RealClimate logo

Climate Reporting in Physics World

Filed under: — rasmus @ 23 February 2007 - (Português)

PhysicsWorld cover, Volume 20, no. 2, February 2007 The February 2007 issue of PhysicsWorld contains several articles relevant to climate research, with a main feature article on climate modelling written by Adam Scaife, Chris Folland, and John Mitchell, and a profile on Richard Lindzen as well as an article on geoengineering in the ‘News & Analyses’ section. The magazine also contains an article (‘Living in the greenhouse’) under ‘Lateral Thoughts’ that brings up a bunch of tentative analogies to a wide range of topics completely unrelated to the greenhouse effect in a technical sense, and an editorial comment ‘Hot topic‘, arguing that it would be wrong of PhysicsWorld to ignore those outside the mainstream. To be more precise, the editorial comment devotes a few lines justifying the profile on Lindzen and the report on geoengineering, with a reference to a Feynman quote: “There is no harm in doubt and scepticism, for it is through these that new discoveries are made”. Wise words! Nevertheless, I cannot resist making some reflections.

One thought that immediately struck me was: has PhysicsWorld tried to make a ‘balanced report‘, or does the issue of doubt and scepticism by itself merit the profile article? Is the scepticism or doubt really genuine (doubt is the product)? To be fair, the article does bring up objections against some of Lindzen’s arguments (citing Gavin). However, I’d like to see a more consistent and critical article, as Lindzen’s arguments – at least the way they are echoed in PhysicsWorld – are in my opinion inconsistent.

Here is one example: Take Lindzen’s controversial claim that the good comparison between modelled and historical temperature evolution is an exercise in “curve fitting”. Written between the lines is the assumption that the climate models are driven with forcings based on historical GHG emissions. Later in the article Lindzen argues that the climate models used by the IPCC are far too sensitive to changes in the concentrations of atmospheric CO2. To me, these two statements say opposite things – and are thus in violation with each other. Because, either the models give a good description of the historic evolution or they don’t, given past GHGs, aerosol emissions and natural forcings (surely, Lindzen must have known about these simulations).

So, why didn’t the magazine ask critical questions about these conflicting views, or at least comment on what appears to be faulty logic? Or, perhaps Lindzen bases his claim on other aspects of model evaluation? Lindzen argues that the effect of CO2 on the temperature is small because the effect of additional CO2 molecule decreases as the concentration increases, but at the same time, Lindzen also seems to forget – just for a moment – all the feedbacks which can enhance the warming. Gavin confounds him with an objection on a different point – that Lindzen has not taken the delay response properly into account, for instance due to the ocean thermal inertia. In the next paragraph, however, Lindzen maintains that climate models do not replicate the feedback mechanisms in the climate system, and later on refers to his hypothesis, the ‘infrared iris effect‘, which more or less has been buried by the scientific community.

Gavin makes this point in the article (also see an argument for why it is wrong), but a final thought that dawned on me was that Lindzen is probably no better at calculating the feedback effects in his head than the climate models.

296 Responses to “Climate Reporting in Physics World”

  1. 51
    pat neuman says:

    I downloaded Hansen’s slides (35) presentation.

    Slide 15 shows:

    Summary: Ice Sheets

    1. Human Forcing Dwarfs Paleo Forcing and Is Changing Much Faster

    2. Ice Sheet Disintegration Starts Slowly but Multiple Positive Feedbacks Can Lead to Rapid Non-Linear Collapse

    3. Equilibrium Sea Level Rise for ~3 C Warming (25+- 10 m = 80 feet) Implies the Potential for Us to Lose Control

    I think that in order for equilibrium to occur in sea level additional thaw and ocean water heat expansion would be needed beyond 2100. However if average global temperature increases to 3 Deg C by year 2100 it seems likely that the average global temperature will continue to increase for centuries and thousands of years beyond 2100 which will increase sea level rise as the warming continues, indefinitely.

  2. 52
    tamino says:

    Re: Sea level rise

    One of the reasons sea level rise will continue for so long is that it takes a long time (a thousand years or so) for increased temperature to propagate to deep ocean waters. So, the thermal expansion of sea water will continue long after 2100, even if temperature stabilizes at that time. The IPCC TAR has some interesting graphs in that regard.

  3. 53
    Marco Parigi says:

    re #25 A simple example would be if CO2 concentration was historically correlated with another forcing. In that situation, there would be a wide range of sensitivities to those two forcings that together would match history, but the moment the forcings diverge you could find that you have vastly overestimated the climate’s sensitivity to one of them.

    I made this point regarding CH4 & CO2. What is the possibility that we’ve way overestimated Earth’s climate sensitivity to CO2, but way underestimated it for CH4? I bet that we will only find out when humans manage to reduce CH4 concentrations while CO2 keeps going up.

    [Response: The possibility is so close to zero as to make little difference. For the most part, radiative forcing is radiative forcing, and the fact that CO2 blocks different parts of the infrared than CH4 has almost no consequence for the climate. The vertical profile of the radiative cooling is slightly different, but since the tropospheric convection mixes around the heat anyway, it makes little difference. –raypierre]

  4. 54
    Marco Parigi says:

    Re: response to #53For the most part, radiative forcing is radiative forcing

    And climate sensitivity is climate sensitivity, I suppose. From a cynical perspective, this looks a little too convenient. Most of the uncertainty from a climatological perspective is “loaded” in the climate sensitivity, making all the radiative forcing calculations only accountable to the models, while only the climate sensitivity is accountable to actual measured temperatures. It seems to be an unwritten assumption that the climate sensitivity is unknown but the same for all calculated forcings. Conversely it is another assumption that the calculated properties of a substance override other things that happen in the real world that we don’t know about, that would affect its forcing.

  5. 55
    stefan says:

    Over the past year Lindzen has claimed many times (on radio, in talks and in writing) that global warming has stopped in 1998. This is because 1998 was a warm outlier due to a strong El Nino event in that year – and Lindzen shows a diagram of global temperature starting in 1998 to support his claim. This argument is obviously ludicrous – if he started his graph in 1999 (a year that was cooler than the long-term trend line), he might just as well claim that warming has accelerated since 1999. As a physicist I would have thought that the people at Physics World, even if they don’t know much about climate, should be able to recognise this as a dishonest and desperate argument. A look at the longer time series rather than a cherry-picked short snippet of it would suffice (shown e.g. in our recent Science paper). To me, anyone who uses this kind of argument has said his farewell to serious discussion.

