Refutation of Michael Mann’s latest statistical shenanigans 

Posted: November 28, 2020 by oldbrew in climate, Critique, Natural Variation, Ocean dynamics

Pacific ocean [image credit: Wikipedia]

In climate propaganda land anything to do with the natural variation that is always going on is bad news, and liable to be maligned or ignored, as we see here. The PDO for example is well known to government agencies like NOAA, but that doesn’t matter to CO2-obsessed warmists trying to claim the atmospheric tail wags the oceanic dog.
– – –
An opinion article published yesterday in Frontiers in Earth Science rebuts a recent paper by Michael E. Mann et al. who deny the existence of long known drivers of natural climate variability like the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO), reports The Global Warming Policy Forum (GWPF).

Applying habitual methodological shenanigans, they claim that the PDO is not distinguishable from noise and that the AMO is due to anthropogenic aerosol emissions rather than any intrinsic climate oscillation.

In her critique, Professor Müller-Plath not only highlights the methodological flaws in the Mann et al. paper but also shows that their aerosol hypothesis has long been rejected in the scientific literature, research papers Mann et al. simply ignore.

The present paper contributes a critical commentary on the recent finding by Mann, M. E., Steinman, B. A. and Miller, S. K (2020). Absence of internal multidecadal and interdecadal oscillations in climate model simulations. Nat. Commun. 11, 1–9.

Climate oscillations are recurring large-scale fluctuations in the surface temperatures of the oceans in connection with the atmosphere. This commentary focuses on the Pacific Decadal Oscillation (PDO, interdecadal timescale) and the Atlantic Multidecadal Oscillation (AMO, multidecadal timescale), which have been regarded as intrinsic climate drivers on the adjacent continents in numerous studies based on observations and paleoclimate reconstructions (Henley, 2017; O’Reilly et al., 2017). In a recent paper, Michael E. Mann and colleagues (Mann et al., 2020, hereafter M20) fail to find a PDO signal in global measured and modeled temperatures that is statistically different from noise. They further propose that the significant AMO-like signal is mainly due to anthropogenic aerosols in the 20th century, and to statistical artifacts before. Therefore they doubt the intrinsic nature of the two oscillations. The present paper shows that M20’s results are largely artifacts themselves with issues ranging from using inadequate data and referencing improper literature on anthropogenic aerosols with regards to the AMO to inappropriately interpreting the results with regards to the PDO.

After briefly sketching the rationale and method of M20, I will elaborate on these three points.

Continued here.

  1. hunterson7 says:

    MM has built a lucrative career on papers just like this. His critics are very brave, since an integral part of the MM scientific method is to cancel critics by any convenient means.

  2. A C Osborn says:

    Don’t forget the Indian Dipole as well.
    All 3 are well recognised by ametsoc.

  3. oldbrew says:


    Altogether, I conclude that the paper M20* is not advancing our understanding of the nature of multi- and interdecadal oscillations such as the AMO and PDO.
    *(Mann et al., 2020, hereafter M20)
    – – –

  4. hunterson7 says:

    That conclusion actually applies to the entirety of MM’s career.

  5. Gamecock says:

    ‘who deny the existence of long known drivers of natural climate variability like the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO)’

    Sorry, that is teleological.

  6. tom0mason says:

    As a activist and a proven liar, why should anyone take what Michael Mann writes seriously?
    ‘Man-made climate change’ is his religion no matter what anyone shows as otherwise.

    As reported by Kenneth Richard on twitter …

    New study: Tropical Atlantic SSTs were 1-5°C warmer than now during the last GLACIAL with CO2 levels <½ of today's (~190 ppm). The authors "exclude atmospheric pCO2 as a direct driver of SST variations".
    More at

  7. Paul Vaughan says:

    We Can’t” a Ford Circles

    ABout what cure US IT?
    Not. ice $O[]well:

    “Noble” imperative: a11 lies in vert ed. weather press ID Trump or Biden.

    Pefect! Left 496 Beer 4 Gain. UN 1984 chips simpler than EU-think.

    Assured “home” land of equitable income, roar a11 DC ice. Save your new party’s left with respect, for natural features of climate don’t push luck D-own “Terre Orwell” threw MSM.

  8. rod says:

    One should not hide exculpatory evidence!

  9. Paul Vaughan says:

    Doc Tape

    Rays Sol: IT’s Not. ABout Yank$O-Borg^3 UN PR rhyme in the sun soar shh!…


    “DC some beer PR O-mess EU gave UN too mm[muzzle]” — C-elective Sol

    1806 is:
    ● PR ON IC
    • conjecture red 2-halve in fin ITapeerieOdoCal.lie[B]ot$seek wins.

