The Dividing Line Between Nuisance and Catastrophe: Feedback

I have written for quite a while that the most important issue in evaluating catastrophic global warming forecasts is feedback.  Specifically, is the climate dominated by positive feedbacks, such that small CO2-induced changes in temperatures are multiplied many times, or even hit a tipping point where temperatures run away?  Or is the long-term stable system of climate more likely dominated by flat to negative feedback, as are most natural physical systems?  My view has always been that the earth will warm at most a degree for a doubling of CO2 over the next century, and may warm less if feedbacks turn out to be negative.

I am optimistic that this feedback issue may finally be seeing the light of day.  Here is Professor William Happer of Princeton in US Senate testimony:

There is little argument in the scientific community that a direct effect of doubling the CO2 concentration will be a small increase of the earth’s temperature — on the order of one degree. Additional increments of CO2 will cause relatively less direct warming because we already have so much CO2 in the atmosphere that it has blocked most of the infrared radiation that it can. It is like putting an additional ski hat on your head when you already have a nice warm one below it, but your are only wearing a windbreaker. To really get warmer, you need to add a warmer jacket. The IPCC thinks that this extra jacket is water vapor and clouds.

Since most of the greenhouse effect for the earth is due to water vapor and clouds, added CO2 must substantially increase water’s contribution to lead to the frightening scenarios that are bandied about. The buzz word here is that there is “positive feedback.” With each passing year, experimental observations further undermine the claim of a large positive feedback from water. In fact, observations suggest that the feedback is close to zero and may even be negative. That is, water vapor and clouds may actually diminish the already small global warming expected from CO2, not amplify it. The evidence here comes from satellite measurements of infrared radiation escaping from the earth into outer space, from measurements of sunlight reflected from clouds and from measurements of the temperature the earth’s surface or of the troposphere, the roughly 10 km thick layer of the atmosphere above the earth’s surface that is filled with churning air and clouds, heated from below at the earth’s surface, and cooled at the top by radiation into space.

When the IPCC gets to a forecast of 3-5C warming over the next century (in which CO2 concentrations are expected to roughly double), it is in two parts.  As professor Happer relates, only about 1C of this is directly from the first order effects of more Co2.  This assumption of 1C warming for a doubling of Co2 is relatively stable across both scientists and time, except that the IPCC actually reduced this number a bit between their 3rd and 4th reports.

They get from 1C to 3C-5C with feedback.  Here is how feedback works.

Lets say the world warms 1 degree.  Lets also assume that the only feedback is melting ice and albedo, and that for every degree of warming, the lower albedo from melted ice reflecting less sunlight back into space adds another 0.1 degree of warming.  But this 0.1 degree extra warming would in turn melt a bit more ice, which would result in 0.01 degree 3rd order warming.  So the warming from an initial 1 degree with such 10% feedback would be 1+0.1+0.01+0.001 …. etc.   This infinite series can be calculated as   dT * (1/(1-g))  where dT is the initial first order temperature change (in this case 1C) and g is the percentage that is fed back (in this case 10%).  So a 10% feedback results in a gain or multiplier of the initial temperature effect of 1.11 (more here).

So how do we get a multiplier of 3-5 in order to back into the IPCC forecasts?  Well, using our feedback formula backwards and solving for g, we get feedback percents of 67% for a 3 multiplier and 80% for a 5 multiplier.  These are VERY high feedbacks for any natural physical system short of nuclear fission, and this issue is the main (but by no means only) reason many of us are skeptical of catastrophic forecasts.

[By the way, to answer past criticisms, I know that the models do not use this simplistic feedback methodology in their algorithms.  But no matter how complex the details are modeled, the bottom line is that somewhere in the assumptions underlying these models, a feedback percent of 67-80% is implicit]

For those paying attention, there is no reason that feedback should apply in the future but not in the past.  Since the pre-industrial times, it is thought we have increased atmospheric Co2 by 43%.  So, we should have seen, in the past, 43% of the temperature rise from a doubling, or 43% of 3-5C, which is 1.3C-2.2C.  In fact, this underestimates what we should have seen historically since we just did a linear interpolation.  But Co2 to temperature is a logarithmic diminishing return relationship, meaning we should see faster warming with earlier increases than with later increases.  Never-the-less, despite heroic attempts to posit some offsetting cooling effect which is masking this warming, few people believe we have seen any such historic warming, and the measured warming is more like 0.6C.  And some of this is likely due to the fact that the solar activity was at a peak in the late 20th century, rather than just Co2.

I have a video discussing these topics in more depth:

This is the bait and switch of climate alarmism.  When pushed into the corner, they quickly yell “this is all settled science,”  when in fact the only part that is fairly well agreed upon is the 1C of first order warming from a doubling.  The majority of the warming, the amount that converts the forecast from nuisance to catastrophe, comes from feedback which is very poorly understood and not at all subject to any sort of consensus.

70 thoughts on “The Dividing Line Between Nuisance and Catastrophe: Feedback”

  1. The elephant in your room is the characteristic response time of the various parts of the climate system. To think that we should already have seen exactly 43% of the warming expected from doubling CO2, you have to believe that the climate system responds instantly to external stimuli. Do you believe that?

  2. Epicycle #34 – Measured warming is not sufficiently alarming to drive public policy decisions. Postulate the existence of massive positive feedbacks.

    Epicycle #35 – Time passes. Still not enough warming. Aerosols must mask warming/feedbacks.

    Epicycle #36 – Time passes. Still not enough warming. Feedbacks must have very long lag time.


  3. Hunter (March 2, 2009, 10:00 am) wrote: “The elephant in your room is the characteristic response time of the various parts of the climate system. To think that we should already have seen exactly 43% of the warming expected from doubling CO2, you have to believe that the climate system responds instantly to external stimuli. Do you believe that?”

