RealClimate logo


Technical Note: Sorry for the recent unanticipated down-time, we had to perform some necessary updates. Please let us know if you have any problems.

Solar spectral stumper

Filed under: — gavin @ 7 October 2010

It’s again time for one of those puzzling results that if they turn out to be true, would have some very important implications and upset a lot of relatively established science. The big issue of course is the “if”. The case in question relates to some results published this week in Nature by Joanna Haigh and colleagues. They took some ‘hot off the presses’ satellite data from the SORCE mission (which has been in operation since 2003) and ran it through a relatively complex chemistry/radiation model. These data are measurements of how the solar output varies as a function of wavelength from an instrument called “SIM” (the Spectral Irradiance Monitor).

It has been known for some time that over a solar cycle, different wavelengths vary with different amplitudes. For instance, Lean (2000) showed that the UV component varied by about 10 times as much as the total solar irradiance (TSI) did over a cycle. This information (and subsequent analyses) have lent a lot of support to the idea that solar variability changes have an important amplification via changes in stratospheric ozone (Shindell et al (2001), for instance). So it is not a novel finding that the SIM results in the UV don’t look exactly like the TSI. What is a surprise is that for the visible wavelengths, SIM seems to suggest that the irradiance changes are opposite in sign to the changes in the TSI. To be clear, while the TSI has decreased since 2003 (as part of the descent into the current solar minimum), SIM seems to indicate that the UV decreases are much larger than expected, while irradiance in visible bands has actually increased! This is counter to any current understanding of what controls irradiance on solar cycle timescales.

What are the implications of such a phenomena? Well, since the UV portion of the solar input is mostly absorbed in stratosphere, it is the visible and near-IR portions of the irradiance change that directly influence the lower atmosphere. Bigger changes in the UV also imply bigger changes in stratospheric ozone and temperature, and this influences the tropospheric radiative forcing too. Indeed, according to Haigh’s calculations, the combination of the two effects means that the net radiative forcing at the tropopause is opposite in sign to the TSI change. So during a solar minimum you would expect a warmer surface!

Much of the longer term variance in solar output has been hypothesised to follow what happens over the solar cycle and so if verified, this result would imply that all current attributions to solar variability of temperature changes in the lower atmosphere and surface ocean would be of the wrong sign. Mechanisms elucidated in multiple models from multiple groups would no longer have any validity. It would be shocking stuff indeed.

Conceivably, there might be another missing element (such as a cosmic-ray/cloud connection) that would counteract this physics and restore the expected sign of the change, but no-one has succeeded in finding any mechanism that would quantitatively give anything close the size of effect that would now be required (see our previous posts on the subject).

So is this result likely to be true? In my opinion, no. The reason why has nothing to do with problems related to the consequences, but rather from considerations of what the SIM data are actually showing. This figure gives a flavour of the issues:

(courtesy Judith Lean). Estimates of irradiance in three bands are given in each panel, along with the raw measurements from various satellite instruments over the last 30 years. The SIM data are the purple dots in the third panel. While it does seem clear that the overall trend from 2003 to 2009 is an increase, closer inspection suggests that this anti-phase behaviour only lasts for the first few years, and that subsequently the trends are much closer to expectation. It is conceivable, for instance, that there was some undetected or unexpected instrument drift in the first few years. The proof of the pudding will come in the next couple of years. If the SIM data show a decrease while the TSI increases towards the solar maximum, then the Haigh et al results will be more plausible. If instead, the SIM data increase, that would imply there is an unidentified problem with the instrument.

In the meantime, this is one of those pesky uncertainties we scientists love so much…


254 Responses to “Solar spectral stumper”

  1. 101
    BobRecaptca says:

    ClimateProgress.org rips apart the resignation of Lewis,
    http://climateprogress.org/2010/10/11/hal-lewis-resigns-from-the-american-physical-society/

  2. 102
    John Baez says:

    Interesting stuff!

    “What are the implications of such a phenomena?”

    I’d say:

    “What would be the implications of such a phenomenon?”

