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Presentation: climate change and the precautionary principle

September 20th, 2006

I’ve uploaded my presentation on climate change and the precautionary principle, which I gave at City Hall on Monday night. It’s here in
Powerpoint (4.9Mb)
or
PDF (1.9MB)
formats.

Finally, here’s a version Zipped Mac Keynote (4.8Mb).

Thanks to everyone who’s given helpful suggestions for the upload, and noted problems with the download.

Sorry for the accidental temporary disappearance of this post. I somehow set it to “private”, which meant that it appeared for me, but for no-one else

Categories: Environment Tags:
  1. econwit
    September 23rd, 2006 at 10:18 | #1

    It was my original statement so I will elaborate on the reasoning behind it.

    Our environment by nature is revolutionary so any change could be deemed “normal�

    The GW debate is dominated with qualitative arguments as opposed to quantitive ones. Until that balance changes it is difficult to give “justification� to any arguments therein.

  2. jquiggin
    September 23rd, 2006 at 10:41 | #2

    We debated the PPP issue at length a while back. I agree that the use of PPP measures, where they are available, would be preferable, but the likely impact would be small, and the result could be either to increase or decrease projected future emissions.

    On the sulphur emissions question, I agree with Ken Miles. It’s not useful to debate this on the basis of back-of-the-envelope estimates over a short period. If you think the response should be instantaneous rather than lagged, point to the way in which the models differ from the science on this.

    More generally, Ian, I think you need to decide whether you’re acting as an advocate on the skeptical/denialist side of the debate, or as someone seeking to improve the modelling process. The two roles aren’t compatible.

  3. September 23rd, 2006 at 11:02 | #3

    Ian Castles – “You’re right Ender. Australia, Europe & the US are vastly more wealthy than Third World countries. So?”

    So my original point was that people in wealthy countries will not take action while wealth accumulation is the main priority.

    “So does your tolerance for dissent extend to the paper in the March 2006 issue of “Climatic Changeâ€? by Alison Stegman of the Climate Risk Concentration of Research Excellence at Macquarie University, on the subject “How Should Emissions Projections Be Evaluated?â€?”

    Sure that is great – why do you think I have a problem with this? Again and again you concentrate on the economic modelling and miss the science. The point of this whole post is the precautionary principle which is something you have seem to have forgotton.

    If we were sensible and applied this precautionary principle then who cares a &*&(&*& what the economic models say. As any economic modelling could be just as bad as any other and/or contain bias so they are of little or no value. You seem to want the i’s dotted and the t’s crossed before you will agree to any action on climate change that might affect the holy grail of GDP.

    You are not going to get it. There are 2 facts that I stated in my last post. That is what we know for certain. Anything else, including economics, is just speculation and could be wildely wrong or spectacularly accurate – we don’t know.

    In the face of this uncertainty the whole point of this post SHOULD be applied. We SHOULD be being cautious. However because we cannot stop accumulating wealth and that is our main priority we dismiss what scientists are telling us as speculation and faulty modelling and press on regardless madly accumulating more and more wealth.

    It would be nice if we could act before some catastophe happens that forces us to re-order our priorities. Mind you that catastrophe may never happen and we may just adapt without problems however that is a bit like thinking that a burning building will burn slow enough so I do not have to leave and stop working.

  4. Ian Castles
    September 23rd, 2006 at 22:28 | #4

    John, This is a point-by-point fisking of your comments above (“Fisk: verb – To deconstruct an article on a point by point basis in a highly critical manner. Derived from the name of journalist Robert Fisk, a frequent target of such critical articles in the blogosphereâ€?). I apologise for its length, but it’s 500 words shorter than the fisking by Roger Jones of an article by Alan Wood inThe Australian that you published some weeks ago.

    JQ: “We debated the PPP issue at length a while back. I agree that the use of PPP measures, where they are available, would be preferable, but the likely impact would be small, and the result could be either to increase or decrease projected future emissions.”

    IC: I think your memory may be failing you. Let me remind you of a few details that you did know about when we had that debate, and add a few more that you don’t.

    In your posting “Diewert on Quiggin, Castles and Henderson� on 31 March, you said:

    “These debates [about purchasing power parity (PPP) vs exchange rate (MER) converters] are inevitably complicated, but someone with the right skills can make them a lot clearer. I can think of no one better than Erwin Diewert, who has been the leading researcher in the theory of index numbers for the last thirty years… So I asked Erwin for comments and was both surprised and pleased to receive not just comments but a whole paper, not quite by return mail, but after only a few days. I think it’s fair to summarise by saying that Diewert agrees with my main point, but also agrees with Castles and Henderson that the IPCC should change its modelling approach.â€?

    Professor Diewert’s paper, dated 28 March 2006, was entitled “Comment on ‘The Choice of Exchange Rate on Modelling the Impact of Climate Change: A Response to the Castles-Henderson critique of the IPCC’ by John Quiggin.â€? Your paper – the subject of his comment – was dated 2 August 2005. I thought that it was rather odd that you sent it as a submission to the UK Stern review and, later, published it on your website, without at any time consulting David Henderson or me.

    Be that as it may, you gave your readers a mistaken impression when you said that “Diewert agrees with my main point.� In fact, Erwin’s conclusion was that you, John Quiggin, were “right to implicitly criticise the entire SRES modeling strategy�. So your statement that he “also agrees with Castles and Henderson that the IPCC should change its modelling approach� needs amendment. What you should have said was that Professor Diewert agreed with all of us that the IPCC should change its modelling approach. And he didn’t say that “the likely impact would be small.�

    After reading your interpretation of his comment, I wrote to Erwin to seek his clarification. His immediate response included the following:

    “… [W]hether the assumption of gradual convergence in per capita energy use is any more sensible than the assumption of gradual per capita real income convergence is a different matter. I am extremely sceptical on the prospects of either type of convergence occurring.â€?