    OK. I’ve been looking for a flow-diagram representation of the IPCC’s temperature models for quite some time. I would appreciate it if Hunter (or anyone) could provide me with a “feedback loop” diagram of the various feedback mechanisms (something like the “single feedback loop” diagram below) with definitions of (a) input/output temperatures (temperature units–degrees Kelvin, degrees Centigrade, etc–and are they actual temperatures or temperature changes relative to a nominal temperature), (b) the multiplier, and (c) the delay?

    | |
    Input Temperature —>| Sum |————————————-> Output Temperature
    |_____| |
    ^ |
    | ____________ _______ |
    | | | | | |
    |<—| Multiplier |<—-| Delay |<—|
    |____________| |_______|

    Note: I agree with Mr. Meyer that the above “feedback model” is an oversimplification of both the earth’s climate system and the IPCC’s climate model for two reasons. First, climate is a multivariate non-linear phenomenon, and as such, over the full range of climate temperature variability, it probably can’t be represented with a linear feedback model. Second, even if it could be represented with a linear feedback model, the model undoubtedly contains more than a single feedback loop, and may even contain feed forward loops. However, Hunter criticized Mr. Meyer because Mr. Meyer didn’t include a “characteristic response time” in his analysis. I think it’s fair then to ask Hunter three questions: (1) “What are the characteristic response times of the IPCC feedback sensitivities ?” (2) “Can the IPCC’s climate temperature feedbacks be linearized over a meaningful temperature range?” (3) “If so, what is the flow diagram for that linearized model?”

  4. Well my “flow diagram” (March 2 2009, 12:40) didn’t turn out so well. Apparently, Mr. Meyer’s blog removes consecutive “spaces”. I’ll try one more time. This time I’ll use “.” in the place of “spaces”–so just try to ignore all “.”. If this doesn’t work, I give up.

    Input Temperature —>| Sum |——————————————–> Output Temperature
    …………………..|<——–| Multiplier |<—-| Delay |<—|…

  5. As Warren writes, the climate models do not directly have a feedback element. The models are extremely complex (parameterizations are most of this) and the feedbacks are buried in there – not explicitly but as a consequence of the model.

    Hence a simple feedback diagram doesn’t necessarily reflect what the models are doing. The feedbacks are likely first, second, third, etc order in multiple variables.

    Naturally, models this complex, with low spacial and temporal resolution, and with many critical values resulting from parameterizations which often cannot be well calibrated, should not inspire any confidence.

  6. “To think that we should already have seen exactly 43% of the warming expected from doubling CO2, you have to believe that the climate system responds instantly to external stimuli. Do you believe that?”

    The entire climate system doesn’t. But the part of the climate system effected by CO2 should. Do you notice how the temperature changes rapidly between say, 3am in the morning versus 12 noon in the same place? A time span of only a few hours. This is because atmospheric response times *are* very rapid, unlike, say, ocean circulation.

    Of course, AGW believers recognise this as a problem, so have postulated that the heat is “hiding” somewhere. One possible place they’ve suggested is the deep oceans.

    Hunter, this is really really really basic stuff. Try to think about the criticisms you attempt to come up with for more than a few seconds before you fire them off. Even AGW believers acknowledge the problem and have come up with hypothesis to deal with them. (Which may or may be valid.) The “elephant in the room” is once again sitting on your brain.

  7. The lack of understanding! The fiction! The paranoia running throughout! Hunter, ignorance mixed with suspicion is a noxious mixture. No-one thinks that any heat is ‘hiding’ anywhere. No-one thinks that anything much is going on in the deep oceans. Their response time is of the order of centuries.

    To understand how ridiculous your ideas of response times are, consider this. At sunset, temperature drops. The cause, of course, is the removal of all energy coming into the climate system. If that energy never returned, the temperature on Earth would drop to about 3K, eventually. How far towards its equilibrium value does it ever get during the night? If you think the response times are very fast, then it should get an appreciable fraction of the way.

  8. “If that energy never returned, the temperature on Earth would drop to about 3K, eventually. How far towards its equilibrium value does it ever get during the night? If you think the response times are very fast, then it should get an appreciable fraction of the way.”

    You forget the massive thermal mass of the planet. Even if the planet didn’t produce it’s own heat, it would take quite a long time for the entire mass of the planet to reach thermal equilibrium with the microwave background.

  9. I would only add that since CO2 based warming cannot plausibly (or even possibly) be catastrophic, it is not a nuisance either, but is very clearly a benefit. Since the warming effect is small, the benefit is small, but the important thing is that it is unambiguously a benefit. Anything less than some very large amount of warming is benign, while even a small amount of cooling is brutal. Historically, the earth’s climate ranges between much too cold (ice ages), and a little too cold (interglacials). Warmer is better.

    Since high estimates of climate sensitivity, or feedback, are a product of the most blatant statistical fraud, we know that catastrophic warming is not a rational concern, leaving only benign warming as a possibility. (My post on the omitted variable problem here. Leaving out the well known correlation between solar-magnetic activity and temperature, so that the warming due to this omitted variable gets misattributed to any correlated variables. Since solar activity and CO2 increase were both at record levels in the second half of the 20th century, that means solar warming gets misattributed to CO2, which shows up in the form of exaggerated estimates of climate sensitivity.)

    The upshot is that we the actual external value of CO2 is positive, not negative. We should if anything be subsidizing it, not trying to deter it via taxation or cap-and-trade.

  10. Hunter,

    “The lack of understanding! The fiction! The paranoia running throughout! Hunter, ignorance mixed with suspicion is a noxious mixture. No-one thinks that any heat is ‘hiding’ anywhere.”

    You’re such a dumb nuts. Do you even understand the basic concepts you try to criticise? Anyone with half a brain (even you, with a quarter of a brain) can Google “global warming missing heat” in 3 seconds and read hundreds of articles discussing this important issue. You brain dead dick. LOL. Oh the paranoia! LOL.

  11. Billy Ruff’n

    OK. I’m going to give your procedure a try. I think a URL to my picture of a Single Feedback Loop is:

    When I entered that URL into by “control line”, a picture came up. My Single Feedback Loop is the small picture at the bottom. When I single click on the small picture, it expanded to something usable. I hope it works for you.


