Internal Multidecadal and Interdecadal Climate Oscillations: Absence of Evidence Is No Evidence of Absence

Reposted under a Creative Commons License

Gisela Müller-Plath*

Department of Psychology and Ergonomics, Technische Universität Berlin, Berlin, Germany

Introduction

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, 2017O’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.

M20 (p. 3) argue that any truly oscillatory AMO or PDO signals should generate a spatially coherent and large-scale variability pattern in the climate system with a narrowband signature in the frequency domain. They search for such signals in global (observed and modeled) temperature grids of different time lengths with the multi-taper method of singular value decomposition (MTM-SVD), which was developed and widely applied by Mann and Park (Mann and Park, 1994Mann et al., 1995Mann and Park, 1999). Significance tests of the test statistic LFV (local fractional variance) are carried out with Monte Carlo simulations generated according to the null hypothesis of colored (red) noise. The method can generally be applied to reconstruct the time course and the spatial pattern of any potential oscillatory climate signal.

Inadequate Data

M20 examine three global sets of temperature data for oscillatory signals, all spanning a minimum length of 158 years: Control simulations (control runs of the IPCC model ensemble CMIP5, using pre-industrial conditions of the atmosphere without any external forcing so that “any apparently oscillatory behavior must arise from internal variability”), historical observations (annualized global monthly average surface temperatures from the HadCRUT4 land and ocean surface temperature dataset), and historical simulations (IPCC model ensemble CMIP5, containing external anthropogenic and natural forcing). They find robust significant spectral peaks in the multidecadal AMO range (period 40–70 years) in the historical observations and the historical simulations, but not in the control simulations. However, the latter data set is the only one that covers a greater length of time, with almost half of the model runs spanning 500 years or more.

The absence of robust multidecadal AMO oscillations in the control simulations stands in sharp contrast to numerous studies finding the opposite in paleoclimatic data (Kerr, 2000Gray et al., 2004Chylek et al., 2011Lanci and Hirt, 2015). Even with the same MTM-SVD method, the main author of M20 himself formerly identified robust and significant AMO frequencies in four independent sets of global proxy temperature data (Mann and Park, 1994). The most obvious explanation for the discrepancy is that control runs of the CMIP5 models have little to do with reality (Power et al., 2017). Since it is unclear to which extent the modeled “internal variability” reflects real conditions, the control simulations cannot be trusted unless their results were validated with paleoclimate data.

On the other hand, the historical observations and the historical simulations are insufficient in length in order to detect AMO frequencies with sufficient statistical power. They cover barely two cycles of the putative oscillation, which may span 80 years and more (Schlesinger and Ramankutty, 1994) and may consist of a broader band of low-frequency signals (O’Reilly et al., 2017Sutton et al., 2018) than can be identified with the short time series. Furthermore, M20 leaves some confusion about the actual length of their control and historical simulations. Although they state in the text that a minimum length of 158 years is required and fulfilled by N = 44 control runs and N = 118 historical runs of the CMIP5 models, Table 1 in their Supplement reveals that only N = 42 (not 44) from the altogether N = 47 control simulations and only N = 8 (not 118) from the altogether N = 164 historical simulations satisfied the requirement of a minimum length of 158 years. So even though the latter data set showed a robust significant AMO frequency around a ∼45 year period, other multidecadal frequencies might have been missed.

Improper Literature Reference

Having found significant AMO frequencies only in the historical observations and simulations for the industrial time, M20 suggest that this multidecadal fluctuation is due to anthropogenic aerosols rather than to an intrinsic climate oscillation. They argue 1) that no multidecadal fluctuation is present under preindustrial conditions, 2) that in industrial times its phase is synchronized across three independent global time series, which would be unlikely if it were an intrinsic oscillation, whereas 3) the fluctuation with positive (warm) peaks near 1940 and 2000 and a negative (cool) peak near 1980 coincides with the response of the climate system to anthropogenic sulfate aerosol emissions. The first part of the argument is questioned above. The second refers to the observation that three global time series, namely two specific models and the historical observations, are roughly in phase (Figure 3 of M20). I agree with the authors that this would be unlikely if they were (stochastically) independent, but “internal”/“intrinsic” is not necessarily the same as “independent”: The same phase points to a structural relationship, but it says nothing about whether its cause is external or internal to the climate system. For the third part of the argument, M20 refer to a recent paper by Kasoar et al. (2018). However, this referenced paper supports only the spatial correspondence of sulfate aerosol effects and the putative AMO signal, both emphasizing the North Atlantic region. With regard to the alleged temporal correspondence, the reader is referred to Figure 3 of M20, which not only leaves several questions open, but also ignores a substantial refutation in the literature: M20 do not provide enough detail to clearly understand what they are plotting in the time series of their Figure 3. Is it just one realization or an average of the two and five members that they have for the MPI-ESM-LR and HadGEM2-ES models? If it is the latter, they are methodologically canceling out any internal variability the model could show. If it is the former, on which criteria did they select the member, and do the rest behave similarly? Furthermore, in the MPI-ESM-LR model (Figure 3C of M20) the signal amplitude and the signal-to-noize ratio appear to be very low, which is reflected in the small percentage of explained variance. I doubt that this signal exceeds the statistical significance limit, which the authors do not comment on. Regarding the HadGEM2-ES model, Booth et al. showed already in 2012 that it closely reproduced the AMO-like multidecadal North Atlantic sea surface temperature (NASST) variability in the 20th century, and claimed that aerosols caused this variability. However, Zhang et al. (2013) refuted this claim on various methodological grounds, for example by comparing the heat content anomaly of the upper ocean in the North Atlantic with the HadGEM2-ES model with constant aerosols vs. all drivers, or by showing differences between observed and modeled spatial patterns of multi-decadal SST changes inside and outside the North Atlantic, and observed and modeled anomalies in salinity in the subpolar North Atlantic. Due to the large and multivariate discrepancies in the mechanisms, Zhang et al. concluded that the aerosol effects simulated by HadGEM2-ES cannot be responsible for the multi-decadal temperature variations observed in the North Atlantic in the 20th century. M20 make the same claim again now without mentioning this debate in the literature.