  6. 56
    Jim Dukelow says:

    Re #43

    There are some aspects of the original Lindzen et al. Bulletin of the AMS (BAMS) adaptive iris paper that were technically or logically/ethically problematic to a naive engineer/mathematician, not-a-climate-scientist.

    A technical puzzle that I have never seen properly treated in the original BAMS paper or the subsequent Lindzen et al. papers or their rebuttals of other papers: Lindzen et al. discarded from their analysis a substantial chunk of Indian Ocean data that was included in the Japanese satellite data they used.

    A more serious technical problem: Once the Australian land mass was masked out and the Indian Ocean data was discarded, the balance of their data was not symmetric with respect to the equator and was analyzed using the full 17 month time period of the Japanese data. This raises the question of whether there is seasonality in the data. Several months after the BAMS paper, I was able to get the raw data for the Lindzen et al. magical mystery function A(T) from the nice people at the UDub (Univ. of Washington, for you outlanders) Atmospheric Sciences department, who were in the middle of slicing and dicing the BAMS paper. A naive approach to assessing the seasonality question is to look at 12 month windows into the data. When I did that, somewhere between 25% to 45% (depending on which 12 month window) of the purported “negative feedback effect” disappeared.

    Logical/ethical questions:

    1) The BAMS paper was filled with language that properly reflected the speculative nature of the proposed negative feedback mechanism (this language was perhaps required by the peer reviewers). Subsequent comments by Lindzen and the denialist amplification machine have lacked those linguistic qualifiers.

    2) Lindzen purports to believe that the observed warming is primarily a reflection of internal dynamics of the climate system and the BAMS paper claims that their asserted “negative feedback effect” might be applicable to all of the tropics and that climate codes will need to be modified to account for it. Lindzen bases these assertions on a 17 month data set from which he and his co-authors have discarded, without explanation, a substantial chunk of the open ocean data and which appears to be significantly impacted by seasonality. To make such extravagent scientific claims using what is really a 12-month data set is a bit like claiming that the 1998 El Nin~o is all we need to know about climate history.

    Best regards.

  7. 57
    Ray Ladbury says:

    Re 54 and preceding argument. Marco, a hypothesis by itself does not constitute science, and you have zero evidence–and indeed, zero physics–upon which to base your hypothesis. On the other hand, the models show CO2 works very well in explaining the observed trends. So, on the one hand we have a well validated scientific theory with verified mechanisms that reproduces the trends and on the other hand…
    Re 55. The thing is that Lindzen is too intelligent NOT to realize that this is a swindle, which makes him worse than a contrarian, and even worse than a anti-science hysteric (e.g. Crichton). It is hard to characterize this as anything short of scientific fraud served up to an uneducated public. As far as Physics World goes, I’m afraid that they, too, have succumbed to economics and the “Fair and Balanced” model of Journalism. I would bet that the decision to emphasize the “Controversy” was made by managers who have no science background. I’m just disappointed that the scientists went along with it.

  8. 58
    Burgess Laughlin says:

    Re #55: “A look at the longer time series rather than a cherry-picked short snippet of it would suffice …”

    What principles should guide a climatologist in deciding what time-frame to look at? Is a decision to look at the last 9 years or 30 years or 100 years an arbitrary decision, or should it depend on principles on which all reasonable and informed individuals can agree?

    I am a layman. I have only begun looking into the global warming hypothesis. I am trying to sort out the nomenclature — all new to me — and the reasons climatologists make the decisions they make. Maybe someday I can get to the point where I can understand — and evaluate — the decisions of climatologists. Your answer to my question above may help.

  9. 59
    tamino says:

    Re: #55

    Ironically, if you look at the HADCRU data, even starting with 1998 the trend determined by linear regression is still positive, not negative. Of course the trend is not statistically significant — but it puts the lie to the claim that there has been global cooling since 1998.

    Re: #58

    The most applicable principle in deciding what data to study is: use it all. Analyses of global and hemispheric average surface temperature generally begin in the late 1800s because that’s all we’ve got.

    If (and only if) you then find that there are moments in time at which the behavior changed, then it’s valid to isolate different time frames. For example, around 1975 global average temperature started increasing dramatically, and has been doing so since; I refer to that time period as the “modern global warming era.” But I don’t choose that turning point because it makes my case look good, but because study of the entire data set clearly indicates that it’s a turning point in the actual behavior of the system.

    It’s also valid to study arbitrary time slices (say, every 30-year period or every 10-year period), so long as the slices are chosen without regard to any desired result, and the strictest statistical tests are applied to evaluate the significance of the results.

  10. 60
    Lynn Vincentnathan says:

    RE #53 “find out when humans manage to reduce CH4 concentrations while CO2 keeps going up.”

    What makes you think CH4 concentrations will go down if humans manage to reduce their CH4 emissions (which is a no-brainer — just convert it into energy + CO2, & don’t eat spoiled food, and cut out meat)? Haven’t you been reading about how CH4 from permafrost & ocean clathrates are posed to be released if the world continues warming? Aside from the fact that CH4 is now only a small part of the GHGs (admittedly with a much bigger bang), and that it has not been increasing, does not guarantee it won’t increase in the future, based on the principles that when exposed to enough heat ice melts, and melting ice that contains methane releases it.

    I wasn’t able to get onto the ColdCase entry to respond to a contribution, so here it is: I was able to get the Scheffer, Brovkin, Cox article ( ). They say positive feedbacks have NOT been adequately factored into the models, and actual warming due to human emissions may be 15 to 78% higher than previous estimates. AND they are only talking about CO2 positive feedback (not based on models, but on data from ice cores of the “Little Ice Age”). They are NOT EVEN ACCOUNTING FOR METHANE!!!! I guess that may add another whopping chunk on the higher estimate side.

    So this uncertainty cuts both ways, and my guts tell me (which is as good an indicator as any other used by those of us yapping around the fringes of science) that GW is much more likely to be worse than scientists are telling us, than better.

