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  1. It is not surprising that a banker like Nigel Lawson should want the IPCC dismantled. As a chancellor in the Thatcher government he was, and remains, a strong advocate of the ‘free market’, dedicated to unrestricted economic growth.

    IPCC pronouncements, upon the growing body of evidence regarding the reality of climate change, put doubt in people’s minds about the wisdom or plausibility of the untrammelled growth that Lawson favours. The best way around this, obviously, would be to get rid of the body that keeps pointing out inconvenient truths, and hand over the reporting function to bodies more sympathetic to the free market posture.

    Whether such bodies have relevant expertise is immaterial, of course. Actually it would be rather better if they had no such expertise. It would be the equivalent of blindfolding the city guard, so that they cannot see the barbarians coming over the hill. Thus, there will be no calls of alarm from the walls to disturb the trade of the market place below.

    Comment by Phil de Jonge — 9 Nov 2005 @ 5:28 AM

  2. I love when people who couldn’t write the Schwarzchild equation to save their lives weigh in on the science of climate change. Kind of like creationists with engineering degrees talking about biology. What is it about the modern culture that makes people think anyone’s opinion, no matter how little they’ve studied an issue, carries equal weight to anyone else’s?

    Comment by Barton Paul Levenson — 9 Nov 2005 @ 7:03 AM

  3. To comment on a particular point of the original article – what kind of a stupid idea: Because the economists failed to establish an equally important body like the IPCC is, one of them demands to shut it down and re-establish it under the Bretton Woods institutions, and he does so with an absolutely unprofessional conglomeration of wild assumptions, even mixing up the IPCC and the Kyoto Protocol. I really wonder how Lawson comes to the conclusion that next to the IMF´s offices there would be a more open and transparent process, as will anyone else wonder who once tried to understand the IMF´s policies. It´s even more disturbing that he does not even have the imagination of creating a SECOND body which tries to make an equally profound assessment of the economic issues of global warming, as the IPCC does of the scientific issues of climate change (or as the UN Millennium Ecosystem Assessment did of all ecosystems). So this economic-based new body could use the IPCC´s findings, trying to work out effective and necessary instruments of mitigating of and adaptation to global warming. But I seriously doubt that the IMF would get along with taking a back seat in this game, relying on what climatologists send to it an then working out something that might really help preventing a global warming exceeding 2 degrees celsius.

    [Response: Actually, it’s fully within the scope of WG II to discuss models of the economic impact of climate change, and to discuss economic models of the cost of mitigation (i.e. emissions reduction). To some extent they actually do this. WG III does many of the rest of the things you argue for. This includes things like evaluating technologies for carbon sequestration and carbon capture from power plants. It even includes “meta economics,” or the evaluation of various ways to evaluate costs and benefits. At one point, there did seem to be a move within IPCC to have an economic modelling assessment parallel to the physics of climate assessment in WG I, but this fell apart because the people involved in the process seem to have become persuaded that the state of the art of economic modelling — or even the question of whether costs and benefits can be measured as money at all — were not up to the task. Thus, all the statements regarding economic modelling and damage estimates are very much hedged and often rather vague. It’s just a reflection of the poor state of the art of economic modelling (a view to which not many practicing economists subscribe, unfortunately) –raypierre]

    Comment by Nils Harder — 9 Nov 2005 @ 7:42 AM

  4. Re: #1 I believe it’s called post-modernism.

    As an aside, I recently read that the IPCC process was originally set up because the US insisted on it in order to control what climate scientists were doing [and saying] because they [the US politicians] weren’t happy with pronouncements made by scientists at various conferences [Villach I think?].

    Is it correct that non-scientist government officials are directly involved in the final phase of agreeing on the text of the IPCC reports?

    Comment by Timothy — 9 Nov 2005 @ 8:16 AM

  5. My, problem with this though, is that the low case scenario seems to be estimated on (maybe) unrealistic growth. Ok so fair enough it seems like it isn’t that important (hence the 0,1) but do we know that? What kind of effect would a lower growth have on the lower temperature border (estimation)?

    Comment by Magnus — 9 Nov 2005 @ 9:20 AM

  6. Gavin-

    A few thoughts. First, I don’t know anything about Lawson, but the IPCC does have some problems. First, its working groups II and III have very much taken on the role of the FCCC’s Subsidiary Body for Scientific and Technical Advice (SBSTA),the group convened to give advice on implementation of the FCCC amd Kyoto. That is, the IPCC WGs II and III have turned their focus to issues related to the implementation of Kyoto, which is quite contrary to your assertion of policy independence. (And note that WG III does not focus on policy as you suggest, that was its focus in the FAR, but no longer, now it is mitigation.) One result of this focus on Kyoto and the FCCC is that the WGs downplay the role of adaptation in climate policy (this was very much the spirit of my comments on one of the AR4 WGII chapters that I reviewed). I discuss how this has come about in some depth in this paper:

    Pielke, Jr., R. A., 2005 (in press). Misdefining Climate Change: Consequences for Science and Action, Environmental Science and Policy.

    Second, you assert incorrectly that “no scientists have made a claim of direct cause and effect” between global warming and hurricane Katrina. Not true. In fact, the lead author for the IPCC WG I chapter on hurricanes has made exactly such a claim. In a peer-reviewed paper? No. In a congressional briefing. See slide 18 here:

    Perhaps there are good scientific reasons for making such a claim, but they probably should go through peer review before being announced as fact (with no sense of uncertainty!) before policy makers. Especially when other scientists, like Kerry Emanuel, assert that such precise attribution is not possible. And further, given that the IADWG has published in JOC May 2005 that attribution of trends in precipitation to GHGs has not yet occurred, it stretches the credulity of this non-climate scientist to think that such precise attribution is possible for specific events. Such reckless action with science in policy do not give friendly outsiders confidence in the IPCC process. They also give plenty of grist to unfriendly IPCC opponents.

    The IPCC has accomplised a lot, but it’s handling of many issues suggests that there might be room for some improvement in its practices. I can make a strong case that the IPCC can improve its connections with the policy process, e.g., by explicitly discussing policy options in WGIII. Given that complaints are mounting, folks involved in the IPCC might listen carefully to them before circling the wagons.

    [Response: Roger, thanks for your comments. I happy with the idea that IPCC can do better than it has, and judging from the AR4 results that I have seen already, I think it is making steps. However, much as I don’t want to get into an argument here about hurricanes and climate change, you appear to be putting words into Trenberth’s mouth. He does not claim that Katrina was caused by global warming, and I’m surprised that you continue to interpret his words now and last year to conclude this. He has claimed that global warming is changing the background in which hurricanes form (which is clearly true), but that can in no way be construed as arguing that Katrina can be directly attribtued to global warming. Trenberth is as aware as we are that individual events are not attributable in the sense that Lawson implies, and any consensus statement on the issue will agree. Let’s not be distracted by semantics. -gavin]

    [Response: I’d be the first to agree that the WG II and WG III reports in many ways seem less focused on a task and less useful than the WG I reports. However, unlike Roger, I think this mostly reflects the very poor state of the art of impact modelling, whether economic or biological, as compared to physical or geochemical modelling. This isn’t likely to change anytime soon. These working groups are doing the best they can with a practically impossible task. I can’t speak for AR4, but Roger’s criticism is off-base with regard to the WG II and WG III reports in the TAR. These reports inevitably stray a little bit into policy areas, but they do a quite valuable job in summarizing things like technical options for carbon capture and sequestration, and of evaluating methodologies for policy decisions. I know Roger is a strong partisan of adaptation over mitigation, but I have never found this approach very convincing, except in certain limited cases. There’s a case to be made that the balance in discussion between adaption and mitigation shown in the IPCC reports just reflects an honest appraisal of the limited success technology has had in things like helping natural ecosystems adapt to human-caused environmental change. Just ask how much technology has helped endangered salmon survive dams, or how many endangered species we’ve rescued by technological fixes. –raypierre]

    [Response: Looking at this from across the Atlantic, I cannot help but be amazed once again at the style of discussion in the US. I looked at Kevin Trenberth’s slides. He presents an entirely reasonable analysis, stating little more than the obvious: that global warming has contributed to warmer ocean temperatures, and that warmer ocean temperatures affect evaporation and precipitation associated with hurricanes. Any good physicist would follow this up with a back-of-envelope estimate of how large this effect might be, and that’s what he does for the example of Katrina. He does not argue Katrina was caused by global warming, he merely argues that the warmer ocean temperatures have probably enhanced the associated precipitation. I find it very worrysome that a natural scientist who presents a reasonable physical argument is publically accused of “reckless action” from political science quarters. I feel such an ad-hominem attack has no place on our site. It serves to stifle rather than nurture the kind of dispassionate, unideological science discussion which our site is devoted to. It is fine if you want to take issue with Trenberth’s argument – but please present a scientific argument why you think warmer temperatures would not enhance hurricane precipitation.
    I also find it strange that Pielke criticises Trenberth for saying something that is not yet published in the reviewed literature. What are such briefings for: to get a first-hand impression of current thinking of scientists, or for scientists to read out sentences from their papers?
    Finally, I find it strange and revealing that Pielke writes: “Such reckless action with science in policy do not give friendly outsiders confidence in the IPCC process.” With due respect to his strong opinions – criticism of the IPCC should at least be based on a minimum of understanding how it works. I also do my duties for the next IPCC report, like several hundred other scientists, and I can assure you that the IPCC does not in any way limit our ability to act as individuals in what we say in the public. For the IPCC we meet and discuss the scientific evidence and we write a report about what is widely agreed amongst us. If you want to know what the assessment of the IPCC is, read that report. When you read what I have to say on Realclimate or elsewhere, this is definitely not the IPCC assessment, unless I cite the IPCC as the source, and the same holds for Trenberth or any other scientist contributing to IPCC reports. Therefore, it is just ill-informed to criticise the IPCC process for anything that I might say in public. -Stefan]

    Comment by Roger Pielke Jr. — 9 Nov 2005 @ 9:29 AM

  7. The IPCC can ignore the world’s leading economists and statisticians with impunity, because it has the support of ‘the worldwide scientific community’. In its submission to the House of Lords Committee, the Royal Society (UK) explained that:

    “The work of the IPCC is backed by the worldwide scientific community. A joint statement of support was issued in May 2001 by the science academies of Australia, Belgium, Brazil, Canada, the Caribbean, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden and the UK. It stated: “We recognise the IPCC as the world’s most reliable source of information on climate change and its causes, and we endorse its methods of achieving consensus.”

    I almost agree with this, but there are some some unclear places.

    John Tweller

    [Response: It’s not so much ignore… I don’t think that they should or will, on the CO2 scenario generation side. IPCC “does” climate science, economists do economics. This is fine. Climate modellers, and hence the IPCC, needs future CO2 scenarios. That’s not climate science, but they needed it, so they made some (in collaboration with economists). There is a very good case for people like the HoL Economics Committee, or Castles and Henderson, getting off their bums and actually generating their own scenarios instead of just criticising from the sidelines. My suspicion is that the reason they have not done this is because they know full well that they will get much the same result – William]

    [Response: A small correction: IPCC WG I “does” climate science. In fact, IPCC WGII and WGIII “do” economics in more or less the same sense that WGI does climate science. Differences in the way the different groups handle their disciplines are striking, though. While there are many standard climate models to intercompare, and agreed yardsticks to compare them against, there is no analogous suite of economic models. In many cases, economic models (like the WEFA one used to argue against Kyoto) are proprietary, so you can’t even see the equations used. Economists do not seem to have a big culture of model intercomparison and verification. This lack of the state of the art, I think, is one of the reasons that the focus in WGIII shifted from its original conception in the SAR (the notorious case where one draft valued Indian lives at one tenth the value of First World lives, leading to a conclusion that you could kill 10 Indians with heat waves but save one American from death by winter cold, and it would all balance out). A laudable exception to the generally dismal scientific standards in the economics community is Bill Nordhaus’ modelling effort. For all its faults and shortcomings, about which Bill is very clear, the model is completely transparent, peer-reviewed, and reproducible. I am planning to write a RealClimate piece eventually covering these issue, but focusing on the issue of climate damage functions so we don’t stray too far from the RealClimate mandate. –raypierre]

    Comment by John Tweller — 9 Nov 2005 @ 10:01 AM

  8. Gavin-

    Thanks. Slide 18 in Trenberth’s presentation that I linked to unambiguously attributes 1 inch of Katrina’s rainfall near New Orleans to global warming. These are Trenberth’s words, not my interpetation of them, presented as fact in a policy briefing, not as hypothesis in a scientific meeting. This is a clear and precise attribution of the effects of GHGs to the behavior of a single storm. The photo next to the statement of attribution is of flooding and damage. This is not an issue that can be dimissed as semantic. Have a look at the slide.

    [Response: I read the slide, and frankly, even if the context in which Trenberth placed the comment is as you assume, it is still not a direct attribution of a specific hurricane to global warming. To keep belabouring this point, it is quite clearly not what Lawson is referring to. -gavin]

    Comment by Roger Pielke Jr. — 9 Nov 2005 @ 10:14 AM

  9. Trenberth did say something both to the point and scary, to wit, that based on studies of hurricane INTENSITY, he calculates that 1″ of extra precipitation was dumped into area around New Orleans because of global climate changes. This would be about a 10% increase. It would be interesting to figure out how much this contributed to flooding across the affected area, not just in NO.

    Trenberth is making a direct attack on the arguments of BOTH Pielkes. In the case of Roger Pielke Sr. he points out that global changes has important LOCAL effects also (there is an interesting report and perspective in a recent Science about how global trends are amplified in the Artic). It also directly contradicts Roger Pielke Jr.’s peddling of the idea that no globally climate change connected consequences have yet (if they ever will) been seen in hurricane damage). Pielke Jr. in particular is trying to assert ownership of the issue and needs to be pushed back.

    Comment by Eli Rabett — 9 Nov 2005 @ 1:01 PM

  10. I haven’t been keeping up with the IPCC reports, after reading some of the 1995 report. I had been following the science journal articles on GW (for my thesis on environmental victimology), and I felt SAR was pretty bland. So I’m way on the other side of the debate from Lawson.

    I think world policy should be: hope for the best, prepare for and try to avert the worst. So my sight is trained more on the higher end projections, and goes beyond 2100.

    My personal policy: become energy/resource efficient & conservative & save gobs of money, while saving the environment from GW, acid rain, local pollution, in addition to mitigating numerous other problems by the same actions.

    I wonder if Lawson might be tied into some dinosaur industry that might go extinct if people really started solving the GW problem. Because the excuse that he’s concerned about the free market doesn’t seem to hold water. What we really need is more freedom, so entrepreneurs can invent and produce stuff that saves the world, without being stomped on by dying dino industries. Maybe we should take the gloves off completely, and do away with all subsidies for fossil fuels (including war costs) and internize (make them pay) ALL harms – from GW, acid rain, local pollution, etc. Then let’s see who wins the free market game.

    [Response:Well, the IPCC summarises and asesses the scientific literature, so if you have managed to keep abreast with the scientific literature on climate and global change, then there should not really be a strong reason for plowing through the IPCC reports (other than that they give a nice summary of the state of the science). In fact, by criticising the IPCC prosess, I believe that Lawson misses the point, as I see IPCC as being faithful to the published science on climate change. After all, the majority of the published scientific work on athropogenic climate change seem to point to an enhanced greenhouse effect. I cannot see any ‘alternative’ interpretations (what should that be, given that there is not much scientific literature suggesting otherwise?), unless you go to other [unscientific] ‘sources’, and I see this as perhaps the failure of the IPCC/climatology community: that interest groups without scientific credentials have managed to plant such false ideas in people’s minds. -rasmus]

    Comment by Lynn Vincentnathan — 9 Nov 2005 @ 1:04 PM

  11. I think Trenbreth’s slide caption is a result of too much condensing. I’d bet that his Implies 1″ extra rain is in the subjunctive mood with a kind of “If we’re correct on this …” hovering over the entire presentation. I know: his words clearly don’t say that, and I couldn’t point to a construction that would support my interpretation. All I have are my own experiences with trying to condense complex arguments into shorthand.