    In the light of this reply, I wrote again to Erwin making four suggestions – first, that he make clear that he was not necessarily endorsing the convergence hypothesis as a prediction of the future, but was discussing the way that emissions should be modelled ON THE ASSUMPTION THAT CONVERGE WOULD OCCUR; secondly, in support of my own position that the convergence assumption as applied to per capita energy use was questionable, I suggested that he refer to the paper “Convergence and Per Capita Emissions� by two Australian economists, Alison Stegman and Warwick McKibbin (published as Brookings Discussion Papers in International Economics No. 167, May 2005); thirdly, I asked Professor Diewert if he would cite the three key papers in which the Castles and Henderson critique of the economic and statistical work of the IPCC had been fully articulated – you did not mention any of these in the posting on your website, but only an earlier piece (see below); and fourthly, I suggested that he submit his comment on your paper to the Stern review.

    On 8 April, Professor Diewert wrote to you, and copied to me, a letter in which he said “Ian Castles sent me several very useful comments on my note and so I have revised it a bit in the light of his comments. I would appreciate it if you could replace the previous version of my comment on your website with the attached version.� In the new version, Erwin cited the all three Castles & Henderson papers as I’d suggested, and added the following footnote:

    “The convergence hypothesis is somewhat questionable to say the least; see the discussion on this point by Stegman and McKibbin (2005). However, discussing the merits of various convergence hypotheses is not the purpose of this note.�

    The new version of Erwin Diewert’s paper, dated 8 April 2006, is posted on his website. It was published on the Stern Review website soon afterwards. But as of today, 23 September, you have not replaced the earlier version on your website with the later version, as Professor Diewert requested. Are you intending to do so?

    A few related questions:

    (1) On “The End of the Global Warming Debate� thread on your website (5 January, 2.49 p.m.) you said “I think the Castles critique is a complete beatup. Up to a first approximation, it makes no difference, for an exercise like this, whether you use PPP or exchange rate conversions.� Do you still adhere to this view? The following subsequent developments are relevant:

    (a) Professor Diewert said in his Comment on your paper that “Castles and Henderson are right to criticize the first part of the SRES modeling strategy, which relies on market exchange rates to calculate per capita real income differences between countries. It would be much better to use ICP PPPs for this first part of the SRES modeling strategy. The differences between PPP’s and market exchange rates can be very large so their criticism is not a negligible one.�

    (b) Dr. Alison Stegman of Macquarie University and Brookings Institution stated, in her recent paper in Climatic Change, that “Given the importance of economic activity in generating emissions, the Castles and Henderson critique highlighted a serious shortcoming in the SRES�; and that “The SRES must be based on accepted modelling and statistical practice. It is not clear what the impact on emissions of using exchange rate converted data is in the SRES because the report is not transparent in its assumptions and methodology.� If the impact of using exchange rate converted data in the SRES is not clear to Dr. Stegman, or to Professor Warwick McKibbin and Dr. David Pearce who have also studied the issue closely over an extended period and produced several papers on the subject in co-authorship with her, I wonder why it is so clear to you.

    (2) In your posting on the “Castles and Henderson, again� thread on 30 January 2006 at 9.17 am you said that you would “now respond� to the main questions that you could derive from Willis Eschenbach’s comment made on 29 January at 6.33 pm. As yet you do not appear to have responded. Are you still intending to reply to Willis’s pertinent questions, and to the questions in my related posting on 30 January at 9.05 am?

    (3) You said in the same posting that the submission that you had made to the Stern Review “was prepared fairly quickly, and is still in draft form.� Did you advise the Stern Committee that the paper was in draft form? There is nothing on the Review’s website to indicate this. Do you intend to submit a final form of your paper to the Review?

    (4) You also said in your post on the “Castles and Henderson, again� thread that you would “be happy to add [to your submission] the references Ian suggests many of which (including the House of Lords report) I have read.� Are you still intending to add the references I suggested (including to the other Castles and Henderson papers) to your submission?

    (5) You said in your initial posting on the “Castles and Henderson, again� thread that the Castles and Henderson critique had “emerged in a rather confused form, with a number of letters and opinion pieces before finally being published in contrarian social science journal Energy and Environment.� You did not mention the fact that David Henderson and I had subsequenty restated and extended our critique in the three papers that are listed in the “References� to Professor Diewert’s comment. Do you think that these papers are equally confused?

    Also relevant is the fact that my initial letters to Dr. Pachauri, Chairman of the IPCC, were sent at his invitation and that the presentations by Professor Henderson and me to the IPCC Expert Meeting in Amsterdam on 10 January 2003 were made at the Panel’s invitation. The circumstances that led us to send out these and other documents “as is� were fully explained in our “Authors’ Preface� to the first of our papers in Energy and Environment, as follows:

    “The contents of these documents are more diverse, and less systematically put together, than would have been the case if we had set out with the intention to provide a full critique. All the eight texts were prepared at short notice, in response to immediate opportunities and concerns. Critics of our critique have rightly made the point that what we are saying has not been subject to peer review. But given that the IPCC was entering into the task of preparation of its Fourth Assessment Report (AR4), and was due to meet in the third week of February [2003], we decided to send out the documents via the Internet without recasting them – as a contribution, timely albeit rough and ready, to an important debate which was already under way. We welcomed the Editor’s subsequent (and unsolicited) proposal to publish them in this issue of Energy and Environment, making only the condition, which was readily accepted, that the IPCC should be invited to contribute an article by way of comment and response. We are glad that an article by SRES authors is to appear alongside our own contribution� (“The IPCC Emission Scenarios: An Economic-Statistical Critique�, E&E, vol. 14, 2 & 3: 161).

    With respect to your description of Energy & Environment as a “contrarian journal�, I need to mention that the Report of the meeting of the IPCC Bureau in Paris on 18 February 2003 states that “The Chair [Dr. Pachauri] noted that Dr, Nakicenovic [Coordinating Lead Author of the Special Report on Emissions Scenarios] will shortly publish, in a leading international journal, an article that responds to the substance of [the Castles and Henderson] criticisms.� This “leading international journal� was Energy & Environment, which subsequently published two responses by teams of SRES authors to the Castles and Henderson critiques.