Inappropriate Interpretation

In the interdecadal time range attributed to the PDO (16–20 years according to the authors), M20 found no robust significant spectral peaks in any of the three data sets. Again, this stands in sharp contrast to a large body of literature (for a review see e.g., Henley, 2017), including previous work by the main author using the same MTM-SVD method (Mann and Park, 1994). M20 explain the discrepancy by the time window being larger in their present than in their former work, rendering the present results more reliable. However, on closer inspection the respective Supplementary Figure S2 in M20 suggests another interpretation: The moving window shows that the frequencies on the interdecadal scale are not constant over time – in other words, narrowband PDO oscillations are episodic (see Figure 1). This is fully consistent with the work of Folland et al. (2002), which M20 themselves mention in their introductory discussion on whether the PDO has a broad or narrow frequency band. However, with reference to their own former work (Mann and Park, 1994Mann and Park, 1999) they decide a priori that the PDO is confined to a narrowband 16–20 year period. When they later find that this narrowband frequency is not robust over a larger time window, they conclude that there is no intrinsic PDO at all. However, a more appropriate interpretation would have been that their assumption of a continuous narrowband PDO frequency was premature and should be revised. FIGURE 1

FIGURE 1. Evolutionary spectra of historical observations in M20, using a moving window of 100 years length. The year at the horizontal axis represents the center of the 100 years moving window, with the vertical line indicating the window 1890–1990 analyzed by Mann and Park 1994. The colored scale depicts LVF values (In the 100 years time series in Mann and Park, 1994, LFV values exceeding roughly 0.53 were significant at p < 0.05 level). The red arrows point to two slightly different frequencies showing up episodically significant and thereby supporting the view that the PDO is characterized by a rather broad and changing frequency band over time (Figure adapted from Mann et al., 2020, Supplementary Figure 2. Using the figure is permitted by the Creative Commons Attribution 4.0 International License).

Conclusion

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.

Author Contributions

The author confirms being the sole contributor of this work and has approved it for publication.

Conflict of Interest

The author declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

The author would like to thank a reviewer for valuable hints concerning argumentation and literature.

References

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Keywords: Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, sulfate aerosols, climate oscillations, multi-taper method of singular value decomposition spectral analysis (MTM-SVD), CMIP5 model simulation

Citation: Müller-Plath G (2020) Internal Multidecadal and Interdecadal Climate Oscillations: Absence of Evidence Is No Evidence of Absence. Front. Earth Sci. 8:559337. doi: 10.3389/feart.2020.559337

Received: 05 May 2020; Accepted: 04 November 2020;
Published: 26 November 2020.

Edited by:Jing-Jia Luo, Bureau of Meteorology, Australia

Reviewed by:Elsa Mohino, Complutense University of Madrid, Spain

Copyright © 2020 Müller-Plath. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

AUTHOR=Müller-Plath Gisela

TITLE=Internal Multidecadal and Interdecadal Climate Oscillations: Absence of Evidence Is No Evidence of Absence

JOURNAL=Frontiers in Earth Science

VOLUME=8

YEAR=2020

PAGES=580

URL=https://www.frontiersin.org/article/10.3389/feart.2020.559337

DOI=10.3389/feart.2020.559337

ISSN=2296-6463

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Tim Gorman
November 29, 2020 6:35 am

“Control simulations (control runs of the IPCC model ensemble CMIP5, using pre-industrial conditions of the atmosphere without any external forcing so that “any apparently oscillatory behavior must arise from internal variability””

Models all the way down. You simply cannot use a model as verification of anything. Especially when the models suffer from growth in uncertainty due to successive iterations. The inherent uncertainty would mask any actual signals.

fred250
Reply to  Tim Gorman
November 29, 2020 11:48 am

Yep, the models are SO INADEQUATE that they can’t even simulate the AMO and PDO cycles

That is what Mickey Mann and his playpen mates has found.