    The “would be” is a little warning to readers eager to jump to conclusions.

  3. 103
    Jim Ryan says:

    Ray @99,

    Please note I didn’t say “read it all”. Melanie Phillips said it! You might find it useful not to shoot the messenger. Raising awareness of the contrarian mindset is not the most redundant exercise; at the very least it allows us to appreciate their appalling scientific ignorance.

    That said, chewing broken glass is probably the better option compared to anything Mel P writes.

  4. 104
    Ray Ladbury says:

    Jim Ryan,
    My fire was not directed at you, and sorry if some of the vitriol splashed your way.

    However, I think we spend way too much time paying attention to what are in effect, morons and loons. If they rejected the heliocentric solar system, they would be called such. If they rejected evolution, they would be called such. Likewise, smoking related illness, HIV-AIDS causation, etc. The fact that some of these loons and morons hold power and influence should not increase the attention we pay them.

  5. 105
    Edward Greisch says:

    71 John P. Reisman (OSS Foundation):
    \Triple redundancy = MilSpec\

    NO. For integrated circuits [ICs] and electronics parts in general: A machine sorts them into categories after they are made. The classes start with Class S then Class M [Mil spec] then……memory fails. Consumer spec is just above broken.

  6. 106

    #102–good edit. (Including correct agreement as to number!)

  7. 107

    By the way, I’d like to offer belated thanks to readers here–and of course, the moderators, who’ve allowed various shameless plugs like this one at (hopefully) discreet intervals–who’ve taken time to read and sometimes comment on my backgrounders on global warming science.

    The milestone that prompts this commentt is the recent achievement of over 1,000 page views for the most-viewed article–fittingly, that on the life, work and times of John Tyndall:

    http://hubpages.com/hub/Global-Warming-Science-In-The-Age-Of-Queen-Victoria

    Coming up behind are the articles on Arrhenius and Fourier–the former will probably hit 1,000 about five months out, the latter about 10. It’s education on the retail scale, I suppose, but satisfying none the less.

    Thanks again!

  8. 108

    103 (Jim Ryan),

    FYI… a fairly easy thing to do is to surround text in your comment with blockquote tags (<blockquote> and </blockquote>), like this:

    <blockquote>Quoted text</blockquote>

    which then looks like this in your post:

    Quoted text

    It helps to avoid confusion, particularly in large, multi-paragraph text blocks, about where quoted text ends and one’s own comments begin (or not, in this case!).

  9. 109
    Radge Havers says:

    104 Ray

    “I think we spend way too much time paying attention to what are in effect, morons and loons.”

    Well, you can’t whack every mole, and they just pop back up anyway. OTOH, I’d submit that the problem is no longer one of a few marginal or isolated noise makers, that it’s getting worse, and that there doesn’t seem to be an effective way to leverage the situation. Maybe I’m overly pessimistic.

    Nevertheless we plug away as best we can.

  10. 110
    AJ says:

    Without examining Haig’s calculation, unless the total albedo integrated over the spectrum is lower, I can’t fathom why the surface temperature would increase with decrease in TSI. The stratosphere temperature is not nearly high enough to make a marginal boost compensate (through radiation, since ~ T^4) for the increase in total energy supplied to the atmosphere. Right? Therefore, I would still expect surface temperatures to decrease with decreasing TSI, albeit with possibly longer delay…

  11. 111
    Ray Ladbury says:

    John P. Reismann and Edward Greisch,

    WRT active semiconductor parts, Class S is nominally space qualified. Beyond that, should you really be interested:

    http://nepp.nasa.gov/nepag/info/parts_risk_matrix.htm

    Triple redundancy is only one hardening strategy–and don’t for get you have to vote all three branchs, so your hardening is only as good as your voting–kind of like democracy.

  12. 112
    Ray Ladbury says:

    Radge Havers, Well, look on the bright side–at least we now know the answer to the Fermi Paradox.

  13. 113
    Shandahr Sheppe says:

    The impending TeaPublican victories in America tell us that we can expect no rational behaviour from the American people until the current generation has expired.

    Isolate, Encapsulate, Constrain.