    Also relevant to your characterisation of Energy & Environment is the fact that this journal recently published an Australian volume which included the paper “Observed climate change in Australia over the past century�, by Neville Nicholls and Dean Collins of the Meteorology Bureau. Two CSIRO scientists were invited to contribute to the volume on aspects of their work on climate change issues: one declined to do so, while the other initially accepted but did not reply to subsequent correspondence from the Editor of the Australian volume. The abstract of the Nicholls and Collins paper reads as follows:

    “Temperatures across nearly all of Australia increased through the 20th century, as did sea surface temperatures in the surrounding oceans. It seems likely that much of the warming is due to increased atmospheric concentrations of greenhouse gases. Rainfall trends have been less spatially consistent than the temperature trends with areas of increase (especially in the northwest) and areas of decrease (especially in the southwest). There is some evidence suggesting that some of the rainfall trends are the result of human influences, but this evidence is less convincing than is the case with the increases in temperature� (E&E, vol. 17, no. 1, January 2006).

    Do you regard these opinions as “contrarian�?

    JQ: “On the sulphur emissions question, I agree with Ken Miles. It’s not useful to debate this on the basis of back-of-the-envelope estimates over a short period. If you think the response should be instantaneous rather than lagged, point to the way in which the models differ from the science on this.”

    IC: I believe that both you and Ken Miles have completely missed my point. The IPCC published 40 emissions scenarios in an Appendix to the SRES entitled “Statistical Tables�. There are 200 pages in this Appendix, and it says “Statistical Table� at the top of every page. It’s surprising that the IPCC did not include any official statisticians in its 53-member writing team or in the team of 89 expert reviewers (It’s especially surprising in the light of the fact that 13 of the members of the writing team were from the Netherlands, which boasts one of the most highly regarded statistical agencies in the world).

    For all emissions of greenhouse gases and aerosols, including sulphur, the 1990 and 2000 data entered in these tables were the same for every scenario, both globally and in each region. For the global totals, published in 2000, the estimates for each of the 40 scenarios showed a decrease of 3% in sulphur emissions between 1990 and 2000. There is now substantial evidence that the actual decrease was over 20%, and that most of this decrease had already occurred by 1995 – over 10 years ago. For the ASIA region, the SRES shows an increase of 42% in sulphur emissions for every scenario. According to the most thorough estimates that have been made (I acknowledged that they were uncertain) the increase in sulphate emissions in ASIA between 1990 and 2000 was only 7%.

    John, I don’t know whether the response should be instantaneous or lagged, I don’t know whether the models differ from the science, I don’t want to do back-of-the-envelope calculations and I certainly don’t know that the models are wrong. Ken Miles’s outraged reactions to the contrary notwithstanding, all I did was to identify model error as ONE of the possible implications of the huge difference between the IPCC’s estimate in 2000 and the best estimates that can now be made.

    I sought expert comment on this matter on your blog precisely because I don’t think that it’s useful to debate it on the basis of back-of the-envelope calculations. I acknowledged that an assessment of the implications was outside my own sphere of expertise. I’m fascinated that you and Ken Miles don’t see the need to explore this for yourselves, but abuse me for trying to do so.

    It seems to me to be bizarre that on a matter of such importance I should be having to guess in 2006 about the implications of the IPCC’s lack of knowledge in 2000 of significant changes in the world’s atmosphere that occurred between 1990 and 1995. Why are you putting the onus on me to “point to the way in which the models differ from the science�? Instead of proclaiming three years ago that “the SRES scenarios provide a credible and sound set of projections, appropriate for use in the AR4�, and accusing David Henderson and me of spreading disinformation and of “questioning� the scenarios (heresy!), the IPCC milieu should have been acting promptly to correct this and other inaccurate information that they had inadvertently provided to governments and researchers, and advising on the implications. The SRES Team were quick to proclaim that “Mr. Castles and Mr. Henderson have focused (at tedious length) on constructing a ‘problem’ that does not exist�, but the leading researcher in the theory of index numbers for the past thirty years seems to think that the problem does exist.

    JQ: “More generally, Ian, I think you need to decide whether you’re acting as an advocate on the skeptical/denialist side of the debate, or as someone seeking to improve the modelling process. The two roles aren’t compatible.”

    I’ll respond to this comment when you’ve answered the questions I’ve raised above.

  5. jquiggin
    September 24th, 2006 at 06:39 | #5

    That’s a long fisking for a three-para blog comment! I’ll try to respond in due course, but for the moment I’ll just restate my main point.

    In an internally consistent economic model, the aggregation procedure used to derive national income index numbers should have only a small effect on predicted values of other variables, such as CO2 emissions.

  6. Ian Castles
    September 24th, 2006 at 08:32 | #6

    Ender, There was an interesting piece in the Sun Herald on 2 September by Ed Shann, former chief economist at Shell Australia, under the title “Some say peak oil, some say global warming.” Ed pointed out that the peak oil advocates who say oil output will be determined by supply and the global warming advocates who see booming energy supply and demand cannot both be right. I’ve had the impression from your posts that you think that both camps ARE right, but maybe you’ll correct me on that.

    Anyway, Ed was certainly correct in pointing out that “estimated carbon emissions are based not on science, but on economics, involving assumptions about world population, economic growth, energy demand, fuel mis, technology and prices.” He has much the same opinion of the value of economic models as you do.

    You say that “again and again [I] concentrate on the economic modelling and miss the science.” No I think it’s the scientists who concentrate on the economic modelling (i.e., the emissions scenarios). The present suite of models conjure up a series of scenarios of the future in which either the whole world is extremely wealthy and even the poorest countries use several times as much energy per head as the richest countries do today, or the global population rises to levels that no demographer now thinks possible. The resulting emissions scenarios are not credible.

