ.

    I gave this cheese-cutting problem in a math course I taught years ago. None of the students even had a clue how to solve it. The top student (who was scoring in the high 90s towards 100) needed a LOT of clues and tips. Finally I gave a really good clue and he solved it. The purpose of the exercise was to teach the students about math anxiety experienced by their students (these were education students who were going to become math teachers).

    A shitty math education system is the ROOT of the West’s current problems. The Chinese math education system produces VASTLY superior outcomes. The deficit is dangerous for BOTH the West and China.

  37. Paul Vaughan says:

    adding 2 more notes:

    I’m not challenging “2400” (a crudely symbolic number) qualitatively. I’m highlighting quantitative sensitivity to minor parameter tweaks with qualitative features held constant.

    No one ever states Arnholm’s model parameters, so the Arnholm model is comparatively useless. In order to do careful discrete taxonomy and classification of pattern, we need comparisons. A common error we still see in western climate discussion is persistent inattention to geophysical patterns aliased from discrete switching. Can someone please define the parameters of the Arnholm model? Probably no one has the mean elements summarized properly.

  38. oldmanK says:

    Re oldbrew says: July 28, 2020 at 5:12 pm

    A couple of comment on the link from the curryja site, namely fig2.

    In fig2 curve ‘d’ says “(d) strong increases in iceberg detrital discharges (red curve, inverted; Bond et al., 2001) “. This info from Bond 2001 paper has two important markers as reproduced in the link in my earlier post. The points at 5k2 and 7k2 show marked disturbances and are near spot-on on the Eddy cycle roots (which is mentioned but not reproduced in fig 2). I linked the two dates to geological/seismic disturbances, both from abrupt and large changes in calendar orientations (tectonic rotations), and also as evident in Mediterranean as two distinct layers of sapropel at those two dates. See

    Another point in fig 2 is curve ‘a’ obliquity. As presented it is misleading. The scale has been blown up to partly match curve ‘b’ while completely ignoring the cliff-edge at 11,000. It goes back two centuries to the calculations of JN Stockwell for the secular change in obliquity. Other evidence shows that it is a minor component of the total obliquity changes. Those other changes appear at 4735bce, 3550, 2345. An earlier possible (based on ice core comparisons) was the 6200bce and a later one that was very elusive. It is the 7k7 yr (5k7bce) event in fig3 (I have found that date elsewhere too).

  39. oldbrew says:

    Re Dansgaard-Oeschger (1470 anom. years) and 27 U-N:

    27 U-N = 4627.967y
    233 J-S = 4628.553y

    85 D-O = 6290 J-S (85*74)
    6290 / 27 = 232.963 J-S = 4627.818y
    (27*233 = 6291 J-S, one more than 85*74)

    85 D-O / 52 = 2402.905y
    – – –
    89*27 = 2403
    89*52 = 4628