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Climate Hustle

The sun upside down

Posted on 12 October 2010 by Riccardo

A recently published paper from J. Haigh et al. made it through the media (EurekAlert, CNN) and for a good reason. Indeed, using the data from the new Spectral Irradiance Monitor (SIM) instrument on the SORCE satellite they may have found that the influence of the sun on earth climate is upside down. Scientists and common sense agree that increasing the total solar irradiance warms the earth. On the contrary, the data presented in this paper seem to indicate otherwise.

Before going any further, it is important to quote J. Haigh herself:

"We cannot jump to any conclusions based on what we have found during this comparatively short period and we need to carry out further studies to explore the Sun's activity, and the patterns that we have uncovered, on longer timescales."

Keeping this important caveat in mind, let me summarize their results.

During the 11-years solar cycle, the total solar irradiance varies of about 1 W/m2 (Watts per square meter). It is also known that it does not vary proportionally throughout the spectrum (Lean 2000), i.e the amplititude of the change is different at different wavelengths. What this new paper finds is that the change in the ultraviolet (UV) part of the spectrum is 10 times larger than previously thought and, even more importantly, the change in the visible part has the opposite sign. This means that during solar maxima there's less visible light reaching the earth surface, thus producing less warming. The opposite is true for UV light, which is absorbed in the stratosphere by ozone molecules without reaching the surface. The implications for the earth climate-sun connection should be clear, it works upside down.


Splar Spectran change 

Fig. 1:  difference in solar spectrum from 2004 to 2007. Note the different left and right scales. (from Haigh et al 2010).

Up to this point, one may think that even if confirmed this effect should not have an impact on the long term trends because of the cyclic behaviour. But what if this behaviour proves to be general and not just related to the 11 years cycle? Given that, for example, part of the warming during the first half of the 20th century has been attributed to an increased sun activity,

"[...] if further studies find the same pattern over a longer period of time, this could suggest that we may have overestimated the Sun's role in warming the planet, rather than underestimating it."
Dr Haigh has been very cautious and open to the possibility that it all happened by coincidence::
"The sun has been behaving very strangely. Its magnetic activity is lower than it has been for several hundred years, perhaps. And so the fact that it's doing strange things in its spectrum is perhaps not that unexpected"
One may ask why they published so uncertain results. Haigh gives the answer: "our findings could be too important to not publish them now."

My personal (irrelevant) opinion? I don't know if it's just a coincidence or not, but I'm happy to see our sun doing something interesting, lately. Even if upside down.


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Comments 1 to 42:

  1. RealClimate had a post about this too.

    The way I understood, if this turned out to be right, TSI would have the opposite influence in surface temperatures than previously thought. (did I understand right?)

    I think this is the kind of claim that will need extraordinary evidence to hold. The influence of TSI over temps seems quite well established and well supported by evidence, like the Maunder Minimum and Little Ice Age, or the rise in temps until the middle of the 20th century.
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  2. As I understand this, the UV differences are over the 11-year solar cycle.

    Given that the Maunder Minimum seems to have been a different solar regime than we're currently in, is there any support for high UV levels during the Maunder Minimum? A 1000-fold difference in sunspots would likely have had other effects as well.
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  3. Alexander
    you're right that we need extraordinary evidence. We apparently do not understand the sun spectral irradiance very well and it migt be related just to the solar cycle or even, say, the cycles after the early 20th century increase in overall activity.

    it is the 2004 to 2007 difference, not even half a cycle.
    As far as I know we do not have any reliable proxy for UV irradiance.
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  4. What a revolutionary finding. I'm intrigued by the fact that the satellites which have tracked total solar irradiance for the past few decades did not detect the changes in the spectra of solar radiation that this study finally disclosed. Why did the satellites miss something this conspicuous?
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  5. Karamanski #4: "Why did the satellites miss something this conspicuous?"

    A: It has not been established that they DID. The findings of this paper could be erroneous or anomalous to the short time frame studied. Odd that you missed those caveats from the authors of the paper.

    B: The magnitude of the changes in question is so small as to be easily overlooked unless being specifically checked for... which most satellites were not set up to do. So, not particularly "conspicuous".
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  6. Karamanski
    a few numbers to put the variations in context.
    The irradiance change at 200 nm of the order of 0.5 mW/(m2 nm) over a value of about 7.5 mW/(m2 nm); something like 6.7%. At 500 nm it's about 0.3 mW/(m2 nm) over 1955 mW/(m2 nm), i.e. 0.01%.
    In the visible range I would not call it a conspicuous change.
    You can look at these numbers yourself here
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  7. It will be interesting to see how well this correlates with some other indicators such as the AA magnetic index which have only been considered relevant by few researchers.