    We don’t expect to see much climate science coming from America once the teapublican budget cuts kick in.

  14. 114
    Margo Meede says:

    “OTOH, I’d submit that the problem is no longer one of a few marginal or isolated noise makers, that it’s getting worse, and that there doesn’t seem to be an effective way to leverage the situation.” – 109

    Your observations are correct of course, and the reason is obvious, but still unfathomable to most scientists who spend their days surrounded by reasonably rational people.

    The denialist insanity is almost exclusively concentrated in the Conservative American population who have decided to reject reality and place their faith in Conservative Political Dogma.

    This isn’t rational of course, but mass self delusion is common in history.

    As I have said many times, there is only cure for this Conservative disease and it is death.

    Now given that the current “educate the willfully ignorant” strategy has clearly failed, (no surprise there) what strategy is best to adopt now?

    Some here seem to believe that it should be more of the same.

    Of course that is a presc.x.ription for continued failure, and given the stakes evidence of insanity IMO.

  15. 115
    Margo Meede says:

    “However, I think we spend way too much time paying attention to what are in effect, morons and loons.” – 104

    Those “morons and loons” TeaPublican are about to cancel most climate science funding in America.

    The tolerance of idiocy has it’s consequences.

    Allowing the citizenship around you to devolve into mindless apes, means that you are less likely to find an umbrella when it is raining.

  16. 116
    Margo Meede says:

    The first task in science is to observe, and classify the natural system under consideration based on morphology of patterns of behaviour.

    If the natural system is denialists, what are their collective behaviours and morphologies?

    You can’t solve a problem without first understanding it.

  17. 117
    Titus says:

    Shandahr Sheppe @113 writes:
    “The impending TeaPublican victories in America”…

    A good and substantive observation. Now, using science as a tool; what do we theorize about the occurrence and development of this observation?

  18. 118
    Edward Greisch says:

    Just curious: I expect that the solar spectrum is unchanged as far as photosynthesis is concerned. To get maximum plant growth we need maximum photons of the right wavelengths + keeping the temperature where it was before GW. Geoengineering would give us fewer photons in hot climate = less food.
    Don’t some plants get sunburned in excess UV? There are more constraints than we realized.

  19. 119
    BobRecaptca says:

    @Shandahr: No, it’s not over unless the big bone lady sings.

    Admittedly, the US continues to fall back and become less relevant.
    Let’s talk again after the mid-term elections.

  20. 120

    #118–I suppose it depends upon what you call “geo-engineering.” For schemes that affect global albedo, yes. For schemes that affect local or regional albedos, or that affect carbon fixation/sequestration, no.

  21. 121
    Ray Ladbury says:

    Margo Meade, I know of no remedy for ignorance other than education. The problem in this case is that the public are too distracted by the circuses to realize the bread is being stolen from their plates, let alone realize that they face a less immediate threat.

    I would submit, however, that any strategy for renewing democracy must be at its root democratic. If the species turns out to be too dumb to survive, as I have said, at least those of us intelligent enough to perceive it will have an answer to the Fermi Paradox.

  22. 122
    Paul van Egmond says:

    @114 Margo: The deniers smell a conspiracy, and no amount of scientific evidence is going to convince them otherwise. Climate science is heading for a rough couple of years, until sometime in the future the effects of climate change become so glaringly obvious in their daily lives that only the most foolhardy will persist in their denialism. We can only hope they don’t do too much damage in the mean time.

  23. 123
    Dan H. says:

    While we are on the subject of educating morons and loons, can we do something about those who exaggerate the effects of global warming in an attempt to create a impending catastrophy. It is no wonder that belief in global warming has waned recently. If one person claims that no warming will occur, and another claims that it will twice as much as actual, they are both off by 100%.

    As far as geoengineering is concerned, that is tops on the list of bad ideas. Part of the increase in plant growth and food production was due to the increased atmospheric CO2 levels and warmer temperatures. Decreasing sunlight and temperatures will decrease plant growth.

  24. 124

    “Catastrophe,” Dan–”catastrophe.”

