Readers may find the title familiar, that’s because Basil Copeland and I also did a paper looking at solar signatures in climatic data, which has received a lot of criticism because we made an analytical error in our attempt. But errors are useful, teachable moments, even if they are embarrassing, and our second attempt though, titled,
hasn’t been significantly challenged yet that I am aware of. Basil and I welcome any comments or suggestions on that work.
In our work, we used Hodrick-Prescott filtering to extract the solar cycle signal from the HadCRUT temperature dataset. In this paper the data are extracted from the ECA&ECD database (available via http://eca.knmi.nl ). According to the paper, they are “using a nonlinear technique of analysis developed for time series whose complexity arises from interactions between different sources over different time scales”. Read more about it in the paper. In both our paper, and in this one, a solar signature is evident in the temperature data. – Anthony
Evidence for a solar signature in 20th-century temperature
By Jean-Louis Le Mouel, Vincent Courtillot, Elena Blanter, Mikhail Shnirman (PDF available here)
J.-L. Le Mouël et al., Evidence for a solar signature in 20th-century temperature data from the USA and Europe, C. R. Geoscience (2008), doi:10.1016/j.crte.2008.06.001
Abstract
We analyze temperature data from meteorological stations in the USA (six climatic regions, 153 stations), Europe (44 stations, considered as one climatic region) and Australia (preliminary, five stations). We select stations with long, homogeneous series of daily minimum temperatures (covering most of the 20th century, with few or no gaps).We find that station data are well correlated over distances in the order of a thousand kilometres. When an average is calculated for each climatic region, we find well characterized mean curves with strong variability in the 3–15-year period range and a superimposed decadal to centennial (or ‘secular’) trend consisting of a small number of linear segments separated by rather sharp changes in slope.
Our overall curve for the USA rises sharply from 1910 to 1940, then decreases until 1980 and rises sharply again since then. The minima around 1920 and 1980 have similar values, and so do the maxima around 1935 and 2000; the range between minima and maxima is 1.3 °C. The European mean curve is quite different, and can be described as a step-like function with zero slope and a ~1 8°C jump occurring in less than two years around 1987. Also notable is a strong (cold) minimum in 1940. Both the USA and the European mean curves are rather different from the corresponding curves illustrated in the 2007 IPCC report.We then estimate the long-term behaviour of the higher frequencies (disturbances) of the temperature series by calculating the mean-squared interannual variations or the ‘lifetime’ (i.e. the mean duration of temperature disturbances) of the data series.We find that the resulting curves correlate remarkably well at the longer periods, within and between regions. The secular trend of all of these curves is similar (an S-shaped pattern), with a rise from 1900 to 1950, a decrease from 1950 to 1975, and a subsequent (small) increase. This trend is the same as that found for a number of solar indices, such as sunspot number or magnetic field components in any observatory. We conclude that significant solar forcing is present in temperature disturbances in the areas we analyzed and conjecture that this should be a global feature.
…
We find that station data are well correlated over distances in the order of a thousand kilometres. When an average is calculated for each climatic region, we find well characterized mean curves with strong variability in the 3-15-year period range and a superimposed decadal to centennial or ‘secular’ trend consisting of a small number of linear segments separated by rather sharp changes in slope. Our overall curve for the USA rises sharply from 1910 to 1940, then decreases until 1980 and rises sharply again since then. The minima around 1920 and 1980 have similar values, and so do the maxima around 1935 and 2000; the range between minima and maxima is 1.38C. The European mean curve is quite different, and can be described as a step-like function with zero slope and a 1.8C jump occurring in less than two years around 1987. Also notable is a strong (cold) minimum in 1940. Both the USA and the European mean curves are rather different from the corresponding curves illustrated in the 2007 IPCC report.
…
We then estimate the long-term behaviour of the higher frequencies (disturbances) of the temperature series by calculating the mean-squared interannual variations or the ‘lifetime’ (i.e. the mean duration of temperature disturbances) of the data series. We find that the resulting curves correlate remarkably well at the longer periods, within and between regions. The secular trend of all of these curves is similar (an S-shaped pattern), with a rise from 1900 to 1950, a decrease from 1950 to 1975, and a subsequent (small) increase. This trend is the same as that found for a number of solar indices, such as sunspot number or magnetic field components in any observatory.
…
We conclude that significant solar forcing is present in temperature disturbances in the areas we analyzed and conjecture that this should be a global feature.