    How clouds respond or otherwise will be of considerable importance in determining the nett effect at the earth's surface both for present observations, and in trying to correlate it to past climate reconstructions.
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  8. See Its the Sun, comment #646 from CBD:
    The bit about the magnitude of any solar change being "dwarfed" by the increase in CO2 forcing makes it somewhat of a minor issue

    Interesting development, nonetheless.
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  9. I think it's quite unlikely this would be true over all solar cycles, because there is a detectable solar cycle influence in global surface temperature and and it's the way round you'd expect.

    Perhaps this is unique to the current cycle, but my guess is that it's more likely to be just wrong.
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  10. I would be looking harder at the implications of the greater variation of UV, on climate, than direct forcing from variable TSI.
    Paper on modeled UV stratosphere/troposphere effects

    There is a fair bit o literature focused on it... and if the variations of UV are greater than what has been previously assumed, this will be quite an interesting lil discovery.
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  11. My initial reaction to the results obtained by Haigh et al is that they are counterintuitive and puzzling. My second reaction is that their results raise a number of questions, the most obvious being:

    Is the satellite data producing their findings accurate and consistent?
    Is the model they are using reliable and properly tested?
    Is the three year period used sufficient to produce credible results?
    How do their results explain recent global warming?

    If, as suggested by Haigh, the findings suggest that hitherto we have overestimated the role of the sun in bringing about global warming, does this mean that we have underestimated the role of greenhouse gases as causing it?
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  12. Agnostic
    I'm not in a position to answer to all of your questions properly.
    What I can say is that the SORCE spacecraft hosts new spectral and the total irradiance monitor instruments, which greatly improve the quality of the data. This, of course, by itself cannot rule out undetected issues with the instruments.
    The three years period is definitely too short, as Haigh herself says.
    If scientists have overestimated the solar contribution to warming, it's not just greenhouse gases contribution that need to be re-evaluated; it is the climate history of the last couple of millennia being involved.

    We are left with speculations. There is nothing wrong in thinking of the consequences of these new finding, albeit with a big "if" as a premise.
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  13. Riccardo,

    I like the caveat. There should be such caveats in all climate science papers. I'd encourage people to be sceptical about papers that don't know their limitations.

    Polemical point overwith I've got a question about the science. This paper seems to have implications that go beyond the upside down response you describe. I'm speculating below, do you know in what ways this may cause us to reassess some past work?

    For example all Hansen's model predictions in the IPCC docs rely on Lean 2000. Are we meant to conclude that Lean 2000 is plain wrong?

    Lean 2000 is cited by 200+ papers according to Google Scholar.

    This must have an impact on work that looks at change spectra given that these are generally based on snapshots comparing year X with year Y. It's not just the sign of these changes but the magnitudes at different wavelengths that seem important. If as this paper suggests the solar spectrum varies in completely unexpected ways there may be natural variance that are completely ignored in these papers conclusions.
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  14. HumanityRules
    the first impact I see is on solar science. Haigh 2010 and Lean 2000 cannot be both right unless in the former the new phenomenon just happens sporadically.
    Having said this, I'd invite you to consider the magnitude of the effect. As in my comment #6 above, it's quite small in the visible range and the impact on forcing should not be exceedingly large. Though, it could make a difference (several %, not tens) in the stratosphere where UV is absorbed.
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  15. HumanityRules... haver you read any academic papers lately? They are liberally spread with uncertainties and caveats, it's part of the job. Can you point out climate science papers that do not indicate uncertainties in results? Uncertainties tend to get filtered out, invariably to the detriment of the paper, when media report on science issues.
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  16. I hope they realized the thing was going to space when calibrating it... anyway an interesting set of data. I actually tried to find the piece from univ library only to find out they put out the papers on a later date.
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  17. #13: "There should be such caveats in all climate science papers. I'd encourage people to be sceptical about papers that don't know their limitations."

    Wouldn't it be nice if that rule applied in deniersville? Imagine reading the headline 'Its cooling and Arctic ice is at an all time high!' followed by the caveat: 'readers should recognize that our use of only 3 data points leads to 100% uncertainty in our conclusions'.
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  18. I''d also like Humanity Rules to see if they can find even a handful of scientific papers that do not come with caveats and uncertainties. I suspect HR has read few or none.

