I was at a literary function the other day and heard a publisher make a cheap shot about a Federal Minister and by extension the present Government. There was much laughter, and I thought again how easy it is for us, all of us, to simplify everything we encounter by using stereotypes. Tony Abbott is such a good example. He seemed to arouse an almost visceral anger in lots of people, including some of my own family. Yet none of my lot has even met him, or seen him close up. He exists in so many minds as a stereotype, and in general a bad one.

I haven’t met Tony Abbott either. He is a generation and more younger than I am, and I didn’t encounter him in his time in Parliament. From those who have worked for him in the Howard period I have learned that he was a competent and intelligent Minister. About his being PM I haven’t heard anything. But I learned a great deal about him from a book written by Geg Sheridan, who is the foreign editor of The Australian. Sheridan’s book, When We Were Young and Foolish, is an account of his own boyhood and young manhood. It is a good read, describing what it was like to be a young Catholic born into a Labor family in Sydney, unsure of whether or not he ought to be a priest, a politician or a journalist. He chose the latter course, and as a journalist he is very good indeed.

Tony Abbott, of like age, was a friend, and a good one, and the second half of the book has a good deal about him, also someone who considered being a priest, was a journalist, and finished as a politician. He comes across as a young man of passion, commitment, energy and intelligence, successful in what he did, unsure of his proper path in life, like Sheridan, pulled in different ways by different people. He could have been a member of the ALP, and Labor did it best to lure him into its ranks. It turns out that the same was true of Malcolm Turnbull, though Sheridan was not close to him.

Sheridan sums up the young Abbott like this:  Tony had all the skills. So did a number of other people — writing well, speaking well, courage in battle, organisational ability, effective and easy in dealing with people. That combination was unusual but not unique. What set Tony apart were two things — the depth of his drive and energy to achieve whatever his present objective was. Some wiseacre said that 80 per cent of success in life is just showing up. Tony always showed up.

The point about Tony Abbott and Malcom Turnbull (and Peter Costello, Kevin Rudd and Bob Carr, also part of the Sheridan network of young aspirants) is that they were marked out as young men by the old and experienced as unusually gifted and determined, an asset to any party. Sheridan thought at the time that Abbott could go on to be Prime Minister, and he was right in that. Turnbull he saw as almost unbelievably talented, and regrets that he didn’t stay in journalism, because he was so good at writing, and had such a flair for finding out.

There’s nothing much in the book about climate change, other than that Abbott was passionate about his view that it was a snare and a delusion. But with the Paris meeting starting today, it interests me to speculate about how the two Liberal leaders would deal with a much-heralded international meeting where there is extremely strong pressure to agree to something, but also a complex mix of national interests, as well as political ideologies. We will know in due course what Malcolm Turnbull does. But my guess is that Tony Abbott would have done much the same, for good reason. There would  be a difference, and I’ll come to that at the end.

Any national leader who goes to a meeting like this needs to have his or her head screwed on well. The NGOs are there making a fuss, and there will be meetings with other national leaders. There will be a draft agreement, which one’s public servants and other advisers will have already argued about, probably inconclusively. Then there will be one’s reservoir of commonsense, both political and personal. And then, what is it that one wants to come home with?

There will be those who think that Tony Abbott would not have gone there at all, and simply sent someone from DFAT. That wouldn’t do. Or rather, you could it only if there were an quiet agreement among a lot of leaders that they would give this one a miss. Since Australia is a big producer and user of coal, and so much of the event is about reducing that use, not to be there would be to give ammunition to one’s opponents, at home and abroad. Every Government department that has overseas interests, and that is at least a half of them, will have views about Australia’s position, because they will have projects, not to mention possible and existing agreements that are important to them.

The whole diplomatic environment is full of useful relationships that might be imperilled if one’s country does something that is unpopular with other countries. The truth is that ‘climate change’, and dealing with it, are agreed high-priority international issues. You can say, as Tony Abbott did, that some of the science surrounding the issue is ‘crap’, but Paris and CoP21 is not the place to say it. Your savvy national leader will talk the talk as neatly as he or she can. If there is an agreement that is not acceptable to those back home, the leader will shrug, and tell those present that while he can sign it, there will be difficulties back home. President Obama ought to say that. Mr Turnbull won’t have to.

