Herschel, sun-spots and the possibility of cooling

I’ll keep yesterday’s history theme going. One of the great astronomers of all time was Sir William Herschel, who flourished in the late 18th and early 19th century. He discovered Uranus, along with two of its moons — and two of the moons of Saturn as well. He was an extremely gifted maker of lenses and telescopes, a fine mathematician and a serious composer as well.

And he had an interest in sun spots that came from his interest in variable stars, those whose brightness waxes and wanes. We have our own star, and Herschel noted that it possessed spots that came and went. Were they somehow linked to brightness, and could the sun’s spots have an effect on the climate of the earth?  He observed periods between 1795 and 1800 where there had been no sun-spots at all, then they had suddenly appeared in great number again. What was going on?

He argued before the Royal Society in 1801 that many sun-spots should lead to ‘a copious emission of heat’, which should lead to warmer weather on Earth, milder seasons and agricultural productivity. The price of wheat was a serious matter at this time, because bread was the basis of life for the poor, and too high a price led to famine and death. So Herschel, unable to consult any contemporary HadCRUt4 data or any satellite observations, tried to work back from the records of good and bad harvests.

Adam Smith had written An Inquiry into The Nature and Causes of The Wealth of Nations in 1776, and Herschel used Smith’s work to identify five periods when the price of wheat had been very high. He had sun-spot numbers to work with, and it seemed to him that a lack of sun-spot activity went along with poor harvests. Greater sun-spot activity corresponded to excellent weather, good crops and lower prices for wheat and bread.

Alas, Herschel was not congratulated by his colleagues or the Royal Society for his novel hypothesis. In fact, it was rejected and dismissed. Many summary accounts of Herschel’s life and work hardly refer to this episode. Nonetheless, there are scientists who have thought Herschel got it right, and others who thought he was just plain wrong. The debate continues today.

As convincing evidence supporting the ‘control knob’ theory of carbon dioxide has been lacking over the last decade or so, the notion that sun-spot patterns might have something to do with the halt or pause to cooling has been gaining more attention. The IPCC has taken no notice, but then the IPCC has the task of measuring human contributions to ‘climate change’, and humanity does not control the sun.

Some solar physicists have  for the past thirty years been talking up the Sun’s role in the Earth’s climate, without gaining any real traction. In the past decade four of them, all notable and highly respected, have been drawing attention to the declining number of sun-spots over the last  few solar cycles (which have an average length of 11 years), and have argued that we could be in for a period of sustained cooling. They are Mike Lockwood, from the UK, Horst-Joachim Luedecke from Germany, Habibullo Abdussamatov from Russia, and Anastasios Tsonis of the USA. All of them have based their projections on solar cycle and sun-spot analysis, and while they aren’t all saying the same thing, they are saying that the number of sun-spots is more important than has been conceded in the recent past. And that serious cooling is in prospect.

They can all point to the fact that the current solar cycle is markedly low in sun-spots, and it appears to have passed its maximum. Here is a view of the current solar cycle in comparative perspective:


The sun-spot numbers are down, and some solar physicists are suggesting that what we are seeing looks like what happened a few centuries ago, when sun-spot figures had a similar trend and the world experienced some very poor harvests indeed. I am no solar physicist, and much of the argument is too technical for my limited competence. I recognise also that correlation does not imply causation, which I have said before about the association of  carbon dioxide growth and the rise in global temperature — when the two were occurring together.

But I am beginning to suspect that there might be something to the notion that the Sun’s effect on our climate is both great and poor understood, and that Sir William Herschel was on to an important connection when he spoke to the Royal Society in 1801.

Join the discussion 13 Comments

  • Peter Kemmis says:

    I do wonder what causes those cycles. I suspect that no matter how important we are, that our Sun rather ignores our Gregorian calendar during its 11 year perturbations.

    • dlb says:

      The orbit of Jupiter takes around 11 earth years, therefore there may be a gravitational effect. But like sunspots and climate this is another hotly contested area.

  • Mike O'Ceirin says:

    Seems to me that all this assumes that sun-spots are a proxy. These days we can measure all EM radiation coming from the Sun I thought. So if it is dropping in lock step with sun-spots then we really do have something. It is known that low sun-spots eg Maunder Minimum have been correlated with cooler times so it is really worth a lot of study. Many on the activist side say the Sun is irrelevant. Obviously it is not irrelevant if so let us imagine what happens if it is no longer there. Probably all heat comes from the Sun the whole AGW debate is about how humans may or may not be increasing it’s effect.

  • David says:

    “The IPCC has taken no notice, but then the IPCC has the task of measuring human
    contributions to ‘climate change’, and humanity does not control the sun.”

    Don to paraphrase Ronald Regan; “There you go again.”

    Why settle for a balanced comment when an outrageous one will suffice? Don’t you think that within all the 10,000 articles on Climate Change the IPCC has reviewed that any of them have considered the effect that sun spot activity might have on
    climate. The issue has been done to death.

    But thank you for your link to “Habibullo Abdussamatov”. Not much in the way of
    credible science but they are advertising flights to Hawaii with 4 nights’ accommodation from $1639 per person twin share. Don do you know if that price includes all airport-hotel transfers?

    • Don Aitkin says:

      There is very little at all in any of the reports about the possible effect of solar cycles or sun-spots. The fact that nothing is mentioned does not mean that the IPCC reviewed the subject to death.

      The IPCC was indeed set up to analyse human contributions to global warming, and to propose measures to remedy these effects.