We have also shown that solar activity, as characterized by the mean-squared daily variation of a geomagnetic component (but equally by sunspot numbers or sunspot surface) modulates major features of climate. And this modulation is strong, much stronger than the one per mil variation in total solar irradiance in the 1- to 11-year range: the interannual variation, which does amount to energy content, varies by a factor of two in Europe, the USA and Australia. This result could well be valid at the full continental scale if not worldwide. We have calculated the evolution of temperature disturbances, using either the mean-squared annual variation or the lifetime. When 22-year averaged variations are compared, the same features emerge, particularly a characteristic centennial trend (an S-shaped curve) consisting of a rise from 1920 to 1950, a decrease from 1950 to 1975 and a rise since. A very similar trend is found for solar indices. Both these longer-term variations, and decadal and sub-decadal, well-correlated features in lifetime result from the persistence of higher frequency phenomena that appear to be influenced by the Sun. The present preliminary study of course needs confirmation by including regions that have not yet been analyzed.
Not another nail in the coffin – though I remember Shaviv pulling his nails. I prefer to see it as another ray of sunshine, resurrecting the true cause with new beauty of proof.
The Sun.
Nasif Nahle (11:45:05) :
Actually, the obvious influences are from primary school lessons
You forgot the biggest of all
0) turn the Sun of if you don’t think the Sun has any influence.
But none of you influences have anything to do with why the climate varies, so are hardly relevant.
bill (09:33:21) :
anna v (05:20:01) :
UV changes by 8% for example and it is UV that penetrates the ocean depths
The same UV of course lands on plants/earth/houses. this would heat the “land” and hence the air above. A change in UV should show up as a temperature change (it does not in the FFTs). Or would you postulate that the UV is reflected from the earth?
Yes, the UV that falls on the continents is turned into infrared which is radiated back.
The light that falls in the oceans penetrates into it, and therefore can heat, according to the wavelength. Infrared only a few mm and the shorter the wavelength the deeper it goes, up to 100 meters or so.
Since the long range cycles are so dependent on the oceans it would not be surprising if the difference between high and low spots in the cycle would modulate the behavior of the currents since there would be an 8 percent difference in what is happening there, rather than a 0.1 one one.
I am not saying it is so. Just ennumerating speculations. There are further speculations with UV, since it has been found that plankton responds to the levels and tries to shield itself by releasing material in the atmosphere http://www.nasa.gov/vision/earth/environment/0702_planktoncloud.html that generates clouds.
We will be thankful, in the end, that sol doesn’t vary her output by more (or, indeed less) than 1/1000.
I don’t normally make predictions but a couple of brilliant people who work here do, so I guess it is rubbing off on me.
Richard Mackey (01:28:04) : – really great post.
timetochooseagain (09:02:23) : – legislative need trumps scientific investigation, court told.
Nick Stokes (00:57:47) :
Is anyone able to explain what is actually plotted in these graphs? For example, what is “lifetime”?
_________
I second this early post! What is this plot? It seems to bear no relation to the description in the second paragraph “Our overall curve for the USA rises sharply from 1910 to 1940, then decreases until 1980 and rises sharply again since then. The minima around 1920 and 1980 have similar values, and so do the maxima around 1935 and 2000”.
Leif Svalgaard (12:22:17) :
Nasif Nahle (11:45:05) :
Actually, the obvious influences are from primary school lessons
You forgot the biggest of all
0) turn the Sun of if you don’t think the Sun has any influence.
I am almost sure that you, as a solar physicist, have had many experiences under the Moon’s shadow during solar eclipses. I am not a solar physicist, but I have experienced and observed dramatic changes of regional climate states during solar eclipses. I have observed how the temperature of ground and the atmosphere decreases as much as 10-14 degrees as the solar eclipses progress. I have experienced eddies which apparently come out from nothing during a calm day under the influence of a solar eclipse. Now… Imagine what would happen if the Sun turns off… Heh!
But none of you influences have anything to do with why the climate varies, so are hardly relevant.
Please, expand your posture on each one of the influences, which, by the way, are not mine.
In Jasper Kirby’s slide show (see previous article on the CLOUD experiments at CERN), on slide 6, he makes the following points:
• Numerous palaeoclimatic reconstructions suggest that solar/GCR variability has an important influence on climate.
• However, there is no established physical mechanism, and so solar-climate variability is:
‣ Controversial subject
‣ Not included in current climate models
What if we applied the same criteria to GHG’s, particularly CO2. We would find that there is no evidence in palaeoclimatic reconstructions that changing CO2 causes significant temperature changes. The evidence indicates that the opposite is true. Indeed, when CO2 is approaching a relative peak, temperatures have already been dropping for centuries. When CO2 is approaching a relative minimum, temperatures have been warming for centuries. Whatever turns global temperatures from one trend to another is uneffected by the concentration of CO2 in the atmosphere!