My guess is that there will be some sort of agreement, but it won’t be binding, to the dismay of the CAGW believers and the Green politicians everywhere. Mr Tunrbull has said, and will say again, that Australia’s proposals to cut greenhouse gas emissions are sensible and achievable and what Labor and the Greens are proposing are neither achievable nor sensible. he’s right there, too. Mr Abbott, had he been PM, would have done much the same.

The difference is that Mr Turnbull will get away with it, and Mr Abbott would have been pilloried. It’s hard for the ABC and the Fairfax media to attack Malcolm Turnbull. He has been their favourite for a long time — a man of the right with some left sympathies. Had Tony Abbott come home with whatever is the outcome, he would have been pilloried: he is the evil one for those media entities, who would see the outcome as his fault, for not having fought harder.

They should read Sheridan’s book.

Later footnote: Anthony Watts carries an updated version of Andy May’s illustrated history of the last 18,000 years, in which climate change and human civilisation are closely connected. This is real climate change… An excellent read, and it comes with a chart that will print out well.

Climate and Human Civilization over the last 18,000 years

Note that this link has a space in it. I can’t seem to correct it!

Join the discussion 91 Comments

  • David says:

    Let’s not re-write history Don. Abbott did not say that “some” of the science surrounding the issue is ‘crap’. What Abbott is reported to have said is

    “The argument [behind climate change] is absolute crap. However, the politics of this are tough for us. Eighty per cent of people believe climate change is a real and present danger.”


    • aert driessen says:

      Here we go again with corrupt language. Of course climate change is a real and present danger and everyone should think that, especially if change means cooling. And some eminent scientists (as well as satellite data) think that we are indeed entering a cooling phase. But what has all that to do with CO2? There is no evidence in the entire geological record that CO2 has ever been a driver if climate change, none. You obviously assume that climate change means only warming. I don’t. I read the language for what it is. Change means change, whether in one direction or another. When applied to temperature there are only two directions — up (warming) and down (cooling).

      • David says:

        Aert, I simply make the point when reporting Abbott’s previous position on the climate science that Don has dropped an adjective (absolute) and added a qualifier (some).

        This gives an impression of Abbott as a reasonable man, which required correction, obviously.

        • PeterE says:

          I do not believe that either of you has Abbott’s ‘crap’ remark right. At the time, I understood that he indicated that the claim that the science was settled was ‘crap.’ That was and is true. This has been distorted over the time since and I will only change my view if I see the actual quote and it differs from the above.

          • Don Aitkin says:

            The Australian’s report of it all is indeed a bit muddled. I cannot find the original report that is in the Pyrennees Advocate, whose editor wrote the original story. The Australian’s account of it includes the following:

            ‘According to many in the room, he [the editor] left no doubt that he [Tony Abbott] was a climate change sceptic. He ruminated there had been many changes of climate over the millennia not caused by man. Finally, he said the science behind climate change was “crap”, at which stage Wilson snapped awake.

            “I think I was nodding off down at the back of the room when all of a sudden he came out with the comment that the science around climate change was `absolute crap’ and I kind of jumped back awake and wrote down his quote,” Wilson says.

            In the fourth paragraph of Wilson’s article, he quoted Abbott as saying, “The argument is absolute crap. However, the politics of this are tough for us. Eighty per cent of people believe climate change is a real and present danger.”

            There’s a real mixture here. But I assumed that Abbott reckoned that some of the science behind the notion of catastrophic anthropogenic climate change was wrong, or at least too weak to justify the policies being put forward.

            I still think that is a reasonable inference to draw. Indeed, on the evidence, surely Abbott is right.

          • David says:

            Here is the text from an interview between Liz Jackson and Craig Wilson from a 4 Corners Interview


            CRAIG WILSON, EDITOR, PYRENEES ADVOCATE: He was talking about how the science said that there was this issue called climate change and that it existed, but he came out and said it was crap.