    I’m interested in the science and I’d like scientists to explain why the predictions of rapid global warming that were being made 20 years ago haven’t been realised. Some months ago I said on a blog (I’ve forgotten which one) that Ian Lowe, now President of the Australian Conservation Foundation, had forecast in his book “Living in the Greenhouse” (1989) that by the time his youngest son, who was 35 years younger than he was, had reached the age that he was then, the world would be warmer by 3 degrees (apologies to Ian Lowe if I haven’t got the words of the quote right, but the substance of the point was that the world would warm by 3 degrees by about 2025).

    I pointed out that half of the 35-year period had now passed and that according to the observational record the world had warmed by, at most, 0.3 degrees: the rate of warming has been only about one-fifth the rate that Professor Lowe had predicted. I asked why this was the case – I suppose this is the sort of question that leads John Quiggin to allege that I’m “an advocate on the skeptical/denialist side of the debate” rather than “someone seeking to improve the modelling process.” But I sm in fact seeking to improve the modelling process.

    The answers to my question were fascinating. No one accepted that there might have been something wrong with the models of 20 years ago – no, the emissions projections that had been fed into them must have been astray.

    Well, they certainly were: no one in 1990 could have predicted that over one-third of the build-up in the concentration of sulphate aerosols in the previous half-century would be reversed within 5 years. My back-of-the-envelope calculations suggest that by now that reduction in negative forcing should be affecting temperatures, if the models are right. If a climate scientist can show how I’m wrong about that, of course I’ll accept it. But I won’t lie down just because Ken Miles says that my analysis is not particularly useful “given the complexity of the climate system which [I'm] ignoring.”

    The last IPCC assessment reported that global temperatures declined slightly between 1945 and 1975 despite a large rise in CO2 concentrations in the atmosphere. The commonly-accepted explanation for that is that the rise in temperatures that would otherwise have occurred was masked by rising aerosol burdens. Ken Miles, do you agree that explanation? Or do you think that it ignores the complexity of the climate system?

  7. chrisl
    September 24th, 2006 at 09:11 | #7

    Computer models are really probability machines. Put in a lot of assumptions with a proability attached. If you had a very good probability of each assumption (say 90%) after putting just five of these assumptions together the probability drops to around 50%. A toss of a coin!

    Imagine how many assumptions need to be made for a climate model!

  8. Ian Castles
    September 24th, 2006 at 09:51 | #8

    Thanks for your interim response John. On my reading of Erwin Diewert’s comment, he considered that your main point was an implicit criticism of the entire SRES modelling strategy. He also said that your point that “In a fully-disaggregated multi-sector general equilibrium model, aggregate index numbers play no role” was “somewhat irrelevant to the problem at hand” and was “not particularly helpful in modeling the catch up process.”

  9. September 24th, 2006 at 10:09 | #9

    Ian – ““Some say peak oil, some say global warming.â€? Ed pointed out that the peak oil advocates who say oil output will be determined by supply and the global warming advocates who see booming energy supply and demand cannot both be right.”

    The point about Peak Oil is that it is not about running out of oil. It is simply the point where supply, no matter what is done, levels off and declines and fails to meet demand. This has huge implications for global warming. As global oil supplies get tight, and it is right now – having to drill though 3 km of rock under 2 km of ocean is getting pretty desperate, we will turn to tar sands and coal to liquids to try to maintain supply. Both of these options release vastly more CO2 that present oil production and could accelerate CO2 emissions rather that reducing them.

    “….The resulting emissions scenarios are not credible.”

    You are absolutely right – so whats the problem? Perhaps it indicates that present growth is unsustainable?

    “I’m interested in the science and I’d like scientists to explain why the predictions of rapid global warming that were being made 20 years ago haven’t been realised.”

    Scientists have explained it. There is a lag due to the heat sink in the oceans. That is why the southern hemisphere is warming slower than the northern – more ocean in the south. Also science is always getting more data and an important part of science is revising and incorporating new data into theories. Again Ian Lowe may just have been wrong in saying that warming would be 3 deg back then.

    “No one accepted that there might have been something wrong with the models of 20 years ago – no, the emissions projections that had been fed into them must have been astray.”

    Again it has been explained to you at enormous length (sigh) on many occasions and many blogs that no-one has any illusions about the accuracy of climate models. Scientists do not use them to predict exaclty what the climate will be in say 20 years but rather to run experiments and learns what may happen. Climate models also get better with better data.

  10. jquiggin
    September 24th, 2006 at 10:10 | #10

    “Computer models are really probability machines. Put in a lot of assumptions with a proability attached. If you had a very good probability of each assumption (say 90%) after putting just five of these assumptions together the probability drops to around 50%. A toss of a coin!”

    Better not fly a plane any time soon, Chris. They are all designed using computer models. More seriously, your description involves a misunderstanding of the way in which models work. Good models do not rely critically on the conjunction of assumptions in the way you describe.

  11. jquiggin
    September 24th, 2006 at 10:34 | #11

    Ian C, comments like those you’ve made about Ian Lowe are indeed the kind of thing that concerns me. Why pick on a popular book by a non-climate scientist when projections made by actual climate scientists like James Hansen have been pretty much spot-on.

    And I assume you would agree that the claims that the denialist/skeptic side were making well into the 1990s (about urban heat islands, the satellite and balloon record, the idea that the observed trend was just a short-run fluctuation) have fared far worse than the projections of mainstream science, yet I rarely see you make this point.

  12. chrisl
    September 24th, 2006 at 11:01 | #12

    A better analogy to Climate models would be if planes took off totally at random,with no timetables or traffic controllers. i.e chaos. Who would care to predict the outcome then?

    Would you get in a plane if you were given a range of “scenarios” as to where and when you may land?

  13. Ian Castles
    September 24th, 2006 at 11:03 | #13

    Ender, Thanks for your agreement that I’m absolutely right that the emissions scenarios are not credible. Can I take it that you have the same view of the projected increase in temperatures?

    I think that Ian Lowe was relying on the scenario prepared for the GREENHOUSE 1987 Conference at Monash University organised by the CSIRO Division of Atmospheric Research. The statement prepared for that conference was headed “Climate Change in Australia to the Year 2030 AD”, and said that “A rise of 2 to 4 degrees C in the annual mean temperature is predicted.” It also said that “While the predicted changes in the gross features of the global climate are highly probable, the regional changes suggested in this scenario are more speculative.”