  12. I’m having trouble posting a response to Billy Ruff’n. This comment is an attempt to establish if I can submit a second comment.

    Sorry for the inconvenience.

  13. Hunter,

    True, climate response is probably not instantaneous. So, what’s the lag time? I’ve posed this question on RC and Deltoid and never gotten an answer. Can you answer it for me?

    Four possibilities seem to present themselves.

    1) There is a lag time between 1 and 20 years. If this is so, one would expect to see an rapid rise in tempurature in recent years, 1 to 20 years after the increase in CO2. this theory might have looked good in 1998, but not any longer.

    2) The oceans have been storing the excess heat. The problem here is that the Argos study claimed that the oceans were actually cooling. It has been argued that the study is flawed and there has been no cooling, but then they haven’t shown any evidence that they’re warming either.

    3) The DEEP oceans are warming. There is no good study showing this and, IMO, it’s highly improbable.

    4) The lag time is greater than 30 years, so we haven’t seen ANY of it yet. In this case, it’s nothing but a theory.

    So, I undestand that climate response time may not be instantaneous, but what’s your evidence that it isn’t? What’s the lag time?

  14. The atmospheric response time is not instantaneous of course, but there is not a 1-20 year lag either. Look at the difference between night and day temperatures–as already explained. Atmospheric response times are ‘relatively’ rapid. CO2 operates approximately by slowing down the escape of solar radiation. It cannot exist in the atmosphere for several years (or decades!) and then as if by magic “switch on” and start effecting temperature.

    This is why there is a “missing heat” problem in the first place.

    Yes, the oceans could be storing the heat. Maybe there is a problem with the Argo instrumentation. This is not impossible. There is just no evidence to believe this is so (yet).

    My understanding is that the DEEP oceans take hundreds of years to circulate heat, so this unlikely. I don’t have the actual estimated time frames handy, so I could be wrong about that.

    As I explained before, you can’t have a 30 year lag time on CO2. It has to be warming the atmosphere more or less immediately. Which means ‘natural cooling’ must be offsetting the CO2 warming in order to explain the lack of measurable warming. That’s the only logical explanation if you want to raise that question. This is pretty much the ‘standard’ climatological explanation.

    However, keep in mind that the atmosphere is highly turbulent and our measurement of it is not perfect. That’s why you need long time frames in order to observe temperature trends. Upper ocean heat content is a better and more stable measure of temperature trends over shorter time periods.

  15. BillBodell: probably? Try obviously. The total response time is a complex function related to the response times of individual parts of the climate system. These range from a few weeks to months for the atmosphere to hundreds of years for the deep ocean. You may find the following links useful:,M1

    Your reference to 1998 doesn’t make much sense. What’s your point? And your reference to argo floats seems to refer to a work subsequently superseded. You probably want to believe in the studies of 2003-2005 which didn’t show much change in ocean heat content, but you should read the wider literature which finds a long term steep rise, but with substantial interannual variability.

    Hunter – ‘response time’ does not mean the time it takes for the response to start. It means the time taken to reach a new equilibrium in the event of external forcing. As such, your blathering on about day and night is irrelevant. Try learning some basic scientific definitions.

    Lack of measurable warming? It’s warmed by ~0.5°C in the last thirty years. There’s plenty of measurable warming. You’d be well advised to learn some climatology before decreeing what you believe ‘standard’ climatology to be. You’re quoting nutjob climatology.

  16. Hunter or Hunter,

    Which “Hunter” made the last comment?

    It can’t be the Alarmist Hunter (Scientist). Is it the Denier Hunter?

    If you’re using the same name on purpose, please don’t. I can’t tell who I’m talking to.

  17. Notice how Alarmist Hunter switches his discussion to ‘total response time’ of the whole ‘climate system’ when the discussion was specifically about CO2 response time only. He can’t even criticise what is being discussed, probably because he can’t follow what’s being written? Maybe the words I’m using are too big for him.

  18. I was addressing “Alarmist Hunter”.

    I was conceding more ground than necessary (or warranted) to try to generate a response to the question I posed rather than bicker about secondary issues. This apparently alarmed denier hunter and alarmist hunter has not responded.

  19. Hunter – apparently you think that the climate system response time depends on the forcing. The words you are using are certainly too big for you. You come across like a small child reading from a book that’s aimed at older kids.

    BillBodell – which question did you want answered? Did the links I gave not help? What was your point with the reference to 1998?

  20. Skeptic Hunter,

    I assume that the post at 5:07 am was from “skeptic hunter”, not “alarmist hunter”.

    My original post was directed to “alarmist hunter”.

    My point is that when skeptics like Warren mention that we’ve only seen 0.6 C of warming for being 43% of the way to a doubling of CO2, the alarmist response is always that the climate response is not instananeous. They think this explains why we’ve seen so little of the forecasted warming. The warming is “in the pipeline”. But I’ve never heard an explanation of where the “pipeline” is or how long it is.

    My point about 1998 is that, at that time, with warming accelerating, one might make the propose that a lot of the warming was because of warming coming out of the pipeline. However, with the flattening of tempurature lately, that won’t fly.

    For the record, I don’t think there is a pipeline. I’m just trying to pin down an alarmist on this topic and get a response.

  21. Question to Hunter (2 March 2009, 10:00 am). I’d like to better understand your comment about “…the characteristic response time of the various parts of the climate system”. Would you please define the “characteristic response time” of any “part” of the “climate system”–but preferably the “characteristic response time” for a “doubling of CO2”?

    For example, in an open resistor-capacitor (Resistance R, Capacitance C) circuit (in series), the “response time” is the time required for the charge on the capacitor to reach “X-percent” of its final value (i.e., the charge on the capacitor at infinite time) after a constant voltage (i.e., step function voltage) is applied across the open ends of the circuit.