  25. 125

    #105 Edward Greisch
    #111 Ray Ladbury

    Thanks for the input.

    Honestly I never looked it up. I was developing a circuit and had been asked to see how much it would cost to make it triple redundant for a military application. The mfg. called it mil spec.

    I did make prototypes but we never went into production on that one.


    Fee & Dividend: Our best chanceLearn the IssueSign the Petition
    A Climate Minute: Natural CycleGreenhouse EffectClimate Science HistoryArctic Ice Melt

  26. 126
    Dan H. says:

    Sorry Kevin,
    Spelling was never my good suit.

  27. 127

    #126–I should probably be the one to apologize, for riding a hobby horse (AKA pet peeve.) A particularly bone-headed denialist I frequently encounter is addicted to that particular spelling, and it probably helped induce the knee-jerk editorial response.

  28. 128

    …can we do something about those who exaggerate the effects of global warming in an attempt to create a impending catastrophe…

    I’d agree with this, except I don’t ever actually hear this except on denier blogs claiming it’s been done by “alarmists.”

    Or, to put it a little more clearly, those “impending catastrophes” you are referencing are in fact very real… 30 to 100 years down the line. No one is saying it’s going to happen tomorrow. What they are saying is that if we wait 30 or 100 years to take action, then it will be way, way too late, and by that point they will be very serious, world changing catastrophes.

    It all depends on how close to the edge we want to ride, and how much we want to stick it to our children/grandchildren for our own creature comforts and presumed entitlement lifestyle in the present.

    So the people that say “that’s silly, look, nothing’s happened yet, there are no catastrophes” either aren’t listening or aren’t thinking it through.

  29. 129
    Ray Ladbury says:

    Dan H. asks, “While we are on the subject of educating morons and loons, can we do something about those who exaggerate the effects of global warming in an attempt to create a impending catastrophy. It is no wonder that belief in global warming has waned recently. If one person claims that no warming will occur, and another claims that it will twice as much as actual, they are both off by 100%.”

    Well, except zero warming would imply CO2 sensitivity of 0, and there is zero probabiliy of that. Double current warming estimates requires a CO2 sensitivity of 5.5-6, and that cannot be ruled out at better than the 98% confidence level. Not equivalent. The problem, Dan, is that we cannot bound the effects of the warming. We don’t know how bad they will be just yet, but we know they will be worse than anything we’ve faced in the history of civilization.

  30. 130
    Dan H. says:

    True,
    We do not know what the overall effects will be. But does that mean making claims of 3C warming in the next 90 years is better than making claims of no warming. Those that assume a positive cloud feedback arrive at your implied climate sensitivity in the 2.75-3.0 range, which with the expected 40% increase in atmospheric CO2, would result in less than 1.5C of warming by 2100.

    How do we know that it will be worse than anything we’ve faced in the history of civilization? The last ice age was quite rough on many species.

    The “impending catastrophes” are only real if they actually happen. I am not saying that they cannot happen, but that we do not know if or when they could happen. We are speculating using several assumptions, which in turn have a high degree of uncertainty.

    Yes, Bob, it is usually denier sites than claim exaggeration by alarmists, and conversely, alarmist sites that claim deniers are spreading misinformation. I have yet to find a site that is truly neutral on this topic. Those that believe in warming continuing on its current pace are branded by both sides as climate morons and loons as Ray so eloquently referred to them.

    [Response: Please provide just one example from one of our RealClimate posts of what you consider exaggeration, because we all think we're pretty conservative here.--eric]

  31. 131

    #128–

    Well, this gets us back to the territory of the “Warmer and warmer” post. Due to the challenges of scientific attribution, it’s hard to know whether or not some catastrophes that have occurred are, or are not, due to climate change.

    Russian heatwave? Maybe.
    Pakistani floods? Maybe.
    Pine bark beetle pandemic? Probably, but can’t be completely sure.
    Katrina? Could have contributed. . .
    2003 European heatwave. 30% increased probability (IIRC.)

