Courtillot on the solar UV climate connection

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From the HockeySchtick

Video: Geophysicist explains how the Sun controls climate, not CO2

Dr. Vincent Courtillot is a professor of geophysics at the University Paris-Diderot and Chair of paleomagnetism and geodynamics of the Institut Universitaire de France. In the recent lecture below he explains how solar cycles control the climate by influence on cloud formation (the cosmic ray theory of Svensmark et al) and via influence on ocean oscillations and length of day. Dr. Courtillot notes that IPCC climate computer models do not correlate with observations and that temperature trends vary substantially between North America and Europe (which is contrary to IPCC computer model predictions).

He also notes that while the total solar irradiance (TSI) only varies by about .1% over a solar cycle, the solar UV varies by about 10% and that secondary effects on cloud formation may vary up to 30% over solar cycles. The IPCC computer models dismiss the role of the sun by only considering the small variations of the TSI and ignore the large changes in the most energetic and influential part of the solar spectrum – the ultraviolet.

h/t to TheTempestSpark


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jack morrow

There are probably more things that change the climate than just the sun, but at least this a much better explanation than just co2 alone.


This video should be required viewing for EVERY Western government official – not only because it debunks the IPCC 4th Assessment and all who sail in her – but because of his absolute clarity and logic.

Ziiex Zeburz

The French,
at last we have a ‘Seine’ review of political science


To be fair, he doesn’t say ‘the Sun controls climate, not CO2’, he alludes to the sun being a factor requiring more research.
The feeling I get from that video is the climate science is too incomplete to confirm either political bias.

Jeff W

No reasonable person could watch this lecture and still believe that we know enough about the climate, and man’s influence on it, to take any sort of remedial action now in the hope that it would necessarily help and not hurt the future of mankind.



It is no surprise that the GCM’s fix most factors in place. The number of variables that are known to exist is astonishing. The warmists adherence to CO2 means that the Milankovitch cycles have to be CO2 based and that forces them to only pay attention to TSI.
I am baffled each time someone ignores the change in hemispheric energy by stating that the TSI changes very little. Some people just don’t want to understand. I am still not convinced on the solar, but it is interesting and it is not a simple relationship either. One day hopefully it will be figured out, but it will be long after AGW is buried.


As far as climate goes, the sun is a leading indicator; carbon dioxide is a trailing indicator. It’s as simple as that, folks.

Dave Springer

It’s worse than they think. Aside from large UV variation is GCR (galactic cosmic rays) variation (Svensmark). The sun’s magnetic field, which varies in both predictable ways (11 year solar cycle and 200 year cycle) throttles the GCR flux but the flux also varies with where in the sun is positioned within the galaxy (very predictable) and what GCR generating events in the vicinity (primarily supernovae) are happening. The sun doesn’t orbit the galactic center at the same rate the spiral arms revolve so it periodically traverses a spiral arm. When inside a spiral arm, with far higher stellar density, there is an increased likelyhood of supernovae in the vicinity. The sun also wanders up and down through the galactic plane which also serves to position it in regions with more or less stellar density. Right now it’s in a lower density region of the galaxy and will remain in a low density region for millions of years to come but that only means the average number of supernovae will be fewer but it only takes one event in the vicinity to radically change GCR flux and supernovae are not at all predictable – we don’t one has occured for as many years as it takes for the wavefront to arrive which can be hundreds or thousands of years after the actual event.

Bloke down the pub

If solar uv is so important to global climate, would it be possible to have a graph on the solar reference page showing uv output? One plotted alongside global temperature would be nice, if you could just knock that out in your lunch break.


That. Was. Awesome. I loved his very quick speaking approach, yet he always took time to be clear for us dunderheads, to maximize his audience impact. The fastest 32 minutes of video I’ve ever seen on the internet. I appreciate his commitment to science, [paraphrased] “I may be wrong, but at least my conclusions are based on real observational data, and not numerical models.”
“If it’s not falsifiable, it’s not science.”
“We have 100% real problems. Why spend resources on the 90%?”

This is going to go down as one of the defining presentations of this century. How much more sense does this make as opposed to the very vague and speculative case for warming by CO2? Not that this is totally new, but instead rejected by the powers that be in the climate science dictatorship because it has serious inplications for their pet theories.
The evidence fits, the concept makes sense and would explain so much about the past as well.
I hope we will see this incorporated in the climate models in the near future.