    When discussing the “response time” of an R/C circuit in series with people unfamiliar with circuits, it would obviously be better to use the phrase “X-percent response time of an RC circuit in series” and then define what is meant by “an R/C circuit in series”, than to use the simple phrase “response time” of an R/C circuit. But like all technical disciplines, when characterizing the properties of a “part” of the technical discipline, descriptions of phenomena are often shortened.

    Not being intimate with the discipline of “climate science”, I’d appreciate it if you would take the time to provide such a definition for the “characteristic response time” for a “doubling of CO2”.

    Thank you in advance.

  22. BillBodell: ah yes, I thought that was probably why you were referring to 1998. Whether through ignorance or through deliberate self-deception, you’re being fooled. There has been no statistically significant ‘flattening’ of temperatures since 1998. The last period of statistically significant non-rising temperatures was over 30 years ago.

    If you’ve never heard any explanation of where the “pipeline” is or how long it is, you must have your fingers in your ears. Try reading the links I gave you. If you don’t believe in a “pipeline” – that is, you don’t believe that the climate system takes time to respond to forcings – then you’re an idiot. Your view is contradicted by basic observations such as the difference between continental and maritime climates.

    Reed Coray: defining the response time as the time it takes to achieve 70% of the total response, the response time of the atmosphere is of the order of months; of land and ice, years; of the mixed layer of the oceans, decades; and of the deep ocean, centuries. More information in the links I already gave.

  23. Hunter (March 8 2009, 12:55 pm), thank you for your response. Your answer elicits two additional questions.

    As I understand it, the Vostok ice core data used by former Vice President Gore in his documentary “An Inconvenient Truth” are used as proxies for measures of Antarctic (a) atmospheric temperatures and (b) atmospheric CO2 levels. Is this correct? If correct, and if CO2 increases were the primary source of the temperature “run ups” over the approximately immediately preceding 600,000 years, and if the atmosphere temperature response time to a CO2 increase is on the order of months, then for each temperature “run up”, why did it take tens of thousands of years for the temperature to reach its peak?

    Thank you

  24. Imagine if you could turn the sun off. How many hours before we’re all dead? That’s the atmospheric response time.

    Obviously, the climate system does take time to respond to forcings, i.e., the deep ocean might take thousands of years to respond to atmospheric temperature changes, to use one example at the other end of the scale. But the question posed was, and still is, if you pump more CO2 into the atmosphere, how long will it take for the atmosphere to warm accordingly?

    THAT response time has to be rapid, because we’re dealing with the basic physics of the greenhouse effect. CO2 slows down the escape of solar energy (to keep the terminology simple as possible). Alarmist Hunter is either a dickhead (we already know this anyway) or being intentionally misleading, because he has no answer to THAT question. That’s why he has to change the subject and talk about the response time of the ‘total climate system’ and not the atmosphere.

    And note the predictable response to follow. He’ll insult everyone, sulk, or answer some different question.

  25. Reed Coray – did it take tens of thousands of years for the temperature to reach its peak? Helpful if you could refer to a graph here.

    Hunter – no, that is not the atmospheric response time. Scientific definitions generally don’t sound like they were thought up by a 12 year old science fiction fan in between masturbation sessions.

    Your question “how long will it take for the atmosphere to warm accordingly?” is meaningless, because you don’t say what you mean by ‘accordingly’. This is because you have no idea that you even need to define your terms, let alone any idea how to. This is because you are a loud-mouthed moron who will never let science penetrate your tiny mind. Clearly you are scientifically illiterate, because you obviously haven’t looked at the links posted earlier.

    Do you get a kick out of appearing stupid?

  26. Hunter (March 5, 2009, 4:05 pm). Sorry about the delay. I’ve tried twice to respond to your request. The first time I hit the “Submit Comment” button, my computer screen went into limbo and I lost the link. The second time, the system appeared to take my comment, but after a few minute wait, the comment hasn’t appeared on the blog. I’ll keep trying. If this message gets posted more than once, I’m sorry for the inconvenience.

    For the graph you requested, I refer you to Figure 2.22 [Variations of temperature, methane, and atmospheric carbon dioxide concentrations derived from air trapped within ice cores from Antarctica (adapted from Sowers and Bender, 1995; Blunier et al., 1997; Fischer et al., 1999; Petit et al., 1999)] on page 137 of Chapter 2 [Observed Climate Variability and Change] of the IPCC’s Third Assessment Report [Climate Change 2001: The Scientific Basis].

    The URL for Chapter 2 is:

    Over the immediately preceding 400,000 years (approximately) I see four “temperature run ups” of approximately 10 degrees centigrade taking on the average roughly 20,000 years each. Am I wrong?


  27. Exactly on queue… barrage of insults because Alarmist Hunter can make no intelligent response to the questions asked. (He never does answer them BTW, because cutting and pasting snippets of information from Realclimate is not sufficient for that purpose. LOL.)

  28. Here is a new paper published in the Peer Reviewed Physics Today discussing the missing heat problem. Relevant quote:

    “”Thus, there is no “warming in the pipeline” using the author’s terminology, nor any heating within the atmosphere! Perhaps the heating that was observed prior to 2003 will begin again, however, it is scientifically incorrect to report that there is any heat that has not yet been realized within the climate system.

    The answer to the question posted in this weblog “Is There Climate Heating In “The Pipeline”? is NO.””

    Of course, just because Professor Pielke Pielke has these credentials:

    Served as Chairman and Member of the American Meteorological Society Committee on Weather Forecasting and Analysis, as Chief Editor of Monthly Weather Review, was elected a Fellow of the American Meteorological Society in 1982 and a Fellow of the American Geophysical Union in 2004, has served as Editor-in-Chief of the US National Science Report to the International Union of Geodesy and Geophysics, as Co-Chief Editor of the Journal of the Atmospheric Sciences, and as Editor of Scientific Online Letters on the Atmosphere.

    doesn’t mean little retard “Alarmist Hunter” won’t poo poo the assessment, because he’s so much smarter than everyone else in his own little mind. 😉

  29. Reed Coray – I don’t see anything taking 20,000 years (which in any case is a period not accurately described by your earlier “tens of thousands of years”). The transitions from glacial to interglacial typically take a few thousand years. You can’t see this very well on the graph you linked to.