    Hmm. That’s many, many billions of dollars and many thousands of premature deaths that we’re talking about here. What about some non-human impacts?

    From today’s in-box: Long term 80% decline in krill population? Could be, but. . .
    Possible increased mortality in whale populations feeding on krill? Well, is mortality up in fact?

    http://www.cbc.ca/technology/story/2010/10/13/brazil-beaches-whales.html

    From earlier this week: Widespread metabolic stress among tropic exotherms? Probably. . .

    http://www.cbc.ca/technology/story/2010/10/07/tropics-animals-global-warming.html

    And so it goes.

    But, as Ray points out, it seems that some people persistently suffer the illusion that uncertainty is their friend. That is, they persistently say that because we aren’t completely sure, action is inappropriate. But the flip side is that it is entirely possible that we have suffered catastrophes already due to climate change, and that clear signs of severe biological consequences are currently unfolding in front of us.

    So, what is a “catastrophe?” How do we recognize it? And how do we relate it to climate change, and our own actions? Clearly there is a concerted campaign to minimize or deny any danger, and clearly it plays into “common sense” and emotional comfort. Clearly there have been some who sensationalize, perhaps in partial compensation for the fact that scientific objectivity and caution have the unavoidable side effect of minimizing possible consequences. (Or at least making them sound kinda boring.)

    At the end of the day, it’s a matter of attitude and judgment. Some people, confronted with a minor skin lesion, will decide it’s nothing. Others will immediately make an appointment with their GP or dermatologist. More often than not, it probably IS nothing–but which group has the higher survival rate, I wonder?

  32. 132
    Richard Simons says:

    Dan H (14 October 2010 at 10:44 AM) asks “can we do something about those who exaggerate the effects of global warming in an attempt to create a impending catastrophy.”

    I have heard claims about people exaggerating the effects of global warming but have rarely seen it done. Dan, could you give us links to one or two people who you think are exaggerating the situation?

  33. 133
    Nick Gotts says:

    “I have yet to find a site that is truly neutral on this topic.” – Dan H.

    Now, why would you want a site that is neutral as between well-established science on the one hand, and a toxic compound of invincible ignorance and bare-faced lies on the other?

  34. 134
    Didactylos says:

    Dan H.: I agree with your basic premise that “the warmists” do more harm than good. I personally find it very frustrating when people use lies, distortions and misinformation in support of a conclusion that I agree with, or in the name of a cause that I believe in.

    We are better than that. And if we’re not, then we should be. We certainly have no need to stoop to denier tricks to make a point.

    Just to reassure the moderators: this sort of hysteria is frequently to be found in the comments, but I have never observed it in articles or comments from the RC authors.

    Dan H. – your numeric assertions seem a little off to me. Climate sensitivity is “likely to be in the range 2 to 4.5°C” and may be higher. However, climate sensitivity is not the same as the projected temperature rise over a given period. The UK Met Office predicts a rise of 2.1 – 7.1 degrees (from pre-industrial levels) by 2100. But the low end of this estimate stipulates immediate emissions reductions. If we follow “business as usual”, the projection is 5.5 – 7.1 degrees. If we subtract the rise we have already seen, that’s still likely to be a further increase of 5 degrees by the end of the century.

    This seems like a sober analysis to me. How did you arrive at your numbers? What emissions model are you assuming?

  35. 135

    130 (Dan H)

    Those that assume a positive cloud feedback arrive at your implied climate sensitivity in the 2.75-3.0 range…

    It’s not “assumed,” it’s inferred from our understanding of the physics and the systems involved. That understanding isn’t perfect, but it’s not the sort of casual assumption that you are implying.

    My understanding is also that the increase in sensitivity arises not from a “positive cloud feedback” but rather a positive water vapor feedback (which is different, and much easier to predict). The important distinction in climate sensitivity is the lack of a significant negative feedback from clouds as expected by some scientists (Spencer, Lindzen) or the possibility of some degree of positive feedback from clouds (in addition to water vapor) depending on the nature/location of the formation of those anomalous clouds.

