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  1. In addition to the article’s quote of the mere draft as if it was authoritative being premature, diagnostic subprojects such as that by Andreas Roesch are still being digested:…/2005JD006473.shtml

    Working group 1 of the IPCC received comments in the latest round, that because of errors such as this systemic bias in all the AR4 models, that all predictions and projections based on these models is premature. The Roesch study is especially significant, because in addition to the average errors being larger in effect than the total estimated increase in forcing since 1850, all the globally averaged albedo biases are in the positive direction, i.e., against solar forcing, the leading competitive theory to the relative significance of the anthropogenic greenhouse gasses for recent warming.

    [Response: You’ve been shown over and again (and again and again) that this is incorrect reasoning. Repeating it will not suddenly make it right. – gavin]

    This shared systematic bias undermines the IPCC TAR argument that the models are independent enough that combining the models into ensembles will cancel their errors, and make their combined results more trustworthy.

    Furthermore, the usage of models in other “observational” assessments of climate sensitivity to CO2 also render those results suspect.

    If the IPCC report is truly subject to peer review, this draft will have to be considerably revised. In fact, so much of the modeling science is now in question, that the IPCC report should be delayed a couple of years, so that the modelers have a chance to implement their corrections.

    [Response: IPCC is not a stamp of aprpoval. It is an assessment of the state of the science. To put it off until things were perfect is the same as never doing it. IPCC’s role is to fairly assess what is well understood, what is less so, and what conclusions, can or can’t be drawn at the moment. There are multiple levels of uncertainty in many aspects of climate research (though the one you keep harping on is not the most interesting or important), but IPCC is there to highlight the nuggets that are reasonably known. -gavin]

    Comment by Martin Lewitt — 4 Sep 2006 @ 1:05 PM

  2. good on ya!

    i disagree with your take on blogs, “As usual the blogsphere is playing a key role in amplifying and further muddying the story.” after all, blogs are not taken sooo seriously are they? and where is the fault in ‘amplifying’ – i take this in the sense of getting a message to more people, as well, even when people get it wrong on their blogs there is then at least a possibility that they may be corrected or otherwise moved to re-examine their thoughts, better on blogs than under rocks eh?

    that said, this blog (it is a blog isn’t it?) always gives me hope, i am not a scientist but your careful, geometric, (even sometimes niggling), approach has my admiration and support

    be well.

    Comment by David Wilson — 4 Sep 2006 @ 1:12 PM

  3. Gavin, I did not realize that you thought you had made your case. Your comment that

    “You need to appreicate that these changes in the fluxes are really small compared to the absolute flux, on the order of a few percent at most – thus they don’t generally change the big picture climate in the models and I have seen no evidence that there is a systematic relationship to the sensitivity.”

    is strange from a modeler and author that claims to have modeled the energy imbalance of the earth to 0.85+/-0.15 W/m^2. That is why I couldn’t take your “few percent” dismissal of the results without more substantiation. When you admitted that you used the GISS-ER model instead of using the GISS-EH model, I assumed you knew that Roesch had reported that it had a larger globally averaged annual surface albedo errors than the GISS-EH model.

    A surface albedo error of just 1% when applied to the globally averaged annual surface solar flux over 160W/m^2 is over 1.6W/m^2. Note that this is at the surface and not TOA.

    The errors in the GISS-ER model probably explain a significant portion of the deviation from 1 of the 0.92 effective forcing that you and Hansen used for solar forcing in your “…Energy Imbalance…” paper, i.e., by using “effective” forcing you apply this model error twice.

    I don’t need to have things explained to me over and over and over again, just once if it makes sense. Far from being convinced, I was expecting retractions of those papers or whatever the climate modeling equivilent of retraction is. How can you justify claiming a 0.92 effectiveness for solar forcing and a matching of the earths energy imbalance to 0.85+/-0.15W/m^2, in a model with errors larger than that, especially when those errors are a specifically against solar forcing? I admit that the models and forcing data have other errors probably much larger than that, but I don’t see how that helps your argument.

    [Response: I did explain it, and for the sake of passer-by’s I’ll explain again – but that’s it. The 0.85 W/m2 imbalance is the difference between a perturbed run (i.e. with anthroipogenic forcings) from a balanced control run (without any forcings). There is no uncertainty in that number other than the interannual variations in the radiative balance over individual simulations (and that is the basis of the error estimate). Now you point out that the absolute value of the absorbed solar is off by some value x W/m2. Since the control run is balanced, the other component (outgoing LW) must also be off by the same amount. In the perturbed runs there is a reduction in LW out due principally to the GHGs (roughly 1.6 W/m2 by 2000) which is only partially cancelled by an increase in temperatures (causing increased emission of about 0.8 W/m2). Neither of these two perturbations have anything to do with x – the absolute error. I gave you, as did Isaac Held, exactly analogous examples of why your comparison of absolute error x with the net difference 0.85 is erroneous. Similarly, the ‘efficacy’ of solar forcing has nothing to do with the albedo errors – the efficacy is defined with respect to the forcing at the tropopause (which has already factored in the albedo issue). Instead it is a function of the latitude and height distribution of solar forcing compared to CO2. Regardless, 0.92 efficacy makes no practical difference to our attribution of changes to solar forcing because long term solar is not known to better than 10%. There is much to criticise about climate models – I do it myself all the time, but you need to understand what is being done. Instead of just reading Roesch’s interesting paper, I suggest you read the modeling papers you purport to be criticsing. Then come back. – gavin]

    [Response: Martin, a more simple analogy I use for this: I can measure the height of my desk above the floor down to an accuracy of a few millimeters. This difference measurement is not called into question if someone tells me that the absolute height of my floor above sea level is only known with an error of +- 5 meters. -Stefan]

    Comment by Martin Lewitt — 4 Sep 2006 @ 3:45 PM

  4. Re: Gavin’s response to #3.

    I read the two papers we are discussing particularly closely as well as many others. The solar effectiveness is derived from short model runs (10 years?) with the ocean held constant. Keep in mind that the surface albedo errors, specifically impact both the lattitude and height distribution of the solar forcing compared to CO2. The GISS-ER globally-annually averaged surface albedo is approximately 0.131 compared to satellite observation values of 0.121 and 0.124. While these averaged values approximately correspond to errors of 1.6 and 1.1W/m^2 reletive to the respective observations, the actual errors are locally much larger. The actual errors are concentrated at the tropical deserts and at the temperate snow cover in spring. I doubt correcting TOA albedo via cloud parameters is equivilent in both its latitude and height effects.

    The fact that you can match an energy imbalance by perturbation with anthropogenic forcings alone, doesn’t mean that it also couldn’t be done with a correct solar, especially since the correct solar isn’t known with the needed level of accuracy. Unfortunately if you want to attribute a watt/m^2 of energy imbalance to different candidate net forcing increases, the models will probably need to be accurate to 0.1W/m^2 to do it with any resolution. With solar activity being at one of its highest levels in 8000 years per Solanki, attributing the recent warming in the context rapidly increased GHGs is problematic. We probably only have a couple decades of data accurate enough to validate the models to the required level of accuracy, and we probably need much more data.

    [Response: You might want to read them a little more carefully then. The model estimates are from coupled runs 120 years long, and the means are estimated from a 40 year mean. You appear to be under the impression that the imbalances are calculated by compariing the absolute fluxes at TOA with the modelled fluxes. They are not. They are calculated by looking at the difference in the modelled fluxes only. Thus the observational uncertainty/model bias doesn’t come into it except indirectly. – gavin]

    Comment by Martin Lewitt — 4 Sep 2006 @ 4:57 PM

  5. Re: Gavin’s response to #4.

    I was referring to the runs from which the 0.92 solar effectiveness is derived. I quote: “We include results for 10-year runs in our tabulated comparisons below.”, and I beleive those runs for the effective solar forcing are done with fixed Sea Surface Temperatures, not coupled runs. See “Efficacy of climate forcings”.

    I occurs to me that such runs emphasize the differences and thus the errors between the forcings. The surface albedo errors when averaged over just land are much larger, since that is where Roesch found the errors. The match over the oceans was generally good.

    [Response: That’s only for the Fs* calculations because they assume fixed SST and so don’t need to be run longer. The efficacies you are talking about are Ei and Ea which are calculated using the coupled model runs. -gavin]

    Comment by Martin Lewitt — 4 Sep 2006 @ 5:26 PM

  6. Back to topic!

    I am continually disappointed at the level of inaccuracy in media reporting of AGW issues. I’ve given up expecting journalists to know the difference between T(2xCO2) and net warming by 2100, or any number of similar (very basic) things. But I suppose I shouldn’t be disappointed; I should realize that this is the way of the world. The question arises, can we do anything to change the state of affairs?

    Perhaps. The moderators of RealClimate might prepare a document about the *basics* of AGW, some of the most common misconceptions and points of confusion, and basic definitions of things, specifically for journalists. This should not be an essay, but as brief as possible — just a few pages at most. Then they’d at least have no excuse for lacking the appropriate background to approach the topic more accurately.

    I’m tempted to do so myself — but as a mathematician (not a climate scientist) it’d be another case of someone stepping out of his field. Lord knows I’ve heard enough naivete from legislators, attorneys, and sociologists — even from Steven Hawking! Perhaps this could be a group effort, by the readers of RealClimate, with the final form requiring the endorsement of the RealClimate mods, and sent to journalists under their auspices — lending both accuracy and credibility to the final result.

    If we can induce even one journalist to “get things right,” then it might be worth it. Opinions?