    RE #54 “Most of the uncertainty from a climatological perspective is “loaded” in the climate sensitivity”

    My stat prof used to tell us, “We live in a stochastic world.”

    Or, “Some call uncertainty #@*#%, but others call it life.”

  11. 61
    Lynn Vincentnathan says:

    Re#58, my understanding is that they look at all the available data, but that temperature taking has only been around for the whole world for only ?100 years or so (and some of this has to be adjusted, bec it was taken at diff times of day or in sunlight, etc).

    They also rely on “proxies,” which I just taught about in my Crim Justice Methods/Stats course — if you don’t have the data for some locations or timeframes, you find something else that very well fits or correlates with the data that you do have in other locations or timeframes, then use this proxy in areas or timeframes where the actual data is unavailable.

    I’m not a climate scientist, but that’s how I understand it — they use whatever data they can, and do a pretty amazing job with it.

    Then with all the actual data that they have, & knowing basic atmospheric and molecular physics properties, they create models to explain the actual data. Once these models are able to replicate the actual data and proxies, they shoot them forward into the future, using both low & high end climate “sensitivities” to give a range of possibilities they are fairly certain about (I think 95% certain is the usual standard).

    “Cherry-picking” or “selection bias” is used by people who want to get a particular result, so they choose only the data that fits their hypothesis; this is the opposite of the honest scientific process.

  12. 62
    yartrebo says:

    Re #58: The stronger the signal (how fast the warming is occurring) and the weaker the noise (the year to year variations), then the shorter the time span should be.

    In the case of global warming, I would pick about a 30 year time frame, though the exact length is indeed arbitrary. A longer time frame will be more accurate, but it will also be less timely.

    In addition, a best fit linear approximation is better then just using the start and end values, since you’re actually using all the data instead of just two values and it’s much less prone to cherry picking.

  13. 63
    Hank Roberts says:

    The AGU release says the Sheffer paper won’t be published ’til May. Looks intriguing:

    “… the authors focused especially on relatively recent climatic anomaly known as the ‘Little Ice Age.’ …. the atmospheric carbon level dropped during the Little Ice Age. The authors used this information to estimate how sensitive the carbon dioxide concentration is to temperature, which allowed them to calculate how much the climate-carbon dioxide feedbacks will affect future global warming.

    “As Marten Scheffer explains, ‘Although there are still significant uncertainties, our simple data-based approach is consistent with the latest climate-carbon cycle models, …. estimates of future warming that ignore these effects may have to be raised by about 50 percent. We have, in fact, been conservative on several points. For instance, we do not account for the greenhouse effect of methane, which is also known to increase in warm periods.'”

    [Response: This sort of thing has been done before. Experiments using coupled climate-carbon cycle models such as Gerber et al (2003) [Gerber, S., Joos, F., Bruegger, P.P., Stocker, T.F., Mann, M.E., Sitch, S., Constraining Temperature Variations over the last Millennium by Comparing Simulated and Observed Atmospheric CO2, Climate Dynamics, 20, 281-299, 2003] suggest that the hemispheric-mean cooling of the LIA indicated by the reconstructions featured in the IPCC TAR are consistent with pre-industrial CO2 variations, and that significant greater hemispheric-mean temperature variations would actually be inconsistent the CO2 record of the past millennium. –mike]

  14. 64
    Jeffrey Davis says:

    #53 My naive understanding.

    The radiative forcing for CO2 can be calculated from the amount of CO2 in the atmosphere. The climate sensitivity calculation is an attempt to figure out how the calculated energy will impact temperatures and other climate phenomena. Like rainfall.

    Without a way to discount the calculated energy (like Lindzen’s “iris effect”), there’s no reason to unlink the two. The energy added to the budget won’t simply go away as we look at other vectors. It has to be accounted for.

  15. 65

    Watch out for fundamentalist reasoning. “either the models give a good description of the historic evolution or they don’t”, reminds me of conversations with religious fundamentalists, “either the Bible is the word of God, or it isn’t”.

    One can consider the models valuable tools without considering matching the 20th century climate a thorough validation. In fact, we know from numerous diagnostic studies, that the match the models achieve with the 20th century climate is “achieved” INCORRECTLY. If the models are either correct or they are not, we know what the answer is. The errors found in the models individually and as ensembles are larger than the net energy imbalance of less than 0.8W/m^2 we are trying to measure. So lets stay away from the fundamentalist thinking.

    Given that CO2 trends correlate so well with the 20th century temperature increase, it was natural for Lindzen to suspect that the “match” with the 20th century was achieved, despite the models errors, by means of an increased sensitivity to CO2. With so much of the climate models parameterized, the “corrections” to match global energy balance and albedo, are likely to be at different altitudes and lattitudes, than the model errors they are correcting. In the complex, non-linear climate system, the burden is on the climate modelers to show that these documented errors are not significant. We are not talking a butterfly effect here, the documented model errors are as much as two to four orders of magnitude larger than the accuracy needed to attribute the origin of the global energy imbalance for individual models, and more than two orders of magnitude for the AR4 meta-ensemble as a whole.

    In addition to overcoming the documented errors, to substantiate claims that the models are good enough for projection and attribution, the modelers also have to do more than handwave about the limited resolution of the models. The low resolution necessarily leaves out potentially significant climatic responses such as a change in frequency and intensity of hurricanes, which while perhaps a consequence of global warming (some evidence for intensity if not frequency), may also be a negative feedback mechanism.

    Are the models better than Lindzen’s thinking? I think a more important question is are the models better than their currently documented errors? For the models to resolve the relative attribution of the recent warming among internal climate modes, solar forcing and various anthropogenic forcings, they would have to be better than their current errors, perhaps to withing 0.1W/m^2 globally and annually averaged. The modelers have yet to produce scientific evidence that they are, yet there is a “scientific” consensus expressing confidence in their projections. Is that science or some kind of religious fundamentalism?

  16. 66

    #19, That is exactly what Lindzen stands for , a theory that does not work, and the point aply raised, iris effect preventing ice ages???, is why this theory is nonsense. So is there anything else we should be not impressed with Lindzen? Aside from his mixing of climate and weather siences to confuse the lay, unlike Hansen and others who make credible predictions on solid theories, contrarians don’t have to brag on something they may be right about, they just have to cast doubt without really understanding the theories that work. They are just fooling themselves, in the process of using the press, a whole lot of others who adhere to the persons title rather than the idea.

