Nicola Scafetta Comments on “Solar Trends And Global Warming” by Benestad and Schmidt
From Climate Science — Roger Pielke Sr.
On July 22 2009 I posted on the new paper on solar forcing by Lean and Rind 2009 (see). In that post, I also referred to the Benestad and Schmidt 2009 paper on solar forcing which has a conclusion at variance to that in the Lean and Rind paper.
After the publication of my post, Nicole Scafetta asked if he could present a comment (as a guest weblog) on the Benestad and Schmidt paper on my website, since it will take several months for his comment to make it through the review process. In the interests of presenting the perspectives on the issue of solar climate forcing, Nicola’s post appears below. I also invite Benestad and Schmidt to write responses to the Scaftta contribution which I would be glad to post on my website.
GUEST WEBLOG BY NICOLA SCAFETTA
Benestad and Schmidt have recently published a paper in JGR. (Benestad, R. E., and G. A. Schmidt (2009), Solar trends and global warming, J. Geophys. Res., 114, D14101, doi:10.1029/2008JD011639).
This paper criticizes the mathematical algorithms of several papers that claim that the temperature data show a significant solar signature. They conclude that such algorithms are “nonrobust” and conclude that
“the most likely contribution from solar forcing a global warming is 7 ± 1% for the 20th century and is negligible for warming since 1980.”
By using the word “robust” and its derivates for 18 times, Benestad and Schmidt claim to disprove two categories of papers:
those that use the multilinear regression analysis [Lean and Rind, 2008; Camp and Tung, 2007; Ingram, 2006] and those that present an alternative approach [Scafetta and West, 2005, 2006a, 2006b, 2007, 2008]. (See the references in their paper.)
Herein, I will not discuss the limitation of the multilinear regression analysis nor the limits of Benestad and Schmidt’s critique to those papers. I will briefly focus on Benestad and Schmidt’s criticism to the papers that I coauthored with Dr. West. I found Benestad and Schmidt’s claims to be extremely misleading and full of gratuitous criticism due to poor reading and understanding of the data analysis that was accomplished in our works.
Let us see some of these misleading statements and errors starting with the less serious one and ending with the most serious one:
1. Since the abstract Benestad and Schmidt claim that they are rebutting several our papers [Scafetta and West, 2005, 2006a, 2006b, 2007, 2008]. Already the abstract is misleading. Indeed, their criticism focuses only on Scafetta and West [2005, 2006a]. The other papers used different data and mathematical methodologies.
2. Benestad and Schmidt claim that we have not disclosed nor detailed the mathematical methodology and some parameters that we use. For example:
a) In paragraph 39 Benestad and Schmidt criticize and dismiss my paper with Willson [2009] by claiming that we “did not provide any detailed description of the method used to derive their results, and while they derived a positive minima trend for their composite, it is not clear how a positive minima trend could arise from a combination of the reconstruction of Krivova et al. [2007] and PMOD, when none of these by themselves contained such a trend).” However, the arguments are quite clear in that paper and in the additional figures that we published as supporting material. Moreover, it is not clear to me how Benestad and Schmidt could conclude that our work is wrong if Benestad and Schmidt acknowledge that they have not understood it. Perhaps, they just needed to study it better.
b) In paragraph 41 Benestad and Schmidt claim that: “It is not clear how the lagged values were estimated by Scafetta and West [2006a]“. However, in paragraph 9 of SW06a it is written “we adopt the same time-lags as predicted by Wigley’s [1988, Table 1] model.” So, again, Benestad and Schmidt just needed to study better the paper that they wanted to criticize.
c) In paragraph 48 Benestad and Schmidt claim that: “over the much shorter 1980-2002 period and used a global surface temperature from the Climate Research Unit, 2005 (they did not provide any reference to the data nor did they specify whether they used the combined land-sea data (HadCRUT) or land-only temperatures (CRUTEM).” However, it is evident from our work SW05 that we were referring to the combined land-sea data which is properly referred to as “global surface temperature” without any additional specification (Land or Ocean, North or South). We also indicate the webpage where the data could be downloaded.
d) In paragraph 57 Benestad and Schmidt claim that: “The analysis using Lean [2000] rather than Scafetta and West’s own solar proxy as input is shown as thick black lines.” However, in our paper SW06a it is crystal clear that we too use Lean’s TSI proxy reconstruction. In particular we were using Lean 1995 which is not very different from Lean 2000. Benestad and Schmidt apparently do not know that since 1978 Lean 1995 as well as Lean 2000 do not differ significantly from PMOD because PMOD was build (by altering the published TSI satellite data) by using Lean 1995 and Lean 2000 as guides. Moreover, we also merge the Lean data with ACRIM since 1978 to obtain an alternative scenario, as it is evident in all our papers. The discontinuity problem addressed by Benestad and Schmidt in merging two independent sequences (Lean’s proxy model and the ACRIM) is not an issue because it is not possible to avoid it given the fact that there are no TSI satellite data before 1978.