    Comment by Jeffrey Davis — 9 Nov 2005 @ 2:05 PM

  12. Lawson suggests that economic issues related to climate change should be discussed within economic departments of government, and I doubt anyone would disagree.

    I don’t know whether you’re able to set up a polling mechanism here but I’ll take a wild guess that at least half of RC bloggers are not interested in any discussions of economic issues. Or, to be more precise, they don’t want mitigation policies to be predicated on such discussions. What they really want is action, ASAP.

    [Response: I think you were more accurate with your first sentence, before you tried to be more precise :-) – William]

    Comment by Sashka — 9 Nov 2005 @ 2:12 PM

  13. I have a few additional comments of my own regarding Lawson’s article.

    First, I find it hard to see why the critics of the IPCC scenarios are so up in arms about the story lines IPCC scenario-writers chose for study. As far as I can see, their criticisms have absolutely zero implications for the utility of IPCC climate forecasts as an aid to policy decisions. The WG III report itself describes these as “story lines” representing possible futures, rather than economic forecasts. There is ample range amongst the scenarios to feed the evaluation of a wide range of policy options. If some policy maker (who could well be a British treasury official) thinks that the Business as Usual scenario is too pessimistic (read, too optimistic regarding developing world economic growth), he or she is free to choose one of the lower emission scenarios, of which there are many.

    The other place where Lawson is completely off-base is in his criticism that IPCC ignores adaptation in favor of mitigation. The Technical Summary of the 2001 WG II report states : “WGII’s mandate for the TAR is to assess the vulnerability of ecological systems, socioeconomic sectors and human health to climate change, positive and negative,on these systems. This assessment also examines the feasibility of adaptation to enhance the positive effects of climate change and ameliorate negative effects” The explicit appearance of the mandates to consider benefits of climate change, and to consider adaptation, gives the lie to Lawson’s criticism that the IPCC has neglected such options. Either he does not actually know what is in the IPCC reports, or he is deliberately misrepresenting them.

    If governments so far have chosen to emphasize emissions controls over adaptation, the fault (if there is any) should be laid at the door of elected officials, not the IPCC. It is not the IPCC that led US officials to ignore New Orleans’ need for better flood control — which would have been a sound adaptation to rising sea levels and increasingly intense hurricanes, with now obvious collateral benefits, even without factoring in global warming.

    Comment by R. T. Pierrehumbert — 9 Nov 2005 @ 2:29 PM

  14. To add slightly to RTP’s excellent comment, the scenario analysis used by the IPCC (and other disciplines in the natural sciences) presupposes that adaptive management strategies will be used that are informed by the scenarios developed.

    That’s why the scenarios were developed – to inform adaptive management strategies.



    Comment by Dano — 9 Nov 2005 @ 3:15 PM

  15. Ray (response to #6)- You mischaracterize my views when you write, “I know Roger is a strong partisan of adaptation over mitigation, but I have never found this approach very convincing, except in certain limited cases.” This is probably because some people view any focus on adaptation as taboo. I have repeatedly written that we need a greater focus on adaptation, and that adaptation and mitigation must be complements. I have argued against trading them off. And on your “there is a case to be made …” perhaps this is true, but perhaps someone should make it!

    Eli (#9)- Thanks. I have been “peddling” my ideas in places like Journal of Climate, Natural Hazards, BAMS, Nature, Science and other peer reviewed fora. I welcome the “pushing back” that you call for in the form of serious studies in the peer reviewed literature. We are organizing a workshop in 2006 to motivate some of this pushing back. Science advances by people putting forward hypotheses and others taking a critical look. Sometimes certain hypotheses are unwelcomed or inconvenient, and often they are proved wrong. Being proved wrong is no crime in science, particularly if it contributes to advancing knowledge. So please do push back, but with substance. Thanks again.

    Comment by Roger Pielke Jr. — 9 Nov 2005 @ 8:15 PM

  16. In reality,

    Scientific description of the global warming problem has most definitely implied specific policy responses. The policy responses from leaders of countries dependent on fossil fuel burning for the “good life” of it’s citizens today have seriously downplayed the concerns that some have about the damage being done to the planet’s future, from fossil fuel burning. Our leaders have followed a policy to do nothing that might threaten the economy for the present, regardless of the well-being for all life on Earth in the future.

    Comment by Pat Neuman — 9 Nov 2005 @ 9:27 PM

  17. I remain astonished that nearly all the commenters, with the refreshing exception of Lynn Vincentnathan, continue to frame the debate as adaptation versus mitigation, or even more coarsely, as environment versus economy.

    It is possible to reduce fossil fuel use economically. The tools are energy efficiency and renewable energy. People like Amory Lovins of the Rocky Mountain Institute, at

    have discussed the technologies and free market policies to get them implemented, in great detail.

    Of course an obvious first step would be to end subsidies for fossil fuel consumption, but I think that would require us to discuss politics . . .

    Comment by Mark Shapiro — 10 Nov 2005 @ 2:56 AM

  18. RE #12, I think your final sentence, Sashka, is to the real point. People concerned about life on earth want action. Preferrably starting yesterday. The debate has been over for 10+ years regarding whether or not there should be action. So those still pretending there’s a debate…well, I’d better not continue this line or I’ll be deleted.

    But I’m sure it’s occured to some of you that debating the fine print while the book is burning might itself be a strategy. So now the latest strategy is to debate whether or not we should have the IPCC — that ought to keep policy wonks from taking any action for at least another 5 years….

    I also understand the meaning of your 2nd to last sentence. Economics in and of itself is a sterile pursuit, at least in the context of GW, because it considers the earth & its biota (& all the complexities that likely go beyond those that biologists & climatologists can currently tell us about) as “resources” without any limits (life, for instance, can be reduced to monetary amounts — as if any amount of money can bring the dead to life). And they consider the sociocultural system beyond economics as “tastes & preferences.” So economics should not be the sole determinant of our policies, and it shouldn’t even be the leading determinant. It’s just one among many, many other voices to be considered in making decisions. Too bad policy wonks don’t understand that.

    Comment by Lynn Vincentnathan — 10 Nov 2005 @ 11:09 AM

  19. Roger: You, and to be fair others such as Chris Mooney, function in an honorable tradition which started with the self publishing pamphleteers of the 16th and 17th century. When enough notice had been achieved a book was/is published. More recently public intellectuals started by publishing in the academic press, working in foundations or universities, with the goal of moving on to policy making positions in government. With good luck they become consultants and movers and shakers. No better example of this than Henry Kissinger. Blogs provide a shortcut for this career path. You had the perspicacity to start your blog early in an area that was not well served.

    What you are doing here, and in your publications, and on Prometheus is to assert ownership of a series of issues, the latest of which is hurricane damage due to climate change. Your incessant self citation is a clear indication. I am certain you will reply that somewhere in a post somewhen you may have mentioned another’s work. You react to any challenge to your theses virulently, and in your replies often distort what others have said, for example your last blow up about the Trenberth slide. In short, you act as a policy person, not a science person. Horrors, at least when this is pointed out. But again, sui generis. This is what one expects of a policy wonk, for example Brad de Long. Yet, you keep telling those of us who reply to you that you are scientifically as pure as the driven snow. I beg to differ.

    If you had a better sense of irony you would have named your blog “Zeus’ Eagle”, not let on to what the reference was, and merrily gone on pecking at the livers of those whose research falisified your opinions.

    Comment by Eli Rabett — 10 Nov 2005 @ 11:56 AM

  20. I am delighted with the forthright nature of Trenberths’s presentation. I have been disappointed with many climate scientists hedging on the role of global warming in hurricanes. I like the analogy of a person with heart disease who approaches a doctor and asks what causes the illness in their case, “Could it be due to my never exercising?”. The doctor would then point out that of course that would have a role, but so would diet, stress etc. We seem to want a singular explanation for causation not just an enhancing role as Trenberth points out warmer ocean temperatures over larger areas for longer would have to have all else being equal. As a glacial researcher for 25 years I am dismayed to have seen five glaciers I observe melt away in the North Cascades of Washington. It is disconcerting to see the magnitude of this change and still be asked if we really are experiencing warming.

    Comment by Mauri Pelto — 10 Nov 2005 @ 12:52 PM

  21. Eli (#19)-

    Thanks for these additional comments, and thanks also for the RC for allowing this brief foray into a subject which I am sure are far beyond the topic here. Let me just offer a quick response to your various points.

    We do use our blog to promote our work and our views. Guilty as charged. We have also published other perspectives and allowed wide ranging discussions. We strive for a high level of respect and courtesy in our exchanges. But make no mistake, we do present some strongly held positions, which are often motivated by a desire for motivating serious debates on important topics on which reasonable people can disagree. We also try to be fair. This is what academics do, and blogs give a window to that world. Often in academia we argue passionately, and they go out for a beer afterwards. And as a professor who teaches policy, and directs a policy center, and publishes on policy, I am focused on policy issues. Again, guilty as charged. I do feel strongly that policy research should appear in the peer reviewed journals, and we try to share what we publish and its significance on our blog. Our blog is an experiment, and with constructive feedback we hope that it improves and contributes to informed debate on contested issues that people have strong feelings about.

    Finally, I simply reject the notion that we have in any way mischaracterized what Trenberth has said, but readers of our blog can and should make up their own mind. Reasonable people can legitimately disagree on complicated, important subjects. Thanks.

    Comment by Roger Pielke Jr. — 10 Nov 2005 @ 2:56 PM

  22. I don’t think this strand is supposed to be about Trenberth, so I apologize, but I read through that slide presentation and think that you can’t know what it means unless you were there to hear the words accompanying the presentation. He says (in my opinion) that if you work through his equations, then Katrina got an extra inch all else being equal (to borrow the phrase from #20). The problem with attribution for single events is, of course, that all else is never equal. If Trenberth acknowledged that at any time during his presentation then I don’t think Roger’s description is correct.

    Gavin, thank you for highlighting the importance of the IPCC and how you think it should run. Roger, thank you for describing ways it could be better. That is an important side of the story. I think it would be more refreshing and interesting, though, if there could be a post from ‘non-skeptics’ on any positive role that skeptics play (if any) and how that role could be more-productively carried out. An example is suggested in Gavin’s post (Lindzen’s iris effect [no link]). I am not trying to take over this strand but instead want to inspire another one that is related. Here is a start: skeptics should criticize the IPCC, skeptics should ask for access to data and analytical disclosures, skeptics should not criticize the science with economic arguments, skeptics should not put words into the mouths of those they criticize, skeptics should define some goalposts so that progress can be understood from their point of view, skeptics should use the peer-reviewed literature…. Okay, so some of these are boring, too. How about applying the logic Gavin applies to the need for the IPCC — should there be a defined, international panel (with sub-groups and everything) for the skeptics?

    As a scientist I know it’s my job to be a skeptic, but expecting others to leave me to do my work (fisheries science) when it affects their livelihoods is unrealistic. That’s why we have representatives of various groups on a panel that oversees work done by me and my colleagues. And they have hired scientists who explain technical details to them. I believe this interaction properly focuses their anger and imagination and other energies on the policy rather than the science when the science is clear. It allows them to be more effective skeptics (focussing their attention appropriately) when the science is not. Lawson’s demands would have to be different if a watchdog group, respected by ‘both sides’, existed.

    Comment by Steve Latham — 10 Nov 2005 @ 3:00 PM

  23. Re : #22

    “As a scientist I know it’s my job to be a skeptic”


    You really need to think seriously about finding another line of work.

    [Moderator: Watch the ad hominem (see our comment policy). We allowed this one through, but next one may not make it if you’re not more careful.]

    Or at least do a simple search of “scientific methods” (note plurality).

    Comment by Thomas Lee Elifritz — 10 Nov 2005 @ 3:24 PM

  24. re #21: Rabett vs RP Jr.
    I look forward to the exchange but doesn’t Rabitt’s post violate the RC comment policy?
    This is a bit of a personal attack, and an attribution of motives.

    [Moderator: This one walked the gray line, but it was focused on substantive rather than gratuitously ad hominem arguments. So we allowed this one through, but we’re watching carefully. Roger provided a thoughtful response, and the exchange was constructive.]

    While I agree with Rabett’s sentiment, I’ve seen similar attitudes from
    a number of other scientists (and often they are the foremost expert in their fields).
    It is very common for anyone to overstate their ideas and positions.

    Re: 22:
    For what it is worth, there was someone there: See the comments on this topic from “OnTheInside” on Prometheus which starts:
    “I was at the Congressional Seminar Series and was surprised by Trenberth’s assertion that global warming may have caused an extra 1″ of rain from Katrina. (He went even further and suggested that the extra water may have been the difference between levees being topped or not.)”

    [Moderator: This sort of hearsay/gossip typically won’t be allowed here. We’re not in the business of providing a forum for unsubstantiated rumors that are attributed to an anonymous source.]

    This whole episode seems a bit overblown, except as an example of a larger issue. I doubt anyone hearing Trenberth came away with anything beside the impression that one scientist thought it was likely that GW contributed something to Katrina–Unless of course they already had a stronger opinion.

    Comment by Gregory Lewis — 10 Nov 2005 @ 3:47 PM

  25. Hey Thomas (#22) – ouch, but why don’t you tell me what you mean? Perhaps it would help if I wrote, “it’s my job to be skeptical of my own findings.” Or are you also picking on something else I wrote?

    Comment by Steve Latham — 10 Nov 2005 @ 4:12 PM

  26. Re #25 But you are not being skeptical of your own findings. You are being skeptical of the findings of the contributors to the IPCC reports.

    Of course, that is no sin. Peer review is based on the principle of skepticism. Where it falls down is that there is no peer review of the criticism produced by the peer review. A peer reviewer can reject a paper because he is not cited, but no one can criticises that.

    Skepticism does drive science, but we have a right to be skeptical of your skepticism, and reject it!

    Cheers, Alastair.

    Comment by Alastair McDonald — 10 Nov 2005 @ 6:06 PM

  27. #25 –

    That’s the whole point, you didn’t qualify the statement at all. First of all, science itself is not a ‘job’, and if your job is actually working in science, for example, if you are paid by someone to actually do science, then your job is certainly not to be skeptical, your job is to produce usable (actionable) results (right or wrong, well, there really is no right or wrong on the front lines anyways, just results, take em or leave em).

    Unqualified skepticism, that is, scepticism without evidence, is generally not considered as part of the rapidly expanding repertoire of scientific methods. If you have a problem with someone’s methodology or results, then produce your own results which contradict their results, or attempt to falsify their methodology, but it is definitely unacceptable in my repertoire of methodology, to just go after their results, or even their methodology, without first trying to reproduce their results first, or by falsifying their methodology. Skepticism has to be the most widely abused methodology of modern day ‘scientists’. History has demonstrated that over and over again, yet the falsification of skepticism as a scientific method seems not to have generally made it’s way into the mainstream scientific community as of yet, certainly not even into the mainstream economic or political arena. It’s my ‘job’ as a ‘scientist’ to point that out.

    Of course, if your job is to practice skepicism, then you are not a ‘scientist’, at least in my highly annotated and now bulging looseleaf folder of scientific methodologies. On the other hand, it’s fine to be skeptical of your own results, that’s the whole fact checking thing.

    I apologize if I ripped that out of context, but the subject of unjustified skepticism is of fundamental importance to climate science, and many other leading edge scientific disciplines, as the repertoire of scientific methods and methodologies continues to expand with rapidly improving knowledge bases and technologies.

    It you want to falsify a result or methodology, I’m sure you will quickly find that skepticism will be of no help to you at all as a scientific method. Skepticism is just not a credible scientific method anymore.