    The estimates of climate sensitivity are also supported by a completely separate line of inquiry, the study of paleoclimate, which also points rather consistently to the same range of climate sensitivity. At the same time, the history of the earth’s climate seems to very distinctly preclude the idea of low climate sensitivity.

    The “impending catastrophes” are only real if they actually happen.

    Statements like this always make me think of the joke about the guy who jumped off of the skyscraper, and was heard to say as he passed an open window “so far, so good.”

    We are speculating using several assumptions, which in turn have a high degree of uncertainty.

    This is patently false, and if you believe it, you have not sufficiently studied or do not sufficiently understand the science. Very, very few assumptions are involved, and so far those assumptions that have been made are proving to be too conservative, i.e. things are looking to be worse than originally expected.

    …and conversely, alarmist sites that claim deniers are spreading misinformation.

    Because they are, and the misinformation is rampant. I could list about a zillion examples, with links, but it would be pointless because you already know it to be true. In fact, I challenge you to provide links to three denier sites that do not spread misinformation.

    I have yet to find a site that is truly neutral on this topic.

    That’s because you are not neutral yourself. You steadfastly desire that it be a non-problem, so your condition for “neutral” is a site that says “well, both sides have good points, so let’s just wait and see.” “Neutral” does not mean give equal weight to every crazy proposition and predilection to the point of insanity.

    Which is the really big problem… “wait and see” and “let’s be careful about this, we don’t have enough information to take action” is equivalent to “hope for the best, and if not, oh well, so what if millions or hundreds of millions die fifty years from now?”

    The main problem here seems to be that you honestly believe that there is not much in the way of evidence, that the jury is very out, and no one really knows what is happening. This is not at all the case.

    Those that believe in warming continuing on its current pace are branded by both sides as climate morons and loons as Ray so eloquently referred to them.

    This is unclear. What do you mean by this? Please clarify.

  36. 136
    Dan H. says:

    1. Prof. Corinne Le Quere of East Anglia http://www.guardian.co.uk/environment/2009/nov/17/global-temperature-rise
    2.Dr. Katharine Richardson from the University of Copenhagen
    http://www.timesonline.co.uk/tol/news/environment/article5882341.ece
    3. Dr. Vicky Pope of the Met Office tries to reign in exaggerations, although sometimes I think she is part of the problem.

    http://www.guardian.co.uk/environment/2009/feb/11/climate-change-science-pope

  37. 137
    SecularAnimist says:

    Dan H. wrote: “How do we know that it will be worse than anything we’ve faced in the history of civilization? The last ice age was quite rough on many species.”

    The last ice age predates the history of civilization.

    If you are comfortable with the idea that the future of “civilization” will be a very small number of people struggling to survive as gatherer-hunters in a dying biosphere, then there is really nothing to worry about.

    After all, worse things than that have happened to the Earth in the past, and even though 90 percent of species went extinct, life went on, and it only took millions of years for a robust, diverse, thriving biosphere to regenerate.

  38. 138
    Dan H. says:

    Bob,
    First off, clouds are still a large uncertainty, whether you personally believe this or not. This ranges from positive to negative feedback due to increased cloudiness and also a positive feedback due to decreased cloudiness, all associated with increases in atmospheric CO2 concentrations. I am not questioning the water vapor feedback, only clouds.

    There is plenty of evidence; people are just using it improperly. How many people have extrapolated the temperature increase from 1979-1998 or the flat line since?

    As far as a clarification in your last post, just read some of the recent posts.

    You can Didactylos above to the list of exaggerators.

  39. 139
    Hank Roberts says:

    > branded by both sides as climate morons and loons

    Nope, the three scientists you name are not so ‘branded’ by other scientists; the high end is a real concern, and uncertainty means more not less concern.

    You can relate that risk to this topic — whether spectral change is happening — if you try to focus:

    “We’re concerned that if the natural sinks can’t keep pace with the increased CO2 emissions, then the physical and biological impacts of global warming will accelerate over the next century.”
    http://www.scientificamerican.com/article.cfm?id=tracking-atmospheric-carbon-dioxide-levels

  40. 140
    Ray Ladbury says:

    Dan H. says, “But does that mean making claims of 3C warming in the next 90 years is better than making claims of no warming.”

