Scientists find errors in hypothesis linking solar flares to global temperature
From Physorg.com. h/t to Leif Svalgaard who offers this PDF with this diagram that makes it all clear.

In contrast to a previous analysis, a new study has shown that the distributions of (a) the global temperature anomaly by month since 1880 and (b) the solar flare index by day over a few solar cycles are fundamentally different. One feature the detrended data do have in common is self-similarity: the probability density functions are the same on different time scales, which means that neither can be described as Lévy walks. Image credit: Rypdal and Rypdal.
(PhysOrg.com) — The field of climate science is nothing if not complex, where a host of variables interact with each other in intricate ways to produce various changes. Just like any other area of science, climate science is far from being fully understood. As an example, a new study has discredited a previous hypothesis suggesting the existence of a link between solar flares and changes in the earth’s global temperature. The new study points out a few errors in the previous analysis, and concludes that the solar and climate records have very different properties that do not support the hypothesis of a sun-climate complexity linking.
In a handful of studies published in Physical Review Letters between 2003 and 2008, a team from Duke University and the Army Research Office including Nicola Scafetta and Bruce West analyzed data that appeared to show that solar flares have a significant influence on global temperature. Solar flares, which are large explosions in the sun’s atmosphere that are powered by magnetic energy, vary in time from a few per month to several per day. Although solar flares occur near sunspots, their frequency variation occurs on a much shorter time scale than the 11-year sunspot cycle. In their studies, the researchers’ results seemed to show that data from solar flare activity correlates with changes in the global temperature on a short time scale. Specifically, their analysis showed that the two time records can both be characterized by the same Lévy walk process.
However, in the new study, which is also published in Physical Review Letters, Martin Rypdal and Kristoffer Rypdal of the University of Tromso in Norway have reexamined the data and the previous analysis and noticed some shortcomings. One of the biggest causes of concern is that the previous analysis did not account for larger trends in factors that affect solar flares and global temperature. For instance, the solar cycle has its 11-year periodic trend, where periods of lots of sunspots cause larger numbers of solar flares. Likewise, the global temperature anomaly has numerous other factors (a “multi-decadal, polynomial trend”) that impacts global temperature fluctuations. By not detrending this data, the analysis resulted in abnormally high values of certain variables that pointed to Lévy walk processes. By estimating the untrended data, Rypdal and Rypdal hypothesized that the solar flare records might be described by a Lévy flight, while the global temperature anomaly might obey a distribution called persistent fractional Brownian motion.
Read the entire article here at Physorg.com
A preprint of the paper is available here
Practice making your own Levy walks here
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Leif Svalgaard (18:45:09) :
“Since TSI [or the mysterious X-force for which it is supposed to be a proxy] does not have any long-term trend [c.f. what I told you above], then what is that ‘astronomical influence’?”
It is not true that solar activity does not have any long-term trend. Notice that I always use the TSI proxy models as approximate proxy of a generic solar activity. Nothing exclude me to use some other solar proxy for the purpose.
Do not be impatient about the exact mechanism! before or later it will be found but the signal is there and also strong. Just, I do not believe that there is only one mechanism at work.
Leif Svalgaard (18:49:05) :
Unfortunately science is not a perfect structure for determining the truth! The logic in science is: A implies B, observe B is true, then A is possible.
If you do not like it, you needed to be a mathematician, not a solar scientist!
However, now this topic was discuss long enough.
I will stop now.
thank you to all of you. !
Nicola Scafetta (19:17:21) :
I will stop now.
thank you to all of you. !
And thank you for stopping by, trying to make us understand what you think you see.
I am not letting Nicola have the final word:
Nicola Scafetta (17:07:19) :
“Your methodology has removed a known solar signature on climate which is associated to the Gleissberg (50-80 years) and Suess (160-260
years) solar variability. Moreover, if the record were twice as long what kind of fit would you use? A 4th, 5th or 6th order polynomial?”
As explained earlier our methodology removes things that may be of solar origin. But everything of solar origin does not have to derive f rom Levy-walk statistics. On of the great problems with your methodology, and this permeates everything you do in climatology, is your uncritical mixing of categories.