    [Response: There already is a very well written journalist guide to climate change written by Bud Ward, Reporting on Climate Change: Understanding the Science. This gets frequently updated to follow the science and is highly recommended, as is itself. -gavin]

    Comment by Grant — 4 Sep 2006 @ 6:46 PM

  7. Re: Gavin’s response to #5

    You appear correct regarding the 100 year vs 10 year, although it appears to not make any difference, because per the definition of Fe in table 1 of “Efficacy…”

    Fe = EaFa = EsFs

    And table 3 where the Solar figures and Fe are derived from bears out the equation/definition, since both calcuations give an Fe of 1.10. I find that you are also correct regarding the use of coupled models, at least for the EaFa version. I apologize. I must have been confused by the large amount of fixed SST calcuations that were discussed, and the fact that somehow an “a priori fixed SST forcing, Fs” value can match a coupled model calculation so well.

    None of this supports the idea that calculating Fe with a model with these positive surface albedo errors is valid or eliminates the anti-solar bias, especially given the latitude and height dependency of the figures.

    I will review other sites where I have discussed your work, and make corrections, if I have incorrectly portrayed these calcuations.

    Comment by Martin Lewitt — 4 Sep 2006 @ 7:08 PM

  8. The paper that originally propogated the misinformation in this case is a Murdoch-owned Australian daily which frequently takes a climate skeptical editorial line. It seems to me they just seized on some numbers in the IPCC draft which they could spin to support their usual viewpoint. I guess “IPCC narrows climate sensitivity error bars” doesn’t have quite the same appeal as a headline.

    Comment by Sherry Mayo — 4 Sep 2006 @ 7:24 PM

  9. The guilelessness of some of our hosts on this blog is both endearing and frustrating at times. It’s possible that this example is an accident, but the tactic of planting false or misleading information in an obscure newspaper in order to have it picked up by the wire services and published as fact in major newspapers is a standard operating procedure of those who wish to impede progress (on global warming as well as other issues). Vicious personal attacks on the bearers of bad news (e.g., Jim Hansen) is another SOP. I’m afraid Hanlon’s razor is not a useful rule in these times.

    Comment by S Molnar — 4 Sep 2006 @ 7:36 PM

  10. I’m not a climatologist (a retired biologist with a math phobia) but have been following realclimate for about 6 months (ever since I read Flannerys book). Much of it I don’t understand but the above article sent me back to the original article on CO2 sensitivity which I reread along with the very long discussion.

    Here is my naive take on all this (I hope I’m wrong). The calculation of 2XCO2 sensitivity by 2100 does not take into account any of the positive feedbacks to warming which we are already seeing and which are very large compared to the negative feedbacks. So the estimate of around 3 degrees C has little to do with what one really can expect i.e. we really expect much higher increases and much sooner. If that’s the case, the situation looks very bleak indeed and I might as well give up my efforts at conservation and efficiency and spreading the message???

    [Response: You are not alone in being confused! The first thing is to separate out the sensitivity to 2xCO2 from what will end up happening in the real world. The 2xCO2 number is not tied to any particular year and (as you correctly point out) doesn’t include a number of potentially important feedbacks on the carbon cycle (because if it did, you’d have more than 2xCO2!). This number is also something you can realtively easily calculate from models or from (some) observations. Now the second number – what will temperatures be like in 2100 is a different thing entirely. This depends not only on how sensitive the climate is, but on what we end up doing to push the climate around. We might not reach 2xCO2 at all, or we could exceed it. Carbon cycle feedbacks may be small, or large. Thus there is a lot more uncertainty in the 2100 temperature. It is important as well to note that while you personally cannot do anything about how sensitive the climate is (that is purely a function of the physical system), you (along with the rest of us) are able to affect the trajectory of greenhouse gas growth and thus affect temperatures in 2100 (and before of course!). There is nothing in the IPCC report that should give you cause to think that there is no hope left to avoid the worst consequences of climate change. – gavin]

    Comment by Dianne Fristrom — 4 Sep 2006 @ 6:36 PM

  11. This applies to # 343 as well:
    A journalist is a person who knows nothing about it, but he is the public’s messenger. [The people at scientific publications are exempt from this category because they are publishing exactly what scientists write.] I found this out in the early 1960s when I was still in high school. The story in the newspaper had nothing to do with the real event. What it sounds like is more important than what it is. Since then, this has been confirmed many times. Sensationalism [Yellow Journalism] sells subscriptions. Broadcast news programs are classified as entertainment because that is what they are. It won’t get better until a high school diploma includes a B.S. degree in science. Until then, it would be nice if EVERY news story about science were required by law to be edited by the scientist, not just the early publications. Of course, this runs afowl the First Ammendment to the US Constitution. You are between a rock and a hard place or between the “devil” and the deep blue sea. Anything you say will be not just MIS-interpreted thruough profound ignorance but eventually DIS-interpreted by willful propagandists and by people who just want to make you angry. You have to consider insanity, stupidity, ignorance and a third grade level of reading comprehension to be “normal” because they are. The only solution I have is to “wait 4 million years for further evolution to produce a creature worthy of the name Homo Sapiens”. [Yes I know that evolution doesn’t have a direction like that.] I mean: as far as a solution to the problem goes, I give up, but the problem is bigger than you thought. You were lucky that the journalists got the subject right and you should praise them for that.

    Comment by Edward Greisch — 4 Sep 2006 @ 7:50 PM

  12. Errors such as these are peppered through the press. I recently came across an article in Australia’s Business Review Weekly (BRW), which stated that, under an emissions trading scheme, electricity prices will rise by 300%. Underneath the text was a graph that clearly showed a peak increase of around 15%.

    It’s so frustrating, because this type of misinformation can have a big impact on the sentiment of the population, which influences political legislation, and the general public is particularly susceptible to anything that will hit the hip pocket. Nobody would have bothered to look more closely at the graph, I only did it because I am involved with emissions reduction technology and intuitively I knew that the number was wrong.

    I think that everyone needs to be on their toes to correct and inform those that are making the (let’s assume) error. While the damage has been done in the initial print run, the combination of a correction in the next edition plus a sense that people are watching can’t hurt. Maybe it won’t solve the problem, but what else can be done?

    Comment by Tim Burrows — 4 Sep 2006 @ 11:38 PM

  13. Gavin, with regards to “Reporting on Climate Change: Understanding the Science” from your reply to #7, since you linked to it, I decided to read through it a bit to see if it covers some “basics” I might have missed. In chapter 1 on page 2 it says:

    Climate change, during the whole human past, has forced fundamental changes in how people live. It has influenced the beginnings and ends of cultures and civilizations. Global cooling – what we know as “ice ages” – has occurred as regularly as global warming, bringing large-scale benefit and harm to humans and other species. During the mid-1970s, many leading climate scientists were warning of the onset of another ice age and urging the government to take action to avert disaster.

    I felt rather uncomfortable about the last sentance there – comparing it to what’s written here:

    I also wasn’t particularly impressed with how some of the “facts and myths” questions were written or answered. For now, I’m going to carry on reading…

    [Response: Point taken. I have interacted with Bud Ward on a number of occasions and he is very open to improvements that can be made to the materials. Feel free to email him with any suggestions. -gavin]

    Comment by Chris Rijk — 5 Sep 2006 @ 6:23 AM

  14. Dear Group, nice to see you are still not commenting on comments on the IPCC. Just a friendly : I told you so.

    The Economist looks like a must buy this Friday for its special on Climate Change. Given that, and to its disgrace and only last year, it was almost a sceptic and denier it will be interesting to see what its position is today. We should all be able to guage better the accessibility of Climate Science to the rich and powerful and to the intelligent reader and voter.

    Comment by Eachran — 5 Sep 2006 @ 6:56 AM

  15. Re: a different part of Gavin’s response to #1

    I agree that Roesch’s results are not that important or interesting as far as climate research. It is not a new discovery that snow is highly reflective, nor is it a surprise that a forest and other vegetation in a snow cover area casts shadows on the snow that significantly alters albedo, adding complexity to models.

    However, as far as climate modeling (not the climate itself), Roesch’s work is perhaps the most important of the IPCC diagnostic subprojects, because of two results.

    ALL OF THE AR4 models had a systematic POSITIVE albedo bias, so they are less independent than has been assumed and the practice of summing or averaging the results in the hope of cancelling errors or reducing noise is plainly shown to be based on false assumptions.

    Second, Roesch’s work shows that regional albedo errors are large in their impact on the global energy budget, and therefore we cannot just accept modeler and IPCC handwaving about how the models differ in their regional distributions of temperature and precipitation. They must do much better in certain regions such as the temperate snow cover areas in both the total amount of cover, the type of vegation, the snow water equivilent (so that they get the timing of the spring melt right), because the effects on the albedo and energy budget are highly non-linear and the errors are larger than the energy imbalances that have caused the recent warming.

    Unfortunately, the models also have significant positive albedo errors in the tropical deserts, and Roesch did not provide much insight into what the models might be geting wrong there. In terms of the climate and not the modeling, I find this the most curious part of the his results, because it still seems unexplained. One would think that they would be a simpler part of the surface and the observations and thus easier for the modelers to get right. Perhaps dust and aerosols are the confounders.

    As far as putting off the IPCC report, I agree it is useful to have an assessment of the state of the science, if it is objective. However, the authors are climate scientists and those that are not modelers are probably still highly dependent on models for components of their research. It is simple human nature for them to want to cling to several years of work and not throw it out based on the obvious implications of the Roesch results. The errors are systematic and larger than what we are trying to measure and project and cannot be papered over by summing and averaging. All the global attribution and prediction work must be thrown out and redone, and much of the other work must be dismissed quantitatively and just mined for possible qualitative insights. It will be much easier on the authors human natures and less stressful on their scientific integrity, if we just postpone the next report a couple years.