    [Response: I have to strongly disagree here. Being a scientist means being a professional skeptic (in the true sense of the word). i.e. one doesn’t accept statements without good evidence. I’m pretty sure this was the sense that the previous commenter meant. Similarly, I do not need to redo someone’s attempts to make a perpetual motion machine to be skeptical about it’s existence. More relevantly, if someone claims a significant trend from 2 points on a graph, I don’t need to get out Excel to be skeptical of the result. To be sure, ‘skepticism’ in the climate realm has become synonymous with refusal to accept anything despite good evidence, but that is a distortion of the word and an affront to true skeptics. Skepticism is not per se a ‘method’ but it is a valid starting point and attitude. -gavin]

    Comment by Thomas Lee Elifritz — 10 Nov 2005 @ 6:22 PM

  28. Hey, this is weird — how did I get dressed in a black hat? I’m not an AGW skeptic. I started writing letters to newspaper editors back in 1996 telling them how their economy-based attacks on the science were wrong-headed. I’m still at it. But what I’m saying is that constructive criticism is good and maybe the energy of AGW skeptics can be put to good use if directed properly. Does anything need to change? My relatively uninformed opinion is that it does, especially if the public elects representatives to act like Nigel Lawson. Alistair’s complaint (#26) that the mud-slinger can’t get criticised is perhaps an argument in favor of a recognized watchdog with a fixed set of principles that it enforces. Such a watchdog might marginalize the real crazies and help the public to separate the reasonable/legitimate criticisms from the inaccurate, inappropriate, and ridiculous. It’s just a suggestion for consideration and maybe discussion at some point in the future. I hoped the idea would be more interesting than, well, who I am.

    Comment by Steve Latham — 10 Nov 2005 @ 7:09 PM

  29. You asked what positive effect the sceptics have had. Let me name a few:
    1. They have made AGW proponents redouble their efforts to be accurate and double check their models.
    2. If AGW proponents controlled policy the U.S. would now be throttling back its economy to the especial detriment of the poor.
    3. Sceptics have helped to prevent rash policies that may not have had any effect on GW.
    4. Sceptics have pointed out that if GW is not actually anthropogenic, huge cutbacks in energy production would not help.
    5. Sceptics have pointed out that many of the proponents of AGW are against increasing necessary energy supplies through the use of hydro-electric and nuclear production.
    6. Sceptics have pointed out to AGW proponents that the needed future supplies of energy cannot be provided only by alternatives to fossil fuels.
    7.Sceptics have pointed out that much of the debate over GW is a debate between members of the environmental movement who are against all modern industrial production and those who want to continue the use of all forms of energy to improve the lot of humans.
    8.Sceptics have forced scientists to look at what adapting to GW versus mitigation might entail.
    9. Sceptics have pointed out that there has been a parade of books predicting Malthusian disaster, none of which has come true.

    [Response: I’m also sure a few of the sceptics have also advised that I look both ways before crossing the road. You need to distinguish issues that are/were tackled or thought about without the ‘sceptics’ (and we know who we are talking about) getting involved, and issues that have been raised only by the sceptics that have actually lead to interesting science. That cuts out items 2 through 9 on your list. However, you could add work on upper tropospheric water vapour feedbacks which were quite clearly motivated by Lindzen’s criticisms and ….. errr….. that’s about it. (Anybody have some other examples?). -gavin]

    Comment by Jim Glendenning — 10 Nov 2005 @ 8:43 PM

  30. Re : skeptical response

    I think you do agree with me.

    I claim that skepticism as a scientific method, is trivially falsifiable.

    When you are able to falsify a result, you are not practicing skepticism, you are practicing science. On the other hand, when you are able to act on a result, to create new results, you are also practicing science, but with a much better ‘attitude’. Skepticism must be balanced or offset by speculation. Sooner or later you have to have enough confidence to act on your results.

    Skepticism and speculation in science is a whole topic in itself. Science itself seems to be a kind of highly directed semantics. It’s no wonder nobody seems to be able to agree on anything, which is why the hard numbers and the analytical and computational results are so valuable.

    Anyways, I have enough confidence in modern scientific methods, to speculate that smoking all of the rest of our planet’s hydrocarbon resources, by inefficent combustion methods, will not produce the desired long term planetary results, in system with life is a major component.

    Comment by Thomas Lee Elifritz — 10 Nov 2005 @ 9:55 PM

  31. Skeptics greatest contribution is that they support pollution!
    May Hydrogen engines clear their minds…..

    Comment by Wayne Davidson — 10 Nov 2005 @ 11:01 PM

  32. Stefan (2nd response to #6)-

    Thanks for your perspective. I appreciate the exchange. Some responses.

    First, let’s be clear, my comments about Trenberth’s representation of science in a political setting in an area where I have some knowledge (hurricane impacts) is not at all an ad hominem attack. RC frequently evaluates comments made in public and political settings by scientists and non-scientists, and the comments in the RC moderated discussions often focus in this direction. I think that such perspectives are valuable if done in a professional manner.

    Second, you ask exactly the right question when you write, “What are such briefings for: to get a first-hand impression of current thinking of scientists, or for scientists to read out sentences from their papers?” If you want to see the current thinking of scientists, go to a professional scientific society meeting. Congressional briefings, which are generally pretty irrelevant, should be for presentation of information with policy and political relevance. Don’t be seduced by thinking that policy makers or their staff have an intrinsic interest in the science. I’d assert that an appropriate role for science in congressional briefings is to present (a) the consensus/diversity of views on a particular topic, and crucially,(b) the significance of that science for action. The AMS briefing met neither of these criteria. Of course, it bears repeating that reasonable people can disagree on such things.

    Third, I agree in general with your point about distinguishing the IPCC from individuals who may or may not be associated. But the reality is that people matter. The public statements by people associated with the IPCC, as well as those in visible roles in the climate science community, like RC, do affect how people view the credibility of the IPCC. You may not like this, but that makes it no less real. Think about how the world looks from Lawson’s perspective (Aha, back on topic!). You emphasize the importance of the IPCC, and the IPCC most recently says no connections of hurricanes and climate change. Some experts say there is a large connection, others say no connection. What is Lawson supposed to think? You want Lawson to be able to pick the “right” expert before the IPCC renders its judgments. On what basis should he choose between Trenberth and Gray? When Gavin makes a statement that many reasonable people could take issue with (hence the Trenberth example), it does not lend to credibility. The point here is not who will be proved right or wrong in the end. Credibility is based on many things and understanding how it is earned and lost is critical to keeping it. Loud defenses of the IPCC and continued invocations of the fidelity of IPCC processes are not recipes for maintaining credibility. You may disagree, but the evidence is in perspectives like Lawson’s which are casually dismissed at some risk. Sometimes people who you disagree with have good reasons for seeing the world the way that they do.

    Thanks again.

    [Response: Roger, my statement was not ambiguous. I stated that no scientist had made a direct attribution of Katrina to global warming. i.e. that Katrina was caused by global warming. Your paraphrase however is incorrect. There may well be connections between hurricanes (in general) and global warming as have been highlighted in the discussions of the Knutson et al, Emanuel and Webster et al papers. The conflation that you make between the two statements (i.e. general connection implies specific cause) may explain why the conversation appears to make no headway. To me these are very different statements. To you (and possibly to policy makers) they appear to sound the same. I agree that it is incumbent upon scientists to strictly delineate statements where there might be a possibility of mis-interpretation and maybe I should have been even clearer in my statements. I should also make clear that I am not part of the IPCC process except as an external expert reviewer. -gavin]

    [Response: I leave it to our readers whether they consider publically accusing someone of “reckless action”, and doing this behind their back, an ad hominem attack or not. In your comment # 21 you speak about “a high level of respect and courtesy in our exchanges”. Would it not have been just an average level of courtesy to contact Trenberth directly and check with him what he actually said? And if you feel you want to criticise it, do it to his face? He was not even aware what you had written about him on our site. “Understanding how credibility is earned and lost is critical to keeping it.” I think that is good advice.
    Could you specify what you’re referring to when you say “Loud defenses of the IPCC”?
    And you still have not provided any factual argument of why you criticised Trenberth. That a hurricane would pick up and rain out more water when the ocean is warmer is very reasonable physics – is the political climate in the US now such that one is not allowed to point out simple physical connections? I’m a physicist, and I’m afraid the laws of physics will not be swayed by what policy people like to hear. -stefan]

    Comment by Roger Pielke Jr. — 11 Nov 2005 @ 10:01 AM

  33. Gavin (response to #32)-

    Thanks. I think that you have correctly put your finger on the communication issues here. But I am surprised by your view that your staement was not ambiguous. Clearly it was as you point out.

    Your original post stated, “no scientists have made a claim of direct cause and effect.” If you meant by that the cause being GHGs, and the effect being the very existence of Katrina, then I did not interpret your statement that way. I interpreted your statement as meaning, cause = GHGs, and effect being discernible influence of GHGs on Katrina or its damages. Trenberth clearly did the latter. The former I’d assert is a strawman, which I suppose why I didn’t interpret in the way that you describe (i.e., I can’t imagine Lawson meant that either.)

    You also state in your response to #32, “There may well be connections between hurricanes (in general) and global warming as have been highlighted in the discussions of the Knutson et al, Emanuel and Webster et al papers. The conflation that you make between the two statements (i.e. general connection implies specific cause) may explain why the conversation appears to make no headway.” Let’s be clear, it was Trenberth who clearly made the connection between general conclusion about hurricanes and GW (which I have no reason to doubt, e.g., see out BAMS paper which cites all three papers that you refer to) and a specific event – Katrina and its impacts, in a political forum. Enough said on that. Let’s move on.

    [Response: Let’s not quite move on yet. You have strongly attacked a colleague, and you still have not provided any rational argument why his physical reasoning is incorrect. -stefan]

    And while you are not an author in the IPCC process you have engaged in its defense. As a leading voice in this community your views, for better or worse, reflect upon the IPCC.

    [Response: It is getting a little weird. So the IPCC process can be criticised for what any individual climatologist says – no matter whether he is even associated with the IPCC reports?
    And you still owe us the explanation why you called Gavin’s defense of the IPCC “loud”. That is a put-down, and I think specifying what you meant is demanded by the respect and courtesy that you like to appeal to (which in my view is not measured in the number of times one adds “thank you” at the bottom). -stefan]

    Thanks again.

    [Response: Roger, Stefan, Please let’s move on. This issue is a huge distraction from the point of the post – gavin]

    Comment by Roger Pielke Jr. — 11 Nov 2005 @ 12:01 PM

  34. Re #32 Response

    Yes, in the US one is not allowed to point out simple physical connections, like how transpiration increases when growing seasons are longer, like how evaporation increases when lakes and reservoirs are warmer, like how rainfall intensity increases when climate is more humid and warmer, like how winter floods increase when climate is more humid and warmer ?

    Comment by Pat Neuman — 11 Nov 2005 @ 1:50 PM

  35. I think Trenberth’s suggestion of 1″ extra precip due to Katrina is really fairly mild, based as it is on huge regional & world averages, and not on the actual amount AGW may have increased SST & WV in the exact areas that spawned Katrina (which science can’t tell us…yet). (Nevertheless that last extra 1″ does a lot more damage than that first inch, which doesn’t even tickle the levee & is quite welcome by gardeners everywhere.)

    My thinking is this: Trenberth’s inch seems a bit mild & well within the bounds of reasonableness. But what if in a “God only knows” scenario in which humans had never evolved & there was no AGW, the Gulf had been slated to be below normal in SST & precip at the time of Katrina. Then in an “add in the humans” scenario (today’s reality) GW might have contributed nearly the whole Katrina. I think that is within the realm of possibility, even if it cannot be proven one way or the other…yet.

    Policy-makers & lay persons should be considering that high end possibility — not only modest, “best science can do” scientifically cautious statements. The implications are clear – there’s just no excuse anymore not to turn off those lights not in use!

    BTW, by “bland” in my earlier reference to IPCC’s 1995 SAR, I did not mean inaccurate. And the fact that the 2001 TAR gave more robust support for AGW & its possible harms, does show the SAR to be bland by comparison. So I think, acc to sci jnl articles since TAR, the 4th report in 2007 should make TAR seem somewhat bland by comparison — maybe that’s what Lawson is worried about & wants to quash or discredit IPCC before the 4th report comes out.

    Comment by Lynn Vincentnathan — 11 Nov 2005 @ 1:55 PM

  36. Gentlemen – Stefan, Gavin, Roger, Eli – perhaps you are not aware of how personal and harsh this thread comes across. As a stranger to all of you, I would suggest to you all that a public blog is not the best place to air this. You should all be mindful that accusations are amplified a couple of orders of magnitude when put in writing for the world to read.

    Regarding Trenberth, having looked at the slides, I don’t see Roger’s interpretation, personally, but on the other hand I don’t find his accusation of “recklessness” nearly as ad-hom as Eli’s quite sarcastic and personal rebuttal post. My understanding of climate science has not been increased by Eli’s comparison of Professor Pielke to Henry Kissinger.

    This is unfortunate in what has been, up to now, a terrific site.

    [Response: I agree completely. This is no longer constructive and we should move on to something substantive. Apologies all round. -gavin]

    Comment by Dan Allan — 11 Nov 2005 @ 4:29 PM

  37. Re # 35 – You are treating AGW like a religion. You start off by suggesting that Trenberth’s 1 inch of extra rain was mild. Then you go on to suggest that even all of Katrina could be due to AGW. You have no scientific basis for your statements. Wake up, huuricanes have been around during the “colder” periods centuries ago.
    Katrina could even have been worse on New Orleans if the eye had made landfall about 50 miles more westerly. The additional tide would have made the one inch of rain insignificant. Competent scientists have stated that it is difficult to attribute the specific amount of severity of a hurricane to global warming.

    Comment by Gerald Machnee — 11 Nov 2005 @ 7:17 PM

  38. In reply to Dan, I agree that this is not the place to continue this thread. Please accept that I had my say and did not continue. I believe that there is a place for such interchanges, but to avoid them degenerating one should not post more than once a day, perhaps less frequently, and allow those who disagree to have time for their reply. In the process of stopping allow me to clear up one point.

    I did not mean to use Kissinger as a negative comparison, but as the best illustration of someone who used his academic writings to move into a position where he could make public policy. A more recent US example might be Larry Summers. With respect to Prof. Pielke, this was meant as a compliment (seriously). He is one of the few who have a very clear idea about how to effectively use a new medium. My issue (continued elsewhere…the bad news for William is that I am thinking to post on this issue on neutral ground at Stoat….

    Comment by Eli Rabett — 11 Nov 2005 @ 8:26 PM

  39. Please, gentlemen — Slide 18 is titled:
    How big is the effect of Global Warming?

    Followed by:
    * Since 1970 tropical SSTs have increased 0.5ºC
    * Water vapor has likely increased ~4%.
    * This also likely enhances winds by this order
    * Surface latent heat fluxes in storms likely increase by at least this much [Research topic]
    * Thus moisture convergence in boundary layer goes up by 8% (1.042).
    * Corresponds to expected increases in rainfall and latent heat release in storms: order 8%. [4 to 12%]

    And FINALLY:
    [Implies 1″ extra rain near New Orleans in Katrina]

    The fact that Mr. Rabett doesn’t understand this obvious 4 to 12% (8% – when forced to a number) link to GW effects is regrettable; however, the fact that many others here don’t get it, is depressing. With all this concern for fairness and rebuttal of a colleague of many of you (Professor Trenberth), I would like to read a comment from another colleague, Professor Landsea, on whether the above presentation and particularly the summary slide 18 linkage of GW to increased hurricane and specifically Katrina intensity, is an example of why he resigned from the IPCC in early ’05?