    The CSIRO now puts the projected range of global temperature increase between 1990 and 2030 at 0.54-1.24 degrees C, so the range of warming that was thought to be “highly probable” in 1987 has now been reduced by 70-75%. The upper end of the range is only as high as it is because of the increased negative forcing from the reduction in sulphur emissions that is now expected (and which has in fact already occurred). So what exactly is the new data that “science is always getting” that has led to a big REDUCTION in projected temperatures? Is it possible to get an answer from a scientist on this point?

  14. September 24th, 2006 at 11:24 | #14

    Ian – “Thanks for your agreement that I’m absolutely right that the emissions scenarios are not credible.”

    No that is not what I said at all. I said that endless growth is not sustainable and indicates that there will be a discontinuity in the future where the limits to growth are reached. That is why they are not credible. They will continue to grow until such time as they can’t. You seem unable to accept that there are limits. Again even if you had done all of them yourself they would be no more credible as accurate predictors of the future than any other modelling. They MAY indicate the range that future growth MAY fall into in the future. No more or less that this can be said about any modelling however accurate.

    “Can I take it that you have the same view of the projected increase in temperatures?”

    As far as the science is concerned the conditions that we are setting ie: pumping billions of tons of greenhouse gases which control the thermostat into a chaotic system that we understand so little then yes the rise in temperatures will continue. The real fear is that we are underestimating the rise and when positive feedbacks start to kick in as they are now the rise could get very swift far beyond the conservative predictions that scientists agree to now.

    Also as a chaotic system the atmosphere has many ‘stable’ states. It is the nature of chaotic systems to very quickly change from one state to another in response to a stimulus or ‘pumping’. We are and have been for 8000 or so years in a warm wet state of the interglacial. Pumping the atmosphere system MAY actually tip the earth into another stable state. This could happen VERY quickly, as in the Younger Dryas, over decades and leave the Earth in a very different climate regime like cold/dry. One of the times in the past the Earth was in cold/dry the human population got down to something like 20 000 individuals.

    This is why we must be cautious. We do not know enough about the climate to predict exactly what it is going to do and it may do something that we never predicted. This is why rabbiting on about economic models and this and that makes no sense. Whatever happens in the future and whatever the cost we should be cutting back drastically on greenhouse emissions to stop pumping the system.

  15. Ian Castles
    September 24th, 2006 at 11:36 | #15

    John, My reply to Ender answers your point also. The climate projections to 2030 that I’ve quoted are published in Pearman, G.L., ed., 1988, “Greenhouse: planning for climate changeâ€? (CSIRO Division of Atmospheric Research), pps. 737 ff. In Australia, I don’t see how you can get more mainstream than that.

    James Hansen’s latest projections are in his December 2005 paper (with 45 co-authors, including Gavin Schmidt of Real Climate) “Dangerous human-made interference with climate: a GISS midel E studyâ€? (Geophysical Research Letters, submitted). According to this paper the projected warming to 2100 in IPCC scenario B1 is 1.1 degrees C (p. 23). In the US, I don’t see how you can get more mainstream than that.

    The projected increase in fossil CO2 emissions in the B1 marker scenario from 2000 to 2030 is 62.3%, which is exactly the same as the growth in energy-related CO2 emissions under the Reference Scenario of the International Energy Agency, as published in “World Energy Outlook 2005�.

  16. chrisl
    September 24th, 2006 at 11:49 | #16

    Ian-
    – What you seem to be saying is that we can predict the eath’s temperature by predicting the amount of co2. We can predict the amount of co2 by the world’s economic growth. And we can predict the world’s economic growth by… you will have to help me out here…

  17. Ian Castles
    September 24th, 2006 at 11:57 | #17

    Chrisl, I’ve been so busy disagreeing with John and Ender that I haven’t had a chance to say that I agree with you.

    The draft IPCC Fourth Assessment Report says “Projected probability ranges (mean plus or minus 1 standard deviation) for globally-averaged surface warming in 2100 compared to 1980-2000 … are scenario dependent and estimated to be … 3.0-5.0 degrees C for the … A2 … scenario.â€?

    What it doesn’t say, and what I bet the IPCC won’t say, is that the A2 scenario projects a global population of 15 billion in 2100 and that the International Institute of Applied Systems Analysis (IIASA). which prepared the population projection used in that scenario, puts the subjective 95% probability range for population in 2100 at 4.3-14.3 billion. Or at least it did put the 95% probability limits for global population in that range in 2001. The chance of global population exceeding 14.3 billion in 2100 would now be well below 2.5%, and it decreases with every year that the global demographic transition proceeds. The UK Stern Review discussion paper used the the IPCC’s A2 as its “business-as-usual” scenario.

    As with the projections of sulphur emissions, the views of the IPCC’s modellers in the late-1990s would be only an historical curiosity now, but for the fact that they were enshrined in the Special Report on Emissions Scenarios and the IPCC has made an “ex cathedra” pronouncement that these are sound and suitable for use in AR4.

  18. jquiggin
    September 24th, 2006 at 12:25 | #18

    Ian, on your final point, and much of the discussion above, I think it’s unhelpful to conflate discussion of climate-science issues like the modelling of SO2, about which none of us here know very much, with discussion of economic projections, where we can have a useful discussion. If you want information on climate-science topics, I suggest you raise these questions at Real Climate.

    I’ll try to respond to your other points before too long.

  19. chrisl
    September 24th, 2006 at 12:47 | #19

    Ian , I have often wondered what it is that is going to turn the earth’s temperature graph upwards so sharply.Given the previous century rise of .06 degrees and according to the CSIRO a rise of 3 parts per million in co2 last year,you could almost describe that as no change/nothing to see here.
    However in the next 94 years we are projected to have a temperature rise of 3-5 degrees.
    A population of 14.3 billion would certainly explain things nicely.