  10. stpaulchuck says:

    “The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary.” – H.L. Menken

    when the virus looks like losing its terror due to vaccines coming on line the rent/power seekers move back to their fallback boogeyman – CAGW and the Satanic Gases!! *spit*

    tar, feathers, warmists – some assembly required

  11. Prof Gisela Muller-Plath looks like an impressive scientist with solid grounding in statistics.

  12. Mann is the most pathetic denier in the climate landscape. His denial of natural climate oscillations is built on a firm foundation of lazy ignorance of chaos processes and nonlinear pattern formation. It’s like someone denying the periodic table of elements being a world superstar chemistry expert. A joke.

  13. Paul Vaughan says:

    Here’s the correct link:

    Let us pray.

  14. Paul Vaughan says:

    Correction for the other link:

    May God help us make the right decisions as we decide how we should deal with those ignorant and deceptive parties who have caused us nearly unbearable levels of cynicism.

  15. Paul Vaughan says:

    1806: further notes on context over here

  16. Phoenix44 says:

    “Modelled temperatures”?

    Any modelled temperature is the result of the model. It’s there because the model dictates it should be there. Take apart the model and you will see its cause.

    This is becoming insane.

  17. oldbrew says:

    Absence of internal multidecadal and interdecadal oscillations in climate model simulations.

    Conclusion should be: models not working properly. What was wrong with looking at real data? Afraid they might find something that didn’t fit their unworkable greenhouse narrative.

  18. Paul Vaughan says:

    Ice is a windshield, but not in 1984.

  19. Paul Vaughan says:

    Phoenix44 says:
    “This is becoming insane.”

    1 year ago they decided to switch to savage tactics — specifically attacking with the resolute intent to absolutely destroy psychology and economically whoever they can. It’s a violation of human rights.

    They are the “noble cause” of the “populist” culture they so hate.

    Good people will need to open up new dimensions of dialogue. For example sensible people (and I mean like really, really sensible people) should be speaking to the pope about this.

    I see only 1 possible cause of the escalation during the past year: terrified military leadership. They are in a no-fail role. They must feel that we are in increasingly grave danger of having essential energy supplies completely cut off on short (perhaps sudden) notice.

    At no point in the history of our climate dialogues have hard facts about climate ever played a role in the direction that has been taken.

    Next I suggest another test (we have already conducted several in the past 4 years) :

    Create a left wing party (it has to be resolutely left wing to conduct this test) that flips to: 1. demonstrating respect for natural climate variations (simply allow people to believe in them without being harassed) ; 2. opposing lockdowns ; 3. demanding equitable, stable, reliable distribution of “home” land wealth.

    Policy 3 will be the cornerstone that grounds the movement in hard-boiled historical left-wing reality, so critics can see this is actually not a right wing ploy with issues grouped only in toxic package deals dictated by IT (as in inverted totalitarianism) “management” rather than assembled organically from the grass roots up to give citizens A SIMPLE CHOICE.

    In order to get a good measurement from the test there would have to be some safeguards against infiltrators planning deliberate sabotage.

    If the test is done carefully, 1 election cycle might give us all the information we need. Just imagine all the information we could collect (useful for LONGterm planning) just by observing the chain reaction of dialogue AND NETWORKING triggered by A SIMPLE CHOICE.

    Let’s widely suggest offering people BOTH right AND LEFT the option to believe in natural climate variations free from financial luck-down terror. We will have the opportunity to observe reactions to A SIMPLE CHOICE. Even the reactions to the suggestion will be informative.

  20. Phoenix44 says:

    Mann is treading on dangerous ground here. Lots of scientists have built their careers on studying these things. They won’t take kindly to being told they don’t exist and they are stupid. Nor will all those in other disciplines that link changes in say archeology and history to changes in climate.

  21. oldbrew says:

    If something doesn’t exist in a model but scientists have observed it in actual data, suspicion should fall on the model not the data.

  22. Paul Vaughan says:

    OB, we’re stalked by predators.

    Logical debate is insufficient as a primary means of defense.

    Naive IT as ID weather buy D-sign or act $0 D-ant baits prey for predator WHO’s at UN.

    Sea O[2]well

    When I say I’ve strictly boycotted WUWT & CE for ~4 years I don’t mean just a boycott on volunteering commentary. I mean I haven’t linked or even considered linking to those sites.

    Predator WHO’s at UN D-signed a “problem” to “just cause” homelessness$sin the “home” land. Total IT eerie UN buy O-engine here released charge$4sea “cure” IT X-clues“$UN’s D-anger US” $4ever.