      You can check out the science of the four for yourself via Google Scholar.

      • David says:


        If your mean to say “There is very little at all in any of the [IPCC] reports about the possible effect of solar cycles or sun-spots.” Don’t write “The IPCC has taken no notice, ….”

        Here are four links to IPCC publications which mention sun spot activity.





        So your claim the IPCC has taken no notice on sun spot activity is incorrect.

        Furthermore Professor Muller with his huge data set looked at the effect of Solar activity (aka sun spots) and Volcanic activity on climate and reports zero effect for sun spots and a weak effect for volcanic activity.


        Finally, I will conclude by referring you back to the data you linked to on the history of climate change. These data do not demonstrate any cyclical change in temperature that would correlate with sunspot activity.


        So your claim that “serious cooling [due to sunspot activity or otherwise] is in prospect” is unconvincing!

        • Don Aitkin says:

          All these references devote themselves to TSI, and there is little disagreement, either among the orthodox or the dissidents, that TSI has not changed very much over time, and therefore cannot have much influence on global temperature. What is not clear are the other aspects of the Sun’s effect on the Earth. The IPCC position has been to disregard them.

          The sun-spot argument has been going on for two hundred years, as I pointed out. The IPCC has simply taken one side, without any explanation. Indeed, what is mostly wrong with all the IPCC reports is that they do not discuss the alternative possibilities, but devote much time to developing those aspects of explanation that support the position that carbon dioxide is the key factor.

          It is this that so frustrates people who are used to considering both sides of a question. (Like me.)

          You’ve been a frequent commenter, and a Merry Christmas to you. I shan’t be writing further until 6 January.

          • David says:

            Merry Christmas to you to Don.

          • David says:

            Don ,
            With the greatest respect, you rebuttal is so vague as to render it meaningless.

            1. The title of this post clearly refers to Sunspot activity.

            2. You make the claim that the IPCC has not considered Sunspot activity.

            3. I give you 4 examples where the IPCC has examined sun spot activity

            4. You now claim you were not only referring to sun spot activity but instead are refereeing to “other” unspecified
            mechanisms which affect TSI

            How can we know if the IPCC has given these “other” mechanisms due consideration, if you are unable to specify them?

          • Don Aitkin says:

            David, I won’t be posting again for a week or so, and will be out of Internet action until then, but here is a reply:

            Your first IPCC reference mentions sun-spots, but then says nothing other than some people have argued that sun-spots have a relatively
            small effect on climate. The notable author cited here is Judith Lean (who is a member of the IPCC team). Richard Mackey has a long paper with 200 references on the solar effects on climate, of all kinds. Judith Lean’s work is included. None of these references, other than Lean, is mentioned or anything discussed
            of the alternative views. The last paragraph on the first page (which is the end of this section) says that ‘More research to investigate the effects of solar behaviour on climate is needed before the magnitude of solar effects on climate
            can be stated with certainty.’ The possibility that there are important effects is then ignored throughout.

            I would not call that any kind of serious discussion.

            Your second reference likewise says that the relationship between the isotopic records
            indicative of the Sun’s open magnetic field, sunspot numbers and the Sun’s closed magnetic field or energy output are not fully understood (Wang and Sheeley, 2003). Sun-spot numbers are then ignored, and the rest of this section is about total solar irradiance (TSI),
            which is agreed to vary only slightly.

            Your third reference is similar: sun-spots are mentioned and then effectively ignored. Lean is again the reliable source used, but of course is a member of the team.

            Your fourth reference is again mostly about TSI. Sun-spot numbers are mentioned only twice, and again put to one side so that attention is placed on isotope evidence.

            These four references, in sum, point to the lack of serious consideration of the importance of sun-spot numbers — and I repeat that the effect of reading these pages is to see, again, how the IPCC reports push a line, rather than consider all the evidence. It is faintly possible that the authors have in fact considered 10,000 papers, but there is no evidence at all of such work.

            I have said already that the IPCC is not obliged to consider anything other than human influences, given its mandate, but the outcome of not doing so is an unbalanced account of the influences on the climate of our

            You’ve pushed me into reading in the solar area, and the outcome will be a further post in January.

          • M. Simon says:

            Unspecified does not mean unobservable. Take the precession of Mercury. It was observed. It was unexplained. Until a certain German patent office clerk had a go.

  • John Morland says:

    As a boy living in Cairns in the late 60’s to early 70’s, I remember a person, who lived in southern Qld, called. Lennox Walker who predicted long range weather. His forecasts were amazingly accurate and farmers took notice of his long range weather forecasts rather than the weather bureau to time their planting etc.

    His son has since taken over his dad’s work.

    I also remember the weather bureau continual public condescending his forecasts, but they shown wrong time and again.

    What dd he base his forecast on? Solar sunspot activity.

    Is our star constant – No.

    Is our star a slight variable star- No.

    Is out star variable variable – Yes

    Does it affect our climate? – Absolutely.

    How much? – More than the climate alarmist dare to admit!

    What send the vVkings packing from their productive farms in Greenland in the early middle ages? The Sporer minimum.

    When were the paintings of Londoners skating on the Thames wearing Russian style fur hats ? During the Maunder minimum.

    Merry Christmas to all.

  • […] it. In fact, this post is about the influence of the Sun on the climate of the Earth, a subject I wrote about at the end of the year. The post received a good deal of comment, and some of the comments forced me to go and do much […]

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