  17. 67

    Physics World’s interview with Lindzen might have benefitted from more feedback from MIT- Kerry Emanuel is uniquely placed when it comes to commenting on the strengths and weaknesses of Richard’s point of view, and no stranger to the hazards of
    Armed Cant In The Climate Wars :

  18. 68
    Jeffrey Davis says:

    re: 67

    Who are the liberals whose armed cant is so pernicious in the climate wars? And what are they saying?

  19. 69
    Hank Roberts says:

    I think it’s noble enough to argue that politics won’t work until both sides agree on the same physics.
    When I try I get reminded I’m naive.

    I don’t think our politics has matured to the point that the science is even considered by most politicians.

    Look at what happened with the attempt to control ozone-depleting chemicals: it’s been gamed badly.

    Gaming the rules is an old trick — like a business checking grain or fruit and making sure that just below the allowable limit of crap is always there, and adding some in or speeding up the production line if the product is cleaner than it has to be, or like setting up electric deregulation for fast profits rather than for actual physical coordination of the electric network.

    These are people who have no respect for the public health and physics:

    ” … Michael Wara of Stanford Law Schoolâ��s Programme for Energy and Sustainable Development calculates, HCFC-22 producers in China, India and Brazil are making up to twice as much money from burning HFC-23 than from selling the refrigerant. The CDM is thus giving them an incentive to produce even more HCFC-22 â�� if only for the sake of disposing of the useless by-product. Accordingly, the price of HCFC-22 is falling. The CDM is thus, in effect, subsidising the air-conditioner industry as well. Moreover, the CDM provides an incentive to make the refrigerant in a wasteful manner. After all, the revenue from emissions certificates depends on how much waste is burnt.

    “…. Wara has calculated that the average for refrigerant producers involved in CDM schemes is 2.99 percent. Obviously, producers are meticulously aiming for the maximum waste amount allowed. In this context, Wara finds it maddening that the value of the emissions certificates generated in HFC-23 incinerators today exceeds the costs of avoiding HFC-23 several times….”

    No one’s found a way to write an agreement or law to include respect for physics and chemistry. If they had added such a requirement, this kind of profit from “perverse incentives” wouldn’t be routine.

    “As Asia Keeps Cool, Scientists Worry About the Ozone Layer

    “…. air-conditioners â�� along with most window units currently sold in the United States â�� use a refrigerant called HCFC-22, which damages the ozone.

    “The emissions of things like HCFC-22: we had thought they were sufficiently in control, that we didnâ��t have to worry about them,â�� said Joe Farman, the British geophysicist who discovered the ozone hole.

    ” … The fastest-growing offending gas that scientists say can be better managed is HCFC-22. ”

    I expect you’ll find “liberals” as used above would include anyone who wanted to tell the market to ban CFCs to protect the ozone.

    That’d include people who were, how would you say, “prematurely anti-HCFC-22” — those people who long ago argued for an earlier and more effective phaseout of the chlorofluorocarbons that was won by those who made the economic case for slower response.

    Result now? stratospheric ozone depletion persisted long enough that it’s now at risk of becoming much worse, as the stratosphere cools — as predicted — due to fossil carbon burning. The stratosphere drops below that once rare temperature where high clouds form a substrate for catalysis, and ozone loss speeds up. Well, duh. I know that was a concern when the first ozone science was raised.

    And at the time, the argument amounted to: ‘there’s so little risk the stratosphere could become colder, we needn’t hurry to phase out CFCs’ and ‘surely by 2005 everyone will be smarter and richer so it’ll be cheaper to handle the problem later than fix it now’ — a familiar stance.

  20. 70
  21. 71
    Ian Forrester says:

    Talking about Lindzen, does anyone know if he sent the bottle of Lagavulin to Bill Nye?

  22. 72
    Pat says:

    Re: 66 and other comments on iris effect in interglacial-glacial transitions:

    That’s a good point, that obviously the Earth’s climate cannot be so stable as to prevent ice ages. However – I’m not trying to put life back into the iris effect, but just generally speaking – the feedbacks themselves can be temperature dependent – ie I would imagine that the response to a doubling of CO2 would be reduced if one starts with no ice – and at the surface, I’m thinking warming per unit forcing would decrease with increasing temperature, as evaporative cooling becomes more powerful (of course that goes to warm some part of the troposphere by condensation).


    Re: 27 – I think what 18 meant was that the overall pattern of chaotic behavior should be simulated by a good model – this is climate – it is distinctly different from weather. One way of thinking of it is – that butterfly which can completely change the specific weather beyond two-weeks’ time – it is never noticed because while the specific weather is altered, the weather patterns still seem familiar. Most extratropical storms still move from west to east, the wind changes in a typical way after the passage of a front, every seventh wave is still larger than the others, etc. There will be deviations from the average, but these may fit into a pattern on a short time scale. Deviations from that pattern may still fit into another pattern (ie going from the ‘cycle’ of passages of pressure systems, fronts, and waves, development, movement, and decay of transient atmospheric eddies, to the jet stream index cycle, QBO, oceanic eddies (I’m not sure where to put them in this list, actually), ENSO, PDO, AO, NAO, AMO… is there a master list of _O’s I could look at?)


    Re: response to 53

    As I understand it, in a one-dimensional radiative-convective equilibrium model, the tropospheric temperatures, down to the surface, are essentially determined by tropopause radiative forcing (in this sense radiative forcing includes the effects of feedbacks). But the rate of convection to any level must then be controlled by the radiative heating profile.

    I’m curious about how dynamics respond to changes in radiative heating profiles in three dimensions, so –
    What do the radiative heating profiles look like in different environments (different temperature profiles, cloud and humidity profiles, over different surface albedos, different sun angles), such as those of typical environments, for example, at various points around an extratropical cyclone at various stages of development, at various parts of the Hadley circulation, at the poles, etc.) – and how would they respond to changes in CO2 or other greenhouse gasses. see radiative heating profiles would help in understanding how three dimensional convection would change, and on that note, are there any good books or websites to explore such radiative – dynamic connections?(I was thinking of this when trying to explain how radiative transfer works over at
    – my relevant comments start on Nov 25 and go up to Jan 19; I tried to make use of Collins et al.: ; I was going to go from radiative heating profiles to dynamics and then realized I couldn’t do very much – anyway I’d be curious to know what an expert thinks of my attempt to explain atmospheric radiation.)