“They find robust significant spectral peaks in the multidecadal AMO range (period 40–70 years) in the historical observations and the historical simulations, but not in the control simulations.”

Incompetent models……. all the way down.

Pat from kerbob
Reply to  fred250
November 29, 2020 7:34 pm

Reading that, the data says yes, the model says no
So go with the model

Really?
Science?

Mike
Reply to  Pat from kerbob
November 29, 2020 11:42 pm

Greg
November 29, 2020 6:39 am

Mann finds no climate oscillations in models and thus concludes they don’t exist in the climate, rather than realising that this is a just another failure of their naive modelling and tuning efforts.

Rich Davis
Reply to  Greg
November 29, 2020 7:54 am

Who can believe that Mann’s latest climate-denial claims are anything but a disingenuous attempt to erase all natural variation?

What a vile creature. He rightly expects that corrupt politicians will be willing to look like morons in order to run with his convenient lies.

Chas
Reply to  Rich Davis
November 29, 2020 8:47 am

It is curious ; Mann has gone from claiming to have invented the term AMO and has also reconstructed it back to 1550 to recently claiming that it doesnt exist.
Maybe he is correct. Or perhaps he is indeed trying to eliminate natural climate change.
Its good to see that psychologists psychiatrists are getting involved.

https://www.nature.com/articles/srep40861

Jeff Alberts
Reply to  Greg
November 29, 2020 9:00 am

Exactly, Greg. More evidence that the science isn’t settled, and Mann is a fruad.

John Harrison
November 29, 2020 6:42 am

Periodically I see mention of the drop in global temperature in the 70s being due to industrial aerosols (in Western countries) but have yet to see any justification for such and for the claim that it just went away when clean air acts were gradually implemented despite rising emissions in the East. It is not clear whether this effect was mirrored in the Southern hemisphere and if so whether this be expected given atmospheric circulations. Surprisingly this hypothesis has not been challenged in the light of massive aerosol emissions from China and India far in excess of those experienced in the West. Should we not be seeing global temperatures plummeting?

Greg
Reply to  John Harrison
November 29, 2020 8:04 am

Don’t worry, that inconvenient cooling has been almost entirely removed from the climate record now. No longer a problem.

John Harrison
Reply to  Greg
November 29, 2020 8:13 am

That has been noted, this could be due to 0.5degC being “shaved off” here and there by certain climate “scientists”.

MarkW
Reply to  Greg
November 29, 2020 11:59 am

I remember some our warmists trying to claim that the “adjustments” must be good, because there are as many cooling adjustments as warming adjustments.

What they don’t tell you is that all of the cooling adjustments are for the older records, and all of the warming adjustments are for new to modern records.

John Harrison
Reply to  MarkW
November 29, 2020 1:12 pm

Mark. Smart response, like it.

Reply to  John Harrison
November 29, 2020 8:24 am

There are papers that state, aeorosols don’t have the importance as earlier presumed.
https://pubmed.ncbi.nlm.nih.gov/33204244/

John Harrison
Reply to  Krishna Gans
November 29, 2020 9:05 am

Krishna. Thank you for that. It seems that they are uncertain as to whether the models or the observations are more reliable, uncertain as to the effects on cloud formation and uncertain as to whether clouds exert a positive or negative influence on forcing. Is it just me or, considering the degree of uncertainty in such important factors, (and in countless other variables) do the modellers seem to have an excess of confidence in their program outputs?

MarkW
Reply to  Krishna Gans
November 29, 2020 12:02 pm

Beyond that, al estimates of the amount and types of aerosols being released into atmosphere are little better than guesses. And that’ for the newer records, as for records going back the 70’s, those pretty much are guesses.

DMacKenzie
November 29, 2020 6:50 am

The author has an interesting background in statistics and cognitive psychology. Usually these folks try to determine why climate sceptics have psychological disorders….but she has noted that the data and climate consensus are not corroborative with respect to AMO and PDO. She will probably be fired.

Scissor
Reply to  DMacKenzie
November 29, 2020 7:30 am

It’ll be worth watching. They might just find 97 scientists against her.

Jeff Alberts
Reply to  Scissor
November 29, 2020 1:15 pm

With Liberal Arts degrees.

Dave S
Reply to  DMacKenzie
November 29, 2020 7:32 am

One can conclude that the author is apparently no Stephan Lewandowski and is concerned with logical conclusions from statistics and ethical science.

Rich Davis
Reply to  DMacKenzie
November 29, 2020 8:24 am

We should share some of our oil funding with her and get her to join the Heartland Institute. I don’t really need all these checks! Now that Putin’s paying me, these piddling $10,000 weekly checks are hardly worth the trouble anymore.

Trying to Play Nice
Reply to  Rich Davis
November 29, 2020 10:12 am

You only get them once a week?

Pat from kerbob
Reply to  Trying to Play Nice
November 29, 2020 7:40 pm

I won’t get out of bed for less than $10k a day
And it must be oil money
Love that stuff

commieBob
November 29, 2020 7:12 am

M20 (p. 3) argue that any truly oscillatory AMO or PDO signals should generate a spatially coherent and large-scale variability pattern in the climate system with a narrowband signature in the frequency domain.