I got some interesting results from Marion Island
Latitude -46.88333
Longitude 37.86667
Altitude 22
This is quite a bit south of South Africa
So far I looked only at all the temperature data.
I collected all average mean-, maximum-and minimum- temperatures for all months of the year from 1976 and plotted these against time. A linear regression was then performed. The slope of these formulae i.e. the figure before the “x” in each of the reported formulae, is also the rate of incline or decline (if negative) by which the temperature has increased or decreased over the last 35 years in degrees C/year.
Taking the average over each of the 12 slopes for each of the months of the year, I find that from 1976 to 2010
1) the rate of change of the mean temperature was 0.00 degrees C per annum: in other words: flat
2) the maximum temperature has increased at a rate of 0.05 degrees C per annum
3) the minimum temperature has decreased at a rate of 0.02 degrees C per annum
Again these results indicate that heat content has stayed the same even though max. temps. have been rising.
If warming is due to an increase in greenhouse gases, it is the minimum temperatures that should rise as heat would be trapped due to the green house effect. You would then expect the minimum temperatures to rise at a rate as fast as – or even faster than – the mean- and maximum temperatures. What I find is exactly the opposite: minimum temperatures in Marion Island have actually declined by 0.02 degrees C per annum whereas the means have stayed the same and the maximum temperatures have increased. The theory of warming caused by an increase in green house gases is therefore again proved invalid by the evidence presented from the measured results here, at Marion Island.

Robin Guenier

I came across this (via Jo Nova’s site) a couple of days ago. I think it is possibly the clearest and most compelling presentation on climate change I’ve seen; better even than the always excellent Dick Lindzen. Despite being French and speaking very quickly in English, he held my attention throughout his crisp and precise 32 minutes. To my mind, it’s a first rate overview of current scientific uncertainty with, as you say, an especially interesting summary of solar (cosmic ray) influence. I urge everyone to watch it.
Two quotations:
1. “Uncertainties have been enormously underestimated.”
2.”There are such things as regional climates, but there is no such thing as world climate.”
His remark that younger scientists who choose to work on science that is not in line with AGW theory is chilling.

Robin Guenier

Apologies – my last paragraph should have read: His remark that younger scientists who choose to work on science that is not in line with AGW theory would not get jobs/funding is chilling


I am also convinced changing solar activity is the primary driver of the global climate.
Why warmers almost totally discount solar activity, is incredible. The impact of solar activity is all around us, from night to do, and from season to season.
I suppose the political attraction to CO2 warming is just too overwhelming to many.


The video is exceptional. This scientist is properly skeptical while putting forward data that can be verified and theories that depend on real, experimental data. Furthermore, he is unusually well spoken — straight-forward scientific language (accurate human communication). A joy to listen to. I hope everyone who visits WUWT will give him focused listening time. Thanks, Anthony, and deep gratitude to Dr. Vincent Courtillot


I am also convinced changing solar activity is the primary driver of the global climate.
Why warmers almost totally discount solar activity, is incredible. The impact of solar activity is all around us, from night to day, and from season to season.
I suppose the political attraction to CO2 warming is just too overwhelming to many.

Stephen Wilde

A good summary but I’m not convinced that length of day or cosmic ray quantities are responsible for the observed effects.
Variations in the surface spread of the polar air masses due to solar induced variations in the polar vortex resulting in latitudinal jetstream shifts and changes in global albedo and cloudiness as the length of the air mass boundaries changes around the globe seems to be a simpler and more obvious mechanism to my mind at least.

Alan the Brit

Well, what can one possibly say? With my engineer’s hat on, blimey! It was a wonderful talk, well balanced, argued, demostrated, (& falsifiable!). Shaviv’s talk would be interesting if available. With my eco-carbophobialist hat on, “How dare this upstart heretic shill of big oil/BP/Exon/Mobile et al speak such foul lies & deceit against our true god, Greenism, have him incarerated, flogged, hung until half dead, castrated, disemboweled, his eyeless, toothless face whipped, then burn him at the stake like all vile heretics”. Sarc off!!! Interesting that he mentioned being attacked for his views & his struggles to get published, & nice to hear somebody in the European scientific establishment speak out with what can only be descirbed as common sense! Mr Watts, Dr Courtillot mentioned “Fred” early on, was that Fred S. Singer by any chance?