    [Response: This is my final comment on this. The fact that averaging of different model results demonstrably increases the skill when compared to any individual model is possibly surprising, given that there are systematic biases in the models, but this is not an assumption, it is a result. The conclusion from this result (which was true for the original CMIP, CMIP2 and for the IPCC AR4 models) is that much of the error in climate models is not a systematic bias, but is uncorrelated across different models and thus can be minimised through averaging. Arguing that all models and the successful matches they have to many kinds of variability should be tossed out because of a 1.6 W/m2 error in surface fluxes is frankly ridiculous. – gavin]

    Comment by Martin Lewitt — 5 Sep 2006 @ 6:27 AM

  16. Emergency — some denialists I know are pressing me with the factoid that CO2 lags warming by 800 years in geohistorical proxy data. How do I counter this? Thanks for any help.


    [Response: Conveniently this one is already part of our FAQ. Specifically, see this guest post by Jeff Severinghaus of Scripps. – mike]

    Comment by Barton Paul Levenson — 5 Sep 2006 @ 8:15 AM

  17. Response to Gavin’s response to #14

    The average positive albedo bias of the AR4 models as reported by Roesch (0.016 to 0.019) corresponds to 2.6-3.1 W/m^2. The GISS-ER model was a little better than average. You are right, the uncorrelelated errors must dwarf this and other correlated errors. I am not arguing that the matches to various climate behavior are not a significant achievement and a validation of some of the basic physics within the models, they are. What should be thrown out are the quantative attribution of recent warming and the quantitative projections. The models just aren’t accurate enough to model and attribute under 1 W/m^2 global energy imbalances. I do believe that there is sufficient evidence to consider anthropogenic greenhouse gasses a significant contributer to recent climate warming on the principles of physics alone, but whether its contribution is 15% or 70% vis-a-vis solar, is just not within the skill of the models. The fact that they have been tuned to match variability against a period of warming, while have systematic biases against solar only decreases their credibility and calls into question their 2*CO2 sensitivities, because that is probably where some of the compensating errors landed.

    I consider the models, warts and all, to be remarkable achievements, and well worth further investment, but we don’t have the data and understanding yet to produce and validate the models to the approx 0.1W/m^2 globally and annually averaged, needed for useful attribution and projection.

    Comment by Martin Lewitt — 5 Sep 2006 @ 9:21 AM

  18. Re#14 Individual scientific integrity is not as important as the effects on human society of climate change induced freak weather. Fortunately climate scientists realise this. Bearing in mind the precept that science builds upon former endeavour, to put off the report would be to stem the flow of knowledge.

    Re#17 So, if we do discover, absolutely and without any uncertainty, that the sun is responsible for 50% of the warming, what can we do about the sun? If we suspect that anthropogenic CO2 is responsible for, say, 30%, could we do anything about that? Do you see my point?

    Comment by Sally — 5 Sep 2006 @ 11:19 AM

  19. Re: Sally #18,

    If we find that the sun is responsible for 50%, then we continue to study the Sun. Solanki (Nature) noted that based on past periods of high activity in the paleo record that there is less than 8% likelyhood of the current high levels of solar activity lasting another 50 years. Proponents of the solar conveyor theory predict that the next solar cycle will be particularly active, but that the current slowing of the conveyor means that the following cycle will be much less active.

    If CO2 is responsible for say 30%, we do what the market signals are telling us anyway, become more energy efficient. But given the uncertainty, there is no reason to sacrifice hundreds of billions of dollars of economic growth. The wealthy can afford the luxury of long range environmental thinking and research and have the power and resources to “weather” extremes and develop the technology which may reduce our environmental footprint. I use compact flourescent lights (and am eagerly waiting for LEDs to become economic), and my next roof will be white, these are good strategies no matter what the cause of recent warming.

    My point is, there is not yet good enough evidence to justify uneconomic expendatures and fearmongering about global warming. Curing diseases or discovering and diverting near earth asteriods may be more beneficial to humanity, so maximizing world economic growth is the best strategy to prepare for future known and unknown risks.

    Comment by Martin Lewitt — 5 Sep 2006 @ 12:08 PM

  20. RE: #19 – What happens to California over the next 20 years will be an interesting experiment, to say the least. The first time a major political entity took this sort of risk based solely on the results of still-being-refined models. Here is the perspective. Arnie guesses that enough other political entities will do the same, that we will not lose our industry. He also guesses that the PR value of “being green in California” will retain businesses and even feed new technological spend (e.g. solar cells, etc.) Quite a risk when there are much more business friendly states out there (e.g. they are already demonstrably more capitalistic then this quasi Scandanavian state) who would be superior places for developing and manufacturing “green” technology. Heck, why not do it in the PRC, for that matter? So, we’ll be both capped and tapped.

    Comment by Steve Sadlov — 5 Sep 2006 @ 3:49 PM

  21. I’m sure this is getting well off-topic but, while conventional energy prices are rising, don’t you think that economic growth is being somewhat restricted to the providers? Less expensive, renewable energy is going to maximise world economic growth. Without fouling the air and water, and without promoting more catastrophic and expensive weather events. Climate events and disease restrict economic growth.

    Comment by Sally — 5 Sep 2006 @ 7:06 PM

  22. My hope for the next IPCC report is that the specific criticisms in the recent NAS report are addressed specifically. What a wonderful opportunity for the IPCC core contributors to admit where they have been in error, to defend where they are right (by this I mean, objectively right, not “legend in your own mind” right) and to set out a course for a more refined and in depth understanding of climate change, and all the factors driving it, anthropogenic and non anthropogenic. In the realm of anthropogenic factors, I think it’s time for the IPCC to address things beyond GHGs while of course continuing to improve our understanding of GHG related mechanisms and impacts. In the real of non anthropogenic factors, I thing a much more interdisciplinary approach is needed, bringing in more astrophysicists, experts in incident cosmic radiation, experts in plasma physics, and from another perspective, a much greater contribution from classical Earth Sciences. From the statistics front, there is wealth of experience and knowledge to be tapped outside of the traditional confines of “Climate Science.” A motto of a famous university “Let There Be Light!”

    [Response: Thanks. I don’t think we’d have thought of that …. – gavin]

    Comment by Steve Sadlov — 5 Sep 2006 @ 9:56 PM

  23. Re: #22

    My hope for the next IPCC report is …
    [Response: Thanks. I don’t think we’d have thought of that …. – gavin]

    I’d say the question behind #22 is whether, as an institution, the IPCC is intrinsically capable of adopting a broader church approach. AR4 may tell us.

    [Response: Also re 22: I think it is more realistic to view IPCC as a process which temporarily brings together a large group of scientists to do a particular job, rather than as an institution. I am co-authoring a chapter in the upcoming IPCC report (and it happens to be the chapter dealing with the topic of the NAS report). There is no “institution” telling us what to write – we simply make our best effort at writing what we think is a correct assessment of the existing scientific literature, and we’ve put out our efforts for criticism by the wider community in three rounds of review now. We don’t think of the last IPCC report in terms of “we were wrong or right back then”, or needing to defend anything, because none of us was an author of the last report. It’s simply a new group of people looking at the evidence with a fresh mind. -stefan]

    Comment by Jo Calder — 6 Sep 2006 @ 3:24 AM

  24. Re #13 Chris, you really shouldn’t believe everything that those scientists tell you :-)

    They got it wrong about phlogiston , aether, and about the sky is falling.

    I wonder what they have got wrong now :-(

    Comment by Alastair McDonald — 6 Sep 2006 @ 12:31 PM

  25. Re #22 I had a look on the NAS web site for a recent report, but could not find anything. Do you have a link to the report you are discussing?

    [Response: See response to comment #7. -gavin]

    Comment by Alastair McDonald — 6 Sep 2006 @ 12:53 PM

  26. I thought he was referring to: Wigley, Tom M. L., Ramaswamy, V, Christy, J.R., Lanzante, J.R., Mears, C.A., Santer, B.D. & Folland, C.K., (2006) “Temperature Trends in the Lower Atmosphere – Understanding and Reconciling Differences”, Executive Summary, NRC. at: which is a NAS website!

    I did not want to comment in case I had the wrong report.

    Comment by Alastair McDonald — 6 Sep 2006 @ 1:25 PM

  27. Re: Stefan’s response to #23

    You note that:

    “We don’t think of the last IPCC report in terms of “we were wrong or right back then”, or needing to defend anything, because none of us was an author of the last report.”

    If that is the case, shouldn’t more care or clarifying information be provided when using phrases such as “more…confidence”, “higher…confidence”, “increasing…confidence” and “greater…confidence”, since the natural implication is that this refers to that perhaps unjustifiably high confidence expressed by the authors of the TAR?

    Any “high…confidence” in models’ skill to reproduce the paleo climate, should be quantified, so that it is clear what level of skill was required for such relatively coarse reproductions of paleo climate behavior modes, and that these comments should not be viewed as supportive of the skill levels needed to attribute the recent warming or to project the next century or so of future climate. The meaning of expressions such as “high…confidence” should be standardized or explicitly qualified so that it is clear that their meaning does not spill across the various chapters.

    Comment by Martin Lewitt — 6 Sep 2006 @ 1:46 PM

  28. RE: #27 – Indeed I have found that spending some quality time writing down well thought out operational definitions can really help get everyone on the same page in terms of analyzing a problem.

    Comment by Steve Sadlov — 6 Sep 2006 @ 2:07 PM

  29. Re 24

    Yep, sometimes scientists get things wrong – like maybe the feedback from permafrost? See

    Is this being included in IPCC projections?