    [Response: I think you summarise Trenberth’s argument correctly, and it is an entirely reasonable argument. In the thread above I have tried (in vain) to get Trenberth’s critics to put their scientific reasons on the table why they think he is wrong, so that we could have a good science discussion. Note that Trenberth discusses a physical connection between warmer ocean temperatures and enhanced precipitation, and the physics applies to every individual hurricane, including Katrina. (He is not talking about a statistical connection, from which no conclusion about one individual event should be drawn, only about ensembles. Maybe confusing those two is what got some people excited.) The physical link between SST and precipitation for any individual hurricane is not controversial, it is routinely exploited in the hurricane forecast models used by the national hurricane center.
    Incidentally, those who claim the extreme 2005 hurricane season is entirely due to a natural cycle, like Bill Gray, also say it is due to warmer ocean temperatures – the difference in opinion is in why the ocean temperatures are so warm, not in the effect this has on hurricane intensity or precipitation. Gray says the ocean is warm because of an increased thermohaline circulation in the Atlantic, which varies as a cycle (see comment #15 here). The reason why climatologists do not believe this is the whole story is because an increase in thermohaline circulation would warm only the north Atlantic, but it would cool the south Atlantic and would have hardly any effect on the Pacific or the global mean temperature. However, ocean temperatures have warmed almost everywhere on the planet, with 0.5 ºC being the global mean rise of sea surface temperature, hence Trenberth’s reasonable estimate that this much is the contribution from global forcings like CO2. Superimposed on this are any regional and natural oscillations due to changes in heat transport (which redistributes heat, making some places warm more than average, some warm less or a few even cool). Also, the effect of CO2 on temperatures is very well established, and nothing suggests it somehow stops at the tropics. -Stefan]

    Comment by McCall — 11 Nov 2005 @ 9:08 PM

  40. They say a picture is worth a thousand words, but I will try to create this cartoon with rather less. Imagine a large snowball on a slope. It represents the earth science establishment united by a system of peer review, and labelled IPCC. Further up the slope on the right, both physically and politically, stand the sceptics trying to push the snowball downhill. Below the snowball and on the left is me, a greenie, trying to push the snowball back up the hill. The slope is calibrated with increasing time along the x-axis and temperature up the y-axis. This means that the edge of the snowball can be read off against the axes to give a range of times and increases in temperature for a doubling of CO2. In that cartoon, I seem vulnerable to the danger of being crushed by the IPCC as it is pushed by the vast host sceptics, but fear not, there is so much momentum in the snowball that those pushing it from the right are having little effect. Although I am well outnumbered, it is not my strength that prevents the snowball moving; it is just inertia!

    So, I see myself as an outsider, and as a critic of the IPCC, but an unusual one. I believe that any effects that the other critics (sceptics) have had has been bad. They have been trying to move the argument in the wrong direction. However, they have found like me, that action equals reaction, and no matter how hard they push or how valid their arguments are, they cannot make the damn snowball budge! Hence, Lawson’s argument that the IPCC should be abolished.

    My criticisms are the same as those of the other critics, but the conclusions, which I draw, are diametrically opposite. I do not want to open old wounds in this thread, but in order to explain what I mean I will have to risk that by explaining them it may lead to a diversion into discussion of their merits. However, concrete examples are always better than abstract ramblings, so here goes.

    Take the Hockey Stick. The argument is that because temperatures are higher now than at any time in the past 1,000 years therefore global warming is anthropogenic. The standard criticism is that no, temperatures may have been higher, and it even descends into uninformed questioning of the data. My criticism is that even if temperatures are higher now, that does not prove that the warming is due to anthropogenic causes. They could well have been higher over the last 2,000 years, or 10,000 years, and they were certainly higher 100,000 years ago during the Eemian Interglacial, as is shown by the ice cores. (Incidentally as I see it, the proof that global warming is anthropogenic is that night and winter temperatures are rising faster than when the sun is shining. If the warming was natural then it must be due to the sun. Therefore, day and summer temperature would show the greatest increase.)

    Another case where I agree with the criticism but come to a different conclusion than the skeptics is with the MSUs. They argued that since the MSUs did not show the same warming as the surface then the Earth was not heating. My conclusion is that if the data does not fit the model then the model is wrong. I wonâ??t go further and discuss the Snowball’s response of adjusting the data for fear of libel charges :-)

    So, it is possible to be a global warming “believer” and yet accept the criticism. However, criticise from the right or from the left, and you still get violent opposition. The Snowball is like any group of people such as a family, clan, profession, or nation who unite and fight together against an attacker. So what to do? Well I don’t accept Lawson’s “final” solution of abolishing the IPCC. The peer review system may not be perfect but like the system of democracy, which elected him, Mrs Thatcher, and George W. Bush, it is the best system we’ve got. What is needed is that earth scientists realise that they, as Michael Crichton has pointed out, are unlike other scientists. They cannot experiment. Therefore, they must pay more attention to outside critics. They must search for the truth hidden in what they are saying, rather than dismiss their ideas out of hand on the grounds of “professional” scepticism.

    What I have done here is to take Lawson’s rather uninformed and prejudiced remarks which I have then distilled to find the truth which inspired them. Earth scientists must not be skeptics looking for the counter arguments. They should be sleuths searching for the gems of truth in the dark streets of real life.

    Comment by Alastair McDonald — 12 Nov 2005 @ 10:34 AM

  41. Here is the “curious report” from the house of lords. (here)

    [Response: I thought I had linked to it, but thanks for reminding me (the link is now in the main text too). -gavin]

    Comment by Johan Richter — 12 Nov 2005 @ 3:32 PM

  42. Re 41 – Where? I have been keen to read that Lord’s report for some time now.

    Comment by Alastair McDonald — 12 Nov 2005 @ 3:51 PM

  43. Re 41 again. I did a Google search and found a links to the “Second Report – The Economics of Climate Change” at

    Few of the Lords are heritary peers, most having been appointed by the Prime Minister of the day, and serve for life, rather like the US Supreme Court. But there is no scrutiny of the PM’s selection, nor is there any limit to their number. So now, Tony Blair has in effect packed the Senate with place men of his own choice. Comparing these lords with senators will become clearer when you read this oral evidence to a question from Lord Nigel Lawson, probably appointed before Blair became prime minister.

    Lord Lawson of Blaby: Are you aware that this, which has had a very profound influence on thinking, is explicitly stated in the Government’s White Paper to be based on proxy data, whatever proxy data may be, because there are no instrumental observations, they did not begin until the late 19th century, and that for these proxy data, which it says in small writing at the bottom, that the IPCC relies entirely on a study by a Professor Mann in 1998 and this has subsequently been examined and it was found that that Mr Mann got it all wrong in a rather fundamental way. Professor McKitrick, for example, has gone into this in great detail and so I believe have others. Is this something you have studied?

    Professor Robinson: I have not studied in any detail this question about whether we are in a trend or in a cycle but if you simply cover the projection part at the end of that graph with your hand you can see (it is not all that clear) what is happening. I am merely raising the question because I think it is an important issue because if we were in the warming phase going to a cooling phase, and the Government takes action on the assumption it is warming, then we are doing precisely the wrong thing presumably. So it is quite an important issue and I was really raising it as a question that might be addressed to the scientistsâ??what confidence they have that this is a genuine trend.

    [Response: I agree that this exchange is good evidence of the low level of debate at the HoL – you’d get better on sci.env! But Lawson is a Tory – hardly a Labour placeman – William]

    Comment by Alastair McDonald — 12 Nov 2005 @ 4:39 PM

  44. My least favourite memory of Nigel Lawson’s tenure as Chancellor of the Exchequer was my mortgage doubling in an 18 month period.
    Leaving that aside, Nigel is in a fairly unique position. As an ex-Chancellor he can still command respect and media attention – but as a member of the House of Lords he has no longer has any accountability. He can therefore say anything he likes, without any fear of reprisals from the cabinet, whips, or the electorate. His current “job” will never be at risk.

    Comment by Stewart Argo — 12 Nov 2005 @ 7:24 PM

  45. I am not quite sure what Mr. McCall’s point is. Dr. Trenberth clearly stated that his calculations imply ~1″ of the rain that fell on New Orleans during Katrina could be attributed to the change of sea surface temperature associated with global warming since 1970. I clearly recognized that in my reply #9.

    The claim is made in the last summary slide of a presentation.

    Look at the preceeding slides. Which other statements on that last slide and the other slides is wrong. If you cannot find any then Trenberths conclusion is reasonable.

    The current Landsea/Trenberth/Emanuel discussion has been parsed by many to mean that Landsea claims that the number of hurricanes is constant, and Trenberth is claiming that their intensity should increase as global warming heats the ocean surface and these claims can both be true.

    However, if we are talking about hurricanes and not just cyclones, a certain proportion of cyclones will move up to hurricane status if Trenberth is right, and there will not only be increased wind speed, but also more hurricanes.

    Comment by Eli Rabett — 12 Nov 2005 @ 8:47 PM

  46. Katrina did not form in the average ocean where sea surface temperatures have indeed risen. It gained its strength in the Gulf of Mexico, where temperatures are currently high but there is no long term trend. I do not see how it is possible to link the rainfall associated with Katrina to global warming.

    Comment by Blair Dowden — 13 Nov 2005 @ 1:11 PM

  47. #46

    Actually Katrina did form over waters warmed by global warming, it formed as a tropical depression #12 (formerly #10 had dissipated), from a slow moving wave, on the night of August 23, and the morning of August 24, on the Great Bahama Bank, according to my notes and my memories. I was watching these storms form all summer from those waters, and they were demonstrably the warmest water temperatures we have ever measured. Even before Katrina, we were stunned when measurements of surface waters of the deep Atlantic were in the high 80s. I watched these storms nucleate all summer out there, Franklin, then Katrina, and finally I observed TD#16 (Ophelia) point nucleate directly above my location, from a featureless flat calm trough, on Sunday, September 4th, and observed the cyclogenesis event almost immediately thereafter, directly into a tropical depression surrounding me completely, in only a few hours, and then I was subsequently battered by 30 knot winds.

    Those were extraordinarily hot times and waters out on the Bahama Bank this summer. That was the closest that I have ever observed multiple tropical cyclogenesis events. Something bad is going on out there, it will be interesting to see how next year shapes up. Sometimes these things go two years on and one year off, but there was a definite lack of Cape Verde types this year.

    Comment by Thomas Lee Elifritz — 13 Nov 2005 @ 4:58 PM

  48. But Katrina was only a category 1 when it reached Florida, so does it matter how warm the Atlantic waters were? It became a significant storm only when it crossed the Gulf of Mexico. Since the Gulf of Mexico shows no warming trend, global warming has nothing to do with Katrina’s strength, so I do not see where Trenberth gets his one inch of rain from. The warm Atlantic may well affect other hurricanes, but we are specifically talking about Katrina here.

    Comment by Blair Dowden — 13 Nov 2005 @ 10:29 PM

  49. #46

    I am just addressing the statement that you made about the formation and evolution of Katrina, which I witnessed, which was false, and then you claim some unjustified skepticism. Now you further claim there is no warming trend in the Gulf of Mexico, but provide no evidence of that claim.

    I myself find it fairly difficult to understand how unprecedented water temperatures in the southwest north atlantic basin, the caribbean sea and the gulf of mexico could *not* have contributed to the cyclogenesis and rapid evolution of many of the major hurricanes we witnessed this summer.

    Comment by Thomas Lee Elifritz — 14 Nov 2005 @ 1:40 AM

  50. RE #37, people usually make decisions and policy on less that “beyond a resonable scientific doubt” evidence, and it’s always good to consider the worst case scenario & see what can be done to avert it. (Where are the “Be Prepared” scouts when we need them?) Since reducing GHGs, if done smartly, also saves money without reducing productivity, then there’s really no excuse not to vigoroously pursue such strategies — rather than continue subsidies to fossil fuels (which we pay for April 15th, if not at the pump or on our utility bills, or at least we pan costs & eco-harms off to future generations).

    (Your argument sort of reminds me of a relative. We had to go for a long walk, and there were ominous black clouds. I said, “Looks like it might rain. Let’s take umbrellas.” She said, “It might not rain, let’s not take them.” Well, it didn’t rain that time, but if it had she would’ve gotten soaked.)

    Is there any scientist who has irrefutable evidence and can prove with 95% confidence that GW did NOT contribute to Katrina? I rest my case.

    But even if I were to lose the Katrina case, & it’s proven to be totally natural beyond a shadow of a doubt, then we only have worse to expect in the future when GW really kicks in. Care to try for a Category 6, or would you prefer offing that light not it use?

    Comment by Lynn Vincentnathan — 14 Nov 2005 @ 5:17 PM

  51. Re #49: It is hard to give you my data because I used interactive maps. But I will try.

    1) Go to this NOAA page, and press Submit (accept the defaults).

    2) Select June to October (the hurricane season) and use the default time interval (from 1880 on).

    3) Select the area on the map that Katrina passed through in the Gulf of Mexico (I used longitude -95 to -85, latitude 28 to 24).

    The resulting map shows cycles, but no rising trend. I think the inputs are reasonable (ie. not cooked).

    I am only questioning Trenberth’s statement about Katrina. Temperatures in the Gulf are high, but in my view show no long term warming trend, and thus cannot be attributed to global warming, at least yet. If there is something I am missing I hope someone will explain it.

    I am not saying there is no global warming, or that it does not affect hurricane strength. The effect on hurricane frequency seems to be a matter of debate. But that warming is not uniform, there are parts of the globe that show no trend or a cooling trend. The relevant part of the Gulf for Katrina appears to be one of those areas. Of course, if global warming continues there will be fewer of those areas.

    Temperatures in the Caribean and Atlantic are rising, so storms in that region may well be affected by global warming.

    [Response: I think there is a misunderstanding here. We have pointed out before on this site that you cannot use a single time series for attribution of causes. A simple example: assume a uniform global warming has warmed all SST by 0.5 ºC in the whole world. Superimposed are regional natural oscillations. So in some region, you observe 1 ºC warming (half GW, half natural), while in others no warming at all (as the natural variation cancels the GW). In both cases, global warming has contributed equally (0.5 ºC) to the temperature (and hence, to turn to Trenberth’s argument, enhanced precipitation somewhat), even though in the latter case you observe no warming trend. To say that global warming has raised temperature by 0.5 ºC is based on the overall evidence for global warming, not on observing a local trend. It is reasonable to assume that the effect of global warming is smooth and large-scale, and does not stop at the Gulf of Mexico. -stefan]

    Comment by Blair Dowden — 14 Nov 2005 @ 8:11 PM

  52. Re #51 (BD): I’m no expert on this, but off-hand I would note that the link appears to show just sea *surface* temps. I saw it noted on a number of occasions this year that the loop current was very unusual in that it was quite deep as well as quite warm. Depth is important since one of the ways hurricanes lose energy is by churning up deeper cold water. If they just churn up more warm water, it could be expected to have the opposite effect. Also, I believe it’s the case that the loop current is the product of heating in the Caribbean.

    Comment by Steve Bloom — 14 Nov 2005 @ 11:33 PM

  53. Re #52: Here is a discussion of loop currents at Wikipedia. No mention of the cause of a stronger loop current. But it is a good point that sea surface temperatures do not carry information about the 3 dimensional temperature profile, which can be very important.

    Comment by Blair Dowden — 15 Nov 2005 @ 12:05 AM

  54. BD-

    You were questioning a result by making *false* claims about it, which I quickly corrected. For instance, we get our modern data from here :

    Just because you *think* something is true doesn’t necessarily make it so. For instance, I can hypothesize that you are Blair Dowden, president of Huntington University. This is a hypothesis that may be easily falsified.

    Comment by Thomas Lee Elifritz — 15 Nov 2005 @ 2:02 AM

  55. re: response in post 39. Sorry if my post wasn’t clear, but you have misread my point — I agree with Professor Pielke, that the lead IPCC WG1 author has claimed a link between hurricane strength and GW. My criticism of Mr. Rabett and others was that they were denying the obvious — the presentation and particularly slide 20 were clearly constructed with exactly that linkage to be conveyed (whether the audience was technical or not)!

    I believe the courtesy afforded Professor Trenberth should also apply to Professor Landsea, and I would still like to hear from him about this presentation and particularly slide 20. It would not be a stretch to perceive Professor Trenberth’s positions in that presentation as exactly the those that contributed to Professor Landsea’s IPCC resignation.

    Again my apologies for the confusion.

    Comment by McCall — 15 Nov 2005 @ 3:02 AM

  56. Gavin, You argue in your initial posting that “First, it should be emphasised that the scenarios are used solely for the providing input into climate models, and not for generic economic planning decisions. Therefore only the final differences in the total greenhouse gas emissions actually matter.”