Once you see the word ‘oscillation’, you start to bark up the wrong tree. You think the phenomena should be periodic. They aren’t. They are pseudoperiodic. An example would be sunspots. There is an approximate eleven year cycle but, as everyone here should know, their period and amplitude are variable.

Saying that a pseudoperiodic time series like the AMO or PDO don’t exist because they lack a narrowband signature in the frequency domain, is just plain wrong.

Of course, this is our beloved Dr. Mann we’re dealing with so I’m not even surprised.

Rich Davis
Reply to  commieBob
November 29, 2020 8:17 am

It’s just another nature trick, commiebob. Like you, I’m not even mildly surprised. No doubt there will be 700 papers coming that all replicate his “work”.

MarkW
Reply to  commieBob
November 29, 2020 8:19 am

I believe this is the key failure with this so called paper.

The only way to get a narrowband signature in the frequency domain is for the original signal to have a tight and regular frequency. Tight and regular frequencies just aren’t found very often in nature, and are never found in something as complex as climate.

The author’s of this paper either don’t understand the tools they are using, or they are seeking to obfuscate. With this crowd, either is possible. As well as both.

Tom Abbott
Reply to  MarkW
November 29, 2020 10:04 am

My vote is for “obfuscate”.

There’s too much talk of the temperatures being just as warm in the Early Twentieth Century as it is today, so Mann wants to try to paper over this, because the bogus, Modern-era Hockey Stick distorts the temperature record and changes the look of the warm period in the 1940’s and the cool period in the 1970’s.

If Mann admitted that it was just as warm in the Early Twentieth Century as it is today, which an unmofified chart would show, then he would be unable to continue to promote the idea that CO2 is the control knob of the Earth’s temperature. There’s more CO2 in the atmosphere today than in the Early Twentieth Century, yet it is no warmer now, than then, so CO2 had no measureable effect. Case Closed.

So Mann doesn’t want us to make this case.

He does acknowledge a high temperature point around 1940 and a low temperautre point around 1980, but the Hockey Stick charts downplay the magnitude of both the warmth around 1940’s and the cold around 1980.

And then he claims the decline in temperatures from 1940 to 1980 was caused by aerosol emissions of humans, which supposedly lowered the temperatures during this period. But there’s no way this is possible. The temperature spread from the highpoint of 1934 (in the US) to the lowpoint around 1979 is about 2.5C.

Now we know that a huge volcanic eruption can lower the atmospheric temperature by about 0.5C, and this lower temperature can last for about two years or less. We have evidence for this from two different large volcanic eruptions in the recent past.

If we got together all the human aerosol emssions created from the beginning of time, the whole mass would only amount to the equivalent of a small volcanic eruption, so there is a question that all human emission of aerosols at one time could come close to lowering the temperatures even by 0.5C. And of course, humans did not emit all their emissions of aerosols from 1940 to 1980,. so to claim that human-derived aerosols had any mearseable effect on the Earth’s climate is absurd.

Below is a comparison of the US surface temperature chart (Hansen 1999), alongside the bogus, bastardized, Modern-era Hockey Stick chart:

http://www.giss.nasa.gov/research/briefs/hansen_07/

Notice that the US chart shows the temperature difference between the highs of the 1930’s and the lows of the 1970’s as being a difference of about 2.5C. The bogus Hockey Stick chart shows this same time period with a difference of only about 1.0C. The bogus Hockey Stick fraudulently cools the 1940’s which necessarily causes the 1970’s to show warmer on the bogus Hockey Stick chart. The cooling of the 1930’s allows the alarmists to falsely claim that the world is currently living in the hottest period in human history. But it’s all a Big Lie. The bogus Hockey Stick chart is the ONLY “evidence” they have for these claims, and it is obviously false when it is compared to an unmofied surface temperature chart

Unmodified, regional temperature charts all over the world resemble the temperature profile of the US chart, which shows it was just as warm in the Early Twentieth Century as it is today. No unmodified, regional temperature chart resembles the bogus Hockey Stick chart.

And as you can see, the AMO temperature profile (below) agrees with the US temperature chart and refutes the bogus Hockey Stick chart.

comment image

That’s why Mann did this study.

It was just as warm in the Early Twentieth Century, Michael, and the regional temperature charts of the world show it. CO2 is a minor player in the Earth’s atmosphere.

Rich Davis
Reply to  Tom Abbott
November 29, 2020 11:17 am

👍

Reply to  Tom Abbott
November 30, 2020 5:55 am

“… an unmofified chart …”
In Afrikaans, that translates as “an unqueered chart”, as in poofter? Climatologists in a nutshell!

commieBob
Reply to  paranoid goy
November 30, 2020 8:17 am

Buy a donkey.

fred250
Reply to  commieBob
November 29, 2020 12:55 pm

AMO is fairly obvious in the Icelandic sea ice record

comment image

M Seward
Reply to  commieBob
November 30, 2020 1:12 pm

The “Mannipulation of Data”. Again. Plus ca change. The defining tautology of climate science?

bethan456@gmail.com
November 29, 2020 7:24 am

The author of this article has the same credentials as John Cook, in psychology.