    Comment by Ron Taylor — 6 Sep 2006 @ 3:13 PM

  30. Dear climate thinkers, Given the current lack of regualiton of Greenhouse gas emissions, I assume there is a theory that claims that our increasing of greenhouse gases are not contributing to global warming? If so, can anyone direct me to the location of a credible resource showing a head to head comparison of the weight (and type) of evidence for the effect of GHG versus the weight of evidence for the claim that GHG is not contributing to global warming?

    That is, evidence that supports the Greenhouse Gas Effect theory Vs evidence that support the counter theory that increasing greenhouse gases are not contributing to global warming.

    [Response: Curious logic…. But the best assessment of all the possible theories is the IPCC report (see the links on the right). – gavin]

    Comment by Mark B — 7 Sep 2006 @ 1:44 AM

  31. Are you sure that the phrase: “1.4C and 5.8C on current levels by 2100, but better science has led them to adjust this to a narrower band of between 2C and 4.5C.” Doesn’t refer to the improvements in the sensitivity over the whole range of emissions scenarios?

    [Response: 2 to 4.5 C refers to sensitivity to 2xCO2 – but is applicable to the whole range of forcings. 1.4 to 5.8C is the range of temperature at 2100 over all the different scenarios – they are related but they are not the same. Most of the range at 2100 is related to the range of scenarios, not the range in sensitivity. -gavin]

    Comment by andrew worth — 7 Sep 2006 @ 7:49 AM

  32. Man, this story really brought out the anti-climate science lurkers! I guess that most of them only bother talking when the story is an IPCC one – maybe that’s the only one that they’re really worried about, since a strong IPCC could actually lead to policy outcomes. I mean, every other story on RealClimate gets maybe zero to two “”skeptical”” posts, but this one has several, and not just from Mr. Lewitt. The Prometheus link you cited, , has a bees’ nest of lurkers, many of them more misinformed than here. The sociology of this story is fascinating, as much of the native-English world is waking up to the reality of fossil-fuel-caused climate change. Most of the rest of the world is there already, of course.

    One tiny correction, gavin, in your response to Mr. Lewitt’s increasingly voluminous posts #14, you said that “The conclusion from this result… is that much of the error in climate models is not a systematic bias, but is uncorrelated across different models and thus can be minimised through averaging” The bias in each model may be systematic, or it may not. However, the fact that the error is uncorrelated means that averaging will improve the result. This is often done in measurement generally – if I measure a given length with 3 rulers from different manufacturers, and take the average of the 3 lengths, I will get a more precise result if the rulers’ errors are uncorrelated. Manufacturer A may always be high, and B may always be low – hence systematic errors – but the average is more precise because of this. This is silly for rulers, but not so silly for femtogram masses or pooled astrophysical measurements. Anyway, you’re still almost assuredly right – the biases aren’t systematic, but they *could* be, and averaging would still be a good trick. By the way this “average of independent models” is called bagging in the machine learning literature, and it’s been working there since Leo Breiman suggested it in 1996. See for examples.

    [Response: Thanks. You are correct of course. I was referring to systematic biases across models (which do nevertheless exist), as opposed to systematics biases within each model (which certainly exist and can be very significant). In climate circles, this averaging is generally referred to as a ‘meta-ensemble’ but thanks for the link to the other fields’ usage. -gavin]

    Comment by Steffen Christensen — 7 Sep 2006 @ 10:41 AM

  33. With respect to comment #3 and the two responses to it, we might try another tack. With respect to total error of the model, a 1 W/m^2 absolute error is about 1% of the total – which is not bad, actually, 99% correct. An example of another measurement with significant global error but only modest relative error is mass of the Earth. We know the absolute mass of the planet in kilograms to the precision of Newton’s constant G, which in 2006 has a 95% chance of being accurate to 0.030% (|search_for=G ). Before 1998, discrepencies in reported values led to an absolute error 100 times this, namely 3% ( ). Clearly before 1998, we could measure things to relative precisions of better than 3%! In fact, the gravitational attraction power of the Earth, GM, has been known to about 1 part per billion = 0.0000001% since 1996 from bouncing lasers off the LAGEOS satellites ( ). I really fail to see how this absolute error in the models matters, save as a linguistic tool to cast doubt on unfavourable results.

    Comment by Steffen Christensen — 7 Sep 2006 @ 11:12 AM

  34. RE: #30 – “I assume there is a theory that claims that our increasing of greenhouse gases are not contributing to global warming? ”

    If there is, I have yet to find it. That said, there is certainly room for debate regarding the apportionment of overall warming (and cooling) trends to which forcings.

    Comment by Steve Sadlov — 7 Sep 2006 @ 1:12 PM

  35. By the way, what does “Chinese whispers” mean?
    I’ve never encountered that phrase before.

    [Response: -gavin]

    Comment by SecularAnimist — 7 Sep 2006 @ 1:38 PM

  36. Re #32 where Steffen wrote “the fact that the error is uncorrelated means that averaging will improve the result.”

    There are two mistakes being made here. First we do not know if there is a systematic error, because the models cannot be tested against the future climate they are predicting. Second, if a systematic error does exists it will not be uncorrelated because all the models share the same algorithms, which are published in the literature. In other words it is a double whammy!

    Comment by Alastair McDonald — 7 Sep 2006 @ 1:55 PM

  37. The wealthy can afford the luxury of long range environmental thinking

    That presumes that the consequences of environmental change are slight and absorbable. Some scenarios are horrific for all and produce economic conditions that would make wealth evaporate like snow in the sun.

    Comment by Jeffrey Davis — 7 Sep 2006 @ 3:21 PM

  38. 1.4 to 5.8C is the range of temperature at 2100 over all the different scenarios in the 2001 report, Do you know if the leak contains the eqivalent data in the upcoming report?

    Comment by andrew worth — 7 Sep 2006 @ 4:40 PM

  39. I guess this is off-topic, but it’s just out and it sounds to me like bad news.

    Anyone care to whisper in Chinese that it’s not as bad as it sounds?

    Scientists Find New Global Warming ‘Time Bomb’
    by Seth Borenstein
    September 7, 2006
    The Associated Press


    Global warming gases trapped in the soil are bubbling out of the thawing permafrost in amounts far higher than previously thought and may trigger what researchers warn is a climate time bomb.

    “The effects can be huge,” said lead author Katey Walter of the University of Alaska at Fairbanks said. “It’s coming out a lot and there’s a lot more to come out […] I don’t think it can be easily stopped; we’d really have to have major cooling for it to stop.”

    Scientists worry about a global warming vicious cycle that was not part of their already gloomy climate forecast: Warming already under way thaws permafrost, soil that has been continuously frozen for thousands of years. Thawed permafrost releases methane and carbon dioxide. Those gases reach the atmosphere and help trap heat on Earth in the greenhouse effect. The trapped heat thaws more permafrost and so on.

    Comment by SecularAnimist — 7 Sep 2006 @ 7:08 PM

  40. There is nothing in the IPCC report that should give you cause to think that there is no hope left to avoid the worst consequences of cliamte change. – gavin

    If we can avoid ice ages and cold winters, and expose more land area currently made useless by ice coverage, why shouldn’t we embrace climate change?

    Has the IPCC done a cost-benefit analysis of climate change?

    Comment by Crocodile Hunter — 7 Sep 2006 @ 7:36 PM

  41. Alastair, #36: “… the models cannot be tested against the future climate they are predicting.”

    Er, why? And when do you believe this testing ceased to be possible?
    Certainly there’s a long record of these tests succeeding.

    Just one example:

    Comment by Hank Roberts — 7 Sep 2006 @ 8:14 PM

  42. Also, tangential to the thread but fascinating —

    Comment by Hank Roberts — 7 Sep 2006 @ 8:15 PM

  43. Re: #39

    I saw the story too.

    Anyone care to whisper in Chinese that it’s not as bad as it sounds?

    I wish I could. But — unfortunately — it just might be as bad as it sounds. It might be even worse.

    *As far as I know*, climate models include as many factors as practical but do *not* include feedbacks to the GHG cycle. In particular, they don’t treat the increase in GHGs, esp. methane, that may result from global warming. Frankly, the model forecasts are plenty scary without such feedbacks, but *with* them (and their reality is hard to deny) things are, as you say, far scarier.

    Be afraid. Be vary afraid. And vote the bums who are obstructing action on this issue, the hell out of office.

    Comment by Grant — 7 Sep 2006 @ 8:26 PM

  44. Well, even if the actual state of affairs is that climate warms by, say, 4.5 degrees C by 2100 (the new upper sensitivity of 2Xco2), or even 3 degrees, (1) that’s pretty dangerous; and (2) it says nothing about how hot it will be in 2150 or 2200. So, we’re certainly not in the clear.

    And with that Antarctic ice core data, we now have a new runaway tipping point of no return, set for possiblty a decade from now: see

    Comment by Lynn Vincentnathan — 7 Sep 2006 @ 10:39 PM

  45. As much as we might debate the pros and cons of Steve Irwin’s career, I don’t think Crocodile Hunter (#40) has a right to his legacy. Barley at high latitudes as a trade-off for disruption of low- and mid-latitude agriculture that sustains billions? Crikey!

    Comment by David Graves — 8 Sep 2006 @ 2:41 AM

  46. Re #39 It is not as bad as it sounds because in an atmosphere as rich in oxygen as that here on earth, methane has a very short lifetime of 8.4 years. Moreover, the amount of methane being emitted as the permafrost melts, 3.8 Tg per year, is small compared to the estimate of total global methane production, which is 600 Tg per year. Finally, there is a fixed amount of methane in the Arctic, so once it has been released and oxidised it is no longer a threat.