    This may be all that actually matters to you, but the simple fact of the matter is that the IPCC’s Special Report on Emissions Scenarios (SRES, 2000) is explicit that the scenarios are intended for THREE uses, and that the Panel has decided that they are suitable for all three of these uses in the AR4. The FIRST use is indeed to provide input to climate models. The SECOND use is “To provide input for assessing mitigation and adaptation possibilities, and their costs, in different regions and economic sectors”, and the THIRD use is “To provide input to negotiations of possible agreements to reduce GHG emissions” (SRES, s. 1.3, p. 64).

    You say that Lord Lawson is the victim of “a confusion between the IPCC and the policy options exemplified by the Kyoto Protocol”, and that “These are two quite separate things.” In one sense you are correct: the Royal Society (UK) and fifteen other scientific academies were certainly wrong when they issued a statement in May 2001 in which they conflated their support for the IPCC “as the world’s most reliable source of information on climate change” with their support for the ratification of the Kyoto Protocol as a “small but essential first step towards stabilising atmospheric concentrations of greenhouse gases” (HoL Committee Report, vol. 2, pps. 295, 305).

    This statement provided useful material for the former Chairman of the IPCC, Robert Watson, to use in evidence to a Committee of the Australian Parliament soon afterwards (Dr. Watson was, and remains, the Chief Scientist at the World Bank, an organisation that you describe as “not noted for its scientific expertise”. He ceased to be Chairman of the IPCC in April 2002, but still claims to hold this post in his page on the World Bank Experts website).

    However, as Lord Lawson rightly pointed out in his evidence to the US Senate Committee on the Environment and Public Works on 5 October 2005, the key question of what should be done about such global warming as may occur is not a matter for scientists. Governments would have been assisted in their assessments of mitigation and adaptation possibilities and the provision of input to negotiations of agreements such as the Kyoto Protocol and possible successors if the IPCC’s SRES had been technically sound. The UK has now remedied this deficiency by establishing an inquiry into the economics of climate change under the direction of Sir Nicholas Stern, Head of the Government Economic Service and former Chief ECONOMIST at the World Bank.

    You go on to say that “From reading the Committee report itself, these differences in emissions for one particular scenario are only around 15% by 2100, and only lead to a 0.1 deg C difference in temperature by 2100 (Table 3, p. 39) – and this is certainly much less than the spread among the different storylines, and so is unlikely to affect the range of climate model results.” With respect, you are here disregarding three distinct issues.

    First, so far as “climate model results” are concerned, simulations using models other than the MERGE model illustrated in Table 3 of the Lords Report have shown much greater differences in TOTAL emissions arising from the mismeasurement of output than those shown in that Table. For example, the second of the papers cited in footnote 53 on p. 33 of the HoL Report found that the difference between MER and PPP-based estimates was three times as great as in the unpublished Manne and Richels (M&R) working paper that the IPCC chose to use to dismiss the Castles and Henderson critique.

    (Incidentally, I’m surprised at your claim that the IPCC makes no proclamations in between the full assessments. The IPCC’s press statement in Milan on 8 December 2003 claimed, on the basis of the unpublished M&R paper to which I’ve just referred, that “The claim of C&H, therefore, that there is an upward bias in the SRES scenarios is totally unfounded.” What is that, if it is not “a proclamation” The Lords Committee, which certainly investigated this matter more closely than the IPCC, noted that “several critiques show that predictions could be significantly affected by the use of PPP exchange rates” and that “PPP is the right procedure, as Professor Nordhaus’s study amply clarifies” (para. 72). When asked by Lord Skidelsky whether “the critics have influenced the methodology”, Dr. Pachauri, Chairman of the IPCC, said that “It only validates the methodology that the IPCC used earlier” and that “It does not require any deviation from it.” At the International Statistical Institute meeting in Sydney in April 2005, I met with scores of national accounting statisticians from all over the world. None of them believes the IPCC approach is correct. The Panel chose to use the United Nations Statistical Commission definition of GDP, but to ignore the outcome of fifty years of research into the proper procedures for aggregation. This was bad science, but the IPCC has been able to get away with it by excluding all national accounts statisticians from AR4. To the best of my knowledge, no member of the International Statistical Institute was chosen by the Working Group II and III Bureaux for the writing teams of the Contributions of these Working Groups to AR4.

    Secondly, it is important to recognise that the error in the SRES procedures is not uniform between regions. So far as emissions are concerned, the predominant effect of the use of the faulty procedure is on the aggregates for developing countries. Even if TOTAL emissions were unaffected by the use of the wrong measure of output, the SRES projections of REGIONAL emissions would still be seriously astray. The SRES projections of regional emissions are therefore unsuitable for mitigation or adaptation analyses.

    Thirdly, the policy processes mediated through the UNFCCC and the Kyoto Protocol require estimates of output and GHG emissions per unit of output: not just the product of these two variables (emissions). Partly as a result of the failure of the SRES authors to adopt the internationally-recognised System of National Accounts, the UNFCCC monitoring processes are in a complete mess. For example, the international team of experts that conducted the review of the progress of the European Union in meeting its obligations under the Kyoto Protocol calculated GHG emissions per unit of GDP (PPP), but the international teams that conducted the Expert Reviews for some major individual countries within the EU, such as France and Germany, presented GHG emissions per unit of GDP(MER). The IPCC proclaims that this doesn’t matter because “The economy does not change by using a different metrics (PPP or MEX), in the same way that the temperature does not change if you switch from degrees Celsius to degrees Fahrenheit” (IPCC Press statement of 8 December 2003). This is of course palpable nonsense. Does any IPCC scientist think that it’s OK to compare Country A’s temperature in degrees Fahrenheit with Country B’s in degrees Celsius, and then take an average of the two, without adjustment, to get the mean temperature of the two countries taken together?

    You say that Lord Lawson’s claims that IPCC’s ‘ignoring of dissent’ is a ‘scandal’ betrays a fundamental ignorance of how the IPCC works, and that the next IPCC report “will assess the validity of any criticisms published in the scientific literature in its next report, due in 2007.” You also claim that the IPCC “makes its assessments in a very thorough writing and review process involving hundreds of scientists, open to critics, with transparent and predefined procedures.” These are your perceptions, but in the aspects of the Panel’s work with which I have personal knowledge, Lord Lawson’s perception is far closer to the truth. The IPCC has never published a report of the Expert Meeting on Emissions Scenarios at which I made a presentation, at the Panel’s invitation, in Amsterdam in January 2003. In an effort to ascertain how elementary errors escaped detection in the IPCC’s Third Assessment Report (TAR), I asked the IPCC Secretariat where I could find review comments on selected chapters that, according to the Panel’s procedures, are held in an open access archive for five years. I have never received a reply.

    Finally, I must disagree with your reference to “small and vocal minorities” complaining that they have been shut out of the IPCC process. I pointed out in my first letter to the Chairman of the IPCC in August 2002 that statements that were made in the TAR had been found to be “material errors” in a unanimous report of experts to the United Nations Statistical Commission. These experts do not represent a “small minority”: so far as I know, all national accounts experts and index number theoreticians agree with them.

    [Response: Ian, thanks for your comments. I am unable to spend any time going through the economics literature to sort out the claims of different models (maybe an Intergovernmental Economic Assessment process is required?), and I am not qualified to assess them in any case. However, in the years that you have been working on this, I am not aware of results from you demonstrating that climate modellers need to pay attention to this. In the meantime, we have run many of the IPCC scenarios while at the same time we have developed our own scenarios (albeit in a less sophisticated way than the SRES process). None of the modelling groups are locked into exclusive contracts with IPCC, so here is my challenge to you: Produce a set of scenarios (global mean CO2, CH4, N20, CFCs etc.), that correct the problem as you see it, and if they are of sufficient scientific interest (i.e. if they diverge significantly from the range of scenarios we’ve already done – see for the range we have already run), then we’ll run them as well. One can waste an awful lot of time writing letters and arguing about whether something matters, but since us modellers are basically empiricists, a practical demonstration is worth a thousand blog comments. -gavin]

    Comment by Ian Castles — 15 Nov 2005 @ 8:10 AM

  57. Gavin (response to Castles #56)-

    This exchange highlights a dynamic documented (empirically) regarding scientific assessments by Cash et al. (citation and link below). Specifically to the IPCC, its champions focus on its “credibility” to the exclusion of its “legitimacy” (specific definitions below). In your reaction to Lawson and also to Castles you emphasize the credibility of the process, but this is not what either is talking about. The result is, as documented by Cash et al., risks to credibility, salience and legitimacy.

    Cash, David, Clark, William C., Alcock, Frank, Dickson, Nancy, Eckley, Noelle and Jager, Jill, “Salience, Credibility, Legitimacy and Boundaries: Linking Research, Assessment and Decision Making” (November 2002). KSG Working Papers Series RWP02-046.

    Here are some definitions from Cash et al.:

    “Legitimacy refers to whether an actor perceives the process in a system as unbiased and meeting standards of political and procedural fairness. Legitimacy involves the belief that S&T systems are “fair” and consider appropriate values, interests, concerns, and specific circumstances from multiple perspectives. Audiences judge legitimacy based on who participated and who did not, the processes for making those choices, and how information is produced, vetted, and disseminated.”

    “Credibility refers to whether an actor perceives information as meeting standards of scientific plausibility and technical adequacy. Sources of knowledge must be deemed trustworthy and/or believable, along with the facts, theories, and causal explanations invoked by these sources.”

    Here is what Cash et al. say about how the IPCC has tended to focus on credibility to the exclusion of legitimacy and salience. (My interpretation is that legitimacy has more to do with politics and salience with policy.) Their argument is that it is counter-productive to try to build a wall around credibility, even though there are incentives to do so.

    “Traditionally, scientists, managers and scholars of science, technology and policy have focused on credibility – how to create authoritative, believable, and trusted information (Price 1965; Wildavsky 1987). For example, during the creation of such bodies as the Intergovernmental Panel on Climate Change (IPCC), priority was given to creating organizational structures that assure credibility of the information being produced – through peer review, rigorous vetting of participants, etc. (Agrawala 1998). Recent research and practice, however, point to the danger of overestimating the importance of credibility alone, while undervaluing two other attributes of science and technology systems: salience (how relevant information is to decision making bodies or publics) and legitimacy (how “fair” an information producing process is and whether it considers appropriate values, concerns, and perspectives of different actors.)”

    You simply cannot address concerns about legitimacy by reverting to exhortations of credibility. Lawson and Castles are primarily raising issues of legitimacy. This is why it matters when people write letters, author blogs and generally seek to determine what matters for political and policy discourse. When science encounters society you can expect that science will have to adapt to the realities of policy and politics, and not vice versa. Of course, if the science issues are not relevant for decision makers or the public, most of this is moot. All of this is to say, for a scientific assessment to be successful (whether a UN IPCC or group weblog) it will have to pay attention to legitimacy and salience in addition to credibility.

    [Response: Fair enough, yet what has happened is that people who don’t want the process to be credible, instead focus on legitimacy as their criticism, and so as in the ‘scientization’ of policy debate, you see a ‘legitimization’ (to coin a term) of the credibility argument. As is clear, this argument has more traction, and so is being favored by many different actors. Since the real argument is not about ‘legitimacy’ at all, but about the credibility of the conclusions, it is pointless to get engaged on the legitimacy question. It just ends up being a distraction (which is of course the point of the criticism in the first place). – gavin]

    Comment by Roger Pielke Jr. — 15 Nov 2005 @ 12:13 PM

  58. IPCC should win, whatever

    Comment by mike — 15 Nov 2005 @ 1:00 PM

  59. Roger,

    I think it should be acknowledged that there are many critics of the process who simply want AGW to not exist, and will criticize regardless of how well the process is perfected. How far should one bend then in the hopes of gaining “legitimacy” with these people, when we basically know ahead of time that this is futile?

    In other words, one needs to define legimitacy in such a way that it is possible to achieve.

    Comment by Dan Allan — 15 Nov 2005 @ 3:25 PM

  60. Gavin (reponse to #57) and Dan (#59)-

    To succeed, the IPCC needs all three of legitimacy, credibility and salience. For example, as I have discussed on our blog, legitimacy is risked when the IPCC leadership engages in political advocacy. Legitimacy is also risked when the IPCC reacts very negatively to complaints such as those leveled by Castles/Henderson and Landsea. Salience is risked when the IPCC uses different definitions of “climate change” across its three reports. These are but a few examples of issues which the IPCC could pay closer attention to. The overriding focus on credibility comes at a cost. I disagree with gavin that issues of legitimacy are just a distraction. They are very real. Lawson’s essay is a good example. By the way, this argument on legitimacy, saliency, credibility is based on a well-developed perspective from the GEA project at Harvard led by Bill Clark. At a minimum worth thinking about carefully.

    Comment by Roger Pielke Jr. — 15 Nov 2005 @ 3:41 PM

  61. Re # 50
    Your first paragraph has nothing to do with the discussion. If you want to “Be prepared’, you prepare – ie, do not build below sea level, do not build on fault lines, have stockpiles of supplies available for disasters (a lesson not learned beforehand for New Orleans). You do not need to debate whether GW caused the problem – it is called – ” Be ready”. You just want to get your “religion” into every discussion.
    ***(Your argument sort of reminds me of a relative. ***
    This preceding statement is the same as your AGW comments about hurricanes. You make them with no scientific evidence. You know nothing about me, and hurricanes are not your expertise.
    A couple of comments will suffice – a) I do not own an SUV, b) I have been preparing and conserving for a long time. I was 25 years ahead in insulating my house to above standards and thereby conserving heating energy supplies.

    ***Is there any scientist who has irrefutable evidence and can prove with 95% confidence that GW did NOT contribute to Katrina? I rest my case.***
    This is a meaningless statement you should think about. I have already indicated that competent scientists have said that it is impossible to attribute how much GW contributes to the INTENSITY of hurricanes (some have indicated 5-10 percent). But I can say that we are more than 95 percent certain what CAUSES hurricanes to originally develop. And I am quoting competent research. So my comments still apply – do not make statements about GW causing most of a hurricane unless YOU have proof.

    Comment by Gerald Machnee — 15 Nov 2005 @ 9:20 PM

  62. Gavin,

    Do you really believe that all criticism, regardless of its basis, is a distraction?

    No person is correct 100% of the time. The same holds true for an organization. Errors are made because it is human to err. When a person or an organization makes an error, the most important thing that can happen is for that person or organization to recognize that an error occurred and to discover why the error was made. Knowledge of what happened allows learning from the error.

    Only after you recognize what happened and correct it can a person or organization put controls in place which serve to prevent such errors from re-occurring.

    [Response: Of course not. People involved in IPCC as in all other domains make mistakes and incorrect decisions. Don’t mistake my criticism of specific (spurious) arguments for a claim of general perfection. For instance, I think it would have been useful to attach subjective probabilities to the different scenarios – I understand the reasons why they weren’t, but still… There are other minor issues that I’ve had with the process, but they don’t come anywhere near justifying shutting the process down. To paraphrase Churchill (I think) – the IPCC is a terrible idea, except for all the others. -gavin]

    Comment by Brooks Hurd — 15 Nov 2005 @ 9:31 PM

  63. Gavin, Thank you for your response to #56. In saying that “what balance between adaptation … and mitigation … is likely to be more cost effective is not a question within the remit of the IPCC”, you are essentially agreeing with Lord Lawson’s statement to the US Senate Committee on Environment and Public Works 5 October that the key question of what should be done about such global warming as may occur “is not a matter for scientists at all.” I agree. However, in answering that question the world’s governments depend (excessively, in the view of Lord Lawson and many others, including me) upon the assessments of the intergovernmental panel that they have set up for the purpose. With the support of around 200 governments, and with the science academies of Australia, Belgium, Brazil, Canada, the Caribbean, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden and the UK proclaiming that they “recognise the IPCC as the world’s most reliable source of information on climate change and its causes” and endorse its method of achieving consensus, I see little point in Ian Castles asking GISS to produce a different assessments of the outlook for emissions, forcings and temperature change.