Rich Davis
Reply to  bethan456@gmail.com
November 29, 2020 8:06 am

Hard to make sense of your comment, bethan. Are you saying that because Cook is a worthless tool, that Müller-Plath must also be a fool, or that since you find Cook so compelling, Müller-Plath is believable in her debunking of the beady-eyed bald fatarse doofus?

Redge
Reply to  Rich Davis
November 29, 2020 10:01 am

It’s called playing the man not the ball or ad-hom if you like

MarkW
Reply to  bethan456@gmail.com
November 29, 2020 12:05 pm

Thank you for once again admitting that you can’t refute any of the arguments. That’s why all you can do is attack the author.

Fran
Reply to  bethan456@gmail.com
November 29, 2020 2:03 pm

In all of science, psychology students get the most training in statistical methods (always excepting those whose degrees are in Statistics). Check this out on both graduate and undergraduate programs at the university of your choice.

commieBob
Reply to  bethan456@gmail.com
November 30, 2020 3:06 am

Her area of specialisation (click on her name at the top of the story):

Teaching: Research Methods and Statistics at graduate level

His area of specialisation:

John earned his PhD in Cognitive Science at the University of Western Australia in 2016. link

So, apparently, she has the qualifications to write the above article. Cook, not so much. I can’t find anything that indicates any specialisation in research methods and statistics for him.

Psychology and economics share the problem that there’s a lot of bogus research. For that reason, there’s a lot of attention to research methods and statistics. It’s the same reason that Ross McKittrick, an economist, was one of those who was able to debunk the hockey stick.

Gordon A. Dressler
November 29, 2020 7:54 am

Charles Rotter, thanks for publishing the above article that reveals how models are being used to actively displace reality and create false “science”.

However, with all due respect to you and author Gisela Müller-Plath, I personally would have inserted this parenthetical remark at the end of the first sentence in the Introduction of Müller-Plath’s article above:
(***Warning to Readers: Michael E. Mann does NOT find scientific data, rather he manufactures it. This fact is revealed in this article, just as it was previously revealed in his infamous hockey-stick graph.***)

David Streeter
November 29, 2020 8:14 am

Instead of wasting time and resources on speculative investigations it would be better to spend them on the development of means to deal with changes in climatic conditions.

Tom Abbott
Reply to  David Streeter
November 29, 2020 10:15 am

“it would be better to spend them on the development of means to deal with changes in climatic conditions.”

What climate conditions do you think we need to deal with? I presume you are referring to CO2. If that’s the case, where is the evidence that we need to deal with CO2? Where is the evidence that CO2 is anything other than a benign, life-giving gas?

MarkW
Reply to  David Streeter
November 29, 2020 12:07 pm

Please let us know when “climatic conditions” get outside the range of normal. We’ve still got a degree or two to go before we get back up to the average temperature for the last 10K years.

Jeff Alberts
Reply to  David Streeter
November 29, 2020 1:05 pm

“Instead of wasting time and resources on speculative investigations it would be better to spend them on the development of means to deal with changes in climatic conditions.”

You mean adaptation, right? We have no problem adapting. And right now there’s nothing to adapt to. When something comes along, we’ll adapt. It’s much better than trying to control the weather.

Steve Case
November 29, 2020 8:27 am

(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

I guess my bias is showing, I first read that last sentence as:

The present paper shows that M20’s results are largely artifacts [OF] themselves

Themselves meaning Henley, O’Reilly & Mann

That aside, the 33 year cycle seems to fit the empirical record pretty well. 1878-1911-1944-1977-2010

Steve Case
November 29, 2020 8:35 am

Off Topic-

My email this morning has the following headline from the local liberal rag (Milwaukee Journal-Sentinel)

       Meatpacking plants tied to more COVID-19 cases than known before

Looks suspiciously like all the “Worse than Previously Thought” headlines for Global Warming stories.

Rich Davis
Reply to  Steve Case
November 29, 2020 9:46 am

Surely you didn’t expect PETA to let a perfectly good crisis go to waste, Steve? In the past they have leveraged Climate Change (TM) with cow farts causing methane apocalypse. So obviously if there’s a case to be made for meatpacking to be shut down to reduce COVID infections, they’re going to make it.

Steve Case
Reply to  Rich Davis
November 29, 2020 10:47 am

No, Rich (I can be condescending too) I didn’t expect PETA to miss an opportunity. It’s that a so-called mainstream organ i.e., the Milwaukee Journal-Sentinel chose to spam my mailbox with it as the top story.

But thanks for the reply, I appreciate it.

Rich Davis
Reply to  Steve Case
November 29, 2020 11:01 am

Condescending? How so?