  20. Brian Bahnisch
    September 24th, 2006 at 15:22 | #20

    Ian Castles/Ender, I’m no scientist so it is a case of where angels fear to tread. But I found the diagram of climate forcings on p6 of Hansen’s Scientific American article helpful. There are positive and negative aerosols. Also I understand they persist in the atmosphere for a much shorter time than co2 – 15 years vs 100 years plus. Beyond that I can’t help.

  21. Brian Bahnisch
    September 24th, 2006 at 15:34 | #21

    Econoclast said:

    And the biggest indisputable fact – we are pumping ****loads of it into the atmospere! More than the earth has ever had done to it before.

    Not everyone takes James Lovelock seriously, which doesn’t mean he’s wrong. He says the best analogy is 55 million years ago, when similar quantities of carbon were released into the atmosphere. James Zachos has found that this time we are releasing it 30 times faster.

    On that occasion the temperatures went up 5C at the tropics and 8C in the more temperate regions. It took 200,000 years to return to the pre-event trend line.

    If nothing else a good argument for the precautionary principle!

  22. Ian Castles
    September 24th, 2006 at 16:39 | #22

    Brian, I’d like to respect John’s ruling that I not discuss climate science issues on this blog. However, the projections of sulphur emissions used by the IPCC ARE economic projections and, as I pointed out above, the IPCC’s simple model climate projections are specifically stated to be based on the assumption that the global burden of sulphate aerosols varies directly and immediately with emissions: see the Note to SRES Table II.2.7: “Global burden [of sulphate aerosols] is scaled to emissions: 0.52 Tg burden for 69.0 TgS/yr emissions.”

    So I don’t see how you can be right that these aerosols persist in the atmosphere for 15 years – if they did, the projections of burdens would not be scaled to current emissions but would be some sort of function of emissions over the previous 15 years

    I think the forcing chart in Hansen’s paper is essentially the same as that given in the Summary for Policymakers of the last IPCC Report at http://www.grida.no/climate/ipcc_tar/wg1/figspm-3.htm . The forcing assumptions in this diagram would be those used in the Hansen et al paper that I’ve cited, which finds a temperature increase to 2100 of 1.1 degrees C for the B1 scenario.

    Even for the A2 scenario and a global population of 15 billion the projected warming in the Hansen et al simulation only reaches 2.7 degrees C. The Hansen simulation for the A1B marker scenario (which assumes “very high” economic growth, “very high” per capita income and “very high” energy use – SRES Table 6-2a) is for a warming of somewhere between 1.1 and 2.7 degrees C.

  23. Ian Castles
    September 24th, 2006 at 16:51 | #23

    My statement that “the forcing assumptions in this diagram would be those used in the Hansen et al paper” is carelessly worded. The paper says that “We carry out climate simulations for 1880-2100 with GISS modelE driven by measured or estimated forcings for 1880-2003 and extended to 2100 for IPCC A2, A1B and B1 scenarios …” So the measured or estimated forcings underlying the GISS model would be reflected in (a) the estimates shown in a diagram of the type that appeared in Scientific American and (b) the climate projections in Hansen et al.

  24. jquiggin
    September 24th, 2006 at 16:53 | #24

    Working backwards through your comments, Ian, I don’t see it as particularly useful to debate whether Energy & Environment is a contrarian journal. The editor is generally regarded as a skeptic and the journal publishes a lot of papers in this vein. On the other hand, as you say, it publishes some papers with other views.

    More generally, I don’t want to spend a lot of time on third-order issues like this, which are irrelevant to the main point at issue. So, as regards the various points about referencing, version control and so on, my response is that I will deal with them when I get time.

  25. jquiggin
    September 24th, 2006 at 18:20 | #25

    As regards your comments above, Ian, are the temperature changes you refer to estimated for the period 2000-2100 or do they include the warming that has already taken place? Even with the latter assumption, I find it hard to see how you can refer to warming of “only” 2.7 degrees. If it’s the former, then we are talking about a temperature change of more than 3 degrees relative to the pre-intervention situation.

  26. Ian Castles
    September 24th, 2006 at 18:26 | #26

    John, Here’s what you said of a paper in Energy & Environment on 27 January last, on the thread “More nonsense on global warming�:

    “… The abstract is enough to tell me that this paper wouldn’t have got up at any reputable journal. It’s just a fancy restatement of the tired contrarian talking point that global temperatures declined in the middle part of the 20th century (aerosols, anyone?). By the way, given that E&E purports to be a social science journal, why is Boehmer-Christiansen publishing climate science papers (apart from the fact that no-one else would take them).â€?

    Now you’ve decided that (a) you think it’s unhelpful to discuss issues like the modelling of sulphate aerosols “about which none of us here knows very much�; (b) you “don’t see it as particularly useful to debate whether Energy & Environment is a contrarian journal�; and (c) you “don’t want to spend a lot of time on third-order issues.�

    I won’t bother to point the moral, but I think that it’s fair to point out that Energy & Environment could publish more papers with “other views� if the relevant experts were prepared to submit them to E&E rather than publish in house journals or in publications that are known to have friendly reviewers.

    I mentioned earlier that a CSIRO scientist had declined E&E’s invitation to contribute a paper on CSIRO’s regional climate projections to the Australian volume that was published last January. In the event, eight members of the CSIRO Climate Impacts and Risk Team (including three lead authors of the forthcoming IPCC Assessment Report) published the paper that they could have submitted to E&E as “Whetton, P. H., McInnes, K. L., Jones, R. N., Hennessy, K. J., Suppiah, R., Page, C. M., Bathols, J. M., and Durack, P. J. (December 2005). Australian climate change projections for impact assessment and policy application: a review (CSIRO Marine and Atmospheric Research Paper 001).