3. In Paragraphs 48-50 Benestad and Schmidt try to explain one of our presumed major mathematical mistakes. Benestad and Schmidt’s states: “A change of 2*0.92 W/m2 between solar minimum and maximum implies a change in S of 1.84 W/m2 which amounts to 0.13% of S, and is greater than the 0.08% difference between the peak and minimum of solar cycle 21 reported by Willson [1997] and the differences between TSI levels of the solar maxima and minima seen in this study (~1.2 W/m2; Figure 6).” Benestad and Schmidt’s are referring to our estimate of the amplitude of the solar cycle referring to the 11-year modulation that we called A7,sun = 0.92 W/m2 in SW05. Benestad and Schmidt are claiming that our estimate is nor reasonable because in their opinion according to our calculations the change of TSI between solar maximum and solar minimum had to be twice our value A7,sun , so they write 2*0.92=1.84 W/m2, and this would be far too large. However, as it is evident from our paper and in figure 4a in SW05 the value A7,sun refers to the peak-to-trough amplitude of the cycle, so it should not be multiplied by 2, as Benestad and Schmidt misunderstood. This is crystal clear in the factor ½ before the equation f(t)= ½ A sin(2pt) that we are referring to and that Benestad and Schmidt also report in their paragraph 48. It is hard to believe that two prominent scientists such as Benestad and Schmidt do not understand the meaning of a factor ½! So, again, Benestad and Schmidt just needed to think more before writing a study that criticizes ours.
4) Finally, Benestad and Schmidt’s paper is full of misleading claims that they are reproducing our analysis. Indeed, Benestad and Schmidt’s paper is self-contradictory on this crucial issue. In paragraph 85 Benestad and Schmidt claim that they “have repeated the analyses of Scafetta and West, together with a series of sensitivity tests to some of their arbitrary choices.” However, in their paragraph 76 Benestad and Schmidt acknowledge: “In our emulation, we were not able to get exactly the same ratio of amplitudes, due to lack of robustness of the SW06a method and insufficient methods description.” It is quite singular that Benestad and Schmidt claim to have repeated our calculation, at the same time they acknowledge that, indeed, they did not succeed in repeating our calculation and, ironically, they blame us for their failure. It is not easy to find in the scientific literature such kind of tortuous reasoning!
In fact, the reason why Benestad and Schmidt did not succeed in repeating our calculation is because they have misapplied the wavelet decomposition algorithm known as the maximum overlap discrete wavelet transforms (MODWT). This is crystal clear in their figures 4 where it is evident that they applied the MODWT decomposition in a cyclical periodic mode. In other words they are implicitly imposing that the temperature in 2001 is equal to the temperature in 1900, the temperature in 2002 is equal to the temperature in 1901 and so on. This is evident in their figure 4 where the decomposed blue and pink component curves in 2000 just continue in 1900 in an uninterrupted cyclical periodic mode as shown in the figure below which is obtained by plotting their figure 4 side by side with itself:
Any person expert in time series processing can teach Benestad and Schmidt that it is not appropriate to impose a cyclical periodic mode to a non stationary time series such as the temperature or TSI records that present clear upward trends from 1900 to 2000. By applying a cyclical periodic mode Benestad and Schmidt are artificially introducing two large and opposite discontinuities in the records in 1900 and 2000, as the above figure shows in 2000. These large and artificial discontinuities at the two extremes of the time sequence disrupt completely the decomposition and force the algorithm to produce very large cycles in proximity of the two borders, as it is clear in their figure 4. This severe error is responsible for the fact that Benestad and Schmidt find unrealistic values for Z22y and Z11y that significantly differ from ours by a factor of three. In their paragraph 50 they found Z22y = 0.58 K/Wm-2, which is not realistic as they also realize later, while we found Z22y = 0.17 K/Wm-2, which is more realistic.