    Anyway it’s not at all clear what your point is. The duration of the change between glacial and interglacial doesn’t tell us much about climate response times. And CO2 does not trigger the ends of ice ages – very small changes in Earth’s orbital parameters do that.

    Hunter – when you don’t understand an answer, say so. Don’t just pretend that there was no answer. And check a dictionary, by the way – look up “queue” and then look up “cue”.

    Will Nitschke – because you are scientifically illiterate, you’ve been taken in by commentary on the paper which misrepresents its contents.

  30. Hunter (6 March 2009, 9:57 am). You’ve caught me in an exaggeration. The characterization “tens of thousands of years” is misleading. I should have said “thousands of years”. Specifically, in the referenced figure, I see four “temperature run ups”. The first run up starts at approximately 330 KyBP (330,000 years before present) and terminates at about 320 KyBP–an interval of 10,000 years. The second run up starts at about 240 KyBP and terminates at about 230 KyBP. The third run up starts at about 135 KyBP and terminates at about 125 KyBP. The fourth run up starts at about 15 KyBP and terminates at about 5 KyBP. All run ups are thus approximately 10,000 years in length. As such, my statement of “tens of thousands of years” is correct only if one unit of 10,000 years constitutes “tens of thousands of years”–which it doesn’t. Therefore I apologize for the incorrect statement. However, I think it’s fair to say that the temperature run ups on the average take approximately 10,000 years. But for the sake of this discussion, I’ll use the conservative “temperature run up time” of 1,000 years to make my point.

    Specifically, as I understand it the UN IPCC acknowledges that CO2 did NOT trigger the end of previous ice ages; but I was under the impression that the UN IPCC believes CO2 “amplified” whatever temperature increase initially occurred. I don’t recall reading what the UN IPCC said the “amplification” was for the ice age temperature run ups. But doesn’t the IPCC claim that if at the present time CO2 levels double, such a doubling by itself will raise the temperature by approximately 1.2 degrees centigrade, and CO2-induced feedback amplification will cause an additional temperature rise on the order of from three to five degrees centigrade? If true, then I assume similar feedback amplifications existed in the past–which brings me to my point. If atmospheric temperature response times to CO2 increases are on the order of a few months and CO2-induced “feedbacks” are the cause of the majority of past temperature rises, why did it take on the order of 1,000 years to reach peak temperatures?

    Thank you

  31. The IPCC itself does not study climate or form beliefs. It only reports on the current state of understanding in climate science. You may think it’s a point of pedantry but it’s wrong to say “the IPCC believes x” or “the IPCC claims y”.

    There’s no doubt that CO2 amplifies a temperature increase. It’s physically impossible to increase CO2 concentrations and not raise the temperature, all else being equal. However, an amplifying factor can only amplify an input. If whatever was changing took 10,000 years to change, then clearly the entire temperature rise would take more than 10,000 years.

    And the response time is not just the atmospheric response time, but the total response time of the climate system, like I said earlier. The response time of the deep oceans is of the order of centuries, not months. If you ignore everything except the atmosphere, then you won’t get a meaningful answer.

    Have you read the links I posted earlier?

  32. Hunter (6 March, 11:40 am). Until a few hours ago, I had not read either of the two links you posted earlier. The first link was a complete paper by Ronald J. Stouffer, which I printed out and have now read. The second link consisted of selected pages from a book. The second link limited the pages I could read. When I get a chance I’ll read those pages. However, I would like to comment on Stouffer’s paper: URL:

    But before doing that, I’d like to take the issue of what the UN IPCC “believes” versus what it “reports” out of the discussion. In fact, let’s take the UN IPCC completely out of the discussion. I’d like your opinion regarding the role CO2 played in the temperature fluctuations of the Vostok ice core data? For example, was CO2’s role minor (and for this discussion minor is anything less than 5%) in either/both (a) the temperature fluctuation time intervals, or (b) the temperature fluctuation amounts? If either role was “not minor”, then could you quantify CO2’s contribution (your opinion) to these phenomena?

    Now my comments on the Stouffer paper.

    First, much of Stouffer’s paper discusses topics with which I have extremely limited knowledge. That is, my understanding of (a) ocean currents, (b) stratification of the atmosphere into “nine uneven vertical levels”, (c) “horizontal distributions are represented by spherical harmonics and associated gridpoint values with 4.58 latitude by 7.58 longitude spacing”, etc. is minimal if not non-existent. What’s probably worse, I don’t have the time to delve into these issues to the degree necessary to become knowledgeable. However, I do have a fair physics background–so the remainder of this comment comes from that perspective.

    Second, the paper doesn’t describe observations (either direct or proxy), but rather describes the outputs of a coupled atmosphere-ocean general circulation model–in particular the GFDI_R15_a model. The paper makes references to “passive oceanic tracers” as a means of evaluating the model’s oceanic mixing; and mentions (1) “On the decadal time scale using CFCs, it has been shown by Dixon et al. (1996) that the model CFC simulation is similar to the observations.”, and (2) “In section 3, using radiocarbon as an oceanic tracer, it is shown that the model’s oceanic mixing on centennial to millennial time scales may be also realistic.” These observations can’t and shouldn’t be ignored, but they do not constitute confirmation that the model is accurate. In fact, Stouffer himself writes: “However, it is noted that the good present-day tracer simulation may result from compensating model errors.”

    Third, when discussing “response times” for the various components of the “coupled ocean-atmosphere-land surface system” I think Stouffer “changes horses in mid-stream” so to speak . For example, the first paragraph of his introduction is given below in its entirety.