    I read this paper for interest and was surprised to find that these scientists believed that “the SRES scenarios currently available were deliberately constructed to be equally plausible� (p. 32). As I had pointed out that this was not the case in a widely circulated letter that I had sent to the Academy of the Technological Sciences and Engineering in April 2002, and 15 members of the SRES Team had reiterated this in their first intemperate response to Castles & Henderson in May 2003, and I had travelled to Melbourne at my own expense for discussions with the CSIRO Climate Impacts Team (including several of the authors of this paper) in September 2004, it was disappointing to find that these scientists still had it wrong in December 2005. I wrote to one of them in March 2006 pointing out the error. He agreed that the statement was wrong and said that it would be corrected, but so far the statement remains in the CSIRO paper. My guess is that the error won’t be corrected or even admitted, because to do so might prejudice CSIRO’s remunerative consultancy business in producing “climate change projections for impact assessment and policy application.�

    In my view, this reflects very poorly on CSIRO.

  27. jquiggin
    September 24th, 2006 at 20:53 | #27

    Ian, it’s pretty clear what I think of E&E. I was hoping to focus our discussion on more relevant issues than this.

  28. Ian Castles
    September 24th, 2006 at 22:47 | #28

    John, I can’t find any clear statement in Hansen et al about when the projection of 2.7 degrees C dates from – I think it’s probably from the end of the period used to model the forcings, i.e. 2003.

    In using the word “only�, I didn’t intend to imply that warming of this order would not be extremely serious. The “only� is by comparison with the inflated numbers commonly used in public discussion, including by leading spokespersons for the IPCC, as if they were predictions of the actual future temperature. For example, the top of the IPCC’s temperature range went up from 4.0 degrees C in the TAR draft of 6 November 1999 to 5.0 degrees C in the second draft of 16 April 2000, and then to 5.8 degrees C in the third and final draft of 22 October 2000. IPCC Chair Bob Watson reportedly told COP 6 at the Hague that new forecasts (sic) put the expected (sic) temperature rises until 2000 at between 1.5 and 6.0 degrees C – double the previous estimates.

    Last February I complained to the ABC about the Four Corners “The Greenhouse Mafia� documentary in which the narrator had said that “By 2050, [carbon dioxide emissions] are expected (sic) to more than double, causing a dramatic increase in warming of as much as four degrees.� In response, I was told that “Climate change scientist Dr. Graeme Pearman, who appeared in the program, says ‘the kinds of expectations (sic) from what is now a very solid set of science is that we could have several degrees change in temperature this century possibly as much as five degrees.’�

    Against the background of statements such as these, I thought it was fair enough to characterise the Hansen et al projection (not estimate) as I did, bearing in mind that it was derived from a scenario which put the end-century population well above the top of the 95% confidence range. I don’t think a simulation based on A2 which was carried out in 2005 can properly be characterised as “a temperature change of more than 3 degrees relative to the pre-intervention situation”, because A2 is based on a hypothetical outcome that might have been considered plausible ten years ago but can’t be regarded as plausible any more.

    But I’m happy to clarify that I didn’t mean to suggest that an increase of “only� 2.7 degrees from now (with a further increase after 2100) would not be a matter for extreme concern.

  29. Chris O’Neill
    September 25th, 2006 at 01:52 | #29

    “Until that balance changes it is difficult to give “justificationâ€? to any arguments therein.”

    That’s fine. I now know that econwit makes arguments that he knows he cannot justify.

  30. jquiggin
    September 25th, 2006 at 05:55 | #30

    Ian, you appear to be confusing point estimates with upper bounds of ranges, and disagreements with scenarios with disagreements about reporting.

    A point estimate of 2.7 is certainly consistent with a range going up to 4 degrees, so, given the choice of scenario, there is nothing wrong with the statements you’ve cited. On any sensible analysis of costs, low-probability events at the upper end of the range are going to play a large role.

    I agree that a population estimate of 15 billion is implausible, even as an upper bound, though it seemed possible not long ago. However, it would be more helpful to make specific criticisms like this in the context of a constructive contribution to the modelling process, rather than mingled with a general attack on the IPCC and all its works, raising a whole range of unrelated issues.

  31. econwit
    September 25th, 2006 at 11:55 | #31

    Chris O’Neill

    “I now know that econwit makes arguments that he knows he cannot justify.�

    That comment has been put to me so many times before I’m beginning to think there could be some basis to it, but I’m as yet to see* any convincing justification or evidence. Your line of argument is in a very similar mode to the GW debate, lots of conjecture (hot air) very few facts.

    * ps. I could be blind?

  32. econwit
    September 25th, 2006 at 11:58 | #32

    Chris O’Neill

    “I now know that econwit makes arguments that he knows he cannot justify.�

    That comment has been put to me so many times before I’m beginning to think there could be some basis to it, but I’m as yet to see* any convincing justification or evidence. Your line of argument is in a very similar mode to to proponents of the GW debate, lots of conjecture (hot air) very few facts.

    * ps. I could be blind?

  33. chrisl
    September 25th, 2006 at 15:53 | #33

    Ian, Why do you think the IPCC has bothered to predict/construct a scenario of Global temperature in 2100 given the difficulties and uncertainties involved?
    You have already shown that sulphur emmissions and world population predictions were wildly inaccurate to name only two of the numerous assumptions that have been made.
    Wouldn’t it have made more sense to construct a scenario for five year intervals given the uncertainties?

  34. September 25th, 2006 at 18:40 | #34

    Ian – the main problem with your arguments seems to be this. You seem to be pretty fixed to the idea that X economic activity = Y greenhouse emissions. ie that economic activity causes greenhouse emissions therefore more economic activity = more greenhouse. You are also arguing that the IPCC got the economic projections wrong, in your view, therefore the economic activity in say 2100 will be less then what the IPCC projected and that the trend is that economic activity/greenhouse emission ratio is dropping therefore even the higher activity will lead to less emissions.

    Have I got that right?

    If so then you are not taking into account that the actions of the atmosphere is not coupled only with economic activity. As has been pointed out before we have not seen all the rises due to positive feedbacks like the melting permafrost and the lowering of albedo due melting ice. Not to mention the fact that warmer oceans absorb less CO2.