    Simply, flat-assed wrong. Did you even bother to read my post? Dude, what is the probability that CO2 sensitivity is zero based on the evidence we have. I will tell you: it is zero. What is the probability that it is above 3 degrees per doubling? Better than 50%

    Here’s the deal, Dan. In risk assessment, the first step is to ascertain whether the threat is credible. Since a CO2 sensitivity of more than 2 degrees per doubling will result in significant stress on the planet’s carrying capacity, I claim that we have 95% confidence that the threat is credible. That is more than sufficient to establish the credibility of the threat.

    Now step 2. Bound the risk (=probability of threat x cost if realized). Oops! Big problem. Cost of a rise in temperature diverges as we get near 6 -8 degrees. Even at 3 degrees it is quite significant and has a significant high-side tail. When you cannot bound risk, Dan, the only responsible risk reduction strategy is to avoid risk.

    So, Dan, on the one hand, we have nearly everybody who has actually studied the issue voicing serious concerns, and then we have people like you who can’t be bothered saying “Oh, it’ll be all right,” and complaining the the informed are alarmed and therefore alarmist.

  41. 141
    SecularAnimist says:

    Dan H: I read the articles you linked to in comment currently numbered 136.

    I see nothing whatever in the comments by Prof. Le Quere or Dr. Richardson that could be reasonably described as “exaggeration”.

    Some people seem to regard anything as “exaggeration” that is not in accord with their a priori ideas about what “can’t possibly happen”.

  42. 142
    Ray Ladbury says:

    Dan H. says, “How many people have extrapolated the temperature increase from 1979-1998 or the flat line since?”

    Flat line? I get more than 1.8 degrees per century even with those cherry picked endpoints, Dan.

  43. 143

    138 (Dan H),

    I am not questioning the water vapor feedback, only clouds.

    You missed the point. What you previously had said (which is completely incorrect):

    Those that assume a positive cloud feedback arrive at your implied climate sensitivity in the 2.75-3.0 range…

    This implies, to me, that you believe that a positive cloud feedback is required for the sensitivity in the range 2.75-3.0C.

    But this is not the case. That range arises primarily (but not only) from water vapor feedback, not from a positive cloud feedback. There is a difference, and it’s important.

    …clouds are still a large uncertainty, whether you personally believe this or not…

    I don’t dispute this. What I dispute is (a) that this is necessarily tied to current projections of climate sensitivity (it’s not), and (b) that there is any solid scientific evidence in favor of the case for a strong negative feedback from clouds.

    There is small handful of scientists making a case for it, and in two decades they’ve been unable to advance that case through scientific means (only through propaganda and rousing, sarcastic speeches at Heartland “climate” conferences). I’m not a big fan of believing people just because they say something and it sounds like what I’d like to hear.

    …a positive feedback due to decreased cloudiness…

    A minor correction, although this in a nutshell demonstrates how very weak your own understanding of the science is, and should be a signal to you that you should study more before settling on your own opinions.

    Positive feedback from clouds would be due to an increased greenhouse effect from the cloud themselves, not a decrease in clouds. This is in contrast to a negative effect which would primarily come from an increased albedo. The main distinction here is in what sort and how many additional clouds might form in a warmer world; high clouds made of relatively transparent ice crystals, or lower level clouds consisting of water droplets… as well as whether or not those clouds tend to form earlier in the day (so their impact on albedo is relevant) or later in the day and persist through the night (when change in albedo is irrelevant).

    Clouds made of ice crystals will have a minimal effect on albedo, and so let in the same amount of sunlight, while still having a greenhouse effect. Clouds made of water droplets, and present in daytime, could increase the earth’s albedo, reflecting back more incoming radiation than it is trapping through a greenhouse effect.

    But as I said… right now there are multiple lines of evidence that show a sensitivity in the range of 2C-6C (but scientists go with the 2C-3C range), and no reliable evidence that I am aware of that puts climate sensitivity any lower.