    You say that a point worth making is that “if Lawson really feels that the high end emissions forecasts are unrealistic, then the costs of keeping to a climate-based target are much less – ‘Kyoto for free’ as it were.” Sorry, but I don’t believe the point IS worth making, or that it’s even correct. The costs that the world bears to get to any defined target are incurred ex ante. They are the costs that are BELIEVED to be necessary to get to the specified level, and these depend in turn upon the IPCC projections of future emissions profiles, concentrations of GHGs, forcings and temperature change in the absence of policies that explicitly address climate change. What Lawson “really feels” is irrelevant, as are the assessments of Ian Castles or David Henderson or James Hansen. Governments are spending billions (and committing themselves to trillions) because they are constantly being told that the threat of climate change calls for urgent and drastic action. We won’t be able to get our money back if it turns out that the IPCC “without climate change policies” projections were overstated and we could have had ‘Kyoto for free’.

    You have challenged me to “produce a set of scenarios (global mean CO2, CH4, N2O, CFCs etc.) that correct the problem as you see it, and if they are of sufficient scientific interest (i.e., if they diverge significantly from the range of scenarios WE’VE already done …), then WE’LL run them as well” (EMPHASIS added). This misses the point. Governments aren’t interested in Ian Castles’ scenarios or GISS scenarios: they are relying on the IPCC scenarios: the Panel has determined that these “provide a credible and sound set of projections, appropriate for use in AR4”.

    I am puzzled by your comment that “In the years that you [i.e., me] have been on this, I am not aware of results from you demonstrating that climate modellers need to pay attention to this.” I’m not sure what you mean by “this”, but let me give an example of the kinds of questions that I have been raising. In my presentation to the IPCC Expert Meeting in Amsterdam in January 2003, I said:

    ‘In his very interesting paper in the session “The SRES scenarios and application in climate research” on Wednesday afternoon, Dr. Tom Wigley identified the A2G IMAGE and the B1T MESSAGE scenarios as “the extreme scenarios in terms of the 2100 forcing pattern”. He noted that the A2 IMAGE scenario projected a burden of 780 ppm [equivalent] CO2 in 2100, whereas the B1T MESSAGE scenario projected a burden of 480 ppm. And he described these extremes as capturing “the total range of possible variation” ‘.

    I went on to question whether the B1T MESSAGE scenario DID capture the low end of the range of possible variation. I noted, for example, that this scenario assumed faster economic growth in the developing countries in the medium term than the highest of three scenarios being considered by the World Bank in its monitoring of progress towards the Millennium Development Goals. In a supplementary paper, I listed eight reasons why B1T MESSAGE might overstate emissions – e.g., that this scenario assumed a 44 per cent growth in global CH4 emissions between 2000 and 2050, whereas it was stated in James Hansen (ed.), “Proceedings of a Workshop on Air Pollution as a Climate Forcing” that “Such efforts [to contain methane emissions for non-climate-policy reasons], if international, will clearly stabilise methane abundances, avoiding the large increases projected in some of the SRES scenarios.” If I were writing now, I could add more points – e.g. that under the International Energy Agency’s “Alternative Scenario”, which “considers those policies that countries are currently considering or might reasonably be expected to adopt taking account of technical and cost factors, the political context and market barriers”, annual CO2 emissions from fuel combustion in 2030 will be lower than under ANY of the 35 SRES scenarios (IEA, International Energy Outlook 2004).

    The Australian Government apparently thought that I had a point, because in its submission to the IPCC on the scoping of AR4 (March 2003) it suggested that the Panel “consider whether there are plausible emissions scenarios outside the range indicated in the SRES and if so, manage integration of such scenarios into the AR4 (for example, consider developing a further scenario with lower developing country growth than the B1 scenarios, but without the high population and slow rate of technology growth associated with the A2 and B2 scenarios).” But the IPCC decided, in its wisdom, that the set of scenarios developed in the late 1990s were appropriate for use in AR4 and that no new scenarios would be developed.

    No respectable business enterprise would use ten-year-old forecasts as a basis for developing its long-term plans, and I’m concerned that governments, many of whom believe that climate change is the greatest challenge facing the planet, seem content to rely on projections which are already running well ahead of actual outcomes.

    Thanks for the offer to run my alternative scenarios, but I don’t see the point: it would only be a Castles/GISS scenario, not an IPCC one. The Australian Government could have asked CSIRO to run off the scenario that I suggested in Amsterdam as soon as the IPCC decided to rely on the SRES set for AR4, but what would that have achieved? The result would have been an Australian scenario and, as you said in your initial post, “It should go without saying that the assessment bodies should be international in scope to avoid the impression that they are somehow pushing national agendas in very sensitive areas such as energy or trade.”

    In my paper “The role of the IPCC is to assess climate change not advocate Kyoto” (available at ), I drew attention to the paper “A Brighter Future” (Climatic Change, 2002, 52: 435-440) in which James Hansen explicitly rejected the claim that the actions needed to avoid a “gloom and doom scenario” in climate change were “economically wrenching”. He argued that, on the contrary, these actions “made sense independent of global warming”. He was critical of “the IPCC predilection for exaggerated growth rates of population, energy intensity and pollution”, and of its “failure to emphasise data”, and gave a number of reasons for believing that the IPCC scenarios were “unduly pessimistic”. He questioned whether these scenarios were necessary or even plausible, and contended that “global warming can be slowed, and stopped, with practical actions that yield a cleaner healthier atmosphere”. He argued that the focus of international action, at least in the short run, should be directed towards the reduction of air pollution through concerted efforts to develop and share clean technologies. He contended that “this approach would unite the interests of developed and developing countries, and that the benefits (not least in the saving of human lives) would accrue immediately rather than in 100 years.”

    I’m surprised that you claim that the bulk of Lawson’s case actually appears to stem from a confusion between the IPCC and the policy options exemplified by the Kyoto Protocol and that “These are two quite separate things.” James Hansen said in his appearance before a US Senate Committee in May 2001 that “the real problem is probably the close binding between the IPCC and the Kyoto Protocol discussions”; that “Kyoto excludes consideration of air pollution (such as tropospheric ozone and black carbon), for example, so IPCC basically ignores these topics and downgrades them”; and that “the only IPCC ‘review’ of our paper [canvassing the Hansen alternative scenario] was by the IPCC leaders … who saw our paper as potentially harmful to Kyoto discussions.” I don’t read Hansen’s evidence as saying that the IPCC and Kyoto are two quite separate things: on the contrary, he argued that the close links between these things had inhibited examination of the Hansen alternative (and he implied that his difficulty in publishing his paper in ‘Nature’ could be attributed to the same close linkage). I don’t believe that James Hansen was confused on this matter in 2001, and I don’t believe that Lord Lawson is confused in 2005.

    In my April 2004 paper (link provided above) I concluded that:

    “I am not competent to assess the full implications of Hansen’s ‘alternative scenario’. But it is a matter of public record that, four years after its publication, this radical proposal, which – if valid – has far-reaching implications for the appropriate policy response to the prospect of global climate change in the coming decades, has not been considered by the IPCC … The IPCC’s failure to consider the Hansen ‘alternative scenario’ and its dismissal of the Castles and Henderson critique are disturbing signs that the Panel’s role in the assessment of the science of climate change has now become subservient to its role in supporting a specific policy agenda.”

    That remains my view. However, the Australian Government’s view has become much more alarmist. According to a recent news report, Australia’s Environment Minister, Senator Ian Campbell, told a reporter that:

    “If we’re to avoid getting to 550 parts per million [CO2 concentration], you need a massive injection of new technology, you need basically everything the world’s got at its doorstep at the moment. You need wind, solar, nuclear, gasification of coal, you need every single thing and you need more” (Matt Price, “Debate over, it’s time to save planet”, The Australian, 27 October 2005, p. 1).

    Obviously Australia’s Minister and James Hansen can’t both be right. The Minister says that in order to avoid getting to 550 ppm it will be necessary to do a whole range of things that would not be considered other than for climate policy reasons (e.g. gasification of coal, rapid expansion of nuclear energy). By contrast, the ‘alternative scenario’ in Hansen’s 2002 paper implied that a stabilisation level well below 550 ppm could be achieved with actions that “made sense independent of global warming.” According to Hansen, the latter approach would yield immediate benefits, including the saving of human lives, whereas much of the benefit of the former approach would not be realised for 100 years.

    You concluded your comment on my earlier note with the observation that “One can waste an awful lot of time writing letters and arguing about whether something matters, but since us modellers are basically empiricists, a practical demonstration is worth a thousand blog comments.” Could I suggest that you are better placed than I am to make that practical demonstration? Obviously it matters a great deal whether the world has to make large sacrifices to meet the challenge of climate change, as Australia’s Minister for the Environment believes; or whether, as James Hansen argued in 2002, we can have “A Brighter World” by doing things that make sense independent of global warming.

    The GISS ‘Alternative Scenario’ (AS) to which you provided a link appears to have CO2 concentrations stabilising at 475 ppm in 2100. This seems to be around the same as the lower extreme of Tom Wigley’s lower bound of possible variation, as represented by B1T MESSAGE. Is it possible to make any comparisons between B1T MESSAGE and the GISS AS in terms of what is being assumed? For example, B1T MESSAGE assumes that 30 per cent of the world’s energy supply will still be being met from fossil fuel sources in 2100. Many technology futurists are surprised to hear this and believe that the proportion is more likely to be nil. What does the GISS AS assume about the growth of renewables and nuclear energy (the IEA Alternative Scenario mentioned above does not assume any great expansion in energy from these sources by 2030)? What about the gasification of coal, which Senator Campbell believes is needed even to achieve 550 ppm? I realise that these are difficult questions, but the difference between the Minister’s implied projection and the GISS AS is so great that it must surely be possible to say something about the reasons for the difference. This is central to the whole debate.

    Finally, I don’t think that there should be a separate Intergovernmental Economic Assessment process. Economic assessments are a vital element in projections of emissions. The main change required, as David Henderson and I have argued in our paper “International Comparisons of GDP: Issues of Theory and Practice” (“World Economics”, Jan-Mar 2005) is ‘agreement on the basic point that international comparisons of GDP do not yield differences in output: to measure such differences, prices have to be directly compared, and PPP converters estimated accordingly.” If you are “unable to spend any time going through the economics literature to sort out the claims of different models”, you could at least try to ensure that GISS gives no more support to the absurd downscaled GDP database published on the CIESIN website at As I pointed out in my presentation at Amsterdam, these estimates are worse than useless and can only ‘encourage researchers to base their work on faulty data and to reach unsound conclusions.’ Even the IPCC now recognises that these data are inconsistent with the SRES storylines. At the IPCC Bureau meeting in New Delhi in 2004, it was decided that “If researchers would like to use the downscaled data from CIESIN they can do so, but it has to be clear that IPCC does not endorse or recommend them …” (Report, para. 3.4). In other words, the projections are all wrong, but the IPCC is not prepared to prohibit their use because they have already been widely used in papers by lead authors of the Working Group II Contribution to AR4. The continued dissemination of this material by CIESIN reflects poorly on the Earth Institute at Columbia University – and the Director of the Institute, the economist Jeffrey Sachs, has added insult to injury by saying that “having climate scientists at the table to highlight the shortcomings of grossly simplified economic models is invaluable for arriving at proper policy conclusions” (quoted in Royal Society Submission to the HoL Committee Inquiry, vol. II, p. 294). Having climate scientists at the table is indeed invaluable, but it is equally important to ensure that valid data is used in the economic models that are equally essential for arriving at proper policy conclusions.

    [Response: Your failure to produce your own scenario is disappointing. Without one, it will look like you’re just barracking from the sidelines. There would be no need to run a model with your scenario(s) – the point would be to see how different your scenarios are from the current range. The suspicion remains that the answer is, they wouldn’t differ much – William]

    [Response: I’ll make two points. First, please keep your comments brief. Second, you know as well as I do that the difference between the alternative scenario and the SRES scenarios is that the AS considers that efforts will be made to reduce emissions, while the SRES scenarios explicitly don’t. AS is therefore a test of what we may be able to get away with, while SRES and similar are tests of where we could end up if nothing were done. -gavin]

    Comment by Ian Castles — 16 Nov 2005 @ 4:13 AM

  64. William, I do not have any capacity to produce my own scenarios: I have devoted most of my own time for the past five years to reviewing and critising the economic and statistical reporting of the United Nations Development Programme, the World Bank, the Millennium Ecosystem Assessment, the United Nations Environmental Programme, the International Energy Agency, the US Energy Information Administration and the IPCC.

    My critique of the IPCC scenarios, in collaboration with David Henderson, is itself only a part of my wider criticism of the IPCC’s economic and statistical work. Several of the agencies listed above (most notably the UNDP and the US EIA) have welcomed my comments and have greatly improved the quality of their statistical reporting. They have acknowledged my assistance both privately and, in the case of the US EIA, in its publication “International Energy Outlook 2005”. In contrast, the IPCC has refused to admit error: in fact the Panel issued a press statement (its only press statement in a period of more than two years) which was specifically and exclusively devoted to brushing aside our critique.

    I have received no remuneration for any of this work from any source. I pay for my computer, my internet access, my stationery and my telephone bills from my own pocket. I prepared a set of charts for the technical meetings on the IPCC scenarios which I attended, at the Panel’s invitation, in early-January 2003. These were attached to a draft agreed report on the discussions which was provided to the Chairman of the IPCC, Dr. Pachauri, but which Dr. Pachauri has declined to release. The IPCC has not released any report on the Expert Meeting in Amsterdam in January 2003, which was attended by more than 50 experts from around the world.

    You say that “without [my own scenario], it will look like you’re just barracking from the sidelines.” It may look like that to you, but the unanimous view of an all-Party Committee of the House of Lords (including former Treasury Ministers from both sides of British politics) was that, by raising the issue of the IPCC’s scenarios, Professor Henderson and I had “helped to generate a valuable literature that calls into question a whole series of issues relating to the IPCC SRES, not just the issue of MER versus PPP.”

    Your statement that “The suspicion remains that the answer is, they (my scenarios) wouldn’t differ much [from the current range]” shows that you have misunderstood the point of my posting. I didn’t suggest that they would differ much. In fact, I said in my presentation to the IPCC Expert Meeting that “Some of these variants [that I was suggesting should be explored] would probably yield a model with a lower forcing pattern in 2100 than that of B1T MESSAGE, although it is impossible to be more specific until the detailed modelling work is done.” The IPCC’s failure to explore the Australian Government’s proposal that it develop a scenario along the lines that I had suggested is itself revealing.

    The point of my previous message was that the emissions profile in the GISS alternative scenario is FAR LOWER than the lowest of the IPCC scenarios. It is therefore reasonable to ask about the underlying assumptions, and whether they are plausible. James Hansen said that the IPCC was “lethargic” in not examining his Alternative Scenario: was that barracking from the sidelines? Do you agree that it reflects upon the IPCC that the base year for all of the scenarios is 1990, when they are being used in a report to be published in 2007 which will remain current until AR5 is published in about 2012?

    [Response: It would of course be nice for things to updated in a timely manner. But as your comment demonstrates, the ‘big picture’ is not going to depend very much on the details of the scenarios. Given that there are huge uncertainties in all such forecasting efforts, it is more useful to use them to bracket possible changes rather than try and get each one to be exactly right. Such efforts are probably useful, but they aren’t going to make much difference in the end. The bigger scientific issue are the natural feedbacks in the system that might make the CH4, O3 or aerosol forcings significantly different from those estimated solely by changes in anthro. emissions. -gavin]

    [Response: Ian – I think you’ve pretty well confirmed everything I said: you *are* just barracking from the sidelines (unlike Hansen, who is clearly involved with the scientifc work). Leaning on the House of Lords committee for support is feeble: the HoL did a pretty poor job. If your scenarios (were you to actually bother to produce one), after all this complaining, are really no different from the existing spread, then all this complaining is a waste of time. Perhaps if you spent less time complaining you’d find the time to produce a scenario – William]

    Comment by Ian Castles — 16 Nov 2005 @ 8:51 AM

  65. Allow me, in my usual pleasant way, disagree with everyone. While the range of IPCC emission scenerios pretty much bracket the possible and are as good as we need for climate models, the need for better ones has much more to do with the future tax, social and industrial policies. Putting more effort into them is probably not worth the payoff we would get WRT climate studies alone.