    In the future the neat relationship you see between economic activity and emissions may fail and emissions may increase far beyond what would be predicted by you from economic activity alone. This would also drive warming into the upper regions of the conservative ranges that the IPPC will publish.

  35. Ian Castles
    September 25th, 2006 at 20:07 | #35

    Ender, The short answer to your question “Have I got that right?” is “No”. This is a complex issue, but could I suggest that, as a first step, you read Ed Shann’s piece in the Melbourne “Sun Herald” of 2 September, to which I referred you in my posting of September 24 at 8.32 am?

  36. September 25th, 2006 at 20:46 | #36

    Ian – “estimated carbon emissions are based not on science, but on economics, involving assumptions about world population, economic growth, energy demand, fuel mis, technology and prices”

    This is what you said that Ed Shann said. Isn’t this pretty much how I summerised it?

    BTW I cannot find the article – if you have a copy I would read it.

  37. Ian Castles
    September 25th, 2006 at 22:35 | #37

    Ender, The following extract is pasted from section 9.3.3 of IPCC “Climate Change 2001: The Scientific Basis.” The added CAPITALS are mine. You have yourself referred to temperature rises DUE TO POSITIVE FEEDBACKS. I acknowledge that the strength of the feedbacks is uncertain, but it is my understanding that the temperature projections depend ultimately upon the radiative forcing from the SRES emissions scenarios, and that these rest in turn upon assumptions about world population, economic growth, energy demand, fuel mix, tchnology and prices. These assumptions cannot be reduced to the simplistic foumulation “more economic activity = more greenhouse”:

    “The calculation of radiative forcing from the SRES emission scenarios for the temperature projections presented here follows closely that described in Chapters 3, 4, 5 and 6, with some exceptions as described below. Further details of the forcing for the collective procedures (MAGICC model) are given by Wigley (2000). Atmospheric concentrations of the greenhouse gases ARE CALCULATED FROM THE EMISSIONS using gas cycle models… To be consistent with Chapter 3, CLIMATE FEEDBACKS ARE INCLUDED and the model has been tuned to give results that are similar to those of the Bern-CC and ISAM models for a climate sensitivity of 2.5°C (Chapter 3, Figure 3.12). The strength of the climate feedbacks on the carbon cycle are very uncertain, but models show they are in the direction of greater temperature change giving greater atmospheric CO2 concentration.â€?

  38. September 26th, 2006 at 08:27 | #38

    Ender – “These assumptions cannot be reduced to the simplistic foumulation “more economic activity = more greenhouseâ€?:”

    So what is a summary of your position in 100 words or less?

  39. Ian Castles
    September 26th, 2006 at 09:41 | #39

    Ender, Under the IPCC’s B1T MESSAGE scenario, economic activity, as measured by GDP at market exchange rates, is projected to increase between 2000 and 2100 by a factor of 12. Economic activity as measured by GDP at what the IPCC wrongly describes as purchasing power parity is projected to increase over the same period by a factor of 10. After taking account of the IPCC’s assumptions relating to energy demand, fuel mix, technology and prices, fossil fuel carbon dioxide emissions under this scenario are projected to DECREASE by more than 50% between 2000 and 2100. That is 99 words.

  40. September 26th, 2006 at 10:25 | #40

    Ian – “fossil fuel carbon dioxide emissions under this scenario are projected to DECREASE by more than 50% between 2000 and 2100″

    Just a clarification is this total fossil fuel CO2 emissions or emissions per unit of GDP and/or economic activity?

  41. Ian Castles
    September 26th, 2006 at 10:49 | #41

    Ender, It is total fossil fuel CO2 emissions. The actual levels are 6.90 GtC (= 25.3 Gt of CO2) in 2000 and 3.33 GtC (= 12.2 Gt of CO2) in 2100. If CO2 emissions from land-use changes are included, the totals become 7.97 GtC (=29.2 Gt of CO2) in 2000 and 2.68 GtC (=9.8 Gt of CO2) in 2100.

  42. September 26th, 2006 at 14:14 | #42

    Ian – “Ender, It is total fossil fuel CO2 emissions. The actual levels are 6.90 GtC (= 25.3 Gt of CO2) in 2000 and 3.33 GtC (= 12.2 Gt of CO2) in 2100. If CO2 emissions from land-use changes are included, the totals become 7.97 GtC (=29.2 Gt of CO2) in 2000 and 2.68 GtC (=9.8 Gt of CO2) in 2100.”

    so therefore you think that the warming will be less that what the IPCC reports? Or do you think it will still be dangerous?

    Also if your projections are true then a halving of total CO2 emissions by 2100 approx a decrease per year of 0.9%. Now if this is true we should be seeing this now as it should be part of the trend. Unless of course CO2 emissions rise, reach a maximum then fall away. As they are now increasing and show no signs of decreasing what do you attribute the falling CO2 emissions to?

  43. Ian Castles
    September 26th, 2006 at 15:18 | #43

    Ender, These are not my projections: they are the IPCC’s. I said that your formulation “more economic activity = more greenhouse” was simplistic and you asked me to summarise my position in less than 100 words. I pointed to one of the IPCC’s scenarios – there are several more – in which economic activity is projected to go massively up and greenhouse emissions are projected to go substantially down. I’d say that, irrespective of what actually happens, the projection itself shows that more economic activity does not necessarily mean more greenhouse.

    Under the scenario in question, fossil fuel CO2 emissions DO “rise, reach a maximum and fall away”. Specifically, they rise by 42% between 2000 and 2030 and then decline by 66% between 2030 and 2100.

    If you believe that, because emissions are increasing now, they can’t begin to decrease in 25 years’ time, your argument is with the IPCC.

    Note that this scenario does not explicitly address any climate change initiatives such as the Kyoto protocol (SRES, p. 23) and does not include any technologies that had not been demonstrated to function on a prototype scale at the time that the Special Report was prepared (SRES, p. 216).

  44. September 26th, 2006 at 16:19 | #44

    Ian – “These are not my projections: they are the IPCC’s.”

    So what are your projections?

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