Eli has been having some fun with the latest Climate of the Past mistake, by Lüdecke, et al. Although the Rabett's first thrust was about the data used, after all, if the data is bad, it doesn't much matter about anything else, others have been busy piling on.
Georg Hoffmann, over at Primaklima lays out the problems with Lüdecke, et al. and asks a important question
Except for the names of the authors is there anything else in the paper which is correct?Sadly no, but the number of things wrong with the paper is astounding.
1) The temperature series they use are not global. Worse there are other proxy and instrumental series directly "next" to the ones chosen by Lüdecke that look different.You would think that Lüdecke and the Editor Eduardo Zorita would know that, but sadly no, the Rabett reads in the published paper
The characteristic of these records, namely the pronounced minimum around 1880, is equally found in Antarctic ice core temperature data, which are also overall in agreement with M6, revealing this 1880 minimum as a global phenomenon.In Georg's words, putting together a regional time series and then comparing it with a single proxy record half way around the world does not a global time series make. Surely the Editor, Eduardo Zorita should have caught this, given that he intervened against the advice of his referees to publish the paper, but, sadly no, he did not.
Is this but a single mistake? Sadly no. There are other time series of the same length found in the same database, that somehow were thrown down the memory hole by Lüdecke, et al., and of course this was ignored by the Editor, Eduardo Zorita who is probably using many of these time series in a paper to be published as part of the HISTALP project, but, sadly no, this is not all
2) Even if that were not so, using their method to construct a global series, is, of course nonsense.Even a dumb bunny knows that.
3) Their time series have at the beginning a strong and well-known bias to warmer temperatures. This bias controls the oscillatory behavior of the supposed curve.As Eli and Georg point out, the late Reinhard Böhm had figured out how to correct for this, publishing the result in 2010 but sadly no this was not taken into account by Lüdecke and the Editor, Eduardo Zorita, who again, amazingly enough, is working with the HISTALP project on a major paper.
4) Even if that would be not so, one cannot say anything about the dynamics of the climate system using Fourier analysis where the major alleged oscillation is of the roughly the length of the time series.Eli is happy to toss this one to Tamino
Let me elaborate. All they’ve done is model the data as a low-frequency Fourier series, then compared that to the low-frequency (boxcar filtered) version. Of course it gives a good match, especially since the actual trend present in this data is dominated by low-frequency fluctuation. In essense, all they’ve shown is that an arbitrary function can be modeled by a Fourier series. Really. Truly. That’s all.With six (actually eight, but they threw out a couple which had zero coefficients) frequencies from the Fourier analysis and three parameters per frequency there are eighteen choices, nineteen if you throw in a constant. Von Neuman could fit an elephant with four and make him wiggle his trunk with five. Who knows the magic that could be done with eighteen or nineteen. But again, sadly no, the Editor, Eduardo Zorita did not pick up on that either, or rather he tried to wash it away.
And finally, Georg points out that
5) The bumps and wiggles determining the oscillations, have known and not only cyclical causes (eg volcanoes).And again, sadly no, the Editor, Eduardo Zorita did not pick up on that one either and he even accepted the nonsensical statement in the paper that
The agreement of the reconstruction of the temperature history using only the six strongest components of the spectrum, with M6, shows that the present climate dynamics is dominated by periodic processes.Is this all, well, sadly no. Wolfgang Flamme has something to add
It additionally occurs to me that the form of the SP12 proxy, from which L. wants to draw conclusions about the 250 year period is not shown in the paper. Perhaps that has something to do with the fact that it does not display the assumed V form.
As Eli reads in the Wikipedia
Zorita was quoted in the Wall Street Journal as saying that the "scientific debate [on climate change] has been in many instances hijacked to advance other agendas", and that climate science students are "often tempted to tweak their data so as to fit the 'politically correct picture'. "Seems to fit.