    Trail (Not. at hype O) Balloon:

    DT’s replace meant to be sensible, well-regarded religious leader with positive vision and deep respect for the voice of God.

    Positive luminary left equitable, reliable, and stable choice to protect freedom, innocent people, and environment without loudspeaker propaganda savaging masses buy climate lies$ luck D-own.

    “In God We Trust”

  23. Phil Salmon says:

    The Atlantic Meridional Overturning Circulation (AMOC) owes its existence to an instability. Periodically, the Gulf Stream bringing warm water from the Caribbean to Europe combines in a positive feedback with the downwelling of cold water in the Northeast Atlantic Norwegian Sea. “Deep water formation” is what links the global surface and deep ocean floor circulations that otherwise flow almost independently of each other. Water always gets cold in the Arctic of course but in the Norwegian Sea what is different is the extra salinity of the water owing to its transport from warmer regions with the Gulf Stream. Thus you get very cold and very saline water which is exceptionally dense and downwells energetically to the ocean floor, acting as a propeller of the global ocean deep circulation.

    Now this downwelling is self reinforcing because it draws up more water with the Gulf Stream which it mutually strengthens. Also the south flowing deep current driven by the downwelling also further impels the Gulf Stream. So what we have is a positive feedback.

    What climate science fails to understand is that positive feedback does not cause a runaway process for all time, until it causes the end of the world. Instead, in the real world, positive feedback causes a temporary excursion of self reinforcement which is self-terminating because it sets in motion processes that will terminate it. In the case of the North Atlantic, this is Greenland ice melt caused by the warming influence of the strengthening Gulf Stream. This melt causes a raft of fresh water that interferes with the saline downwelling in the Norwegian Sea. So the positive feedback excursion is choked off.

    But weakened Gulf Stream means cooling a d eventually a resumption in the cold downwelling up North which strengthens the Gulf Stream, the the positive feedback switches back on. And so on…

    What you have is an intermittent positive feedback resulting in alternate strengthening and weakening of the Gulf Stream. This gives rise to the oscillation called the AMO.

    But this AMO oscillation is not regular or monotonic. It is not always 60 years in period. Palaeo data makes this clear, sometimes it is shorter and sometimes longer in period.

    Ocean circulation like all liquid flow tends toward turbulence and looking at Nullschool animations of ocean currents nicely shows how turbulent it is. Turbulence represents high dimensional chaos. However internal positive feedbacks such as the AMOC involving Norwegian Sea downwelling as described above, have an important interaction with chaotic systems. Positive feedback, otherwise known as “excitability” of a system, reduces the dimensionality of chaotic systems, changing high dimensional turbulence to lower dimensional chaos. Lower dimensional chaos is much more interesting than high because it is near the border of chaos and linearity that emergent pattern formation arises – such as an intermittent AMO with the AMOC fluctuating in strength.

    Climate science tries to write off chaos as being high dimensional turbulence only. They don’t realise that two things can lower the dimensionality of chaos to the region where climate patterns and oscillations can arise from the system. These are internal feedback as already described, but also external periodic forcing, from cycles such as the annual cycle, tides and solar oscillations. For instance solar oscillations by themselves don’t have enough energy to change climate very rapidly – the ocean has too much heat capacity for that. But if solar cycles periodically force the internal feedbacks of the ocean which possess much more energy, then they can entrain oceanic climate oscillations.

    If external forcing is strong, then the system oscillation will mirror the forcing oscillation. However often periodic forcing of nonlinear oscillations is weak, and here things get more complicated. The emergent frequencies in a weakly periodically forced oscillator can be very complex and bear little resemblance to the forcing frequency. This makes it harder to analyse and identify what if anything a natural oscillation is being forced by. There probably are mathematical clues but you would have to do the maths to identify them.

    Climate scientists such as Mann who deny natural oscillations are denying chaos. The ocean driven climate system has all the ingredients needed for complex chaotic dynamics:

    – an open dissipative system transporting heat from equator to poles on a rotating planet covered with a liquid film

    – turbulence inevitably develops in flowing liquid especially with complex coastlines and ocean topography

    – both internal positive feedbacks – excitability – and external periodic forcing, such as solar or complex tidal, are available to lower the dimensionality of chaotic circulation to low dimensional regimes where spontaneous pattern formation and oscillations arise.

    The AMO as an intermittent oscillation of the AMOC is a good example of pattern from reduced chaos dimensionality caused by internal feedback plus possibly external forcing.

    There is no excuse to saying natural oscillations can’t exist because “we don’t know what causes them”.