    Comment by Eli Rabett — 16 Nov 2005 @ 1:42 PM

  66. RE #63, I disagree about having a separate “Intergovernmental Economic Assessment process,” unless other considerations, such as life & health and eco-valuing the earth are put on an equal footing. I have no faith in a panel composed only of economists. For me, at least, life is a more important consideration than wealth, and neoclassical economists, who reduce all biota, nutrients, the ecosystem, the nonorganic world and all other things that keep us alive to monetary value could steer us in a very wrong direction.

    This is just an idea I had. Instead of money, why not use “life years” as a standard. So, it becomes what is the best way to maximize life years (figuring those alive today, and future generations, perhaps up to 100,000 years from now, when the last of our CO2 emissions of today have finally left the atmosphere – acc. to David Archer’s post )

    Comment by Lynn Vincentnathan — 16 Nov 2005 @ 1:54 PM

  67. Gavin, Thank you for your comments on #63 and #64. On #63, Nebojsa Nakicenovic, Coordinating Lead Author of the IPCC SRES, told the IPCC Expert Meeting on Emissions Scenarios in Washington, DC in January 2005 that “The concept of ‘non-intervention’ reference scenarios is increasingly becoming elusive and hypothetical as climate policies are becoming a reality in many parts of the world” (Report, p. 3). I agree. Moreover, on presently available information, there is no way of knowing whether the GISS Alternative scenario or the “Australian” non-intervention scenario achieves stabilisation of GHG concentrations at a lower level.

    That is because we don’t KNOW the details of the GISS scenarios (because, as I understand it, they don’t include projections of global or regional population, output, energy mix or land use changes). We have SOME of these details for the IPCC scenarios, but as William Nordhaus of Yale has noted, the SRES used “categorically the wrong procedure for aggregating world income” (HoL Report, para. 65). By contrast, the IEA Alternative Scenario, though including only one component of GHG emissions (CO2 from fuel combustion) is fully articulated to 2030.

    Contrary to your statement, I believe the “big picture” depends hugely on the details of the scenarios. The Australian Minister believes that massive and urgent action must be taken to avoid 550 ppm CO2 equivalent being reached, the Hansen Alternative says that stabilisation can be achieved at a much lower level without taking any actions that would not make sense independently of climate change. In principle, it should be possible to identify the reasons for such radical differences. Until this is done, the scenarios are of little help to policymakers. Prompted by the compelling report by the House of Lords Committee, the British Government has now established a review of the economics of climate change to be carried out by Sir Nicholas Stern, former Chief Economist at the World Bank. Perhaps this review will succeed where the IPCC has failed.

    [Response: One point of fact. Hansen’s AS does assume significant efforts to reduce emissions for climate reasons. Some changes for instance to reduce tropospheric ozone and black carbon have significant non-climatic benefits, but in and of themselves are not sufficient. To quote “I am not suggesting that the alternative scenario can be achieved without concerted efforts to reduce anthropogenic climate forcings.” ( -gavin]

    Comment by Ian Castles — 16 Nov 2005 @ 5:17 PM

  68. Thanks Gavin, I accept your clarification that Hansen’s AS assumes significant efforts to reduce emissions for climate reasons. However, the problem faced by the SRES modellers was that “Distinction between scenarios that envisage strict environmental policies and those that include direct climate policies was very difficult to make, a difficulty associated with many definitional and other ambiguities”: Box TS-4, p. 46). I doubt whether they’d agree with your characterisation of the whole suite of scenarios as “tests of where we could end up IF NOTHING WERE DONE”, and they’d certainly disagree with your contentions that “the scenarios are used solely for the providing input into climate models”, and that “Therefore only the final differences in the total greenhouse gas emissions actually matter.”

    Comment by Ian Castles — 17 Nov 2005 @ 8:11 AM

  69. Ian,

    In #56 you wrote:

    “The costs that the world bears to get to any defined target are incurred ex ante. They are the costs that are BELIEVED to be necessary to get to the specified level, and these depend in turn upon the IPCC projections of future emissions profiles…”

    It strikes me that this is true only in the most unlikely of scenarios, where a government invests fully in all of its anti-AGW technology at once. In practice, the investment is almost certain to take place over a series of decades, and thus the government will have lots of time to monitor changes in fossil fuel emissions and scale back future spending on AGW avoidance if it is not warranted.

    Further, some of the ways AGW might be avoided – such incentives for consumers to buy hybrids, etc. – involve no technological investment at all, and can be scaled up and scaled down as needed.

    Comment by Dan Allan — 17 Nov 2005 @ 11:53 AM

  70. Ian, in response to your statements, the American Geophysical Union has a great position statement on its website:

    I’d suggest that you read it.

    Comment by Stephen Berg — 17 Nov 2005 @ 12:45 PM

  71. Re #69. Your point is well taken, Dan. Gavin’s “Kyoto for free, as it were” provoked me into an overstated reaction in #63 (not#56). But the fact remains that the UNFCCC/IPCC/SBSTA process (see Roger’s posting at #6) is almost unbelievably inefficient and unresponsive to new evidence as it accumulates. Around 10,000 delegates are about to meet in Montreal to solemnly review the progress of various countries towards arbitrary emissions targets fixed in all-night meetings 8 years ago, for a commitment period that ends in 7 years’ time. The countries concerned won’t know their actual emissions levels within a wide range even then, and many of them wouldn’t tell the rest of the world about it if they did. And if all governments were honest, and achieved and maintained their targets notwithstanding the electoral consequences, the effect on climate would be imperceptible.

    The current IPCC assessment is using scenarios that were finalised in the late 1990s. According to the downscaled data on the CIESIN site, one marker scenario (B1) assumes that in 2005 (this year!) average incomes in India will be higher than in China, and another (B2) assumes that in 2005 average incomes in India will have fallen to less than 40 per cent of the Chinese level. These scenarios would now be only of historical interest if it were not for the IPCC’s ex cathedra pronouncement that they are suitable for use in AR4, as a result of which hundreds of researchers are basing their assessment of climate change impacts on projections that are known to be technically unsound and in any case superseded.

    In the real world, governments and business enterprise build their forward plans upon observation and evidence of TODAY’S phenomena – not around a range of forecasts about the present which were made 5-10 years ago and which have long since been falsified by events.

    Re #70, of course I’ve read the AGU statement but I don’t see its relevance to this discussion. Stephen, I suggest that you read the papers by three Australian experts that were published earlier this year by the Academy of the Social Sciences in Australia under the title “Uncertainty and Climate Change: The Challenge for Policy.” They’re available online on the Academy’s website.

    Comment by Ian Castles — 17 Nov 2005 @ 8:10 PM

  72. Re #71,


    Just a few thoughts: first, some of the issues you raise re IPCC, I think, are inherent in any large human endeavor with many moving parts – a mixture of bureaucracy, science, endless melding of a variety of opinions into “concensus”, etc.. So I would probably start with a somewhat limited set of expectations, and would ask not whether the IPCC process is pure, but rather whether it is tolerable – because that is usually about the best we can expect, given the complexity of the challenge and the imperfect nature of humans. Maybe it still fails this test in your mind.

    Per Gavin’s point, if the scenarios are significantly off-track, has anyone – not just yourself – come up with an alternative set of emissions scenarios? And if not, how can we even measure the potential impact of the scenario problems you are raising? (Also, if the main problem is that the scenarios are “stale” – based on old info – how often is it realistic to recalibrate them?)

    Finally, while I agree with concerns regarding countries misrepresenting their emissions rates, etc., and might even agree (I don’t really know) that emissions targets are arbitrary, what do you see as the alternative here? Would no treaty be better? Is there not a need to address AGW? If there is a need, how then should it be addressed?

    I’d be happy to look thru any links you have on this.



    Comment by Dan Allan — 18 Nov 2005 @ 11:33 AM

  73. Ian Castles has pointed out that the “curious report” of our House of Lords
    was a unanimous one. Lord May was also quite flattering and, on the 10th
    November, said of it:

    “It is a question not of whether we need to bring greenhouse gases under control,
    but how. That of course is the nub of the debate and the really difficult point. It is the
    issue about which the group of distinguished economists on the committee of the noble
    Lord, Lord Wakeham, said so many good and wise things. I found it reassuring that many of
    the recommendations in that report “carbon taxes and others” resonated with
    comments made in the Royal Society’s report on economic instruments for the reduction of
    carbon dioxide emissions.

    To further understand the criticisms of the IPCC in the HoL report one might read what
    Richard Tol said in his evidence to the committee in reply to Q210.

    “From that perspective, historically, it was not a surprise that the SRES
    scenarios would at some point be criticised by eminent economists such as Henderson. It
    may have been perhaps a surprise that it took so long! Another point came to light during
    this whole debateâ??and I was at the very start of SRES, which was in 1996, and it was
    one of the most controversial debates that I have ever seen. Going back to the convergence
    assumption, from the very start onwards it was clear that the SRES team had placed itself
    under constraints of political correctness, that is to say because it is an IPCC exercise
    it has to be reviewed by all the governments in the world, and if you come up with
    scenarios in which the African countries, which are a fairly large bloc (in the
    UN) “if they do not grow fast enough, they will never approve our scenarios. So this
    is what we cannot assume” and that self-censuring was right there from the

    [Response: So… even though he didn’t like the scenarios way back in 1996 neither he nor anyone else has bothered to produce an alternative scenario? Isn’t that a bit feeble? I would also be rather cautious about taking his words at face value – William]

    As to why he was no longer involved he said in answer to Q226

    “Essentially, I am not involved in the current assessment report because I have
    not been nominated by my government, my adopted government – I am not
    German – please do not think that. Essentially in Germany, for working groups 2 and
    3, only people with close connections to the Green Party have been nominated to the
    IPCC, and that excludes me immediately.”

    Before dismissing their Lordships one might wonder else influenced our PM between the
    G8 and the Clinton meetings.

    [Response: For the economics, I have little to say. But its a shame that – having said The Committee decided to restrict the scope of its investigation to certain aspects of the economics of climate change – they didn’t stick to that, but ventured onto the science, which they didn’t understand – William]

    Comment by David H — 19 Nov 2005 @ 2:44 PM

  74. Re William’s first comment in 63, Richard Tol did not say he disliked the scenarios but they were a political compromise. Ian Castles has told us how difficult it is to get another scenario introduced.

    In the UK we have a curious system of government (and for that matter justice) in which people are actually paid and provided with resources to question and, where they see fit, vigorously oppose the official view. No such checks or balances are evident in the IPCC. Their Lordships clearly identified that on the economics and as the same system of governance applies to the science they are entitled to suggest that the same defect may exist in the science.

    Comment by DavidH — 19 Nov 2005 @ 7:54 PM

  75. What is the source of the claim that, “even though he [Richard Tol] didn’t like the scenarios way back in 1996 neither he nor anyone else has bothered to produce an alternative scenario?” (William’ interpolated comment on #73)? According to the SRES, no less than 171 sources had produced 416 scenarios in the published literature, most of which dated after 1994 (SRES, p. 348). Professor Nakicenovic told the House of Lords inquiry that “there are in the order of 600 scenarios now” (Evidence, p. 133).

    Richard Tol has published many emissions scenarios in the literature: see for example his paper “Kyoto, Efficiency and Cost-Effectiveness: Application of FUND” in the Special Issue of “The Energy Journal”: “The Costs of the Kyoto Protocol: A Multi-Model Evaluation” (1999), which includes projections of global and regional CO2 emissions from 1990-2100 for a “Business as Usual” scenario and six alternative policy scenarios (Figure 4, pps. 143-47). Professor Tol concluded that “The emission reduction targets as agreed in the Kyoto Protocol are irreconcilable with economic rationality.”

    [Response: Perhaps there are more emissions scenarios. I’ve never come across them. Do they say anything interesting (i.e., do they fall outside the SRES range?). Are any of them on the web? – William]

    William also says that he “would be rather cautious about taking his {Tol’s] words at face value.” On this, it should be noted that the Chairman of the House of Lords Committee made the following comment immediately after Professor Tol used the words that William is discinclined to accept: “You have given all those erudite comments, and they sound very convincing to me…” (Evidence, p. 72). In their unanimous report the Committee said that “In his evidence to us, Professor Tol suggested that scenarios in which limited convergence took place would be politically difficult for IPCC to contemplate” (para. 63); that “We find Profesor Tol’s analysis telling” (para. 59); that “the shortcomings in the scenarios identified by Professor Tol do further underline our call for their thourough reassessment” (para. 59); and that “political considerations should not be allowed to cloud what should be a sciedntific procedure in constructing the scenarios” (para. 72).

    [Response: The Chair’s comments make it fairly clear that he was out of his depth: which is to say, he couldn’t evaluate the evidence; the stuff about limited convergence isn’t an analysis, just an assertion. Perhaps Tol could stick to the economics and leave out the politicking? – William]

    Finally, in fairness to Professor Tol, it is worth placing on record (a) that he advised the Committee that he “was a lead author in the second assessment report and a convening lead author in an intermediate report and again a lead author in the third assessment report”; and (b) that he was one of twelve experts who made a written submission to the Committee as well as giving oral evidence. He deserves better than the gratuitous slur made by William in his interpolated comment.

    [Response: I was referring to the comments about “political correctness” that Tol was making – William]

    Comment by Ian Castles — 19 Nov 2005 @ 10:29 PM

  76. William, re the comments that you’ve now interpolated in my #75. Yes there are many hundreds of emissions scenarios that you haven’t come across. For an out-of-date but useful review, please see SRES, Chapter 2 (“An Overview of the Scenario Literature”). In response to your implied assumption that scenarios other than the SRES set are of no interest if they fall within the SRES range, please refer to my #56, second para. Your advice to Richard Tol to “stick to the economics and leave out the politicking” comes oddly from a working climate scientist who claims to eschew involvement “in any political or economic implications of the science” – and then volunteers his views about the “low level of debate in the House of Lords” (your interpolation at #43) and advises their Lordships to get off their bums and actually generate their own scenarios (your interpolation at #7).

    [Response: Tol is welcome to politick in his own time. But testifying to the HoL he should stick to econoics. In fact, the HoL committee should have stuck to economics, as it promised to. Re scenarios, thank for the pointer. You don’t say it explicitly, but I’m presuming that they all tend to stay within the SRES range – William]

    Comment by Ian Castles — 20 Nov 2005 @ 5:45 PM

  77. Roger Pielke Jr. wrote:

    (Comment 6) “Such reckless action with science in policy do [sic] not give friendly outsiders confidence in the IPCC process.”

    and (Comment 8 ) “Slide 18 in Trenberth’s presentation that I linked to unambiguously attributes 1 inch of Katrina’s rainfall near New Orleans to global warming. These are Trenberth’s words, not my interpretation of them, presented as fact at a policy briefing, not as hypothesis in a scientific meeting.”

    and (Comment 21) “Finally, I simply reject the notion that we have in any way mischaracterized what Trenberth has said, …”

    Let me say this about that (to quote a late and unlamented politician):

    Roger has taken a single sentence off of a slide with a title, 6 bullets, and the offending sentence, and mischaracterized the offending sentence. The bullets have three “likely”s and one “expected” and the offending sentence is clearly the conclusion of a chain of hypothetical (albeit very well founded) assumptions. Water vapor **likely** increased by 4% (which assertion follows from the Claudius-Clapeyron equation). Winds **likely** enhanced by the same order (i.e., 4%). Surface latent heat fluxes in storms **likely** increase by at least this much (labelled by Trenberth as a Research topic). Thus, moisture convergence in boundary layer goes up by 8% (1.04 squared). Corresponds to **expected** increase in rainfall and latent heat release in storms: order 8% [4% to 12%].