    “When the radiative forcing of the planet changes, various components of the coupled ocean–atmosphere–land surface system respond to those changes with differing time scales. In the physical climate system, the atmosphere– ocean–land surface–sea ice system, typically the shortest response times are found in the atmosphere. The atmosphere can come into equilibrium with new lower boundary conditions on time scales from days to weeks. The longest response time scales to a change in radiative forcing in the physical climate system are found in the deep ocean. These response time scales can be longer than 1000 yr.”

    [As an aside, I understand “radiative forcing” (expressed in Watts per square meter) to mean a change in the net amount of radiation power leaving/entering the earth (i.e., at the tropopause). For an earth in radiative equilibrium, a radiative forcing of one Watt per square meter implies that the earth’s radiant energy is “out of balance” in that at least initially on the average each square meter of the earth’s surface is receiving from the sun one more Watt of power than it is radiating into space. Do you agree with this definition of “radiative forcing”?]

    In the first sentence of Stouffer’s introduction, components of the coupled ocean-atmosphere-land surface respond to “planetary radiative forcing changes”. In the third sentence the “atmospheric component” of the coupled ocean-atmosphere-land surface system responds to “boundary condition” changes not radiative forcing changes. When discussing component response times, I believe it is appropriate to either use a common forcing function for all components or to specifically note when a change of forcing function occurs. This distinction is important because in the first paragraph on page 317, Stouffer states:

    “As noted in the introduction, the atmosphere rapidly comes into equilibrium with changes to its lower boundary conditions on time scales of days to weeks. The implication of this statement is that the response time scale of the atmosphere is controlled by the response time scale of the ocean surface mixed layer.”

    When temperature is the climate parameter under discussion, I interpret Stouffer’s words to mean that the response time scale of the atmosphere’s temperature is controlled by the ocean surface mixed layer temperature via the mechanism that as the ocean surface mixed layer temperature changes (boundary conditions), those changes will impact the atmosphere’s temperature. In this sense, the atmospheric response time to a change in radiative forcing must be longer than the ocean response time to the radiative forcing because atmospheric temperature changes cease only after ocean temperatures have reached equilibrium. For this reason, I think Stouffer’s atmosphere forcing function (land/ocean boundary conditions) is different from his ocean forcing function (radiative forcing).

    I believe that most of the sun’s electromagnetic energy captured by the earth is captured (i.e., converted into heat or stored as chemical energy) either (a) in the earth’s atmosphere, (b) in the first few feet (inches maybe) of the land, and (c) in the first few tens of meters of the earth’s oceans. If this is correct, with a positive radiative forcing (incoming radiation minus outgoing radiation is positive), the atmosphere and the first few meters of the ocean will heat first and come to “radiative equilibrium” rather quickly. The deep oceans will take much longer (maybe thousands of years, I don’t know) to reach some state of “heat transfer” equilibrium–but the transfer of heat is from the boundary layer to the deep ocean, not the other way around. I believe the primary heat transfer mechanisms leading to this state of heat transfer equilibrium are convection and conduction, not radiation. In this model, radiative equilibrium at the surface of the earth and in the atmosphere is quickly established (relative to deep ocean heat transfer equilibrium); but unless a mechanism on or near the surface of the earth is causing an additional change in the radiative forcing, the atmospheric temperature won’t change as the deep oceans warm up to a “heat transfer equilibrium state”. If Mr. Stouffer is correct when he says the “…response time scale of the atmosphere is controlled by the response time scale of the ocean surface mixed layer”, then the atmospheric response time to “radiative forcing” is not a few weeks, but is at least as long as the ocean response time.

    Bottom line, at this point I have no confidence in the idea(no matter what a model predicts) that the atmospheric temperature response time to a change in radiative forcing is any longer than a few tens of years. As such, the fact that historical temperature run-ups took on the order of 10,000 years says to me (a) the temperature run ups were overwhelmingly governed by natural phenomena, and (b) that CO2 played a very minor role both with respect to temperature run up “time behavior” or “temperature behavior”.

    Thank you

  33. Opinions don’t count for much in science. What counts is facts. The fact is that unless CO2 plays a major role in the climate system, then we cannot understand how ice ages begin and end. And this is not some crazy theory pulled out of the air, it’s backed by every observational test that it’s been put to. It is physically impossible to put more CO2 into the atmosphere and not to see warming, and it’s physically impossible to take CO2 out of the atmosphere and not to see cooling. These are facts.

    You correctly understand the definition of radiative forcing. And you’re correct that atmospheric temperatures depend on what’s happening below as well as above. However, you cannot deduce anything at all about the role of CO2 simply from the duration of the disequilibrium at the end of ice ages. I’m not sure why you think that you can, but you appear not to be considering that responses depend on inputs. If an input changes slowly for 10,000 years, then even if everything were to respond instantaneously to the input, obviously the new equilibrium could not be reached before the input had stopped changing.

  34. Hunter (March 7, 2009, 4:27 pm). “Opinions don’t count much in science.” I agree; but that’s an unusual statement coming from a member of the AGW camp, which I assume you are in. The AGW camp repeatedly uses “consensus” to argue its case. According to my Webster dictionary, the definition of consensus is “collective judgment or belief; solidarity of opinion.” So if opinions don’t matter, then a “solidarity of opinion” shouldn’t matter either; and the “consensus” argument should be dropped by the AGW side of the discussion. I won’t hold my breath.

    You wrote: “The fact is that unless CO2 plays a major role in the climate system, then we cannot understand how ice ages begin and end.” This statement can’t be correct–at least not if “we” includes all mankind. If you replaced “cannot” with “do not at this time”, then your statement is plausible–although I can’t help but believe there are other scientific disciplines that present theories for the formation/termination of ice ages. The only way your statement can be logically correct is if for the period of the ice ages our current knowledge of the earth and its interaction with the rest of the universe is complete. In my opinion, such a position is nonsense.