            LIZ JACKSON: Absolute crap?

            CRAIG WILSON: Absolute crap.

            LIZ JACKSON: Is that the words you have recorded in your notes?

            CRAIG WILSON: Absolute crap. No doubt about it.

            LIZ JACKSON: Abbott’s comment made page five of the local paper and climate sceptics in the Party were delighted.

            I have provided two references, News Limited and the ABC. You have mis-presented what Abbott said.

        • JMO says:

          David and Bobo, we all agree CO2 has a warming influence, but what we still do not know is the equilibrium climate sensitivity ie how much warming by doubling pre-industrial age CO2 concentration (270-280ppm).
          The so called settled science has not pinned this down (latest IPCC says 1.5 to 4.5 C i.e 300% variation – albeit small base). Alarmist still hold the view over 4 to 5 C and the catastrophic would say at least 7C.
          Not pinning down ECS is like pre- Hubble cosmology – having a range of guesses or Quantum physics before Plank’s constant or mathematics before exponentials or calculus and chemistry before the mole number. Need I go on? The point I am making is until climatologisst can pin down an accurate ECS, it ain’t “settled science” Putting it diplomatically it is a young science.
          So lets join the guessing game – what do you think ECS is? My humble view is it is 1.2 +/- 0.3 C.

          • bobo says:

            I’m not sure that ECS has a precise value – I’m inclined to think it’s a (non-constant) function. Have a look at my comment above if you’re interested in my thoughts on this.

            I’m curious to know why you think ECS lies between 0.9 and 1.5?

    • Don Aitkin says:

      No, he didn’t. I used the word ‘some’, and it is my interpretation of what he said, as reported in The Australian, and indeed in a post of mine somewhere. I assumed, perhaps wrongly, that when he referred to argument he included some of the science thought to be behind it.

  • Alan Gould says:

    Whether it was “some” or “absolute”, nonetheless it still took good nerve to say it in a context where an orthodoxy is powered by a widespread social panic, fuelled by some of the most influential media of our time who have accepted that ‘The Science” is “all in” so the toleration of dissent on the issue is not to be countenanced.
    Don, I’m pleased you defend Tony Abbott, not because I have any special connection with the man, nor did I ever vote for him. But I note around the coffee tables and those places where speeches are a form of collusive team-calls, that Abbott’s name is accompanied reflexively with sneer. In the school playground that is called bullying, and I detest it. He has good courage, a clear mind, an oddly awkward walk that makes him look like a jackaroo who has just ridden from Broome to Charters Towers.

  • PeterE says:

    I did meet Abbott some 20 years ago. He struck me then as an outstandingly trustworthy and talented man and I told him that I hoped to see him as Prime Minister one day. In my view, both before and during his Prime Minister-ship, he was ‘spot on’ with all of the big policy issues. I hope he continues to speak up because we need his views. The new man does not have Abbott’s judgement on the big issues of the day.

  • bobo says:

    “You can say, as Tony Abbott did, that some of the science surrounding the issue is ‘crap’”

    That’s an understatement. If his statement
    “I am, as you know, hugely unconvinced by the so-called settled science on climate change”
    didn’t make his position clear, his actions certainly did. Abbott tried to dismantle the full suite of GHG mitigation agencies and policies that had been set up under Gillard: not just the carbon tax/ETS, but the renewable energy agencies ARENA and CEFC and a statutory agency, the Climate Change Authority. Curiously the CSIRO stopped researching carbon capture and storage during Abbott’s prime ministership.

    Direct Action was a fig-leaf policy designed to mislead LNP voters concerned about AGW so that they would not change their votes. But Direct Action is largely useless as a mitigation policy because it does not constrain national emissions.