Secondly, there is no established physical mechanism that takes the measurably small influence of changing CO2 concentrations and turns it into a climate catastrophe. In addition, the history of global climate indicates that such a mechanism can not exist! There is no question that the solar/GCR mechanism for controlling global climate is scientifically more robust than the CO2 hypothesis and is supported much more by the paleo data.
So why is the hypothesis that shows no correlation with climate history and has no scientifically supporting mechanism preferred over the hypothesis that is correlated to climate history and has a developing (yet incomplete), measurable, scientific mechanism?
Answer: We live in a post-rational world.
Nasif Nahle (13:01:40) :
“But none of you influences have anything to do with why the climate varies, so are hardly relevant.”
Please, expand your posture on each one of the influences, which, by the way, are not mine.
But since they are all irrelevant, I’ll not waste anybody’s time on that. I’m sure you can find elementary books that will tell you all you want to know about the points you mentioned. Then, if you difficulties with some of them, I’ll be glad to help, if I can.
Reply: This endless sniping by 3 or 4 commenters and Leif has just got to end sometime. Can all of you just tone it down? Act likes it’s a business meeting and you want to actually make the sale, even if the other guy pisses you off. ~ charles the paternal moderator
REPLY2: Ditto that – Anthony
Jakers (12:53:42) :
Nick Stokes (00:57:47) :
Is anyone able to explain what is actually plotted in these graphs? For example, what is “lifetime”?
_________
I second this early post! What is this plot? It seems to bear no relation to the description in the second paragraph “Our overall curve for the USA rises sharply from 1910 to 1940, then decreases until 1980 and rises sharply again since then. The minima around 1920 and 1980 have similar values, and so do the maxima around 1935 and 2000″.
If I remember correctly, I was a reviewer on an earlier submission to a more prestigious journal and recommended rejection for a variety of reasons, one being vagueness, another that you do not improve statistics by using many nearby stations [that all show almost the same thing], another one was the use of the geomagnetic station ESK [Eskdalemuir in Northern UK] where it is known that the data have been smoothed before 1932 and thus have smaller variability in the earlier years [can be seen in the Figure – raising the ESK curve to compensate for the smoothing actually improves the correlation, but that is besides the point].
bill (06:50:14) :
I have posted these plots many times
http://img162.imageshack.us/img162/84/hadcrutnhshlsgiscetssna.jpg
The average solar cycle is 11.01 years but there hardly ever is one that length.
O3 loss has been attributed to human activity.
So has global warming. Crazy isn’t it?
@Charles-the paternal moderator… It is fine for me. Although I have to say that it was not my intention to upset Leif in any way. I have agreed with many of Leif’s observations, except on two or three of his perspectives. Anyway, I apologize for any insolence in my messages addressed to Leif. We are scientists and we must keep equanimity.
timetochooseagain (09:02:23) :
Raymond Pierrehumbert (a professor of meteorology at the University of Chicago and a fanatical environmentalist) posted a blog supporting Bard and Delaygue, accusing Courtillot et al of fraud, and worse.
This guy posts as ‘raypierre’ on realclimate and also attempted a smear against Roy Spencer which I debunked the other day. He accused Roy of ‘cooking’ a graph which used spencers simple model he uses to show sensitivity to clouds.
It appears he’s repeated the smears against Courtillot there too:
http://www.realclimate.org/index.php/archives/2007/11/les-chevaliers-de-lordre-de-la-terre-plate-part-i-allgre-and-courtillot/langswitch_lang/in
So in a nutshell, they’re saying that solar activity “as characterized by the mean-squared daily variation of a geomagnetic component” correlates well with the “disturbances” of the temperature series. Therefore, they “conclude that significant solar forcing is present in temperature disturbances” and so solar activity “modulates major features of climate”. But it seems they found that solar activity and the actual temperature did not correlate well?
Jakers (15:10:23) :
So in a nutshell, […] But it seems they found that solar activity and the actual temperature did not correlate well?
Something like that. Not convincing or supportive of their notion.
Nylo (01:28:27) “Why do the graphs only plot information until ~1990?”
2 factors:
1) Some of the time series they used probably weren’t up-to-date.
2) More importantly: 22-year averaging – (the future hasn’t arrived yet).