    I agree with you that if inputs change slowly over a long period of time, equilibrium won’t be reached until input changes cease. However, since temperature increases precede CO2 increases, we know that something other than CO2 started the temperature rises. Why can’t that “something” or other “somethings” unrelated to CO2 exist for 10,000 years? I don’t know what those “somethings” might be, but to exclude everything but CO2 is nonsensical.

    If the AGW issue was solely of scientific interest, then over time we (and others) could continue the discussion at our leisure until, with luck, we arrive at a common understanding. However, supporters of AGW are calling for immediate and drastic reductions in man’s use of fossil fuel. In my opinion, such a reduction based on either the premise that man’s knowledge of climate changes over the immediately preceding 400,000 or so years is sufficient to rule out all possible ice age causes except CO2, or the premise that because we haven’t identified a viable alternate cause of the ice ages, CO2 must be the cause is unwarranted.

    Thank you,

  35. I don’t belong to any camp.

    Perhaps you missed the second part of my paragraph about CO2: “And this is not some crazy theory pulled out of the air, it’s backed by every observational test that it’s been put to. It is physically impossible to put more CO2 into the atmosphere and not to see warming, and it’s physically impossible to take CO2 out of the atmosphere and not to see cooling. These are facts.”

    Nobody thinks that CO2 changes cause ice ages. Milanković cycles trigger ice ages. But the magnitude of the changes seen is impossible without the additional effects of CO2.

  36. “because you are scientifically illiterate, you’ve been taken in by commentary on the paper which misrepresents its contents”

    A few posts ago “alarmist hunter” didn’t even know anything about the “missing heat” problem and claimed anyone who asserted such a thing (including myself) must be deluded. (Although he could have spent 5 seconds googling the information first, before making an arse of himself.) Now a Professor Pielke, former Chairman and Member of the American Meteorological Society, is also said to be wrong. You have to marvel at the tenacity of someone who posts idiocy every day, knows barely anything about what he writes about, and is shown every day to be a complete fool, yet posts on relentlessly… LOL.

  37. Will Nitschke – run along, will you, and let people who want to talk about science carry on doing so.

  38. I’m having trouble posting my response to Hunter (March 8 2009, 4:14 am). This is a short test message to see if my response is too long.

  39. OK, I’m going to try to post my response to Hunter (March 8, 2009, 4:14 am) in two parts.

    First Part.

    I didn’t miss the second part of your paragraph about CO2. I agree that CO2’s role in ice age behavior is not “some crazy theory pulled out of the air”. However, I think the statement “it’s backed by every observational test that it’s been put to” is a little strong. To quote Richard Courtney, an expert peer reviewer for the UN IPCC, (1) “Recent rise in global temperature has not been induced by rise in atmospheric carbon dioxide concentrations. The global temperature fell from 1940 to 1970, rose from 1970 to 1988, and fell from 1988 to the present (i.e., mid 2008). This is 40 years of cooling and 28 years of warming, and global temperature is now similar to that of 1940. But atmospheric carbon dioxide concentration has increased at a near-constant rate and by more than 30% since 1940.”; and (2) “Rise in global temperature has not been induced by increase to anthropogenic emissions of carbon dioxide. More than 80% of the anthropogenic emissions of carbon dioxide has been since 1940, and the increase to the emissions has been at a compound rate of [approximately]0.4% p.a. throughout that time. But that time has exhibited 40 years of cooling with only 28 years of warming, and global temperature is now similar to that of 1940.”; and (3) “The pattern of atmospheric warming predicted by the AGW hypothesis is absent. The AGW hypothesis predicts most warming of the atmosphere at altitude distant from polar regions. Radiosonde measurements from weather balloons show slight cooling at altitude distant from polar regions.” See URL:

    Thank you

  40. The statements: “It is physically impossible to put more CO2 into the atmosphere and not to see warming, and it’s physically impossible to take CO2 out of the atmosphere and not to see cooling. These are facts.” are also too strong. First because some scientists argue that if anything adding CO2 to the atmosphere should have a net cooling effect on climate. Chillingar, et al { G.V. Chilingar, L.F. Khilyuk, O.G. Sorokhtin; Cooling of Atmosphere Due to CO2 Emission; argue that CO2 convection effects will cause the earth’s climate to cool, not warm. Quoting from their report: “Accumulation of large amounts of carbon dioxide in the atmosphere leads to the cooling, and not to warming of climate, as the proponents of traditional anthropogenic global warming theory believe (Aeschback-Hertig, 2006). This conclusion has a simple physical explanation: when the infrared radiation is absorbed by the molecules of greenhouse gases, its energy is transformed into thermal expansion of air, which causes convective fluxes of air masses restoring the adiabatic distribution of temperature in the troposphere. Our estimates show that release of small amounts of carbon dioxide (several hundreds ppm), which are typical for the scope of anthropogenic emission, does not influence the global temperature of the Earth’s atmosphere.”

    And second, even if Chilingar, et al are wrong and adding CO2 to the atmosphere has a positive effect on the heat content of the earth’s atmosphere, it can’t guarantee a temperature rise. Just like lighting a match in the Superdome will add heat to the Superdome, it won’t necessarily cause Superdome warming (i.e., a rise in the average Superdome temperature)–especially if the temperature outside the Superdome is dropping. From the perspective of society’s response to anthropogenic release of CO2 into the atmosphere, the important question isn’t whether or not CO2 fluctuations cause heat fluctuations, but rather the amount of those fluctuations and the resulting temperature changes–especially when compared to other heat modulating phenomena such as solar output fluctuations, cosmic rays, volcanic activity, conductive heat transfer from the earth’s core, changes in cloud cover, etc.

    Thank you

  41. I’m sorry. No matter how hard I try, I haven’t figured out how to submit the URL for the Chilingar, et al paper. The blog rejects all my attempts to date. I give up.

    Thank you

  42. Reed,

    It’s not the mainstream scientific view that CO2 can cause cooling. There is some relatively well understood physics involved here. If you want to argue against the plausibility of dangerous AGW you can do so without too much difficulty by sticking with the established science on the subject. In other words, some of the apocalyptic predictions really are very shaky… You will discredit your arguments by going into ‘crank’ territory when there is simply no need to.