    That is the good news – now for the bad news :-(

    There is another melt going on in the Arctic, and that is the Arctic sea ice. As it melts, it is releasing the main greenhouse gas – water vapour. Of course H2O has an even shorter atmospheric lifetime than methane, but the quantities that will be added to the atmosphere will far outweigh the effects of methane. Moreover unlike methane which is destroyed, there is effectively an unlimited amount of water available since it is recycled.

    The reason that the scientists are panicking about methane is because they fear it may have been the cause of the unexplained rapid warming of 20K at the end of the Younger Dryas (YD) stadial. However, recent tests of the Greenland ice cores at the YD/Holocene boundary have shown that there was no sudden increase in methane then. The YD rapid warming was most likely caused by the increase in water vapour when the sea ice that stretched as far south as Ireland suddenly disappeared.

    In other words we are out of the frying pan and into the fire!

    Comment by Alastair McDonald — 8 Sep 2006 @ 5:50 AM

  47. As mentioned in #15, The Economist has a 12 page survey on climate change. You can see the first page for free here:
    There’s also an audio interview here:

    Personally, I’m not particularly impressed with what I’ve seen so far. Dealing with AGW is treated like getting insurance – chuck a bit of money in, and maybe things won’t be so bad. When I get a chance I’ll try to read the whole (or most of) the article. I’m not sure if I’ll learn anything new.

    I feel that one of the biggest issues with actually dealing with climate change is the almost universal assumption that it *has* to cost lots of money to fix. It’ll require investment, yes, but proper investment (in the normal business) sense means you get a return (profit) on that investment. Better energy efficiency means lower costs and higher profits. Given the rather low priority energy efficiency has been given since the 1970s oil shocks ended, I think there’s a lot of low hanging fruit out there.

    Comment by Chris Rijk — 8 Sep 2006 @ 6:58 AM

  48. Re #41 Hank, the current climate models are predicting the climate 50 and 100 years ahead e.g for 2100 CE. We will not know for sure that the predictions are correct until then. Weather models are different. They predict one or four days ahead, and these are always being checked, and improved. There is no feedback from the climate models so we just have to trust that they are OK.

    We can also check to see if they can reproduce past climates, although that is no guarantee that they can successfully predict the future. For instance, they may be able to predict the current linear climate successfully, but fail to predict a future non-linearity.

    This may seem rather philosophical, but you have to bear in mind that although the models can show the cooler glacial climate of the last glacial maximum, that is doene by tuning the CO2 sensitivity. Worse, the models cannot replicate the non-linear abrupt climate changes such as that at the end of the Younger Dryas stadial.

    We have a peer review system where climate model experts check the papers of other climate modellers. If all the modelers are wrong, there is no independent way of discovering it.

    You cite Santer as an example of someone who has checked that the models are correct, but that is not what he did. He argued that the models were correct hence the measurements made by the radiosondes must be wrong.

    The NRC report about that says:

    “Although the majority of observational data sets show more warming at the surface than in the troposphere, some observational data sets show the opposite behaviour. Almost all model simulations show more warming in the troposphere than at the surface. This difference between models and observations may arise from errors that are common to all models, from errors in the observational data sets, or from a combination of these factors. The second explanation is favored, but the issue is still open.”

    If the first explanation is correct then no matter how many versions or parameters are varied, averaging will not improve the results!

    Comment by Alastair McDonald — 8 Sep 2006 @ 6:52 AM

  49. Chris Rijk, I think that you are being a bit hard. It is a bit like insurance and if you have the job of persuading people to do something different which costs money then that is a fair analogy.

    You are correct though, you will not learn anything new : that is not the point of the journal’s survey.

    I have read the leader which is positive and more than I expected. I shall read the supplement over a few beers tomorrow.

    If Gar Lipow is there I shall be pleased to hear what you have to say and of course Lynn, Grant (a bit tough in your latest comment above, statisticians are not supposed to be like that), and all of you regular and not so regular contributors. The Group’s response would be of interest for me of course and always.

    We have a serious problem with warming which needs to be fixed and nobody wants to do anything about it : The Economist leader helps rather than hinders the pressure for action.

    Comment by Eachran — 8 Sep 2006 @ 9:08 AM

  50. Grant (a bit tough in your latest comment above, statisticians are not supposed to be like that)

    Thanks for giving me a good laugh at my own expense! It’s good that you can poke a few holes in my zealous statements in the gentlest possible way. Political zeal is better reserved for political blogs rather than scientific ones.

    Comment by Grant — 8 Sep 2006 @ 12:21 PM

  51. Just a point for Gar or anyone else interested, we were talking about elasticities sometime ago.

    France has reported a drop in car use and in increase in public transport use since price increase of petrol/gas. I dont know what your French is like but the report is not difficult to understand.

    Les Français prennent moins leur voiture à cause du prix de l’essence

    Les Français ont moins pris leur voiture en 2005 qu’auparavant: pour la première fois depuis près de 30 ans, la circulation des véhicules particuliers a diminué sous l’effet de la hausse des carburants et du développement de l’offre de transports collectifs. Selon une étude du ministère des Transports publiée vendredi, la circulation des voitures particulières a baissé de 1,4% en 2005 en France, “pour la première fois depuis 1974, année du premier choc pétrolier”, lorsque les tensions géopolitiques au Proche-Orient avaient fait bondir les cours du pétrole. En 2005, l’automobile a représenté 83% du transport intérieur en France, les transports ferroviaires 10%, les autobus et cars 5%, et enfin le transport aérien 2%. Après avoir augmenté en moyenne de 2% par an pendant les années 90, la circulation des voitures (mesurée en véhicules-kilomètres) en France a peu à peu ralenti, ne croissant plus que de 0,6% par an entre 2000 et 2004, année de “stabilisation du trafic”. “L’augmentation des prix du carburants depuis 2003 explique en partie la baisse de l’usage de la voiture en 2005”, estime l’auteur de l’étude, Guillaume Wemelbeke. La voiture coûte en effet de plus en plus cher au consommateur, et de ce fait “les ménages ajustent leurs comportements face à la hausse des prix des carburants”, relève-t-il dans son étude sur la “mobilité des Français en 2005”. Non seulement les Français prennent moins la voiture mais ils en achètent moins qu’avant: “La croissance du parc automobile est désormais faible”. Ce sont surtout les prix à la pompe qui douchent l’enthousiasme des automobilistes: ils ont augmenté ces deux dernières années de 24%, note M. Wemelbeke. Le baril de pétrole est passé en effet d’une trentaine de dollars fin 2003 à plus de 75 en 2006, en raison d’une demande mondiale en hausse et de tensions géopolitiques persistantes dans les régions productrices. Cette hausse spectaculaire des prix de l’essence a aussi entraîné une baisse de la consommation de carburant: elle a diminué d’environ 0,8% par an durant la période 1999-2005. Une décrue qui s’explique aussi toutefois “par une baisse de la consommation moyenne des voitures” (6,91 litres pour 100 km en 2005 contre 8,2 en 1990) et par celle de la vitesse moyenne des conducteurs (-6 km/h à 83,1 km/h), selon l’étude. Les autoroutes sont les moins touchées par le recul de la circulation des véhicules particuliers: elle y a augmenté en 2005, mais de 0,6% seulement, après une croissance de 2,3% par an entre 2001 et 2005. Parallèlement à la baisse de la circulation automobile, la fréquentation des transports collectifs est en constante progression. “Ils bénéficient d’une augmentation et d’une amélioration de l’offre mais aussi de prix attractifs”, comparé à la voiture, souligne l’étude sur la mobilité des Français. Depuis 1996, la circulation par transport collectif n’a cessé d’augmenter tous les ans (sauf en 2003), en particulier pour le ferroviaire (trains et métro) et surtout à Paris. Selon l’étude, les tarifs des transports collectifs n’ont que “modérément” augmenté depuis 1999, avec une hausse moyenne annuelle de 1,8% soit “à peine plus vite que l’inflation (+1,5%)”. Le secteur profite également de la progression des subventions publiques. Pour les longs trajets, c’est le TGV qui porte la croissance de la circulation, au détriment du transport aérien, lorsque les deux modes de transport sont en concurrence. La circulation sur les vols intérieurs, qui avait progressé fortement entre 1990 et 2000 (+2,9% en moyenne), s’est repliée en 2005 à ses niveaux de 1995. En revanche, vers l’étranger, la circulation des Français en avion progresse, avec notamment une hausse de 7,8% en 2005.

    The only bad news is airline flights to foreign places. We ought to be able to fix that I would have thought.

    Serious stuff here and good news for those like me who want to use the price system to fix things.

    Comment by Eachran — 8 Sep 2006 @ 12:23 PM

  52. Re#40 “If we can avoid ice ages and cold winters, and expose more land area currently made useless by ice coverage, why shouldn’t we embrace climate change?

    Has the IPCC done a cost-benefit analysis of climate change?”

    Rather ironic someone calling themselves “Crocodile Hunter” aka Steve Irwin should speculate about benefits of global warming when the Great Barrier Reef is in great danger of being destroyed in the lifetimes of people alive today. Not to mention that Australia in general is already suffering substantial reductions in rainfall and increases in evaporation that will get worse as global warming progresses.

    Maybe places that are covered by snow for a lot of the year will get some benefit from global warming but Australia is not one of those places. Australia will be a major loser from global warming.

    Comment by Chris O'Neill — 8 Sep 2006 @ 12:38 PM

  53. @52
    I think everybody will loose(Nature doesn’t know what Man-Made borders are), maybe some individuals are able to create a very good adapted life sustain system at the poles, while the rest of the world goes down in chaos?
    Also “places” in snowy areas will be effected by collapsing balances of ecological systems.
    Lifeforms wich can fast mutate and adopt to the changing enviroment will make plagues and destroy other life by taking all the food(I think these are mainly simple organism, organism with fast lifetime, eg. birth rate).