    I was having a discussion with someone who posted information about cloud uncertainty from this website:

    Because of the source, I was at first tempted to ignore it, but it refers to a study by Zhang et al. – I found the abstract here:

    I only had access to the abstract. I’m not quite sure what to conclude – ie what are the SW and LW forcing errors from the cloud errors, and would the cloud errors remain proportional among different CO2 level model outputs – etc. – ie there’s error, but what does it mean in terms of climate sensitivity to greenhouse gas forcing?


    I’ve read that the next ice age, without AGW, may start 50,000 years from now, or later by some tens(?) of thousands of years with AGW.

    I’m curious – how much certainty, or what range of error, is currently considered appropriate for this prediction.

    Also, what defines the beginning of an ice age in such a prediction – is it the occurence of any significant permanent snow/ice cover outside of Greenland, Antarctica, and mountain glaciers?


    What is the current best guess for how rapidly Greenland, West Antarctic, and if it ever comes to it, East Antarctic ice sheets would melt in any given emissions scenario?

  23. 73
    Pat says:

    Re – response to 46

    So if it is true (is it?) that diurnal temperature ranges around the rim of Antarctica (because this would be the equivalent of seasonal near the center) have not shrunk, – aside from short term variability and regional variations in response to climate change, could it be due to loss of stratospheric ozone?

  24. 74
    Ike Solem says:

    RE#70, that’s an interesting paper, but even more interesting is how it is interpreted by Sherwood Idso’s : ” Based upon biogenic silica data plotted by the authors in their Figures 4 and 5 (Figure 5 reproduced below), from which relative temperature can be inferred, it is clear that the current warm period has not attained the warmth of Medieval times.”

    The notion that is trying to promote is that since there was a warm period in Europe in ‘medieval times’, fluctuations in climate are common and what we are experiencing now is just the result of ‘internal variability’ – the same notion that Richard Lindzen trumpets in the PhysicsWorld profile. This argument has been around for decades now. However, the general view seems to be that these were largely regional events. It’s also worth noting that the authors only make claims about local climate, while CO2science immediately tries to tie it to the global situation. (The paper is a description of a single core from a single lake, as well).

    This paper is and its ‘analysis’ is featured on this weeks issue of, which is probably why it showed up here as well. As shows, CO2science is an Exxon-funded public relations operation masquerading as an independent scientific institution. Their position is that “there is no compelling reason to believe there will necessarily be any global warming as a result of the activities of man, especially those activities that result in CO2 emissions to the atmosphere” and they endlessly push the “benefits of increasing CO2 to the biosphere”.

  25. 75

    Re: Ike #74,

    “Regional” events such as the albedos of early or late northern snow melts can have impacts on the global energy budget larger than the net energy imbalance responsible for the recent warming. Regional events also help put anecdotal reports into perspective, and are evidence of internal climate variability on scales models do not yet do a good job reproducing.

  26. 76

    [[A simple example would be if CO2 concentration was historically correlated with another forcing. ]]

    Radiative forcing from atmospheric CO2 is not based on empirical correlations; it is based on radiation calculations. We’ve been studying CO2 absorption of infrared light since Tyndall first demonstrated it in 1859, and now have reliable data on tens of thousands of spectral lines. Aside from some minor questions about how CO2 is distributed with altitude, we can be fairly sure what the radiative forcing is and has been historically.

  27. 77

    [[ I believe Prof. Lindzen has made the point many times that the inadequate climate models have been “overfit” so that they match historical trends, but at the expense of predicting present and future ones. ]]

    Prof. Lindzen is wrong. The models have been doing steadily better in predicting present and future climate observations.

  28. 78

    [[Now can someone answer this question;

    Why as the rate of cooling/heating of the South Pole shown no change dispite the elevation of CO2 since the mid-1950’s?]]

    Well, let’s think about that. I mentioned earlier (see above) the semi-isolation of Antarctica from world climate trends due to atmospheric events, and someone else pointed out that the southern ocean is probably a bigger factor. But let’s assume those didn’t exist. Antarctica is covered with what?

    What would the first effect of heat on that substance be?

    What happens to the temperature of a melting substance during a phase change? Where does the heat go?

  29. 79

    [[However if average global temperature increases to 3 Deg C by year 2100 it seems likely that the average global temperature will continue to increase for centuries and thousands of years beyond 2100 ]]

    I think by then the level of greenhouse gases in the atmosphere will likely be decreasing, and the rise in heat won’t continue forever.

    [[which will increase sea level rise as the warming continues, indefinitely. ]]

    Eventually you run out of ice. There’s an upper limit to how high sea level can go.

  30. 80

    [[Re #55: “A look at the longer time series rather than a cherry-picked short snippet of it would suffice …”

    What principles should guide a climatologist in deciding what time-frame to look at? Is a decision to look at the last 9 years or 30 years or 100 years an arbitrary decision, or should it depend on principles on which all reasonable and informed individuals can agree?]]

    You use as many data points as you can possibly gather. The larger your set, assuming no collection bias, the more reliable your answer. Lindzen is using a sample size of N = 8 (1998-2005). We have highly reliable temperature data available at least back to 1880 (N = 127).

  31. 81
    tamino says:

    Re: #179

    Eventually you run out of ice. There’s an upper limit to how high sea level can go.

    Ice melt isn’t the only factor which increases sea level, there’s also the thermal expansion of water. That’s why sea level is projected to continue to rise, long after temperature has stabilized. See the IPCC TAR for graphs of projected sea level rise.

  32. 82
    Lynn Vincentnathan says:

    RE #68 (re 67) “Who are the liberals whose armed cant is so pernicious in the climate wars? And what are they saying?”

    I think he means people like me who keep yapping about how we can save money by mitigating GW, which doesn’t sit well with those spendthrift conservatives. It seems the debate is becoming more and more between conservatives and environmentalists (like me), rather than conservatives and liberals, both of whom simply like to point scolding fingers at each other, and would not like to address global warming, because the finger points at ooneself. And that’s not fun! Unfortunately while there are a lot of liberals, there are very few environmentalists.