  43. Will Nitschke (March 10, 2009, 12:06 am). Thank you for your response to my post (March 9, 2009, 5:36 pm). I agree that the mainstream scientific view is that a doubling of CO2 from approximately 250 ppm by volume to 500 ppm by volume will by itself (i.e., in the absence of feedbacks) cause between 0.8 and 1.2 degrees centigrade of lower-atmosphere warming, not cooling. Furthermore, I agree that the mainstream scientific view is likely correct. I included the reference to Chilingar, et al’s paper more for completeness, than as a scientific truth. Somewhere in my reading about AGW I came across an accounting of the theory of tectonic plates and its role in the history of geology. If I remember correctly, the original proponents of tectonic plate theory were treated by the “establishment” as cranks in that they were ridiculed and pooh-poohed. At this time, my opinions are: (1) atmospheric CO2 is NOT a pollutant–on the contrary, it is a blessing, (2) an increase in atmospheric CO2 will likely cause an increase in atmospheric temperature, (3) man’s contribution to atmospheric CO2 levels is small compared to nature’s contribution, (4) CO2-induced “feedback theories” that predict temperature increases by a factor of from 2 to 4 over what CO2 by itself would produce are at best problemantic and more likely nonsensical, (5) the concept of “CO2-induced climate tipping points” is almost completely unfounded and is being used solely to promote “calls to immediate action”, (6) some global warming (a few degrees centigrade) on balance will likely be beneficial to mankind, (7) drastic cutbacks in fossil fuel energy production are likely to have a significant and detrimental impact to mankind, and (8) to a large extent, AGW alarmism is being used to (a) advance the causes of socialism and a “one-world-government”, and/or (b) make money, and/or (3) keep the research money flowing. At this time, my technical knowledge of this discipline is insufficient to come to a strong opinion of the science of CO2-induced global temperature effects; and until I acquire such knowledge (probably never, as I am of social security age), I want to be aware of all points of view. Finally, I have a very strong opinion that the science behind the claims of catastrophic AGW via anthropogenic emission of CO2 into the atmosphere does NOT warrant drastic cuts in man’s use of fossil fuels. Given what I believe are the harmful consequences of such cutbacks, I strongly oppose such action in any form.

    Thank you

  44. Reed,

    While I don’t agree with everything you wrote, I see you’ve given the issue a great deal of thought. I would suggest you drop “one-world-government” type of conspiracy angle. Even if it were true, it would be a hard sell. 😉

    Or at least keep political arguments separate from scientific ones. By jumbling them together, you leave the impression that you’ve started with a conclusion and are working backwards from there. Which would be a shame, because you do raise many valid and interesting points.

  45. Will,

    You’re probably correct when you recommend I keep my scientific and political arguments separate; and a “one-world-government” is a hard sell–especially because it’s likely that the majority of AGW advocates are apolitical. Because by education (PhD in physics), profession (electrical engineer), and nature (I’m a born skeptic), I struggle with accepting any scientific theory that demands I “buy in immediately”. I am politically a conservative (not a republican); and since I sense that in the US Senate, the more liberal party is pushing AGW, there’s some truth to the statement that I “started with a conclusion and worked backwards.” I’m not especially proud of this position, but my loathing of liberalism is sufficiently strong that it’s hard for me to refrain from automatically taking the “other side” of any argument. Furthermore, although in my opinion the scientific argument should be paramount, in a practical sense I believe winning the political argument is critical.

    However, even if my “starting point” is questionable, my limited scientific research into AGW leaves me extremely skeptical. As I see it, the scientific argument for AGW has three legs: (1) Over the past 400,000 years or so, the Vostok ice core data shows a good correlation between Antarctic atmospheric CO2 levels and Antarctic atmospheric temperatures; (2) the Mann Hockey Stick, which shows an abrupt upswing in temperature at about 1850–the time man’s use of fossil fuels took off; and (3) Global Circulation Models (GCMs) run on increasingly sophisticated computers. The fact that the Vostok ice core data indicates that temperature increases preceded CO2 increases pretty much falsifies the first argument–at least in my mind. The facts that Dr. Mann (a) included in his analysis a suspect temperature proxy (tree ring data) without which (as I understand it) the hockey stick disappears, and (b) incorrectly applied the mathematics of Principal Component Analysis just about saws off the second leg. This leaves GCMs as the only remaining leg. Since (a) as far as I know those models did not predict the 2001-to-present leveling off/slightly decreasing temperatures, and (b) during my professional carrier I have had a fair amount of experience with computer models, this, the best AGW leg, is not all that strong. So although I may have started poorly, I like the position I’m now in.

    I will, however, take your advice and try to express my political beliefs only in the appropriate forums–of which this is not one.

    By the way, how do you insert the “smiley face” in a blog posting?

    Thank you

  46. Reed,

    A few comments on your post…

    The correlation continues to exist between CO2 and global temperature. Nothing gets falsified here by arguing over causality. I think many people are upset about the issue because of the way Al Gore misrepresented it as *proof for* AGW. On the other hand, I don’t think there is any scientific debate over the issue that *something else* causes temperature to rise, and this releases CO2 and the release of CO2 probably causes some extra warming to occur. But by how much is a issue that is not well understood, and it is clear that CO2 has probably not been a driver of climate in the past. (But that doesn’t necessarily say anything about the present.)

    The Mann study is rubbish, yes. Only fanatics or the grossly ignorant or uninformed would still defend it. However, it’s not clear that a bunch of bad papers by a small group of incompetent individuals (Mann and associates) therefore invalidates AGW. Bad papers get published all the time. Scientists move on and scientific research fields tend to survive them.

    GCM’s are problematical of course. I would agree that most of what is called AGW fairly critically hinges on them. But only time will tell us if there is much or any validity to them.

    (Smiley face is a comma, dash, close round bracket. 🙂

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