    It will be like some have reserves and once these gone it’s all anarchy.

    Comment by — 8 Sep 2006 @ 12:54 PM

  54. In addition to the “survey” of AGW in the Economist, there’s this fascinating editorial:

    It seems to me that the piece doesn’t do a very good job on the science, but doesn’t do *that* bad a job either. It definitely tends to underplay the risk with statements such as, “The bottom end of the range would make life a little more comfortable for northern areas and a little less pleasant for southern ones,” “450ppm is reckoned to be ambitious and 550ppm liveable with,” and “The system could right itself or spin out of human control.”

    However, the encouraging aspect of the editorial is that it emphasizes the need for action. Now. It also points out that even a small chance of catastrophic climate change is sufficient motive to *do* something. Furthermore, it points out that the cost of doing so is unlikely to be prohibitive: “And the slice of global output that would have to be spent to control emissions is probably not huge,” “Some models suggest there would be no cost; others that global output could be as much as 5% lower by the end of the century than if there were no attempt to control emissions. But most estimates are at the low end – below 1%.” They’re also unafraid to name names: “Although George Bush now argues that America needs to wean itself off its dependency on oil, his administration still refuses to take serious action.”

    Perhaps the most important aspect is that the issue is getting such high visibility. Global warming is the *cover story* in this issue of the Economist. And instead of taking the old conservative line, arguing that it’s all a bunch of left-wing hoopla, the issue treats AGW as an established fact. I think the denialists should listen to the Wagnerian soprano doing her warm-ups.

    The biggest omission, in my opinion, is consideration of the cost of *not* acting. Even if it costs 5% of global output to act, the cost of inaction seems to me to be drastically higher. But for a conservative financial magazine to address the issue at all is a breakthrough; to do so with anything near realism is cause for celebration.

    Humorous note: you know you’re thinking about AGW too much when … you see a tag-line for a story, “Fancy a Swedish Model?” but instead of thinking of the Swedish bikini team, your first thought is, “I wonder what’s different about Swedish GCMs?”

    Comment by Grant — 8 Sep 2006 @ 1:11 PM

  55. I’ve now managed to read most of the survey in The Economist on AGW. The remaining pages (ie most of the article) were definitely better on average, I’d say. Still room for improvement – eg, though they covered ice melting on Greenland etc vs new formation, I don’t think they mentioned the satelite based gravity measurements to determine the net changes. There’s a bunch of things I think they missed, but since I haven’t read it all, I can’t be sure.

    The part on feedbacks was good, though very brief. They also made it completely clear later on that the range of potential warming also depended on how the world’s economy could change by 2100, not just uncertainty in the models – but still didn’t give the ranges for (say) 2x CO2. I remember a brief article covering an aspect of AGW in The Economist a few months ago, and they seem to have changed their thinking on that since then – well, assuming that they don’t change back, given that different writers would cover things in different ways.

    [Response: We’ll do a proper survey of their survey once I get my hard copy on Friday…. – gavin]

    Comment by Chris Rijk — 8 Sep 2006 @ 2:55 PM

  56. As one approach to generating a rough order of magnitude estimate of the cost of NOT mitigating AGW consider building a multi-billion dollar New Orleans magnitude levee system around each of the major American coastal cities, including: Boston, Providence, New York, Newark, Philadelphia, Baltimore, Washington DC, Richmond, Charleston, Jacksonville, Daytona, Miami, Tampa, Biloxi, Galveston, Houston, Corpus Christi, San Diego, Los Angeles, Santa Barbara, San Francisco, Portland, Tacoma and Seattle. Add to that the cost of having to rebuild EVERY commercial port facility (and many airports) in America to accomodate the higher sea level. Add the cost of relocating the hundreds of thousands of coastal residents who live outside of cities we can protect with levees. Go ahead and add in any other AGW-related disruptions that come to mind. And finally, add in the cost of converting from a petroleum-based economy to something more sustainable because, whether we like it or not, oil is running out. It quickly becomes apparent that ‘Business as Usual’ is the most expensive choice we can make.

    Comment by Phillip Shaw — 8 Sep 2006 @ 4:51 PM

  57. Busy thread – nice to see the diversity of opinion out there! Re: #36 – Alastair’s comment about not being able to test climate against the future results. First, saying it again and again doesn’t make it so. That never works. Second, while there are legitimate questions about “what is being modelled in your GCM”, and “will feedbacks with small effects so far become large in the future, and mangle these results”, the philosophical argument that the future hasn’t happened yet so modelling is naive at best is quite weak. If true, that would apply equally to, among others, astrodynamical models of the motion of solar system bodies, which have had a spectacularly successful track record. JPL’s DE405 model of solar system motion, for instance, routinely predicts motions of the major bodies to within 0.000003%, or 100 kilometers at the orbit of Saturn, 50 years in the future ( ). They test that model, among other methods, by running it backwards in time and comparing with observations. It is also accurate enough to navigate spacecraft over the solar system, of which there are a good many. Further, it is exquisitely accurate at predicting eclipses, occultations, transits and so on, many of which have sub-second accuracy. I’m not saying that we’re at that kind of precision in the GCMs, but it’s just ludicrous to say that the lack of independent testing means that you shouldn’t have confidence in the results. Citizens of the whole planet rely on the fact that no asteroid is going to smash into them next month or next century – and guess what is predicting the orbits and calculating risk numbers ( )? An untestable model.
    Third, the models do share the same physics (more important than the specific algorithms used, by the way), and so will tend to give the same results that way. Fortunately for us, the universe shares those same physics as well. For instance, JPL has their DE405 integrator; I have my own integrator I wrote from the ground up. Mine uses pure Newtonian gravity and a Cash-Karp integrator right out of Numerical Recipes in C. However, because we’re both using the same physics, when I seed it with numbers out of the DE405 runs, it generates planetary motions that are pretty darn accurate all the way out to the limit of DE405’s range. I wouldn’t send a spacecraft to Pluto using my own orrery, but I would bet a week’s pay that the Earth will be where my program says it will be in 50 years. That’s the power of modelling for you.

    Thanks, folks. I apologize for the rant.

    Comment by Steffen Christensen — 9 Sep 2006 @ 10:15 AM

  58. Re #56: add in the cost of converting from a petroleum-based economy to something more sustainable because, whether we like it or not, oil is running out

    If oil is running out regardless, what has converting away from it as an energy source got to do with a cost-benefit analysis of global warming?

    And why does a sea-level rise of 14cm-43cm by century’s end require us to build New-Orleans-size levies around every major coastal city? Or rebuild EVERY port?

    And then we have #52 and #53: doomsayers sans analyses.

    Given the underwhelming response to my simple request for cost-benefit analysis, you’ll forgive me for concluding that those who advocate drastic action do so on the basis of ideology, not rationality.

    Comment by Crocodile Hunter — 9 Sep 2006 @ 9:29 PM

  59. I would be interested in any comments concerning possible cooling risks and risks associated with low levels of CO2. I thought the earth is colder and CO2 levels are lower now, than at anytime in last 200 million years. What were CO2 levels say 100 million, 65 million, 36 million, and 3 million years ago?

    The CO2 level dropped to about 180 ppm at the end of the last few glacier periods. The Rusian climatologist, M.Budyko, in his book “Climatic Change” stated that total glaciation would occur at around 150 ppm. Is that correct? If not, at what level would complete glaciation occur? At what level does photosynthesis stop?

    How would the earth react to a short term cooling event, say a medium size impact event, without the heat that was in the past stored in the oceans? I thought the deep ocean is now minus 2C to plus 5C where it was I believe in the past 10C to 15C. Is that correct?

    Is the IPPC only concerned with warming?

    Comment by astley — 10 Sep 2006 @ 2:34 AM

  60. “Is the IPPC only concerned with warming?”

    No, the IPCC is only concerned with getting more funding. That’s why the IPCC Third Assessment Report’s “projections” were unfalsifiable pseudoscientific nonsense. And that’s why their Fourth Assessment Report’s “projections” will be the same.

    And why does no one in the “climate change community” (e.g. Real Climate) or scientific journals (e.g. “Science,” Nature…or the hilariously named “Scientific” American) call the IPCC on their pseudoscientific nonsense?

    See statement #1.

    Comment by Mark Bahner — 10 Sep 2006 @ 10:05 AM

  61. Re: #58

    Given the underwhelming response to my simple request for cost-benefit analysis, you’ll forgive me for concluding that those who advocate drastic action do so on the basis of ideology, not rationality.

    Perhaps one of the reasons we’re reluctant to do a “cost-benefit analysis” is that we’re not sure what it is. It conjures images of a formal economic procedure, and we don’t know what that is or how to do it. Perhaps it’s as easy as estimating the costs and estimating the benefits; if so, we can take a stab at that. But probably the most common occupation of regulars here is *scientist*. If I went to a blog for economists about the economics of global warming, and asked them to do an analysis of the TOA energy budget or comment on the appropriateness of 1-D layer models in borehole temperature reconstructions, they’d probably feel a little daunted. I wouldn’t interpret their lack of response as ideological.

    Another reason may be that we’re suspicious of those who would put a dollar value on human (or other!) life and human misery. It seems that cost-benefit analysis may be a fancy way to “discount” what’s really valuable, in order to suggest that action on global warming will ruin our economy. And the greatest burden of global warming is likely to be borne by the poorest people, those in 3rd-world countries. Very few of us trust economic analysis properly to account for the value of their lives and the cost of their suffering.