    RE #78 and ice melting. On another blog an engineer wrote about the enormous amount of energy needed to melt ice: take a glass of water with ice cubes. It will stay fairly close to its original cool temp until all the ice is melted, since the energy is going into the mechanics of melting, rather than into heating. However, after the ice is all melted, the water will warm relatively quickly to room temp.

    So there are 2 types of energy, heat and mechanical. Hurricanes (according to the engineer) turn heat energy into mechanical energy & do help to cool down the locale (Gaia has a temperature & goes into a writhing sweat, which helps cool her??). So in that respect Lindzen is perhaps correct, but the underlying disease of us emitting GHGs is not cured by this, so the warming continues, but every now and then Gaia has a hurricane or storm to try and cool herself, ever more violent (& I think science will find, ever more frequent) storms. But that doesn’t cause us to emit less GHGs, so the disease continues.

    I still think it’s very weird that we got a downpouring of hailstones in Brownsville, Texas, during Hurricane Emily in the summer of 2005 (which our weatherman said he had never heard of before).

  33. 83
    James says:

    Re #82: “It seems the debate is becoming more and more between conservatives and environmentalists (like me), rather than conservatives and liberals…”

    I think it’s incorrect to try to tie environmentalism (in any of its forms) to any part of the political spectrum. There are in fact a fair number of conservative environmentalists out there, and a lot more whose politics, like mine, fit in neither the liberal nor conservative pigeonholes.

    It’s also a tactical mistake, because if you get AGW tied to any political viewpoint (as in fact some of the denialist camp tries to do), you generate a lot of political opposition that has nothing to do with fact. Consider for instance how much of the opposition to “An Inconvenient Truth” centers on Al Gore & his politics. Suppose the same movie had been made by someone like John McCain – you’d have the “AGW is just another liberal statist plot” replaced with “AGW is a conservative pro-business plot”. In either case, you have a political bloc who are going to see it as part of their hated opponents’ agenda, and so ignore any and all facts, and that’s a recipe for doing nothing.

  34. 84
    David B. Benson says:

    Re #72: Pat — There have been several comments, one with a useful link, regarding the onset of the next ice age. These are, as I recall it, on the What causes ice ages? thread, down a few…

  35. 85
    Lynn Vincentnathan says:

    RE #83, I think that’s what I was trying to say #82), only it came out wrong.

    Plus my experiences with liberals who are not aware of or not interested in GW (which goes against the “GW is a liberal issue” myth), and prolife social conservatives, who you’d think would be interested in reducing killing people through GW effects. Both camps tend to see GW as a distraction from their important issues & projects of pointing fingers at the evil-doers.

    When the culprits are us & requires us to change, that just isn’t fun anymore. So for both sides, it’s off across the country to the finger-pointing rallies in their SUVs, forgetting to turn off unnecessary lights or set the thermostat to reduce energy waste while away from home. And switching to GreenMountain’s 100% wind-generated electricity? Can’t be bothered, according to a very liberal/anti-abortion person I know (who’s into the “more important” liberal AND conservative issues).

  36. 86
    Ray Ladbury says:

    Re #82 and #83. One of my concerns is that some conservatives seem to be insistent on making opposition to doing anything about climate change a litmus test–thereby setting themselves in oppostion to science, just as they have done with the whole creation vs. evolution nonissue. There are loons on both sides. So-called “liberals” who insist on draconian measures against CO2 that would cripple the economy while simultaneously opposing nuclear power are just as much denialists and just as irresponsible as those who deny anthropogenic causation. It is never a good strategy to include anti-science in your political platform.

  37. 87

    [[Eventually you run out of ice. There’s an upper limit to how high sea level can go.

    Ice melt isn’t the only factor which increases sea level, there’s also the thermal expansion of water. That’s why sea level is projected to continue to rise, long after temperature has stabilized. See the IPCC TAR for graphs of projected sea level rise. ]]

    True. Nonetheless, there’s an upper limit to how high sea level can realistically go. The oceans will never cover the continents, Waterworld to the contrary.

  38. 88
    Ike Solem says:

    RE#75: Martin, you refer to “the net energy imbalance responsible for the recent warming.” That’s meaningless. Warming of the Earth is by definition a net energy imbalance; the Earth is absorbing more energy than it is emitting, and the cause of this is that we’ve changed the composition of the atmosphere via the use of fossil fuels and deforestation. If we stop burning fossil fuels and stabilize the atmospheric gases, then we’ll reach a new surface-atmospheric steady state – though the oceans will continue to warm and expand for centuries after that, since they take longer to reach steady-state equilibrium.

    The issue of “Medieval Warm Period” and “Little Ice Age” were addressed in the 2001 IPCC report :

    “As with the “Little Ice Age”, the posited “Medieval Warm Period” appears to have been less distinct, more moderate in amplitude, and somewhat different in timing at the hemispheric scale than is typically inferred for the conventionally-defined European epoch. The Northern Hemisphere mean temperature estimates of Jones et al. (1998), Mann et al. (1999), and Crowley and Lowery (2000) show temperatures from the 11th to 14th centuries to be about 0.2°C warmer than those from the 15th to 19th centuries, but rather below mid-20th century temperatures. The long-term hemispheric trend is best described as a modest and irregular cooling from AD 1000 to around 1850 to 1900, followed by an abrupt 20th century warming. Regional evidence is, however, quite variable. Crowley and Lowery (2000) show that western Greenland exhibited anomalous warmth locally only around AD 1000 (and to a lesser extent, around AD 1400), with quite cold conditions during the latter part of the 11th century, while Scandinavian summer temperatures appeared relatively warm only during the 11th and early 12th centuries. Crowley and Lowery (2000) find no evidence for warmth in the tropics. Regional evidence for medieval warmth elsewhere in the Northern Hemisphere is so variable that eastern, yet not western, China appears to have been warm by 20th century standards from the 9th to 13th centuries. The 12th and 14th centuries appear to have been mainly cold in China (Wang et al., 1998a,b; Wang and Gong, 2000). The restricted evidence from the Southern Hemisphere, e.g., the Tasmanian tree-ring temperature reconstruction of Cook et al. (1999), shows no evidence for a distinct Medieval Warm Period.”