    This is a very interesting development - the implications benefit no 'side' of the AGW blog debate.
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  19. 14.Riccardo

    Not to be picky but I get the 500nm difference to be more like 0.1-0.2%. And a 5% change over a 6-7year period sounds like quite a lot to me.

    15 Skywalker

    Yep I spend more time reading climate science papers than blogs. I'm definitely here to educate myself.

    I don't think you can just blame the press on this. Many believe the IPCC do an equally bad job of presenting the limitations and uncertainties. I also don't think all climate scientist are as open about this subject as Haigh is here. Obviously she's put it in her press release and it's prominently displayed in the abstract. There are many papers were serious caveats are buried in the results sections and never mentioned in the conclusions or abstract. This leads to a serious disconnect between the data and the conclusions. It's really what bugs me the most.

    I get you're point (although I've never read anybody write Arctic ice is at an all time high). Sceptical blogs maybe need to be to the standard of newspapers while peer-reviewed papers are althgether different beasts, with different standards.
    Also Pielkes snr and Judith Curry's (and others) blogs for example are very different to your average lunatic rants. Even WUWT presents some interesting stuff (there's definitely a mix of Good, Bad and downright Ugly over there though). You're over simplifying the situation. Muon do you ever read WUWT? Do you ever find any of it challenging?
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  20. #19 HR:"I've never read anybody write Arctic ice is at an all time high"

    Did you miss this?
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  21. Re: HumanityRules (19)
    1. "I don't think you can just blame the press on this."
    I can and I do. They're abysmal. With the exception of Monbiot, I cannot think of anyone at all credible when it comes to science. Even Revkin has pulled a Curry: gadding about on a random walk of his own pretending in his kingdom of one to be centrist. End rant.
    2. "Many believe the IPCC do an equally bad job of presenting the limitations and uncertainties."
    Then they believe wrong. The IPCC is in a thankless position: trying to characterize the science caveated with uncertainties to laypersons who are lucky to find their head with both hands one time in three. Considering that, they do a brilliant job. End laud.

    All riled up now. I shouldn't do this in the middle of moving out of one house and into another. Getting downright peevish in me old age.

    The Yooper
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  22. #13

    There should be such caveats in all climate science papers.

    Caveats are much more the rule than the exception, as anyone who actually bothers to read such papers knows.

    Unfortunately, this doesn't stop "skeptics" from simultaneously accusing climate scientists of overconfidence, and demanding absolute certainty before we take action.
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  23. HR, the IPCC reports on climate are distinguished by their explicit discussion of the significance of uncertaintyu, in company with the NAS report from earlier this year and a few others. Compare the IPCC's care in explaining uncertainty with the structural failure of the just-released Royal Academy report.

    Meanwhile, you go on to make vague complaints about other scientists failing to address uncertainty in specific papers. Those publications are -not- aimed at the general public; you'll be hard pressed to find a paper based on observations that does not address uncertainty but equally you'll find it unusual for such papers to waste the time of their intended audience by providing remedial education for members of the lay public. Conveying a useful understanding of uncertainty to the proverbial man in the street is the job of science journalists.
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  24. HumanityRules
    my bad, it was 3 over 1955 or 0.1% at 500 nm.
    The 6% change in the UV is probably not negligible for the chemistry and the temperature in the stratosphere. One would expect a negligible impact on tropospheric temperature.
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  25. Riccardo

    "One would expect a negligible impact on tropospheric temperature."

    Yea, through direct radiative forcing UV is rather insignificant on the troposphere, it can however have effects on the pressure systems in the troposphere... And weather systems... It can have very measurable effects in the troposphere. Johanna Haigh has actually published a bit on it i believe.
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  26. Joe Blog
    I was not trying to downplay the UV absorption induced stratospheric warming impacts on our climate. Although experimental evidence of the impacts during the 11-years solar cycle is not so well established, some features seems more robust and are qualitatively reproduced by models (see for example Haigh et al. 2005, Rind et al. 2008).