Re: Nylo (01:28:27)
Sorry – that should be 22 year differencing in this case (see p.5, bottom right)).
In science, many times, it turns out progress of understanding only advances as confirmed opinions die out, and younger more open minds, who have had experience with the new ideas and evidence that support those ideas come into positions where they can in turn communicate those ideas.
Therefore, it is not surprising in the slightest that there are those that in spite of the best scientific evidence currently available still cling to the old antiquated ideas.
Although, it still can be remarkable how tenaciously some will hold on to those ideas that were current in their professional youth, but are now pathetically out-dated.
tallbloke:
Spencer responded too:
http://climatesci.org/2008/05/23/follow-up-to-the-response-to-ray-pierrehumberts-real-climate-post-by-roy-spencer/
I get the impression that most climate scientists don’t like cyclical data.
As for me, I’m going to be interested in grain prices over the next couple of years.
Re: John S. (11:11:06)
Thank you for these valuable notes.
– –
Re: anna v (05:20:01)
Well-said.
– –
Geoff Sharp (05:53:31) “[…] resist against those trying to stamp out fires that might one day provide the truth.”
With the stamping reaching a feverish pitch, one has to wonder what (beyond the obvious) is being protected.
– –
Jakers (15:10:23) “But it seems they found that solar activity and the actual temperature did not correlate well?”
The key is in this passage:
“When attempting to find long-term correlations, and possibly causal connections between observables linked to the climate system […] only the longer periods are relevant if the system is a linear one. But if it is nonlinear and moreover turbulent, cascades from the higher to the lower frequencies or the reverse can occur. In that sense, it is important to estimate the long-term behaviour of the higher frequencies (disturbances), a delicate task with many time series spanning several orders of magnitude in characteristic frequencies. […] complexity arises from interactions between different sources over different time scales. […] […] […] overwhelming effect of Earth’s annual orbit […]” – (Le Mouel, Courtillot, Blanter, & Shnirman)
It doesn’t take much of a nonlinear distortion to destroy (or impact) a linear correlation.
Also:
“It is not illegitimate to wonder about the significance and robustness of calculating a worldwide average for a disparate collection of trends.” – (Le Mouel, Courtillot, Blanter, & Shnirman)
They appear braced for irrational reactions.
Re: James F. Evans (18:11:20)
Well-said.
– –
A.Syme (18:27:15) “[…] cyclical […]”
Careful – you could be punished for mentioning that term in connection with anything other than the venerable year & day.
So… um… you’re saying that the planet heats and cools based on the sun’s cycles and that it’s entering another cooling cycle? Not that being alarmed will change anything, but should I be alarmed and start wearing poster boards and hoarding the best winter gear LLBean has to offer?
I don’t see how the sun can be responsible for earth’s current high average temperatures given that, according to the graph shown a few days ago here from Stockholm observations, we have had global dimming since around 1945.
http://wattsupwiththat.files.wordpress.com/2009/06/stockholm_solar.png?w=510&h=414
timetochooseagain (18:13:57) :
tallbloke:
Spencer responded too:
http://climatesci.org/2008/05/23/follow-up-to-the-response-to-ray-pierrehumberts-real-climate-post-by-roy-spencer/
Indeed, but he didn’t argue the point I picked up on, because he doesn’t claim to be an oceanographer. It’s a pity raypierre doesn’t realise he’s not either.
raypierre has also smeared Courtillot and Allegre on realclimate and elsewhere. He’s a nasty piece of work for whom perception comes before principle.
Jeff Larson: You can do Fourier filtering on WoodForTrees – actually, this subject was the reason I created it… But as far as I can see, it doesn’t reveal much of a correlation over the long term, for sunspots at least.
http://www.woodfortrees.org/plot/hadcrut3vgl/detrend:0.7/fourier/low-pass:10/inverse-fourier/normalise/plot/sidc-ssn/from:1850/fourier/low-pass:10/inverse-fourier/normalise
(note, temperature detrended to avoid Fourier edge effects, and both curves normalised)
and as a sanity check, here it is done with a simple running mean:
http://www.woodfortrees.org/plot/hadcrut3vgl/detrend:0.7/mean:120/normalise/plot/sidc-ssn/mean:120/from:1850/normalise
If you open the two links in two browser tabs and blink between them you can see there are still some edge effects.
In the interests of fairness, here it is again without the temperature detrend:
http://www.woodfortrees.org/plot/hadcrut3vgl/mean:120/normalise/plot/sidc-ssn/mean:120/from:1850/normalise