    Thus, CO2science’s ‘analysis’ of this issue (i.e. their “Medieval Warm Period Record of the Week”) is just nonsense, and worse, distorts what the author of the paper actually said. It is nothing but deliberately deceptive manipulation of science.

  39. 89
    SecularAnimist says:

    Ray Ladbury wrote: “So-called ‘liberals’ who insist on draconian measures against CO2 that would cripple the economy while simultaneously opposing nuclear power …”

    What exactly are these so-called “draconian measures” that would “cripple the economy”, exactly how would these unspecified measures “cripple the economy”, and who are the unidentified “so-called liberals” who allegedly “insist” on these unidentified “draconian measures”?

    The only argument that I have ever heard to back up the claim that a buildup of nuclear electricty generation is necessary for reducing GHG emissions is the dogmatic pronouncement that it is so.

  40. 90
    mark s says:

    RE #51,

    Thank you for that, Pat. Has anyone got any opinions on Hansens slideshow?

    The January 2007 surface temperature anomaly…

    The December 2006 chart shows a mild month over virtually all of the earths landmasses, except for Australia and Antartica (which are cool), with the NH showing particularly mild conditions.

    January sees a similiar overall picture, although some areas have cooled somewhat (Western US, most of Africa, Saudi Arabia).

    The bit i don’t like, in the January chart, is the Southern Polar region. Wasn’t Antartica supposed to be remaining cool. How frequently are we getting that kind of month, in an average year?

    I appreciate it is just one month (maybe a month is a long time in climate science, these days :-)), but i thought the circumpolar currents were keeping the Antartic isolated. International Polar Year couldn’t come a moment too soon, really.

    Its lookin like a good start for the hottest year on record, anyway. No ‘surprise’ there then!


  41. 91
    Ray Ladbury says:

    Re #89. Developing solutions to climate change will require a healthy, growing economy–not just in the US and Europe, but globally. A healthy economy requires lots of energy, and there simply is not combination of renewables, etc. that can meet those needs. Even with fossil fuels, the demands of 9 billion people will be challenging. Nuclear power is quite simply the cleanest and cheapest way to produce the energy required for a future economy. All the renewables have a role, but they simply aren’t practical to meet the energy demands of 9 billion people.

  42. 92

    Re: Ike #88

    You are confusing surface temperature changes with an energy imbalance.

    You can have a positive energy imbalance without an increase in temperature, such as the energy going into the melting of ice or the storage of heat into the ocean and subsequent sea level rise after the ocean surface and atmosphere have achieved most of their temperature accommodation.

    “Global warming” does not mean universal regional warming. Some regions can even be cooler. A significant regional warming absent demonstrated cooling elsewhere, is a net global warming given the way we calculate warming, although, given the uncertainties of paleo data, we should probably should look for confirmation by glacial ice melt and/or sea level rise.

    But lets not get side tracked from the main issue, despite the improvements of the AR4 models over those of the TAR, the models are still nowhere near where we need them to be for useful attribution of the current less than 0.8W/m^2 energy imbalance. Until we have the accuracy needed for the relative apportionment of quantities this small, we can’t know if they are correct enough for quantitative projection of future scenerios.

  43. 93
    Ike Solem says:

    Martin, you can have regional temperature changes while the Earth as a whole is in net energy balance in terms of solar radiation input and earth infrared output, but those must be compensated for within the system – that’s why ‘internal oscillations’ such as the NAO or El Nino can’t be used to explain the net global warming that the planet is currently experiencing. The argument that ‘since there was a warm period in Medieval times, this current warm period is nothing special’ ignores this basic fact.

    As far as ‘internal variability’, that’s not some function of ‘the climate system’ but of whatever model you happen to be using at the time. A weather model (one-week timespan) has a different set of internal and external factors than a climate model (century-scale timespan) does, and a very long-term model (a glacial cycle model, perhaps one million year time span) will also have a different set of internal variables (CO2 would be an internal variable in a glacial cycle model, but an external forcing in a climate model, and isn’t a factor in a weather model – similarly, sea surface temperature is an internal variable in a climate model, but an external forcing in a weather model).

    The key thing is to compare the model results to comprehensive data from the oceans, land masses, ice sheets and atmosphere – and they’ve been doing a good job so far. If anything, they may be underestimating future changes because of future positive feedbacks, i.e. carbon cycle responses.

    A news report on the energy imbalance issue is at

    Why do you say that “the models are still nowhere near where we need them to be for useful attribution of the current less than 0.8W/m^2”? That number you reference is actually partially based on model results itself – and isn’t the value estimated to be 0.85W/m^2?

    See also

    Also, keep in mind that (quote from above)
    “The focus of the debate on CO2 is not wholly predicated on its attribution to past forcing (since concern about CO2 emissions was raised long before human-caused climate change had been clearly detected, let alone attributed), but on its potential for causing large future growth in forcings. CO2 trends are forecast to dominate trends in other components (due in part to the long timescales needed to draw the excess CO2 down into the deep ocean). Indeed, for the last decade, by far the major growth in forcings has come from CO2, and that is unlikely to change in decades to come.”

    Also, if the Deep Space Climate Observatory had been built and put at Lagrange 1, there might actually be ‘hard data’ on the energy imbalance issue. It’s a far more important project than putting rovers on Mars, but was cancelled due to conflicting priorities:

    The better experiment when it comes to global warming was to be the climate observatory, situated in space at the neutral-gravity point between the Sun and Earth. Called Lagrange 1, or L1, this point is about 1 million miles from Earth. At L1, with a view of the full disk of the Sun in one direction, and a full sunlit Earth in the opposite, the observatory could continuously monitor Earth’s energy balance. It was given a poetic name, Triana, after Rodrigo de Triana, the sailor aboard Christopher Columbus’ ship who first sighted the New World. Development began in November 1998 and it was ready for launching three years later. The cost was only about $100 million. For comparison, that is only one-thousandth the cost of the International Space Station, which serves no useful purpose. What a travesty.

  44. 94

    Re 68 & 82
    If you want examples,please read the article my piece refers to-it is linked on the blog page side bar.