Nigel Brereton

This is another very good article along the same lines but details further how the Sun is the controlling factor for temperature on Earth.
The Radiative Equilibrium Temperature of the Earth with the Sun.
We‟ll now get into some physics and discover that we can quite accurately predict the
radiative temperature of the Earth given just a small spattering of the laws of physics

Viv Evans

It is no surprise to me that he and his colleagues have run into the brick wall of pal review, as have so many others whose findings are not in line with the AGW crowd. His remark about his co-workers, students because that would have a bad effect on their careers is saddening. One would wish someone of his calibre would be able to teach many a generation of young minds.
The applause for his statement about too many models and not enough observations illustrates one of the great frustrations most of us have with the model- but not reality-based AGW papers.
Personally, I fond the clarity and logic of his thoughts and presentation very refreshing, showing the great tradition of French physicists.

Mike Bromley

Well worth the watch. Key point: his ‘in-your-face’ flouting of the AGW elitist club. In other words, “I’m going to do science, because your ad hominem means nothing to me nor my future.” Very telling.
Back to Phil Jones’ hiding the data from general consumption….how convenient. (sarc) Dr. Courtillot has done a great service by standing up and calmly (with no fear) dashing the warmist ship onto the reef of reality.
Models be damned.

Phil Jones’ does not seem to have been too inclined to favorably review Courtillo’s papers. Here are Phil Jones’ comments (about a presumably confidential (cf. Steig)) review of a Courtillo paper to Gavin Schmidt and Michael E. Mann: I have the journal
rejection emails – the other reviewer wasn’t quite as strong as mine, but they were

(Sorry if this is a duplicate – something strange happened after I clicked ‘Post Comment’…)

David L. Hagen

Courtillot gives a brilliant 30 min back to basics/data presentation of major correlations with solar cycles that are ignored and not explained by the IPCC models.
Enormous underestimation of uncertainties.
Temperature variations different between Eu and US.
Ocean oscillation correlates with solar cycles.
Earth Length of Day – thus winds – vary with solar cycles.
10% variation in UV; > 10% variation in EUV
Variation in atmospheric charging, currents, clouds
Highly recommend.
PS Moderator – Courtillot refers to an associated presentation by Nir Shaviv
Please post Shaviv’s presentation.

Robin said
“Two quotations:
1. “Uncertainties have been enormously underestimated.”
2.”There are such things as regional climates, but there is no such thing as world climate.”
I completely agree and not all regional climates are headed in the same warming direction, as Verity Jones and I pointed out here;


Why does UV make sense? Ionization of water. It’s the essentially the same cloud formation mechanism as Svensmark albeit with action directly from the Sun.
To save you the trouble of looking up the numbers:
1216 kJ/mol to ionize water
1 mole = 6.022E23
h = 6.63E-34 Js
c = 2.99e8 m/s
λ = hc/E
= ~ 100 nm
freq = 3E15 /s
Verification refs:

I have given and received hundreds of lectures in my time as an engineer, Army officer and educationalist, but never have I seen or heard a clearer, more convincing, focused and balanced performance as this by Professor Vincent Courtillot. Well done Sir.

John Marshall

Always the sun.
How can a trace natural gas cause so many problems that the alarmists keep proposing?
It can’t. It never has for billions of years, so why now?
This is quite a good video.


“The IPCC computer models dismiss the role of the sun by only considering the small variations of the TSI and ignore the large changes in the most energetic and influential part of the solar spectrum – the ultraviolet.”
Lief Svalgaard does the same BTW.

Ed Scott

Prof. Dr. Nir Shaviv Präsentation


Ok…so after reading this I wondered if anyone had tried to link “climate change” with supernova activity since there would be a spike in cosmic rays on Earth if one occurred close by. Maybe this has been discussed here before and I missed it…my apologies if so.
With a quick search I found this:
and this
So even on supernovas they cant agree on what would happen…one says cooling, one says warming..
Putting my own deductive hat on, I found that the last two supernovas in our glaxay occurred around 1860 and 1680.
Both of these time periods are associated with lows in the temperature record. Anyone know if this has been explored more indepth?

Ed Fix

Ziiex Zeburz says:
“The French…”
Ahem…he’s German (at least German speaking). You need to find a different river. Sorry.

richcar that 1225

The current TLT temperature drop will soon have to be explained.
With the SOI still at an unprecendented high, a natural forcing needs to be addressed:
Dr Spencer claims that a 1% change in cloud cover can account for the 1980-1998 warming. It appears to me that if the current negative NAO and positive SOI are tied to the low solar peak the forcing is likely external.

Dr. Courtillot has one big problem common to all ‘sun devotees’. Between 1940-1960 there was unprecedented high solar activity ( presumably high UV too) and the global temperatures turned down (no global warming but global cooling !), one might say a case s . d’s law. If you have hypothesis, let alone theory, then you need to explain that global temperature downturn.
The CO2 proponents have dismally failed.
Only credible explanations is in the oceans’ currents, and it is perfectly simple explanation, if one cares to understand how and where ocean circulation and currents are subject to well known physical processes, and how they interact with climate.