We have also explained earlier how we determine the order of the fitting polynomial. It is by increasing the order till the value for H converges, combined with an a posteriori test that the polynomial varies slowly over the largest time scale T for which we find memory (the SDA-curve has a linear slope H up to to a certain time T, after which is becomes flat). But other detrending procedures are equally adequate; smoothing by a running mean is fine, as long as the length of the smoothing window is selected from the same criteria. If the signal is reasonably stationary an increase in the record length should not change the length of the smoothing window. The polynomial order may increase to provide the same level of smoothing.
Nicola Scafetta (17:07:19) :
“Levy-walk noises may present very long trending properties because of their fat temporal tail distributions”.
This statement is too vague. Our attempts to produce the trends observed in the GTA by using the prescription for generating a LW-noise time series in your 2003 and 2004 work have failed. We have asked you several times for a prescription for how you generate realizations for LW time series that can be compared to the measured GTA signal, but we get no answer. Instead you keep repeating the mantra:
“In any case, the real problem with your work is that you mistake the increments with the time structure. We talk about waiting time distribution, you are talking about increment distributions. The scaling is in the time structure, not in the increments.”
In all my later messages I have been talking about time structure and waiting time distributions, and this is perfectly relevant for certain types of solar records. But climate data like the GTA are given as time series of increments sampled at regular intervals. If you remove the information about the increments, there is no information left. In your SDA and DEA analysis of the GTA (which is the only analysis you do on these data) you use of course the increments, because this is all you have. As long as you do not give a clear prescription for how you go from an assumed underlying time structure of waiting times to an observable time series of increments, there is no way your hypothesis can be tested. I think I know why you avoid that. It is because you are afraid that more detailed statistical tests on such a synthetic time series will reveal that it is profoundly different from the observed GTA signal.
Nicola Scafetta (17:07:19) :
“In science the logic is: A implies B, observe B is true, then A is possible.”
I agree with the first statement. But in a Bayesian framework it can be made more precise. It is not only interesting to know that A is possible but rather how probable it is that A is true, and how more probable this has become after we have observed B to be true. If we denote the prior probability of A and B as p(A), and p(B), and the conditional probability of B, given A, as p(B|A), the Bayes’ theorem states that the probability of A, give that we have observed B to be true , is
p(A|B)=p(B|A)p(A)/p(B).
From this expression we see that the confidence in A is changed by the factor p(B|A)/p(B) by observing that B is true. Assume that A is the hypothesis that LW noise is hidden in the GTA signal, and B is the observation of exponents from DAE and SDA analysis with D different from H, but both close to unity. The question is now what values we assign to p(B|A) and p(B). Let us assume that we agree that if if A is true we will observe B, we will have that p(B|A)=1, so our change in belief is really given by 1/p(B).
Here we are coming to the point where our paths diverge. From a glance at the GTA signal I would be certain that B is true, without performing any analysis at all, hence I would assign a prior probability p(B)=1, and hence the analysis would not change my belief. This can be formulated in a less subjective way by showing that there exist a set of mutually exclusive alternative hypotheses H_i that all give the result B and whose probability sum up to nearly 1, i.e. that p(B)=\sum_i p(B|H_j)p(H_j)~1.
You, Nicola, do not realize that there are so many other probable explanations of your observation B, so you will assign a very small value to the prior probability of B, i.e. you would assume p(B)<<1. But that assumption is objectively wrong.
Another (and more subjective) element that determines the a posteriori belief p(A|B) is the prior belief in the hypothesis A. I find it very improbable, and would set p(A)<<1. Your analysis should only change into a believer if the product p(A)/p(B) is close to unity. But since I don't consider p(B) to be much less than unity, I still should not believe in your hypothesis.
Kristoffer Rypdal (02:43:48) :
the final word will be said at the end of history!
The Bayesian framework does not have any physical meaning because in physics one deals also with the unknown.
If we were living in 1600 you would use it to support Aristotle against Galileo.
Nicola Scafetta (05:44:10) :
“The Bayesian framework does not have any physical meaning because in physics one deals also with the unknown.
If we were living in 1600 you would use it to support Aristotle against Galileo.”
Interesting. Could you elaborate on that? How systematic testing of hypotheses against observations within a Bayesian framework would end up supporting Aristotle, who never bothered doing experiment or observation.
Should I understand your statement that you reject Bayesian hypothesis testing as a scientific method?
You don’t have the last word today! As far as i know, the thread will be open time immemorial. The debate is worth having, in my view, and until you both get to an impasse of interpretation ie you agree to disagree. As long as you are both trying to iron out misunderstandings of each others science, no harm done. 🙂