    Probably the reason many of us are motivated to action on global warming is that it will disrupt ecosystems, bring about more natural disasters, and threaten food and water supplies. The destruction and misery wrought by Hurricane Katrina isn’t ideology; it’s fact. Whether or not Katrina was a result of AGW, we don’t know, but it’s very likely that AGW will lead to a marked increase in such disasters. And, changes to the hydrologic cycle may bring our economic, nay our life-support systems, to their knees.

    From what I’ve learned, the last time earth saw a global temperature increase as large as we expect, in as short a time, was the Permian-Eemian Thermal Maximum (PETM). The consequence was: the death of 90% of species on earth. What’s the cost-benefit analysis of that?

    Comment by Grant — 10 Sep 2006 @ 10:20 AM

  62. And why does a sea-level rise of 14cm-43cm by century’s end require us to build New-Orleans-size levies around every major coastal city? Or rebuild EVERY port?

    That’s what some models predict.

    James Hansen has pointed out that the fossil record is another model. And that the last time temps were 3C higher that seas were 25m higher. (That’s ~100 ft. If seas rise 100ft, Florida looks like, well, a sting ray’s tail.) Hansen admits that there are no computer models that share that prediction. Still, the historical record should have an impact on our thinking, don’t you think?

    Comment by Jeffrey Davis — 10 Sep 2006 @ 11:04 AM

  63. Re #57 Steffen, you makes three very good points.

    First you argues that repeating a fact does not make it true. However, neither does it make it false. Of course everyone has a right to believe what they like, but I wonder what you think the global temperature will be in 2100? The computer models say 1.5 to 5.6 C higher than today. That is a pretty large range, and we can only wait until 2100 to know the answer.

    Your second point is “the philosophical argument that the future hasn’t happened yet so modelling is naive at best is quite weak” is also true, but that is not what I am arguing. What I am arguing is that you should only trust models when when they have been verified. The astrodynamical models were verified as long ago as 18th century, when the return of Halley’s comet was accurately predicted. But the dynamical system which describes the Solar System is much simpler than that which describes the Earth’s atmospheric system. As Henri Poincare, the father of chaotic dynamical systems, once wrote:

    “Why do the rains, the storms themselves seem to come to us by chance, so that many persons find it quite natural to pray for rain or shine, when they would think it ridiculous to pray for an eclipse?”

    The third point is a common misapprehension, that the climate models are based on physical laws similar to those used in your integrator. There are two differences. In your integrator, there are a finite number of planets which are all handled using Newton’s well known laws. In the case of the weather/climate there is an infinite number of molecules, and so they cannot be individually modeled using Newton’s laws. Moreover, the greenhouse effect depends on quantum mechanics, which is not only much newer than Newton’s laws it is also much more complicated. Hence its effects are paramaterised along with the clouds which are also too complicated to simulate in real time. You rightly claim that you can predict the position of Pluto up to 50 years ahead. However, neither the global warming sceptic Gray, nor NOAA can predict the number of hurricanes five months ahead!

    Modelling the climate is a diffent thing completely from modeling planets, and we have only one chance to get it right. Any criticism of the climate models should be fully investigated, not brushed aside as has happened with the MSU results. The only check on the models prior to 2100 is that criticism. If we have to wait until then to discover that the models are wrong, it may be too late!

    Comment by Alastair McDonald — 10 Sep 2006 @ 11:26 AM

  64. Re: #60

    No, the IPCC is only concerned with getting more funding.

    Your entire comment is ad hominem. Maybe that’ll be persuasive to the naive, but not to very many here.

    Comment by Grant — 10 Sep 2006 @ 1:18 PM

  65. Re: 61
    “Probably the reason many of us are motivate to action on global warming is that it will disrupt ecosystems, bring about more natural disasters, and threaten food and water supplies”

    Two comments:
    1. What would be the consequent of a Younger Dryas Part 2 be, in terms of climatic disruption and food supplies? Humanity has roughly a 6 week reserve of food. The rapid climatic change events “RCCE’s” of the so called glacier period appear based on the data to be periodic. I would recommend Paul Mayewski’s book “The Ice Chronicles” which presents the results of the latest Greenland Ice Sheet data, analysis. The RCCE’s start in less than a decade. The Greenland Ice sheet cools as much 30C during RCCEs. The Greenland ice cores show an 800 times increase in dust levels in the ice cores when RCCE’s occur during the glacier period. An 800 times increase in dust implies a drastic increases in windness and desertification. How and how quickly the Holecene warm period will end, needs to be discussed, if not by the IPCC then by independent climatic experts.

    2. I am 110% in support of your comment that ecosystems need to protected, third world countries need to be helped, and conservation of energy use is a good thing. But rather than a complex CO2 trading system, which will not help the ecosystem or third world countries, tax energy use(not CO2 use) and use the revenue to directly protect ecosystems and help third world countries.

    Comment by astley — 10 Sep 2006 @ 2:00 PM

  66. Re #61: grant, I believe you mean the Paleocene-Eocene Thermal Maximum (PETM) of about 55 million years ago. This was enough to end the lines of large mammals, which then had to reevolve along new lines. For example, hippos and whales began evolving right at the end of PETM. The end Permian extinction (90%) is now thought to be related to an asteriod impact, but nothing is definitive yet.

    Comment by David B. Benson — 10 Sep 2006 @ 7:24 PM

  67. Re #60 and “No, the IPCC is only concerned with getting more funding. That’s why the IPCC Third Assessment Report’s “projections” were unfalsifiable pseudoscientific nonsense.”

    If your life were at stake, would you be able to write down the equation of radiative transfer? What makes you think you know enough about the science involved to make comments like you make?

    Comment by Barton Paul Levenson — 11 Sep 2006 @ 8:33 AM

  68. Always Google when tasty bait is being pulled past on a long line with a hook:

    Comment by Hank Roberts — 11 Sep 2006 @ 12:47 PM

  69. Alastair, I’m puzzled what you mean above when you say the MSU (Christie) satellite temperature results were “brushed aside” — are you referring to the lack of news coverage when Christie wrote Science agreeing that the error was real and agreeing to the correction?

    Ray Pierrehumbert mentioned it earlier here:

    Comment by Hank Roberts — 11 Sep 2006 @ 12:56 PM

  70. Grant writes, concerning my comment #60, “Your entire comment is ad hominem. Maybe that’ll be persuasive to the naive, but not to very many here.”

    OK, how about some straightforward and basic scientific questions for the authors of Real Climate:

    1) Is it necessary for projections of future events (e.g. the IPCC TAR projections for methane atmospheric concentrations, CO2 emissions and atmospheric concentrations, and resultant temperature increases) to be falsifiable, in order for them to be scientific?

    2) Are the projections of methane atmospheric concentrations, CO2 emissions and atmospheric concentrations, and resultant temperature increases in the IPCC TAR falsifiable? Please consider especially the IPCC warning that:

    “Scenarios are images of the future or alternative futures. They are neither predictions nor forecasts.”

    3) If the projections in the IPCC TAR *are* falsifiable, what hypothetical future events would falsify them?

    4) If your answer to #1 is “yes,” and your answer to #2 is “no,” have you ever pointed out (e.g., on Real Climate) that the projections in the IPCC TAR are not scientific? If not, why not?

    5) If your answer to #1 is yes, and #2 is no, have you ever seen any paper in Nature or Science that points out that the projections in the IPCC TAR are not scientific? If not, why do you think that is?

    Comment by Mark Bahner — 11 Sep 2006 @ 7:39 PM

  71. Croc hunter, suggest you start with the list of papers below to find our more about the cost of climate change. If you want more, then do a cite search (like the rest of us do).

    These may not be the best papers, but are a start. Things look potentially rather ugly for higher warmings. BTW watch out for tricks used to fiddle the story (such as discount rates making future losses artificially near zero).

    Roughgarden, T. and Schneider S.H., 1999. Climate change policy: quantifying uncertainties for damages and optimal carbon taxes, Energy Policy, 27, 415-429.

    Schiermeier, Q., 2006. The costs of global warming. Nature, 439, 374-375.

    Nordhaus, W.D., 2006. Geography and macroeconomics: New data and new findings. Proceedings of the National Academy of Sciences, 10.1073/pnas.0509842103, 8pp.

    Keller, K., Hall, M., Kim, S-R., Bradford, D.F., and Oppenheimer M. 2005. Avoiding dangerous anthropogenic interference with the climate system. Climate Change, 73, 227-238.

    Barker, T., Köhler, J. and Villena, M., 2002, The Costs of Greenhouse Gas Abatement: A Meta-
    Analysis of Post-SRES Mitigation Scenarios. Environmental Economics and Policy Studies
    5, 135-166.

    Barker, T., Foxon, T. Köhler, J., Anderson, D., Gross, R., Leach, M. and Pearson, P., 2005. University of Cambridge and Imperial College London Submission to the Stern Review (UK). 20pp (available from

    Comment by David — 11 Sep 2006 @ 8:55 PM

  72. Hank,

    First I must apologise for a mistake I have made. In your link to Ben Santer it states

    “For well over a decade, climate skeptics undercut the science on climate change by citing satellite temperature records, which showed that the atmosphere was not warming. But all of this changed last August when three papers published in Science (2005, 309, 1548-1551; 1551-1556; 1556-1559) showed that the satellite data were not as accurate as people had reported. When the data were corrected for problems such as satellite drift, researchers found that the earth’s atmosphere has been heating up.”

    The third paper is not about satellites, but about radiosondes which were also showing that the upper troposphere was not behaving as the models predicted! I attributed its authorship to Santer, but in fact the lead author was Sherwood.