    Among the more egregious icons of Armed Cant _a gauche_ are the fast forwarding of sea level rise in _The Day After Tomorrow_ and _An Inconvenient Truth_. The Extinction of Species graph in Al’s 1992 book, _The Earth in The Balance_ has been conveniently dropped from the Revised Standard Version- it showed the rate of species loss going dead vertical to infinity in the year 2000, but the report of our extinction has proved somewhat exaggerated.

    [Response: “The Day After Tomorrow” is a work of fiction that doesn’t pretend to be otherwise. It’s different from Crichton’s book, which masquerades as fact. I don’t see the relevance of the aforementioned film in this discussion. A careful reading of the “fast-forwarding” of sea level rise in “An Inconvenient Truth” shows that it isn’t doing any more than raising the issues that Hansen raised about the long-term consequences of warming for melting of Greenland. It does it in the compact way that is necessary in film, and while it certainly invites and requires further discussion, I don’t think it is fair to call this “armed cant.” I don’t remember the extinction curve in the 1992 edition,, but it’s also true that one has to distinguish between exaggerations that turn a catastrophe into an ultra-catastrophe, and those that create a catastrophe out of whole cloth. There is really no doubt about the pressure human impacts are putting on biodiversity. You could say Al was ringing the alarm bell too loudly, but at least he was ringing the right alarm bell. The “Armed Cant” on the other side is more like people saying the building isn’t on fire, so just sit still and wait it out — when of course the building really is on fire and everybody is going to burn to a cinder while waiting for the fire trucks to arrive. –raypierre]

  45. 95
    Hank Roberts says:

    Dr. Seitz, any rate of change tied to human activity — population growth, species extinction, CO2 — looks about vertical
    on a geologic time chart.

    Are you seriously claiming you read Gore (1992) as having predicted the end of life on Earth by 2000? Or that anyone else did?

    It seems you’re discounting a real problem by exaggerating a fifteen year old description. E.O. Wilson could say this better.

  46. 96

    Re: Ike #93,

    The 0.85W/m^2 figure works just as well. The 0.8W/m^2 figure was from Hansen’s 2005 Science paper. Keep in mind that internal climate modes may be confounding things. See this dicussion here at RC:

    The full text of the paper is here:

    On the space station, some science spending really serves a political purpose, in this case, subsidizing the peaceful employment of Russian dual use personel. Yes, it is a travesty that this is necessary.

    When you say the models have been doing a “good” job compared to the data, I agree. But the question is whether they do a good “enough” job to attribute under 1W/m^2 of warming. The Roesch paper I repeatedly cite, showed that all of the AR4 models have a positive surface albedo bias. The average of that bias is 2.8 to 3.8W/m^2. Gavin has stated that I have inflated the importance of the result, but he hasn’t questioned the figures. Undoubtedly there are far larger errors in the individual models documented in other IPCC diagnostic studies. The question is not whether this result is significant in some absolute sense, but just whether it is significant ENOUGH to call into question the skill of the models in attributing the much smaller energy imbalance.

    It is not enough for experts to claim “good” agreement for their models. They even claim good agreement between the models when they vary by over a factor of two in climate sensitivity, while achieving “good” agreement with each other and the 20th century climate data. The hypothesis that the AR4 models have projective and attributive skill, is in doubt. Given the non-linear climate system with the differences in coupling of the various forcings, and the highly parameterized nature of the climate models, with their documented differences with each other and the data. A case can be made that the models agreement with each other and the data is “poor”. But whether the agreement is good or poor, there is evidence that the models have errors several times larger than the issue at hand. The burden of proof is on those supporting taking action upon the AGW hypothesis based model projections.

    Absent any credibility for those projections, the measured warming so far is not alarming. We need better models.

    [Response: But, as Gavin says, you have indeed inflated the importance of the results, The uncertainties in the model are why we have a spread in forecasts of global warming. I will repeat what Posner says; Uncertainty doesn’t work to the favor of people who say, “Do Nothing.” Given the basic physics of the greenhouse effect and water vapor feedback, one needs an extraordinarily strong argument to say warming isn’t going to happen. The models are uncertain about how much warming, but until we know better, the high end of the forecast is a real risk. No scientifically credible scenario eliminates the warming, though by stretching it there is a chance that the warming from doubling just might be within manageable bounds. Are you betting the world on that? What is your scientific justification for ruling out the high end of model sensitivity? These are scientifically defensible as well. If we had better models maybe we could rule those out, but we don;t we can’t. Are you willing to bet your grandchildren’s lives on your hunch that the high end is wrong? Are you comfortable making that decision for other peoples’ grandchildren as well? –raypierre]

  47. 97
    Rod B. says:

    re 74 “…CO2science is an Exxon-funded public relations operation masquerading as an independent scientific institution. …”

    And I suppose Exxon’s participation on IPCC musses their credibility, too…

  48. 98
    Mark A. York says:

    As a biologist who has worked on endangered species since 1986, I concur with Ray P. whole heartedly. Every year there was less to find for very concrete reasons, the foremost being habitat loss. In fact, the biggest crticism of Gore would be banging too loud a gong, but it’s only a matter of degrees. In this case, as we’ve seen already, 1 is meaningful. I should think anyone could comprehend the fast forward of a slide show film “cut to” scene clearly labeled.

  49. 99
    Steve Kimsey says:

    I hope every person posting on this forum has roughly the same desire I do, referring to temperature preference that is. That being that the claimers of Earth cooling are correct a very little bit ( I’d love to be able to count on snow every couple years here in Pcola,FL ), and that the claimers of the Earth warming are wrong a lot.

    Beyond that, it is good to see many people studying this issue. Personally, no matter what occurs with the climate, I’d like to say my recent delve into climate science has me feeling quite a number of persons of both pro and anti warming opinions are more wanting to be right than caring about what really happens. And though by no stretch of the imagination could I be considered to be anything but a novice on this science, what I do think I am qualified to say and offer is I see the same old two party USA system of government developing on this issue, quite often characterized by eyes and ears shut while the mouth is wide open. The power will eventually go to the side who appears to be most right and who promises the Utopia, but as for my opinion, let me say, being the fence sitter my dad says I am, though it rather likely be against the majority opinion of this group, I truly think there is a decently even boxing match going on right now as to who is right. I keep my eyes and ears open though… keep up the study!!

  50. 100
    Pat says:

    Re 84 Thanks.