Steve Case
Reply to  Rich Davis
November 29, 2020 12:25 pm

Your comment was meant as sarcasm and it contained a condescending tactic – even though you are talking directly to someone, you “First Name” them like you would a child, to make sure they are paying attention to what you’re telling them, to let them know that you are superior, that they are less than worthy. That the message is for them and nobody else because everyone else already knows what it is that you’re saying. Here’s an example:

“Well you know, Rich, everyone else knows condescension when they see it.”

The sarcastic condescension in your post really wasn’t directed at me, it just pointed out a fact we all know about PETA. I just used the same technique you used (and highlighted it) to point out that the so-called mainstream media is a problem for giving PETA not just ink but a headline.

Jeff Alberts
Reply to  Rich Davis
November 29, 2020 1:22 pm

No, Steve, you’re just way too thin-skinned.

Rich Davis
Reply to  Rich Davis
November 29, 2020 2:05 pm

Dear Mr Case,
I beg your pardon. You may not be from the US or of a generation where it’s common to address others, even casual acquaintances by their first names. I assure you, though, that I meant you no offense.
Sincerely yours,
R.
(Not sarc)

Steve Case
Reply to  Rich Davis
November 29, 2020 2:42 pm

Jeff Alberts November 29, 2020 at 1:22 pm
No, Steve, you’re just way too thin-skinned.

Well, I have to admit, it took me a few seconds to get the irony and humor in your post.

and then, “Ha ha ha ha ha ha ha ha!”

Steve Case
Reply to  Rich Davis
November 29, 2020 3:03 pm

Dear Mr Case,
I beg your pardon. You may not be from the US or of a generation where it’s common to address others, even casual acquaintances by their first names. I assure you, though, that I meant you no offense.
Sincerely yours,
R.
(Not sarc)

I do admit that you hit a nerve, I am old school, DOB 1944, and I am always annoyed when I run into some unctuous ingratiating salesman who uses my first name who seems to think that I will like him if he uses my first name when all it does is piss me off.

I suppose what we’ve got here is failure to communicate (Cool Hand Luke)

Rich Davis
Reply to  Rich Davis
November 29, 2020 3:37 pm

May I call you Captain?
🙂

November 29, 2020 9:02 am

I could model my breakfast coffee, but I put greater faith in the real thing. One of my learned friends said:
These people live in a virtual world – they believe their models more than they believe real observations!”

The ability to predict is the best objective means of assessing scientific competence, and the global warming alarmists have NO predictive track record – actually a 100 NEGATIVE predictive track record and thus 100% NEGATIVE SCIENTIFIC CREDIBILITY – the warmist cabal have been wrong about everything, so nobody should believe these climate fraudsters – about anything!

“MacRae’s Maxim”:
“VIRTUALLY EVERY SCARY PREDICTION BY GLOBAL WARMING ALARMISTS IS FALSE.”

The Great Global Warming Fraud is a litmus test for basic intelligence – if you believe is catastrophic human-made global warming (aka “climate change”) hysteria, then you are an unscientific dolt, and no useful knowledge can be imparted to you.

The Great Global Warming Fraud has no place in polite, intellectual company – it is a scary politicized fiction, concocted by wolves to stampede the sheep. It is not real – be comforted by this fact.

Rich Davis
Reply to  ALLAN MACRAE
November 29, 2020 9:37 am

I’m intrigued. The corollary to MacRae’s Maxim would be:
“NOT EVERY SCARY PREDICTION BY GLOBAL WARMING ALARMISTS IS FALSE.”

Which ones do we need to believe, Allan?

Reply to  Rich Davis
November 29, 2020 10:15 am

Rich – your logic is flawed – re-read the Maxim.

The warmists could slip one minor truth into their more-than-50 FAILED predictions and the Maxim would still be correct. To my knowledge, they have not done so and are still 100% FAIL.

“Virtually” definition and meaning | Collins English Dictionary
“You can use virtually to indicate that something is so nearly true that for most purposes it can be regarded as true.”

Rich Davis
Reply to  ALLAN MACRAE
November 29, 2020 10:53 am

I maintain that the addition of “virtually” is an unwarranted weakening of the claim, admitting of the possibility that global warming may conceivably result in a scary outcome.

If you do not wish to adjust your flawed maxim, we may re-christen it as Davis’ Iron Law:

“EVERY SCARY PREDICTION BY GLOBAL WARMING ALARMISTS IS FALSE.”

In my achievements I stand on the shoulders of giants 🙂

Jeff Alberts
Reply to  Rich Davis
November 29, 2020 2:45 pm

Boy, that’s rich. 🙂

Gary Pearse
Reply to  ALLAN MACRAE
November 29, 2020 12:04 pm

Alan, your Maxim is a subset of mine which can be stated as “No predictions of man-caused global harm have ever come to pass.” This is measured from Thomas Malthus’s idea of population growth stripping us of resources published in 1798 to the present. Since we were more puny by many orders of magnitude earlier than that date, I submit my maxim as holding for all time.