    But apart from the numbers, there's nothing new in Haig et al. 2010 for the UV range. What's really new is the "out of phase" change in the visible part of the solar spectrum. As Haigh herself pointed out, problems with the interpretation of the long term climate trends arise if this behaviour proves to be a general feature of the sun and not just linked to the 11-years cycle.
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  27. Thank you Riccardo for the links(the Haigh one didnt work for me, but im pretty sure ive read that one any way)

    Just to me, the stratospheric tropospheric interactions in relation to the solar cycle, seem a more viable hypothesis than say the cosmic ray hypothesis, as far as climate variability go(i could be wrong o course). Bearing in mind we are weighting the stratospheric response with co2 cooling up there, and in the past with CFC depletion of O3... An interesting area of inquiry anyway as far as solar effects on climate variability, through dynamical responses to variable UV.
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  28. I found a link to the entire paper at
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  29. Joe Blog
    I fixed the Haigh 2005 link, thank you.
    UV impact, as we noticed before, is (almost) not questioned by anyone; some details may not be clear but scientists essentially agree that the effect is there. On the contrary, the GCR hypothesis is still missing a strong confirmation and it is anticipted that GCR have a small on our climate, if any.
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  30. Thanks TOP for the link.

    Riccardo at 19:12 PM

    With the benefit of having read the article in question, id have to disagree with your summary of the conclusions of Dr Haigh. I believe in her own words, this better sums up the findings.

    "The SORCE observations are, however, consistent with a solaractivity-dependent change in the temperature gradient of the solar photosphere4, suggesting that the offsetting irradiance trends with wavelength seen in SIM should appear in each solar cycle. If this is the case, then it is necessary to reconsider the current understanding19 of the mechanisms whereby solar cycle variability influences climate: the impact on the stratosphere is much larger than previously thought and the radiative forcing of surface climate is out of phase with solar activity. At present there is no evidence to ascertain whether this behaviour has occurred before, but if this were the case during previous multi-decadal periods of low solar activity it would be necessary to revisit assessments of the solar influence on climate and to revise the
    methods whereby these are represented in global models."

    So basically this is suggesting that the sun may influence climate in the troposphere, through varying UV effects in the stratosphere.
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  31. Joe Blog
    could you please point me to the part of the post that disagree with this quote? I think I've said the same thing.
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  32. Riccardo

    specifically this line
    "But apart from the numbers, there's nothing new in Haig et al. 2010 for the UV range."

    Maybe i misinterpreted your summary, but it seemed to me you were implying that this articles findings didnt suggest maybe a larger dynamical effect through UV in the stratosphere, rather than a change in short wave forcing at the surface.

    No question more data is needed to verify these findings. But interesting stuff either way.

    Obviously more data is needed to draw firm conclusions
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  33. Joe Blog
    you're right, it was poorly worded. What I wanted to say is that the effect of UV by itself is not new, as clearly stated before when I cited the two papers; though, it may be larger than previously thought. On the contrary, the anti-phase change in the VIS is new.
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  34. cloa513 - what about the "99%" (you can make that any number by choosing your criteria) do you think is relevent to this discussion? There a physical limitations to how much of an unknown (say an unknown volcano) can be affecting an estimate (eg global heat flow). Perhaps you could comment further on a more relevant thread than one about the sun? How much certainty do you need by the way for your decision-making? We constantly make decisions in face of imperfect knowledge.
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    Moderator Response: I deleted cloa513's comment because it was off topic for this thread. cloa513, please peruse the "Arguments" page to find a more relevant thread.
  35. Just read the moderator response to #34. Hopefully these responses won't go the way of cloa513. At least some of this is on topic I think ;)


    Not with any wish to defend that guy he does qualify that statement by saying "in the DMI database". And that still doesn't really prove this is a dominant idea amoung sceptics. But you're right the title is mis-leading. The few times I've posted on WUWT have often been around Goddard ignoring the longer term arctic ice history in favour of describing short term conditions.

    21.Daniel Bailey

    I find most of what Monbiot writes unpleasantly misanthropic myself. But there's a strange process going on with climate science journalists ATM. Richard Black was critisised on Joe Rohm's website, unnecessarily in my view. Revkin has been disowned (was that Rohm as well?). It strikes me as a dangerous process, alienating prominant voices in the media because they don't match one's own extreme position. It looks like the action of a zealot to me and counterproductive in building a consensus. If I was an warmist I'd be more concerned about Rohm than I would about the journalists.

    [sarc on]Apart from being in the pay of big oil of course [/sarc off] why would much of the criticism from the 'lukewarmer' climate scientists be around the poor handling of uncertainty by the IPCC?


    It seems perfectly reasonable to critise the overcertainty around theories based on the present incomplete data while at the same time demanding greater certainty presumably by getting some better data in the future. Given that CO2 is a GHG then it strikes me that AGW has to be considered as one explanation of what's been measured these past few decades but I don't think it's the only possible explanation.