This same error in data processing also causes the reconstructed solar signature in their figures 5 and 7 to present a descending trend minimum in 2000 while the Sun was approaching one of its largest maxima. Compare their figures 4a (reported above), 5 and 7 with their figure 6 and compare them also with our figure 3 in SW06a and in SW08! See figure below where I compare Benestad and Schmidt’s figures 6 and 7 and show that the results depicted in their Figure 7 are non-physical.
Because of the severe and naïve error in applying the wavelet decomposition, Benestad and Schmidt’s calculations are “robustly” flawed. I cannot but encourage Benestad and Schmidt to carefully study some book about wavelet decomposition such as the excellent work by Percival and Walden [2000] before attempting to use a complex and powerful algorithm such as the Maximum Overlap Discrete Wavelet Transform (MODWT) by just loading a pre-compiled computer R package.
There are several other gratuitous claims and errors in Benestad and Schmidt’s paper. However, the above is sufficient for this fast reply. I just wonder why the referees of that paper did not check Benestad and Schmidt’s numerous misleading statements and errors. It would be sad if the reason is because somebody is mistaking a scientific theory such as the “anthropogenic global warming theory” for an ideology that should be defended at all costs.
Nicola Scafetta, Physics Department, Duke University
It’s very trendy in “peer-reviewed” circles to use some new analysis method, such as wavelet transforms. Vulgar resort to canned routines instantly provides an aura of high erudition. That the basics have not been mastered by the user (or canner, in some instances) and the technique is misapplied seems, unfortunately, beyond the ken of most reviewers.
While it will be interesting to see how RC plays this; however, this short tale exposes the awful truth, which many of us know already, that peer review doesn’t always mean very much.
I have had one peer review help catch some very bad errors that would have lead to great embarrasment in a paper, and for which I remain grateful to this day. Yet, another at another time suggested some every bad errors that I should, in fact must, make in order to get the paper accepted. Here are some reasons I’ve determined why peer review goes wrong in general, not just in the GW context.
1) Peer reviewers see review as a way to gather intelligence, rather than a duty and service to science and one’s peers. (I have had reviewers leak details of a paper to a third party, and then sit on their review until the last minute.)
2) Peer reviewers do not think that a poorly done review will hurt their reputation because it is often anomymous to the author, so they put in insufficient effort. We really should get rid of reviewer anonimity–or make it double blind.
3) Peer reviewers often do not understand what they are reviewing, but appear loathe to admit as much for fear of loosing reputation with the referee and journal editor.
4) In a particularly contentious area of research and debate, some peer reviewers over estimate their ability or knowledge in a rush to be “defender of the faith.”
5) Peer reviewers sometimes look at the review as a way to promote one’s own work–sometimes to the point of demanding that their own important work be cited (which destroys anonimity, of course).
6) Peer reviewers allow the author’s reputation, or affiliation with prestigious organization to cloud their judgment. In fact, peer review is just about a death sentence to the talented amateur.
Unfortunately, tradition being what it is, and the limitation of journal space and pressure to publish, means that peer review is probably with us to stay. None the less we all need to maintain skepticism against claims about “peer review.”
This is not related but the cool weather is catching up to use here in Ky. Flooding rains are pouring down in record rates. Louisville is flooded, 6″ in one hour. We are getting the same up I-71 towards Cinn. OH. It’s like it’s April or May here.
I’m not particularly impressed with either side. One side presents a, largely incomprehensible, paper, replete with arithmetic, and logic, errors; and the other side responds in kind.
Has ANYONE, ANYWHERE conducted an “EXPERIMENT?”
You know, where they, actually, MEASURE the effects of CO2 concentrations in “real,” “honest-to-goodness” Air?
sorry about the poor spelling, it’s haling here now as well.
This does not surprise me at all. I have said it before, and I will say it once again … Gavin Schmidt is the ultimate hack!
Further, he couldn’t program his ass out of a brown paper bag if he had to….
Leif Svalgaard (08:11:13) :
the likely trend [or lack thereof] in TSI since 1900. There is no large change during the 20th Century.
I think Leif should declare that he is a personal friend of Claus Frohlich, who is in ACRIMonious dispute with Nicola Scafetta and others over ‘adjustments’ made by Frohlich to the data the PMOD TSI series is constructed from.
I would advise those interested to check the EPA presentation by Scafetta linked by nogw on this thread. Especially pages 12-20, particularly the text of the letters on or around page 16.
They’re both wrong. At least according to this “study”. http://news.yahoo.com/s/livescience/20090803/sc_livescience/savetheplanethavefewerkids .