Moreover, my mention of puniness hints at the underlying reason. You are an engineer, as am I. Energy available to human management to cause irreparable planetary harm is not anywhere near a rounding error in the energy of the planet or even it’s atmosphere alone. Roy Spencer calculated that 20 seconds worth of the 240W/sq. m of sun’s energy absorbed by the entire planet is equivalent to all the nuclear bombs and tests over 50yrs. Moreover, Hurricane Harvey had the energy of One million Hiroshima-sized bombs per day of its existence! The asteroid that wiped out the dinosaurs has been estimated to have had the energy of 10 billion hydrogen bombs going off in seconds. The planet swallowed it and it took modern tech to discover that it had even happened.

Eat your beef, drive your cars, have your children and head off into the Garden of Eden plenty of The Great Greening Planet with peak population in the coming few decades (we are 85% there already). Any problems to come along? Engineers will see them developing and as has been the case til now, will take care of them before you have time to worry about it.

Tom Abbott
November 29, 2020 9:04 am

From the article: “The most obvious explanation for the discrepancy is that control runs of the CMIP5 models have little to do with reality”

That’s my impression.

If your theory doesn’t agree with observations, then your theory is wrong.

Phil Salmon
November 29, 2020 9:20 am

Mann is a hopeless case, a total believer in Edenic stasis, that without human influence climate previously never changed. He doesn’t believe in ice ages or the Mesozoic hothouse age of the dinosaurs. Presumably not in dinosaurs either.

Mann is a denier of natural climate change and the inevitability of an always changing climate from basic chaotic-nonlinear dynamics. Like very many scientists he finds it convenient to be wilfully ignorant of chaotic dynamics and their implications in climate.

He’s actually not in the slightest interested in climate at all. The scope of his denial of natural phenomena makes that impossible. But he is intoxicated by the stardom available to practitioners of computer modellers who can fabricate tales of climate doom through circular logic, where a priori assumptions and “experiment” (LOL) conclusions are one and the same. And his strategy is working spectacularly well – so why change it?

Phil Salmon
November 29, 2020 9:28 am

If climate warms it must be CO2.
If it cools it must be aerosols.
So climate is a controllable puppet dangling by those two strings only, performing to the needs of the puppet-masters.

O and there is no ocean.

November 29, 2020 10:04 am

Just when you thought that Mann had plumbed the depths of climate denial.,..

Chris Wright
Reply to  Leo Smith
November 30, 2020 3:09 am

Yes, if there are real climate change deniers, it’s the true believers and not the sceptics.
The straight shaft of the hockey stick is the very essence of climate change denialism.
Ironically, an important sceptical argument is that the climate is changing most of the time.
Chris

Tom Abbott
Reply to  Chris Wright
November 30, 2020 5:05 am

The Earth’s climate has patterns that repeat. So the Earth’s climate does change, but it changes within certain bounds. The current climate pattern for the Earth is the Earth’s atmosphere warms for a few decades, and then it cools for a few decades and then this pattern repeats. We can see this pattern as far back as written temperature records go.

Does CO2 influence this pattern? Or does the cyclic warming and cooling pattern influence the amount of CO2 in the atmosphere? It appears to be the latter.

CO2 increases *follow* temperature increases. Of course humans alter this natural pattern a little, but there is no evidence that the additional CO2 added by humans is having any effect on atmospheric temperatures..

Alarmists claim that increased concentrations of CO2 in the atmosphere cause the temperatures to rise, but there is no evidence showing this is the case. The temperatures cooled for decades, from the 1940’s to the 1970’s, while at the same time humans were rapidly adding to the concentrations of CO2 in the atmosphere during this time.

If CO2 caused temperature increases in the Earth’s atmosphere it should have become evident during this period of time. And it was not evident. Instead temperatures dropped, when alarmists said they should be increasing.

Today, there is much more CO2 in the atmosphere than in the 1930’s, yet CO2 has not been able to push the temperatures higher than they were during the 1930’s, when CO2 concentrations were much less than today.

In the US, Hansen says 1934 was the hottest year and he says 1934 was 0.5C warmer than 1998 and 0.4C warmer than 2016, the two warmest years in recent times (El Nino years). Now, almost five years after we reached the high of 2016, the temperatures have cooled by about 0.3C, and this makes today about 0.7C cooler than 1934. Meanwhile, CO2 concentrations in the atmosphere continue to increase. Does everyone see the discrepancy here with alarmist theory? Lots more CO2 in the atmosphere now, but it’s not any warmer now than in the past when the CO2 concentrations were much lower.

Yes, I know the alarmists say today is the hottest period in human history, but that’s just a Great Big Lie. The only thing supporting this argument is a fraudulent, computer-generated, Modern-era Hockey Stick chart.

Legitimate regional temperauture charts from around the world, derived from actual temperature readings, show it was just as warm in the recent past as it is today. There is no unprecedented warmth today, as the alarmists claim, which means CO2 is not the control knob of the Earth’s climate and this means we do not need to spend Trillions of dollars fixing this non-problem.