    23 Doug

    You seem to be ignoring the role of advocate-scientists in this process. Schmidt, Schneider, Hansen and many more (of course we shouldn't neglect those batting for the other side). These people choose to cross the boundary between scientist and messenger. They seem to break the rules you describe. What do you think their role is?

    Just as an example I can't find any strongly expressed caveats in this new paper
    which is making an extremely strong scientific statement about climate science in a very prominent science journal. What do you think should be the important caveats in this work? Or do you think there should be none?

    (the ealier vagueness was an attempt not to go OT, it hasn't worked.)

    So what would be the results on the rest of the climate system of affecting the stratosphere in a not negligible way?
    Now that we know about the variation in the spectrum it's probably not good enough just to look at TSI in order to see the impact of solar variation on the climate. We need to know how the solar spectrum is varying and how those variations interact to impact on climate. This paper just seems to describe some possible first order affacts (i hope that's the right use of the term). Would you agree with that?
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    Moderator Response: Since we didn't stop the off topic discussion earlier, I'll let your concise (thank you) response stay. But everybody please take further off-topic comments to other threads.
  36. HumanityRules
    in my comment #26 you'll find two references about the impact of UV changes.
    We need to know how the solar spectrum varies and indeed we already knew a lot, though not all. This new paper open the possibility of some undected (occasional?) changes, but before using the word "probably" I'd read again the caveats I quoted.
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  37. Hi evrybody, I am Giancarlo, this is my first post.
    Even though I am an astronomer, and I worked, among the other things, on chromospheric activity in solar-type stars, there are many things on the topic I have no idea of, I hope my question is not too naive.

    If the data from the satellite confirm the "upside down effect" on the long period of time, that would be quite puzzling, wouldn't it? How could you explain the results by Solanki, of a correlation between cycle-averaged solar activity and the temperature?

    I read somewhere in this website that the global warming of anthropic origin characterizes itself as the time in which solar energy input and earth temperature start following different trends, constant the former and increasing the latter. But before a few decades ago the two quantities were closely related. Did I get it right? How did they measure the solar energy input in the optical range in the past time?

    And how could you explain the fact that, on top of the golobal warming trend, there is a cycle that closely match the solar activity cycle?
    In this case, there would be a delay in the effect that solar energy has on terrestrial temperature.
    This was also mentioned in #9
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  38. giancarlo
    no one could have thought in terms of what if it's true. There's no answer at the moment to the question of how to explain much of what we know about the solar influence on climate. My guess is that people will look harder at the impact of UV, apparently the only thing left in phase with the total solar irradiance (TSI). But it's just a guess, I'd better say I don't know.

    The TSI has been directly measured only in the satellite era. There are proxy for it, sun spots, radio frequency emission, magnetic field, radioactive nuclei formation, etc. None of them has spectral capabilities, it all stands on what we know about the link between the proxy and the spectral changes of the sun irradiance. The answer to the spectral changes issue will probably come from future measurments more than from reconstructions of the past.
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  39. giancarlo at 02:22 AM

    What this paper is suggesting, if these trends are not anomalous, is that the solar effects on the stratosphere maybe what is driving the cyclic climatic responses to the solar cycle, Riccardo has linked two papers on the subject at 19:12 PM on 13 October, 2010 , and i also linked one at 09:15 AM on 12 October, 2010 .

    But the stratospheric effects themselves are not new, Ramanthan and Dickenson 78

    This could potentially be far reaching, if the dynamical responses from stratospheric cooling from UV have been having a greater effect than believed, it could also mean that anthropogenic O3 destruction, and co2 cooling of the stratosphere could also be having, uncontributed effects.

    This is wild speculation, but thats what blogs are for ;-)
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  40. My link didnt work, try this one
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  41. Joe

    there seems to be heaps of stuff coming out of Colorado State about Stratosphere-Troposhpere interactions.


    Also I can't get my head around what "could also be having, uncontributed effects." means?
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  42. HumanityRules at 02:51

    Also I can't get my head around what "could also be having, uncontributed effects." means?

    Yea, the "uncontributed" should be unattributed, a good reason why i shouldnt post at 5am... But what i mean is that with co2 being a net emitter (2:1)in the stratosphere, that its cooling effects could be having larger dynamical effects in the troposphere than previously believed. The interactions are complex, more so with O3 because its concentrations vary so much latitudinaly and vertically, but with increasing radiative cooling from elevated co2 it will further complex the matter. The main dynamic effects from stratospheric interactions with the troposphere are caused by temperature/pressure changes, and their effect on the air circulation/pressure systems in the troposphere... and then their effect on water vapor up take, condensation etc.
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