The firing range is open. Take your best shots. 😀
Off post slightly 😀
Sorry about this but someone on this site provided a link to The Greenhouse Conspiracy, on UTUBE, in which Professor Scneider is shown to be a liitle free with the actualite when questioned about his support for Global Cooling.
UTube say “This video has been removed due to terms of use violation.”
If there is another link I would appreciate. Some nutter on CIF is saying that global cooling is an urban myth.
oops sorry please read some misguided person instead of nutter.
Leif Svalgaard (08:11:13) :
http://www.leif.org/research/TSI%201900-now.png
I think the Lean reconstruction of TSI on this graphic may be one of Judith Lean’s earlier efforts and if so should not to be confused with the Lean reconstruction referred to in the letters included in the Scafetta EPA presentation.
Over the last years Lean seems to have gone from a reconstruction which would be consistent with a solar explanation for C20th warming to one more in line with the outlook of her employers.
It seems that the Benestad and Schmidt paper is yet another piece of evidence in support for my theory that any piece of crap gets past peer-review and published as long as it supports the AGW hypothesis. On the other hand, papers disproving the AGW hypothesis have to be extremly well-written, and by known climate scientists, to even have a chance of getting considered for publication.
tallbloke (09:48:13) :
I think Leif should declare that he is a personal friend of Claus Frohlich, who is in ACRIMonious dispute with Nicola Scafetta and others over ‘adjustments’ made by Frohlich to the data the PMOD TSI series is constructed from.
I’m also a personal friend of Wilson and Hudson of ACRIM and of Lean, Wang, Preminger, and Schatten of TSI reconstructions. And what has being a good friend and colleague to do with anything?
Furthermore, the BS and SW papers using TSI before 1978 have nothing to do with PMOD. Lastly, I’m a strong critic of Claus’s contention that [PMOD] TSI is dropping off the chart, having shown him that he has calibration problems.
The real issue is that climate researchers persist in using TSI reconstructions that the solar community has long left behind in the dust.
Galileo’s discoveries were peer-reviewed. Cardinal A said they were dangerous rubbish, Cardinal B said they were heresy and Cardinal D said he ought to be locked up.
John S. : “Then a miracle occurs”
http://www.sciencecartoonsplus.com/pages/gallery.php
(and a backup in case the above intro page changes to a different image…)
http://www.scienceteecher.com/miracle.htm
tallbloke (10:10:07) :
I think the Lean reconstruction of TSI on this graphic may be one of Judith Lean’s earlier efforts and if so should not to be confused with the Lean reconstruction referred to in the letters included in the Scafetta EPA presentation.
Over the last years Lean seems to have gone from a reconstruction which would be consistent with a solar explanation for C20th warming to one more in line with the outlook of her employers.
Lean’s later efforts were with Wang and is labelled ‘Wang’. There is no confusion. Both SW and BS rely on an increase of TSI during the 20th Century that did not occur. Who do you think is Lean’s employer?
Lean in her 2008 SORCE presentation clearly states that no long-term variation of TSI has been detected and questions if any exists. The basic point still stands: Both papers use outmoded TSI and the conclusions of both papers are suspect. That one suspect one disagrees with another suspect one is not important, nor surprising.
Another example of why it is good to provide supporting and intermediate data, since if that had been done in the first instance, it would have been less likely that the errors in the audit would have slipped through the review process. It is trivially easy to claim ‘we failed to reproduce the exact result’ if there is not open access to the source. If the source is made available, the errors can be explicitly addressed (such as using a precise invalid data set). I think that a failure to at least acknowledge a contrary TSI input series must be seen as a failing though.
I wonder if peer review in this case is more than a “right on” from like-minded friends?
While y’all were discussing The Weather, ole Sol went nighty-night again.
The 10.7 cm flux is back down to 67.
http://solarcycle24.com/
Getting close to another 30 spotless days in a row.
I haven’t looked lately, has NASA re-re-revised their forecasts for SC24?
The Big Question: If spotlessnes continues like this (a minor eruption evry 30-60 days, then back to slumber, with flux numbers slowly oscillating between 67 and 72 and spotlessness at ~80%) at what point do we have a probable Dalton-like Minimum (inconvenient)? At what point a Maunder (big disaster)?
If, for example, at Christmas everything’s roughly the same, are we in a Dalton? If next year at this time we are roughly the same, is it a Maunder?