Jim Gorman
Reply to  Tom Abbott
November 30, 2020 7:19 am

I have tried to impress this on alarmists on twitter. Their first argument is that CO2 is well mixed so that the “radiation budget” can be concluded to be true for a global basis. Then they turn around and say that the 30s and 40s heat was only in the U.S. They can’t see the logical inconsistency of this argument or will simply not acknowledge it. If CO2 is a control knob and well mixed then it must operate consistently everywhere on the globe. You simply can’t have any other conclusion.

Tom Abbott
Reply to  Jim Gorman
November 30, 2020 3:05 pm

“Then they turn around and say that the 30s and 40s heat was only in the U.S.”

They would be wrong.

Here are a few regional temperature charts from around the world that show it was just as warm in the Early Twentieth Century as it is today, and it wasn’t just in the United States.

Tmax charts

US chart:

comment image

China chart:

comment image

India chart:

comment image

Norway chart:

comment image

Australia chart:

comment image

Show those charts to the alarmists on Twitter. Or tell them to go look up their own unmodified surface temperature chart for their region and it will probably look a lot like these charts.

The alarmists claim the Earth is currently experiencing unprecedented warming but that is obviously not true going by unmodified, regional surface temperature charts. The proof is right in front of everyone’s eyes. It shows no unprecedented warming.

No unprecedented warming means CO2 is just a minor player in the Earth’s climate.

Jim Gorman
Reply to  Jim Gorman
December 1, 2020 6:54 am

Tom –> That is exactly what another fellow and I have discovered. When you look at regional and local charts you see little unprecedented warming. These folks are unable to find enough significant warming on a regional/local basis to offset the regional/local locations with no warming or even cooling. What they don’t understand is that for each location with no warming, you need another with 3 deg of warming to end up with a 1.5 deg average. It’s even worse if you plan on 4.5 deg of global warming!

ResourceGuy
November 29, 2020 10:41 am

It’s going to be a long wait for definitive work on AMO given the data conditions and few turning points on that long cycle. Willis?

tom
November 29, 2020 12:14 pm

As always- “It is difficult to get a man to understand something, when his salary depends on his not understanding it.”

ThinkingScientist
Reply to  tom
November 30, 2020 7:36 am

I think you will find that saying should be:

“It is difficult to get Mann to admit something, when his entire career depends on his not admitting it.”

Walt D.
November 29, 2020 12:42 pm

Suppose I produce a model to simulate ocean waves.
No simulations produce rogue waves.
What does this mean?
If you are a real scientist, you would conclude that your model is wrong.
If you are a climate scientist, you would conclude that rogue waves do not exist.

Phil Salmon
November 29, 2020 1:24 pm

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. (The AMO is an oceanic, not atmospheric or astrological phenomenon. It is driven like all climate processes by the ocean. The tail does not wag the dog and the sign of the zodiac plays no role.)

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”.

https://ptolemy2.wordpress.com/2020/07/26/from-chaos-to-pattern-in-ocean-driven-climate/

https://www.nature.com/articles/s41612-020-00147-6

jim hogg
Reply to  Phil Salmon
November 30, 2020 6:36 am

Thank you for an interesting insight . .

Reply to  Phil Salmon
December 1, 2020 7:16 am

The ironic thing is that it was Mike Mann who was one of the first to notice that the Gulf Stream was weakening, in accordance with the natural oscillation in strength of the AMOC. He published a paper on the AMO as a fluctuation of the AMOC. Is he now contradicting or denying himself?

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.144.4028&rep=rep1&type=pdf

Chris Hanley
November 29, 2020 1:50 pm

Sad man Mann, he is forced to spend the rest of his life trying to defend the indefensible.

Pat from kerbob
November 29, 2020 8:04 pm

I find it hard to come up with a valid explanation how Mann still has a job and isn’t laughed out of the room every time he opens his mouth.

He makes Justin Trudeau look like Newton

ThinkingScientist
November 30, 2020 6:24 am

The 60-70 year periodicity evident in Hadcrut4 also appears clearly in the sea level data of Jevrejeva (2104) and in the global glacier database of LeClercq et al (2014).

The sea level and glacier agree pretty well back to an implied onset of warming around 1840. Hadcrut4 temp data only shows warming post about 1910.

Given 2 out of 3 and cause and effect, perhaps the temps need looking at again?

Jackie Pratt
November 30, 2020 6:32 am

hmmmm. good stuff, thanks Dr.

Ulric Lyons
November 30, 2020 9:31 am

The aerosol argument is contrary to how the AMO functions. The colder anomalies of the AMO in the early to mid 1970’s, the mid 1980’s and the early 1990’s, were driven by stronger solar wind conditions, via positive NAO/AO conditions. Post 1995 AMO warming was driven by the weakening of the solar wind since then.

https://www.linkedin.com/pulse/association-between-sunspot-cycles-amo-ulric-lyons/

The AMO is always warmer during centennial solar minima:

comment image

Rising CO2 forcing, according to the consensus of IPCC circulation models, would increase positive NAO/AO, that can only drive a colder AMO.

https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-5-6.html

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