Nicola Scafetta sent me this paper yesterday, and I read it with interest, but I have a number of reservations about it, not the least of which is that it is partially based on the work of Landscheidt and the whole barycentric thing which gets certain people into shouting matches. Figure 9 looks to be interesting, but note that it is in generic units, not temperature, so has no predictive value by itself.

While that looks like a good hindcast fit to historical warm/cold periods, compare it to figure 7 to see how it comes out.

Now indeed, that looks like a great fit to the Ljungqvist proxy temperature reconstruction, but the question arises about whether we are simply seeing a coincidental cyclic fit or a real effect. I asked Dr. Leif Svalgaard about his views on this paper and he replied with this:

The real test of all this cannot come from the proxies we have because the time scales are too short, but from comparisons with other stellar systems where the effects are calculated to be millions of times stronger [because the planets are huge and MUCH closer to the star]. No correlations have been found so far. See slide 19 of my AGU presentation: http://www.leif.org/research/AGU%20Fall%202011%20SH34B-08.pdf

So, it would seem, that if the gravitational barycentric effect posited were real, it should be easily observable with solar systems of much larger masses. Poppenhager and Schmitt can’t seem to find it.

OTOH, we have what appears to be a good fit by Scafetta in Figure 7. So this leaves us with three possibilities

The effect manifests itself in some other way not yet observed. The effect is coincidental but not causative. The effect is real, but unproven yet by observations and predictive value.

I’m leaning more towards #2 at this point but willing to examine the predictive value. As Dr. Svalgaard points out in his AGU presentation, others have tried but the fit eventually broke down. From slide 14

P. D. Jose (ApJ, 70, 1965) noted that the Sun’s motion about the Center of Mass of the solar system [the Barycenter] has a period of 178.7 yr and suggested that the sunspot cycles repeat with a similar period. Many later researchers have published variations of this idea. – Unfortunately a ‘phase catastrophe’ is needed every ~8 solar cycles

Hindcasting can be something you can easily setup to fool yourself with if you are not careful, and I’m a bit concerned over the quality of the peer review for this paper as it contains two instances of Scafetta’s signature overuse of exclamation points, something that a careful reviewer would probably not let pass.

Science done carefully rarely merits an exclamation point. Papers written that way sound as if you are shouting down to the reader.

The true test will be the predictive value, as Scafetta has been doing with his recent essays here at WUWT. I’m willing to see how well this pans out, but I’m skeptical of the method until proven by a skillful predictive forecast. Unfortunately it will be awhile before that happens as solar timescales far exceed human lifespan.

Below I present the abstract, plus a link to the full paper provided by Dr. Scafetta.

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Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter–Saturn tidal frequencies plus the 11-year solar dynamo cycle

ScienceDirect link

Nicola Scafetta, ACRIM (Active Cavity Radiometer Solar Irradiance Monitor Lab) & Duke University, Durham, NC 27708, USA

Abstract The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle may be associated to a quasi-11-year solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Spörer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial three-frequency beat cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900–1920 and 1960–1980 and the secular solar maxima around 1870–1890, 1940–1950 and 1995–2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature modulation since 1850. The model forecasts a new prolonged solar minimum during 2020–2045, which would be produced by the minima of both the 61 and 115-year reconstructed cycles. Finally, the model predicts that during low solar activity periods, the solar cycle length tends to be longer, as some researchers have claimed. These results clearly indicate that both solar and climate oscillations are linked to planetary motion and, furthermore, their timing can be reasonably hindcast and forecast for decades, centuries and millennia. The demonstrated geometrical synchronicity between solar and climate data patterns with the proposed solar/planetary harmonic model rebuts a major critique (by Smythe and Eddy, 1977) of the theory of planetary tidal influence on the Sun. Other qualitative discussions are added about the plausibility of a planetary influence on solar activity. Link to paper: Scafetta_JStides UPDATE 3/22/2012 – 1:15PM Dr. Scafetta responds in comments: About the initial comment from Antony above,I believe that there are he might have misunderstood some part of the paper. 1) I am not arguing from the barycentric point of view, which is false. In the paper I am talking about tidal dynamics, a quite different approach. My argument is based on the finding of my figure 2 and 3 that reveal the sunspot record as made of three cycles (two tidal frequencies, on the side, plus a central dynamo cycle). Then the model was developed and its hindcast tests were discissed in the paper, etc. {from Anthony – Note these references in your paper: Landscheidt, T.,1988.Solar rotation,impulses of the torque in sun’s motion, and climate change. Climatic Change12,265–295. Landscheidt, T.,1999.Extrema in sunspot cycle linked toSun’s motion. Solar Physics 189,415–426.} 2) There are numerous misconceptions since the beginning such as “Figure 9 looks to be interesting, but note that it is in generic units, not temperature, so has no predictive value by itself.” It is a hindcast and prediction. There is no need to use specific units, but only dynamics. The units are interpreted correctly in the text of the paper as being approximately W/m^2 and as I say in the caption of the figure “However, the bottom curve approximately reproduces the patterns observed in the proxy solar models depicted in Fig. 5. The latter record may be considered as a realistic, although schematic, representation of solar dynamics.” {from Anthony – if it isn’t using units of temperature, I fail to see how it can be of predictive value, there is not even any reference to warmer/cooler} 3) About Leif’s comments. It is important to realize that Solar physics is not “settled” physics. People do not even understand why the sun has a 11-year cycle (which is between the 10 and 12 year J/S tidal frequencies, as explained in my paper). 4) The only argument advanced by Leif against my paper is that the phenomenon is his opinion was not observed in other stars. This is hardly surprising. We do not have accurate nor long records about other stars! Moreover we need to observe the right thing, for example, even if you have a large planet very close to a star, the observable effect is associated to many things: how eccentric the orbits are and how big the star is, and its composition etc. Stars have a huge inertia to tidal effects and even if you have a planet large and close enough to the star to produce a theoretical 4,000,000 larger tidal effect, it does not means that the response from the star must be linear! Even simple elastic systems may be quite sensitive to small perturbations but become extremely rigid to large and rapid perturbations, etc. It is evident that any study on planetary influence on a star needs to start from the sun, and then eventually extended to other star systems, but probably we need to wait several decades before having sufficiently long records about other stars! In the case of the sun I needed at least a 200 year long sunspot record to detect the three Schwabe cycles, and at least 1000 years of data for hindcast tests to check the other frequencies. People can do the math for how long we need to wait for the other stars before having long enogh records. Moreover, I believe that many readers have a typical misconception of physics. In science a model has a physical basis when it is based on the observations and the data and it is able to reconstruct, hindcast and/or forecast them. It is evident to everybody reading my paper with an open mind that under the scientific method, the model I proposed is “physically based” because I am describing and reconstructing the dynamical properties of the data and I showed that the model is able to hindcast millennia long data records. Nobody even came close to these achievements. To say otherwise would mean to reject everything in science and physics because all findings and laws of physics are based on the observations and the data and are tested on their capability of reconstruct, hindcast and/or forecast observations, as I did in the paper Of course, pointing out that I was not solving the problem using for example plasma physics or quantum mechanics or whatever else. But this is a complex exercise that needs its own time. As I correctly say in the paper. “Further research should address the physical mechanisms necessary to integrate planetary tides and solar dynamo physics for a more physically based model.”

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