Rhetorical questions, as I wouldn’t believe anyone’s answers anyway.
It’s clear to me that prsvious attempts to forecast SC24 were universally based on one extrapolation or another, and that there’s substantailly NO reliable understanding of the fundamentals. Oh, except that Humans caused warming, which is still going on despite the physical evidence to the contrary, and we’re all gonna die because of it. mea culpa, mea maxima culpa.
Leif Svalgaard (10:14:54) :
Lastly, I’m a strong critic of Claus’s contention that [PMOD] TSI is dropping off the chart, having shown him that he has calibration problems.
The data displayed on the woodfortrees.org site shows PMOD as up to date and falling off the bottom of the chart. You said yesterday that PMOD is no longer updated since you convinced Claus Frohlich he had calibration problems. I asked you whose data was being used on the woodfortrees site under the PMOD series but you didn’t reply.
If it is SORCE data, which has dropped around 0.8W/m^2 since mid 2003, then it means TSI is currently well below it’s level at last minimum by at least 0.1W/m^2.
The sun it would seem, is a more variable star than your reconstruction would lead us to believe.
The ACRIM data reflected that too, before it got smoothed into monotonous conformity.
http://www.woodfortrees.org/plot/pmod
I don’t know enough about the TSI recons to know if Leif is right about there being little change (or how certain such a claim really is). What I do know is that Solar versus AGW is a false dilemma. Even spontaneously arising chaotic behavior in clouds could cause warming and cooling. And we can’t know whether such changes occurred or not. The influence of solar factors should be studied, and Scafetta and West are doing well to investigate the issue. Ultimately I think that the lack of “change” in TSI may not matter that much (partly because the response to the solar cycles would be expected to be damped compared to the long term fluctuations) especially since the results in their various papers were marginally effected by the choice of TSI proxies (with even better results for the ones which showed less variability!) But in any case, it just goes to show how uncertain the situation really is.
Lean 2000 and Lean 1995. I wouldn’t say that a claim “Lean 1995 which is not very different from Lean 2000” was robust without performing a sensitivity analysis.
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/solar_variability/lean2000_irradiance.txt
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lean1995/irradiance_data.txt
Having interacted with college students since I first began teaching them in 1970, I assert that they generally sort themselves along the left/right political axis as follows: The students in the numerical-oriented majors such as business, science, engineering, mathematics, computer science, etc., generally tend toward the right end of the political spectrum, while the non-numerical oriented students in the humanities tend toward the left end. Outside of a statistically robust study, I am aware that such a personal, simplistic generalization is subject to criticism, but to the extent that politics is a part of the whole AGW debate, would the preceding observation about students carry over into the scientific community? In other words, would a valid statistical study support or refute the hypothesis that the warmist camp of scientists would be more numerically challenged than the skeptic camp of scientists?
Leif Svalgaard (10:29:05) :
Both papers use outmoded TSI
I prefer to think of their reconstruction and yours as the high and low estimates between which the truth is lurking.
After all, with the obvious and explicitly confirmed calibration and splicing difficulties in play, categorical statements seem somewhat out of place.
tallbloke (10:48:33) :
I asked you whose data was being used on the woodfortrees site under the PMOD series but you didn’t reply.
Because I don’t know where they get the data from. I get PMOD from Claus.
If it is SORCE data, which has dropped around 0.8W/m^2 since mid 2003, then it means TSI is currently well below it’s level at last minimum by at least 0.1W/m^2.
You have always had a tendency to quote data wrongly to support your views. SORCE has dropped 0.53 W/m2.
Here are the numbers:
year SORCE PMOD diff
2003 1362.39 1365.83 4.44
2004 1361.26 1365.70 4.44
2005 1361.09 1365.52 4.43
2006 1361.01 1365.44 4.43
2007 1360.91 1365.33 4.42
2008 1360.87 1365.29 4.42
2009 1360.86 1365.25 4.39 <:=== since Sept. 2008, PMOD is unreliable
The numbers for PMOD are his latest [that he sent me – and are also on his website]. He seems to have gotten some of the calibration problems fixed, except after Sept. 2008.
then it means TSI is currently well below its level at last minimum by at least 0.1W/m^2.
We don’t know what TSI was at the last minimum to an accuracy of 0.1 W/m2, and considering your being wrong about the 0.8 for SORCE, I would not place much credence in your 0.1.
The sun it would seem, is a more variable star than your reconstruction would lead us to believe.
Considering the above, you have no basis for saying this.