  24. oldbrew says:

    Thanks Phil, good explanation. Send a copy to Mr. Mann 😀

  25. Paul Vaughan says:

    Phil, I comment here only on the BIG thing missing from your nice write-up.

    WIND (from temperature and thus pressure gradients) is the primary driver of ocean circulation.

    You’ve got equator-pole contrasts, pole-pole contrasts, land-ocean contrasts, plus seasonal aliasing as there are QUALITATIVE changes in the SHAPE of the windfield with season.

    You have to deal with modular forms. This is exactly where climate “science” is lost. (This is in God’s hands. Dialogue has never had any effect and never will.)

    Years ago I verified the proof of the Schwabe-timescale cyclic volatility of the mid-latitude westerlies. (solar terrestrial weave). That explains why the multidecadal wave matches solar cycle deceleration. It’s simple, conclusive proof.

    Sensible leaders: Anyone telling you otherwise is ignorant or deceptive — dark either way — and should be dealt with carefully (the person is a danger) and accordingly. These people have — whether deliberately or by accident — done formidable damage to the integrity of our society and civilization (trust RAZED). They have triggered monstrous waves of absolutely terrifying cynicism through their incomprehensibly-savage, unrelentingly-hubristic provocations. Their threats to impose TOTAL ORWELLIAN HELL on the population have escalated on an exponential scale during the past year (what is different now).

    It takes power to surrender: The politics are in God’s hands. Let us pray.

  26. Paul Vaughan says:

    Disambiguation: mmm = misunderstanding, misinterpretation, misrepresentation are no. doubt HARD-WIRED into the constitution of 1806. Surely you know the C[e^NSO]Rship has a cloaking D-vice. One day a colleague received the following e-mail in a formal context: “I’ll come early so I can get off sooner.” The concise author intended 4 interpretations. 1806 has something to do with a lunar tidal cycle if you are TOTALLY and ABSOLUTELY lost (in an Orwellian sense).

  27. Paul Vaughan says:

    The Trump Found Daze[shh!]UN of freedemmanndumbmockcrazy

    I tend to assume everyone already knows:

    Review of 96 derivation in reply to TB.

    None of the 4 primary patterns outlined here are controversial. The over-the-top cynicism is just express shh! UN of TOTAL IT eerie on C[e^NSO]ship.

  28. Paul Vaughan says:

    16 Figures: $96 Review

    Here’s a clean, simple outline I shared with talkshop reader Ed:

    “I wouldn’t trust any climatologist who can’t at least follow and deeply understand the simple derivation of 96 in the lunisolar context.”

    EOF1234: Frame-D

    I remember a Rage Against the Machine video from decades ago. The video flashes between George Gore and Al Bush pumping gas while Z channels O: “WHO controls the past controls the future”. IT summarizes inverted totalitarianism succinctly. IT’s only 2 add just meant steps framme (not a type O) ERSSTv3b2 to sum thing $0[]well hid UN.

  29. Paul Vaughan says:

    Let’s again review what evil Orwellian dictators contemptuously dismiss while plotting how to make you sick and homeless so you’ll shut the f**k up on the internet (they’re out of ideas, so they snapped and went TOTALLY savage on us) :

    These correspond with the bottom map from ERSST EOF1234:

  30. Paul Vaughan says:

    Compare and contrast with SCD:

    208.886643858908 = (65.8581963269421)*(50.0715412599931) / (65.8581963269421 – 50.0715412599931)
    208.886643858908 = (96.1829470900285)*(65.8581963269421) / (96.1829470900285 – 65.8581963269421)

  31. Paul Vaughan says:

    Phil wrote: “It is not always 60 years in period.”

    “It” isn’t even just 1 thing.

  32. Paul Vaughan says:

    Buy D-C ! Aid All !! Rev You !!!
    A Pointer From “Joe’s Quick” Bidecadal Review

    Note that the amplitude’s only .05°C or less, but the static pace points to a system backbone structure showing through the mixing framework:

    It doesn’t look like this every cycle (there’s great variability in the spatial pattern) — this is the average spatial pattern:

    Again, bidecadal accounts for little SST variance…

    …but it’s pointing our quantum signal cognizance threw monstrous moonshine mix to better grounding in rich D-lights of number theory.

  33. oldbrew says:

    Published: 01 February 2011
    Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years
    – – –
    Among others, cites 2 papers co-authored by ‘Mann,M.E.’:
    — Observed and simulated multidecadal variability in the Northern Hemisphere.(2000)
    — A signature of persistent natural thermohaline circulation cycles in observed climate.(2005)

    Note the word ‘observed’.

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