    And finally, the offending sentence: “**Implies** 1″ extra rain near New Orleans in Katrina.”

    I’ve been reading English for 60 years now, and describing the slide and the final sentence as **unambiguous** is perverse and **suggests** an eagerness to find something — anything — with which to beat Trenberth about the head and shoulders.

    Jim Dukelow

    Comment by Jim Dukelow — 21 Nov 2005 @ 5:19 PM

  78. I have enjoyed reading this thread immensely. Most of it is well above my head. Much of it seems to completely disregard previous injunctions not to engage personal asides. And, most of it seems to have nothing at all to do with the original post in regard to the august body of the House of Lords Economic Committee, and a rather old and very conservative ex-Chancellor of the Exchequer. But it’s all good stuff, and it is not too difficult to discern the seething passion under the guise of rational scientific debate.

    The problem with the report of the House of Lords Economic Committee (HLEC) and Nigel Lawson’s pronouncements, is that to read these economist’s pronouncements in regard to anthropogenic global warming is comically absurd, it produces an effect as bizarre as would be engendered by reading a critique of the Theory of Relativity by a committee of lawyers. For economists to head their second chapter “The Uncertain Science of Climate Change” is not only an obvious ploy to downplay the status of climate change science, but that it comes from representatives of a social science for whom the future always comes as a perpetual surprise, is just a bit rich.

    The HLEC considers that not enough emphasis has been placed on the positive aspects of global warming, such as the CO2 fertiliser effect, and its report contains curious debates such as those about the likelihood of people accepting lower wages in remaining areas of clement climates, and the ‘distinct amenity gains’ of Northern Europe. (This amenity might however be dependent on being able to afford to move to higher ground which, of course, will become rather more expensive, or by living in a house boat – JKM) Equally the paragraphs on ‘Adaptation vs. Mitigation’ contains the same sort of wishful thinking disguised as thoughtful consideration.

    In the chapter on ‘Forecasting Greenhouse Gas Emissions and Temperature Change’ this HLEC document may be on safer ground, the high forecasts of the IPCC do seem overgenerous. But in criticising these forecasts, they entirely neglect to acknowledge the fact that these forecasts are not worked out for the benefit of economic planning, but merely for scientific illustration, and more importantly that the lower forecasts, which the HLEC are more happy to accept, are still entirely compatible with major and destructive climate change.

    The document then goes on to examine the ‘Costs of Tackling Climate Change’. This is not the place to describe in detail the arguments presented, but when you read such quotes as “the UK research programme (into alternative energy technology) has been ‘captured’ by certain renewable energy interests” and “there is a debatable assumption about the likelihood of passive energy efficiency gains” and “it is better …… to leave the market to select the technologies” and statements such as “costs of 0.4 to 1.7% of GDP are not trivial” (relative to the possible damage of global warming, I think it is right to say these costs are trivial – what did Hurricane Katrina cost? JKM) and “the UK may have taken unilateral action to no purpose” (like the child protesting to his mother as to why he should clean his bedroom when Tony or George don’t have to clean theirs. JKM) and last, but no means least “in terms of percentages of world GNP, damage is relatively low, even for +2.5oC. The damages are not evenly spread. In general, developing countries lose more than developed economies. Some models suggest no real net damage to rich countries” is a classic of blinkered optimism and of an appalling social and moral unconcern.

    In chapter 7, “The IPCC Process”, the HLEC take parts of the IPCC reports to task. Whilst I have no doubt that some of the criticisms are valid, and in such a comprehensive document as the IPCC report there are bound to be inaccuracies and mis-statements, the whole tenor of the chapter is to endeavour to cast doubt on the whole report rather than engage in reasoned and appropriate criticism. For instance, the HLEC can’t resist taking a dig at “scientific consensus” by quoting Professor Reiter’s comment “Consensus is the stuff of politics, not science…..” (the quote continues with some reasonable, but entirely irrelevant, observations about science), a professor of tropical diseases making his personal contribution to debunking major scientific agreement on climate change. If I were to hold a glass of water in front of me, and let it go, there would be a very major scientific consensus that the glass will fall to the floor, shatter and loose a good deal of entropy. By what logic, therefore, can Professor Reiter contend that consensus only applies to politics (a naive suggestion in any case, when did politics, or economics for that matter, have a consensus about anything?)

    But to give some credit to the HLEC, the summary at the end of their document reads rather better than the body. Perhaps I should have read this first. There are at least some important admissions by the HLEC on the possible severe detrimental effects of global warming, the need for the public to be informed, the likelihood of the need for major social adjustments, and the urgent need for massive investment in research, for example, to the scale of the American endeavours to put a man on on the moon. Having said that, they also repeat many of their dubious observations, some of which I outline above.

    And what to say about Nigel Lawson? He uses so many of the fallacious arguments of the global warming sceptics that one might think he had been reading this site to learn what they are, as you have so thoroughly and clearly debunked them in your pages. This quote says it all “But the real cost of this approach is not so much dearer energy as the reduction in world economic growth. It is far from self-evident, not least for the developing world, that over the next 100 years a poorer but cooler world is to be preferred to a richer but warmer one. And why should the present and next generations sacrifice their living standards in order to benefit more distant generations, who are projected in any event to be considerably better off?” The assumptions underlying these arguments are inane, and the conclusion immoral. To assume that future generations are somehow guaranteed to be better off than we are, whatever we do to the planet, however much poison we pour in to the atmosphere, however much we deplete or damage our water resources, and however quickly we plunder its other irreplaceable assets, is breathtakingly presumptuous and overbearingly arrogant. Perhaps he should have a quiet word to a German citizen who lived in Germany before the Second World War in regard to assumptions about the future. Nigel Lawson’s own conclusion, with the alteration of one word, sums it all up nicely: “We appear to have entered a new age of unreason, which threatens to be as environmentally harmful as it is profoundly disquieting. It must not be allowed to prevail”.

    But the basic problem about the argument “Climate Change vs Economic Cost” is that there can never be any meaningful answer. We are measuring two entirely different things, in other words there is no set of scales, no ruler or set of measurements that can encompass a rational comparison between the two. Climate change is a scientific issue, which will be described and answered by entirely scientific means, economics is a social science which, whilst is uses a good deal of maths and statistics, is basically the study of human behaviour as it impacts on a very narrow field of human existence. At a fundamental level the two studies have no common ground. And at a fundamental level, we, as a human species, are going to have to accept the science, which will bear ever more heavily on us, whether we like it or not, and to hell with the economics. After all, the science of global warming is nothing more than the laws of nature. Mankind has no option but to obey the laws of nature. Mankind may temporarily postpone them, like a levee against the floods, but the laws of nature are not to be gainsaid, they will, eventually, have their own way. There are no separate rules for mankind, despite economists’ quest to find them. Our choice is not between economics and science, but between a tolerable future, or no future.

    Comment by John Monro — 25 Nov 2005 @ 8:23 AM

  79. John Monro, You argue (#76) that “For economists to head their second chapter ‘The Uncertain Science of Climate Change’ is … an obvious ploy to downplay the status of climate change science.”

    It is not obvious to me. In his attack on Bjorn Lomborg’s “The Skeptical Environmentalist” in “Scientific American” (January 2002), Stephen Schneider wrote that ‘uncertainties so infuse the issue of climate change that it is still impossible to rule out either mild or catastrophic outcomes’ and that ‘uncertainties are … endemic in these complex problems that suffer from missing data, incomplete theory and nonlinear interactions.’ And in a paper published earlier this year by the Academy of the Social Sciences in Australia, Dr John Zillman, one of the world’s most eminent meteorologists and a strong supporter of the IPCC, wrote that:

    “The uncertainties surrounding climate (and especially climate change) are not limited to what will happen in the future but span the complete spectrum from our knowledge of past climate; and our understanding of the mechanisms of present-day climate; to our ability to predict the future climate. An in-depth understanding of the nature and significance of these uncertainties is essential for the formulation of properly informed national and international action on the greenhouse issue” (‘Uncertainty in the Science of Climate Change’, in ‘Uncertainty and Climate Change: The Challenge for Policy’, ASSA Occasional Paper 2/2005, available at ).

    Stephen Schneider and John Zillman have both been leading contributors to past IPCC reports and have leading roles in AR4. As neither of these leading scientists has been accused of attempting ‘to downplay the status of climate change science’, I don’t understand why you have levelled this accusation at the House of Lords Committee.

    I’m also puzzled by your reference to the ‘important admissions’ in the summary to the report, as a result of which you believe that ‘the summary’ reads rather better than the body. Presumably you are referring to ‘Chapter 9 – Conclusions and Recommendations’, which simply reproduces, word for word, the passages in the main text which are printed in bold. There are no conclusions or recommendations which have not already been reached or made, in context, in the body of the report.

    Comment by Ian Castles — 27 Nov 2005 @ 1:57 AM

  80. Ian,

    I was hoping you might address the questions I raised in post 72, but if there are too many, I will distill it a bit:

    What do you think the world should be doing, given the state of cimate science? No mitigation at all? No treaty? A different treaty? What if, in your mind, the higher-end warming estimates became more certain? Would you then favor governmental action? Or would you still oppose it?

    Comment by Dan Allan — 27 Nov 2005 @ 2:02 PM

  81. To Ian

    Thanks for your comments

    1) I did err in treating the summary as something different from the main text. Of course you are right, it is all there in the body of the report, but laid out as they were in the summary, without all the surrounding asides, it was more obvious to me that there were some useful admissions in regard to global warming

    2) In regard to the heading “The Uncertain Science of Climate Change” I don’t quite agree with your comment. Certainly working out what will happen with anthropogenic global warming is fraught with difficulty and uncertainty. It might well be impossible, as of now, to decide whether AGW will be a mild inconvenience, or a truly revolutionary and destructive force. I think you are a climate scientist? I am just an interested layperson, a general medical practitioner. When you read the heading “The Uncertain Science of Global Warming” you think, yes, that’s true and I can’t argue with it, AGW certainly is real, but the exact prognosis, that’s a tough one. In fact, as a scientist, you can’t help but give me a very detailed and thoughtful response, with references. But, when I, and I believe countless of other laypeople read this heading, I read “Global Warming, is that real or not, even the scientists are uncertain?” and it is difficult to construe any other meaning. In my sample of one layperson that was how the heading was read (my wife!)

    This very site exists precisely because large numbers of climate scientists have become so unhappy with the misrepresentation of the undoubted uncertainties of global warming science as implying equal uncertainties about the very existence of global warming. But I am given to understand by my reading in this site, and elsewhere, that there is hardly a single climate scientist anywhere who does not now acknowledge anthropogenic global warming. And indeed there are many postings to this site making the same complaint about the distortions and half truths on climate science from self-interested parties.

    I am perfectly convinced that this heading was written the way it was to mislead. Why not write something like “The Uncertainties about the Severity of Global Warming” or “The Science Debate on the Effects of Global Warming”. This conveys a much more truthful message.

    You quote “An in-depth understanding of the nature and significance of these uncertainties is essential for the formulation of properly informed national and international action on the greenhouse issue”. I beg to differ. The last thing we need is an in-depth understanding of the nature and significance of the uncertainties surrounding the greenhouse issue. The reason is that we haven’t got time. If humanity had been conducting this experiment on a world in some parallel universe, fine. But we have to pursuade a whole world of laypeople, the ordinary laypeople, not the politicians or the business people, because that is impossible, that global warming is of paramount concern to their and their children’s future, and we have to start now. They just need to know this, is global warming real, is it a threat, could it be an overwhelming threat.? If it is, can we deal with it? When ordinary people start being frightened and start demanding that politicians and business leaders deal with these issues, you will see some action. Your quote could be taken verbatim from one of George Bush’s statements, it is exactly the sort of the thing global warming deniers and sceptics want to hear. More proof, more proof. And while we wait for the sea to lap against the White House lawns, the rest of the world will have suffered whatever consequences untrammelled global warming will have dealt it.

    Comment by John Monro — 29 Nov 2005 @ 3:51 AM

  82. Re #80. These are large questions, Dan, and they go directly to the “political or economic implications of the science” in which Real Climate will not get involved.

    Re #81. John, I am not a climate scientist. I am an economist/statistician who spent 40 years in the service of the Australian Government. In 1973 I was the main author of a paper published by the Australian Treasury which pointed to “suggestions by some scientists … that as the volume of fossil fuels consumed goes up and deforestation spreads, by the early decades of next century there might be such a rise in world temperature as to melt the polar ice caps and inundate the world’s great coastal cities.” In those days it was widely believed that annual global fossil CO2 emissions could reach 12-13 GtC by the end of the TWENTIETH century – see, for example, the MIT Report of the Study of Critical Environmental Problems (SCEP, 1970, p. 54). In the event, CO2 emissions in 2000 were barely half the level that had been projected 30 years earlier, and some of the IPCC scenarios project that, even without climate change policies, fossil CO2 emissions will never reach the level that was projected for 2000 in the MIT study in 1970. Some of these scenarios also project that CO2 concentrations will never reach double the pre-industrial level. This does not mean that the growth in the concentration of greenhouse gases in the atmosphere is not a serious problem – but the MIT Study group had urged that the implications of the build-up in CO2 should be investigated because “it could be within man’s power in the next century to increase the CO2 of the atmosphere by a factor of 4 or more.” It is debatable whether this is true, and it is certainly within man’s power to avoid such an increase, or anything like it.

    I am surprised that you believe that the unanimous report of an all-Party Committee of the House of Lords contained a heading that was “written the way it was to mislead”, and I’m surprised at what appears to be an implication of your comments that scientists should seek to frighten people rather than try to convey the “in-depth understanding” to which John Zillman referred. Scientists should “tell it like it is.” If it is “exactly what the global warming deniers and sceptics want to hear, then so be it. (Incidentally, John Zillman, the author of the quote, was a Review Editor of the Technical Summary of the IPCC Third Assessment Report and also of the chapters on the evaluation and projection of regional climate, on the detection of climate change and the attribution of causes, and on climate scenario development).

    Comment by Ian Castles — 2 Dec 2005 @ 6:42 PM

  83. William writes that I should “stick to the economics and leave out the politicking”. I fully agree. I’m an economist, not a politician. However, William responds to my comments about the assumptions of convergence in the SRES scenarios. Convergence here means absolute convergence of per capita income, a topic that is well within the professional domain of economists (Barro and Sala-i-Martin, 1995, Economic Growth, The MIT Press). I argued before the HoL committee that SRES had decided to ignore the latest facts and theories on economic development; and adopted an unrealistic but politically more palatable “everybody will be rich soon” stance instead.

    If one were interested in climate change alone, then the details of the underlying economic scenarios do not matter much. Emissions are the only things that count. However, if one is interested in the impacts of climate change, or in the regional breakdown of the sources of emissions, then the economic details do matter. If one adopts the Castles-Henderson alternative to SRES, then global carbon dioxide emissions in 2100 fall by 10-20%. This is small compared to the uncertainties. However, some three-quarters of this global drop in emissions comes from South and East Asia. This would considerably change the political dynamics, as China and India would have to shoulder substantially less of the burden of emission reduction. Under the same scenario, although climate change would be slower, the projected economic growth in Africa would be slower too, so that poverty-driven but climate-sensitive diseases such as diarrhoea would be more prevalent in the future, and the impacts of climate change may well be higher.

    Finally, I do have my own, much ignored scenario of future development and emissions. Nowadays, to get a paper published, one needs to run the benchmark SRES scenarios as well. The reason that there so few alternatives to SRES, and no prominent ones, has to do with funding. Scenario development is expensive. Funding agencies are not interested because there is SRES, and the SRES in-crowd is fighting tooth-and-nail to maintain their lucrative monopoly.

    [Response: If one adopts the Castles-Henderson alternative to SRES, then global carbon dioxide emissions in 2100 fall by 10-20%. This is small compared to the uncertainties. Thanks for that information – very interesting. However, C+H don’t put it quite like that, which is not too surprising. See-also – William]

    Comment by Richard Tol — 27 Jan 2006 @ 6:40 PM

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