    There is plenty of evidence; people are just using it improperly.

    Yes, you make that very clear.

    …or the flat line since?

    Flat line? Have you looked at temperatures for the past 14 months (with every single month in the top 4, if not 1 or 2, for the past 100 years)? Please visit Dr. Roy Spencer’s site for AMSU temps. Check the boxes for every year, hit the “Redraw” button, and tell me what you see.

  44. 144
    Didactylos says:

    I’m sorry, Dan H. I completely misunderstood you. People don’t come with handy “denier” labels around their neck, it is something that we have to work out based on what people say, and whether they are susceptible to reason.

    It transpires that your idea of “exaggeration” is simply any number that you find inconvenient, and has nothing to do with whether the number can be supported by solid evidence, or whether it is a reasonable estimate given the stated assumptions.

    “How many people have extrapolated the temperature increase from 1979-1998 or the flat line since?”

    See, statements like this are what get you in trouble – and reveal that you actually are so far out of your depth that we should call the Coastguard.

    Please don’t let this put you off. There is a simple solution to not knowing things. Learn. Ask. Understand.

  45. 145
    David B. Benson says:

    Dan H. — This link is to an extremely simply climate model wherein one uses 130 years of global temperature product (GISTEMP) to estimate the climate’s transient response to increased CO2 [which inlcudes all feedbacks due to water vapor, clouds, etc.]:
    http://www.realclimate.org/index.php/archives/2010/03/unforced-variations-3/comment-page-12/#comment-168530
    note that this gives good agreement with the usual estimate of Charney equilibrium climate sensitivity of around 3 K for 2xCO2.

  46. 146

    I was confused, thinking that the quotes from Drs. Le Quere and Richardson rather undercut Dan’s point of an expected 3C (or less) temperature increase. Instead, they are being cited to show “exaggeration.”

    But don’t BAU projections run as high as 7C? And is there any indication at this point of significant deviation from BAU?

    Don’t mean to sound pessimistic here, but if LeQuere and Richardson are in the high end of the expected range, they aren’t at the extreme high end. And they definitely aren’t beyond it, which is what I’d have thought a claim of “exaggeration” would imply.

  47. 147
    TimTheToolMan says:

    Would it be fair to say that if the UV reduction was greater than expected and consequently stratospheric cooling was more to do with UV reduction and less to do with any arguments of increased atmospheric temperature gradient then the argument that stratospheric cooling justifies AGW equally diminishes?

    [Response: No, you are confusing timescales. This analysis was based on a 3 year time period - stratospheric cooling related to GHGs has been seen over decades - and the solar UV contribution (even if this new data is right) would still have lead to a warmer stratosphere. Still contradictory. - gavin]

  48. 148
    Radge Havers says:

    Didactylos @ 144

    \People don’t come with handy ‘denier’ labels around their neck\

    Sniff test:

    \If one person claims that no warming will occur, and another claims that it will twice as much as actual, they are both off by 100%.\

    Smells suspiciously like to a trolling appeal to symmetrical debate. Some say the earth is flat, some say it’s spherical: Therefore it’s reasonable to say it’s shaped like a football.

    Same with:

    \branded by both sides\

    Then there’s:

    \Part of the increase in plant growth and food production was due to the increased atmospheric CO2 levels and warmer temperatures.\

    Maybe true but in that context sounds suspiciously like it was lifted from a fossil fuel industry pamphlet.

  49. 149
    TimTheToolMan says:

    Is it not true that the SIM data has only been collected since 2003? It seems to me that unless we have the equivalent of that SIM data then we cant confidently claim anything about the previous decades in the light of this result.

  50. 150
    Thomas says:

    We do occasionally see exaggerated claims, by amateurs. Usually it is because they are using rhetorical, rather than mathematical reasoning, such as mistaking any positive feedback as implying instability. Also a lot of amateurs think warming will cause methane hydrates to destabilize yielding the end of the world as far as life is concerned, whereas professionals look at the scales of things, and the timescales for change and don’t make such statements.


Switch to our mobile site