    Santer was the lead author of the second paper. Its abstract concludes:

    “These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.”

    So it is only plausible that the models are correct, not a scientific fact! Everyone is congratulating themselves that they have “proved” global warming is happening, but is brushing aside the point that the models are still not in the clear.

    Your Santer web page also refers to the Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences Report. In its executive summary it says:

    “Although the majority of observational data sets show more warming at the surface than in the troposphere, some observational data sets show the opposite behavior. Almost all model simulations show more warming in the troposphere than at the surface. This difference between models and observations may arise from errors that are common to all models, from errors in the observational data sets, or from a combination of these factors. The second explanation is favored, but the issue is still open.”

    What I am saying is that the sceptics are partly right and the believers are partly wrong. No one is perfect :-)

    NB The upper troposphere is part of the lower atmosphere.

    Comment by Alastair McDonald — 12 Sep 2006 @ 5:27 AM

  73. Re #70:

    BTW watch out for tricks used to fiddle the story (such as discount rates making future losses artificially near zero)

    And watch out for the classic ideological academic’s trick of answering a simple question with a long list of citations.

    I could go and read all those papers, but it would be an enormous chore. How about you summarize the main arguments for me?

    If David Suzuki is correct (“every scientific body has said that global warming is a far greater threat to our security than any terrorist act”), surely a summary of the evidence behind that argument would be a relatively straightforward exercise?

    Comment by Crocodile Hunter — 12 Sep 2006 @ 7:33 AM

  74. Re #72
    It is not that difficult to find out for yourself.

    It would be nice if global warming was just a nightmare and that David Suzuki was wrong. However, poo-pooing an entire science just because you don’t like it is ridiculous. If you believe the spin doctors, otherwise known as climate change skeptics then nothing will ever be clear to you.

    The way I see it, the climate change skeptics, are behaving like lawyers, they are not seeking the truth, they are just trying to prop up their dogma by whatever means.

    In summary, yes, it is a straightforward exercise and it has been done, you just have to look it up!

    Comment by Lawrence McLean — 12 Sep 2006 @ 10:29 AM

  75. Re: 72, Climate Change Skeptics? RCCE Colder Vs GHG Warmer?
    David Suzuki is a great environmentalist; but he is mistaken concerning the relative danger of a warmer vs. colder planet. We live in a two pole ice age, the coldest period in the last 200 million years. For the last 600kyrs years there was been a recurring pattern, a 10kyr so called “warm” period (massive ice sheets both poles, during the warm period) and a 90kyr very cold period (1/3 of the land mass and vast areas of the high latitude oceans covered in ice.) During the last cold period, the so called Wisconsin ice age, the North American ice sheet moved as far South as 40 degrees latitude. The Canadian-US border is of course the 49th latitude.

    The change from cold to colder, may happen, in less than a decade, if it is triggered by the external forcing function that triggered the Younger Dryas, RECC. The Rapid Climate Change Events (Rickeys) were discovered in the 1993 GISP2, Greenland Ice Sheet core. The RECCs were once believed to have been triggered by abrupt stoppage of the Gulf Stream. Seager et al (2002)’s paper, debunked that myth. His and others’ climate models show that the Gulf Stream warms Europe 1 to 2C. (Most of the east Atlantic coast warming is due to the massive Rossby wave that is created by the jet stream as it moves east to west across the Rockies. See Seager’s article for a great explanation of Rossby waves and Atlantic climate. Seager et al’s, (2002) paper was used as the basis for an article that was published in the July-August 2006 American Scientist which I would highly recommend.)

    As a stoppage of the Gulf Stream can not explain the periodic 10C to 30C drop in less than a decade on the Greenland ice sheet which is accompanied by a massive increase in the Polar Circulation Index (very, very windy, during the RCCEs), Seager notes that there is at present no explanation as to what could cause the observed very rapid drop in temperature. During the Younger Dryas, the Atlantic ice pack in the winter extended as far south as Northern Spain. Great Britain’s interior had a summer high of 10C and a winter low of -5C. (Warmer than central Europe due to the Rossby wave.)

    Comment by William Astley — 13 Sep 2006 @ 11:57 PM

  76. Re 75: Thankyou. Very informative.

    Since the climate can change so abruptly and for no readily apparent reason, why should we be particularly concerned about the slow, long-term effects of GHG emissions? It may even be true that we are helping stabilize the climate.

    Somehow I get the feeling that ecosystem collapse is not the real problem for environmentalists. It is ecosystem collapse that might possibly be linked to human activity. But if the climate can change rapidly and seemingly without cause, to what extent can one meaningfully attribute climate change to CO2 emissions?

    Put another way, I have always found the butterfly-flapping-wings-in-Tahiti-causes-tornado-in-Texas explanation of chaos to be utterly fallacious. If the butterfly in Tahiti causes the tornado in Texas, then so does every other flap of a butterfly’s wing that is within the speed of sound of the Tornado. If every butterfly is a contributor, then no single butterfly is the cause, and it is nonsensical to speak of the butterfly in Tahiti causing the tornado.

    It is the same kind of counterfactual error people make when examining their own actions: “if only I had done X instead of Y”. Such reasoning always assumes that the almost infinite number of variables other than X and Y remain unchanged. But that is never the case. If you had done X instead of Y then A would have gone differently, and so would B, C, D, … and most likely the desirable outcome you imagine would have occured would not have happened anyway.

    This ramble has a point: to do a cost-benefit analysis of GHG reduction, you have to be able to predict the counterfactual: what happens if we don’t reduce GHGs? If you don’t know why the climate sometimes changes rapidly, then how can you answer the question?

    Comment by Crocodile Hunter — 14 Sep 2006 @ 3:37 PM

  77. [edit]

    Comment by Marina — 16 Sep 2006 @ 3:07 AM

  78. >Given the underwhelming response to my simple request for cost-benefit analysis, you’ll forgive me for concluding that those who advocate drastic action do so on the basis of ideology, not rationality.

    Actually, I used to give replies to this almost every thread. However I got the feeling that Gavin at least was getting sick of this, as were possibly some of the readers. Of course the reason I kept repeating myself was that the question keeps coming up.

    So the answer is we can phase out fossil fuels at prety close to zero cost. The reason is that due to various market failures all sorts of efficiecy measures tend to be overlooked. If these efficiency measure were put into to place we could save a great deal of the energy, and a lot of the money we spend on fosil fuels besides. That is we could greatly increase the amount of GDP we produced per unit of energy.

    As we phased in those savings we could phase in carbon neutral sources of energy (solar, wind, and so forth). These would be more expensive than fossil fuel energy sources. But as these more expensive sources were being used more effectively the overall energy cost per unit of GDP would be the same. In other words we would use fewer more expensive BTUs per unit of GDP, thus producing the same GDP and growth rate we do now.

    Note this would work regardless of whether absolute energy consumption was reduced. There is plenty of solar energy available; it is just more expensive to utilize than fossil fuels. If increase GDP per unit of energy consumed, then we can afford to pay more those units of energy whether we consume a little or a lot. In other words, Amory Lovins points about “negawatts” remain valid even if total world energy consumption increases.

    Comment by Gar Lipow — 17 Sep 2006 @ 2:35 PM

  79. So the answer is we can phase out fossil fuels at prety close to zero cost. The reason is that due to various market failures all sorts of efficiecy measures tend to be overlooked.

    You need to justify that statement. On face value it is highly implausible – each year China alone is adding almost as much power generation capacity as the whole of Britain. There’s a possiblity they could do a lot more of that with nuclear, but it is not going to be at zero cost. And I’d love to see your cost estimates of adding that much capacity annually with solar, wind, or any other renewable souce.

    Comment by Crocodile hunter — 17 Sep 2006 @ 8:49 PM

  80. Zero cost compared to continuing to use fossil fuels. For a bit on this look at the web site in my link. Also check out the web Rocky Mountain Institute ( Over the course of 30 years we can phase out fossil fuels fairly easily – replacing infrastructure as it needs replacement in any case. You are going amortize fossil fuel plants over the course of 30 years any way – as well as things like cars and factory equipment and space heaters that consume fossil fuels. As you amortize the fossil fuel consuming equipment replace them with more efficient equipment that can use renewable energy (electricity or biofuel). The incremental cost of replacing infrastructure with more efficienct infrastructructure is tiny. Less than zero compared to the NPV of fossil fuel savings. The renewable sources will be more expensive than fossil fuels (not all of them, but on average). But again you are replacing power plants and refineries and such which have to be replaced anyway – so your cost is the incremental difference between renewable sources and fossil fuel sources. And the incremental costs of renewable sources is less than the NPV of fossil fuel savings. So it is zero cost *compared* *to* *continuing* *to* *use* *fossil* *fuels* *at* *present* *efficiency*. Before looking at the empirical data, you need to understand the principle. More efficiency – a cost saving. More renewables, an expenditure. The savings and the expenditure net out compared to continuing to do the same thing. Now with that in mind, go to the RMI web site, and to mine as well. Ignore what is in my opinion hydrogen hype at RMI, and look the RMi efficiency proposals.

    Comment by Gar Lipow — 18 Sep 2006 @ 10:57 AM

  81. From your website:

    The next two chapters will show that industrial infrastructure may be upgraded over the
    course of thirty years to use about 75% less energy per unit of output – at very little
    additional cost.

    My baloney meter just went into overdrive. Unfortunately, we don’t have access to the next two chapters. Energy is a significant cost already to most industry. If there are obvious savings of 75% to be had, why is industry not already doing it?

    Comment by Crocodile Hunter — 18 Sep 2006 @ 1:43 PM

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