David L. Hagen says April 5, 2011 at 8:02 am
Nir Shaviv’s presentation at the same venue:

G. Karst

Please keep this wonderful video on top, for a while. It is very important to witness a scientist speaking as a true scientist. For many warmists, this may be their first time, in their brainwashed existence, they actually hear, what good science, sounds like. GK

Josh Grella

Stephen Wilde says:
April 5, 2011 at 7:30 am
I think adding your explanation to his to describe more fully how the solar/cosmic ray effects manifest in the weather patterns takes us another step closer to the truth. There are far too many variables for one simple explanation to cover the entire thing.


What a marvellous command of English Dr Courtillot has! Congratulations, Professor.

Ed Scott

Prof. Fred Singer presents the Report “Nature, not Human Activity, Rules the Climate” by the Nongovernmental International Panel on Climate Change'(NIPCC) at CFACT’s International Climate Eco-Summit (I.C.E.) at the Center for Political Studies, Copenhagen, Denmark. December 11, 2009. The whole talk lasts for 45 minutes
Fred Singer presents the NIPCC Report (5 parts) by GlobalStewardship


OK. Maybe that was too easy. WHEN does the UV change and how? Does it correlate with any weather phenomena? Is there any evidence like cosmic ray and cloud formation (really good)?
“SIM suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did….”
Which suggests that any UV effect is not the same as the Svensmark hypothesis, acting in the lower atmosphere to influence cloud formation.
Well, have fun in the sandbox, kids. It’s time to go back into my dungeon and earn some money.

Roger Knights

Mr Watts, Dr Courtillot mentioned “Fred” early on, was that Fred S. Singer by any chance?

Probably; he mentioned him by last name at 1:14.
The snippet I liked best was the part at 18:25 where he said that his critics use the chestnut that correlation is not (necessarily) causation as an excuse to dismiss (“forget it”) the possibility that correlation MIGHT be meaningful (indicate causation).
He misspoke at 7:20 when he said, “1886”; he meant “1986.”
He also misspoke at 8:35 when he said, “monotonous behavior”; he meant “monotonic …”
He could have used better terminology at 10:35 when he said, “separated by fairly fast changes”; a better last pair of words would have been “… sharp reversals.”
He also misspoke at about 14:00 when he said “If you cut the data before the optimum,” when he meant “… after the optimum.”
He also misspoke at 28:15 when he said, “they twitter a parameter.” He meant “… tweak ….”

Ed Scott

Including the link is appropriate
Fred Singer presents the NIPCC Report (5 parts) by GlobalStewardship

Ed Scott

Or not!

A few specific notes….
1. Coming from a background in electronics, his way of thinking clarified several things that I hadn’t caught before. Trees are adaptive HP filters! Perhaps the statistical folks have said this in some other way, but it wasn’t a way that I could understand. And the part about ionospheric currents being modulated by cosmic rays makes great sense; corresponds to the Armagh ‘storminess’ index.
2. “We have to work with senior people who are near retirement”. This is a huge problem in many areas of life, not just science. Tenure and careerism are so strong that you can only get truth from retired people who are no longer hoping for employment or consultant gigs.
3. As with most video presentations, the camera operator has the journalistic tendency to focus on the speaker’s face, not on the graphs. This is frustrating!


As a casual observation I have always been amazed that people could imply that a 0.1% change in TSI has little effect on climate, but a 0.01% change in earth’s atmospheric content be the sole cause of all climate change.
(0.01% = 100 ppm, which is the approximate increase in CO2)

Jose Suro

A Brilliant presentation. Just brilliant!

Ed Fix says:
April 5, 2011 at 8:27 am
Ziiex Zeburz says:
“The French…”
Ahem…he’s German (at least German speaking). You need to find a different river. Sorry.

Who is german ?
Professor Dr. Vincent E. Courtillot (born 6 March 1948) is a French geophysicist.

Don K

An excellent presentation I think. And I decided that early on in the video — long before I found out that Courtillot was going to confirm point after point that I have worked out for myself. The only problem is that I have developed a certain amount of suspicion over the years of people that tell me what I want to hear.
One question though, does anyone have an explanation for the different temperature patterns in North America and Europe? Both regions are in the Northern hemisphere and not too different in latitude. It’s all well and good to chortle that the IPCC et al models don’t account for that. But something must. No?