    I suspect Abbott’s attacks on the scientifically-justified GHG mitigation policy and climate research were part of a broader culture war on science that Abbott was prosecuting (the exception here is medical research). Abbott made a clear statement by cutting $878 million in funding from science research agencies and creating a $244 million religious chaplaincy scheme for government schools. These actions put the following remark of his regarding climate science in the realm of the absurd:

    “I certainly accept that there’s been far too much theology and not enough proper scientific scepticism in this area, I certainly accept that…”

    • Don Aitkin says:

      Bobo, since I too am unconvinced by the so-called settled science on climate change, and have been showing why for several years now, your response doesn’t persuade me. If you can show me how and why climate sensitivity is really at least x3, and gentle warming is bad for eco-systems, and sea-level rises are really accelerating, then you have an attentive audience.

      • David says:

        There are some yawning gaps
        in your understanding of the scientific process, and how it should be applied
        to hypothesis testing. If your question bobo were serious, would make the
        effort to upgrade your knowledge. In the past, I have suggested that you go and
        read some non-AGW literature as a way of addressing some of these issues. However,
        you dismissed the idea out of hand. No
        one can teach a person who is not willing to learn.

        • Don Aitkin says:

          Hand-waving again. I read a great deal in this field (the last, this morning, from RealClimate). Why don’t you show me that ECS must be at least 3x, since you are claiming knowledge of the ‘non-AGW literature’. I’d be glad to learn about some new evidence. If it seems plausible, I’ll factor it in to my knowledge base.

          Or you could show my one of my ‘yawning gaps’, in specifics. But, please, no more vague put-downs.

          • David says:

            1. You insist that some knowledge about analysis of cross sectional survey data is sufficient to understand AGW. Understanding AGW requires a good understanding of Time series analysis, which you don’t have.

            As a result even Judith Curry has published papers, which negate some of the data quality arguments which you have been willing to promote in the past.

          • Dasher says:

            David. This is a quality blog and Don is extremely patient with you, most of us are sensible people with open minds and welcome different views but you are bordering on being a troll. You purport to be an expert but argue like a zealot… Let’s hear some useful information rather than the infantile tripe you have been dishing up lately.

          • David says:

            Dasher I would like to apologize for my
            trolly-like behaviour; linking to News Limited articles to support my argument.
            I am sure there is a special place in hell waiting for me. J

          • Dasher says:

            Jimbo and David, we all look forward to your incisive comments in future. Incidentally I welcome other views, the echo chambers that pass for the ABC, Fairfax and some of the warmest blogs e.g. DeSmog would have us either fried, inundated or blown away by now. When is the next tipping point by the way?

          • Dasher says:

            Ok, cheap shot, I withdraw Mr Speaker.

          • JimboR says:

            Quality is in the eye of the beholder I guess. As bobo points out, there are plenty of areas of climate science where the certainty levels are very low indeed. I’ve noticed a recurring pattern that when Don is challenged over his silliest claims, he immediately retreats to the relative safety of areas where there is uncertainty.

            Personally, I think the quality would be greatly improved if he just stuck to those areas. Most of the time this blog seems to be just a partner-blog with a handful of others of dubious quality… all cross-referencing each others “findings” and forming one big echo chamber. There’s very little science to be found in any of them.

          • Don Aitkin says:

            ECS greater than x3? Your view, and why? Not the red herring you have planted in the comments, without any detail. What paper of JCs? What argument of mine negated thereby?

            Oh, I’ve just seen Dasher below… Why do I bother…

          • David says:


            Ok so on July 9th In “Measurement rears its ugly head again” you gave oxygen to arguments which question reliability of climate data, in particular temperatures from thermometers. You wrote

            “Of course, the thermometers don’t measure temperature either. ……….. It seems to me that, for the most part,
            the likely error could be at least as large as the change in temperature over time.”

            The longer these angry arguments drag on the more I am persuaded by some wise words of Tony Brown, …

            It is absurd that a global policy is being decided by our governments on the basis that they think we know to a considerable degree of accuracy the global temperature of
            land and ocean over the last 150 years”

            However, as I pointed out at the time Muller, Judith Curry et al. had published paper supporting the reliability
            of US temperature data.


            As I see it you are attracted, to what you see as anomalies
            and wrinkles in the data, to cast doubt on AGW, which is fine. However, you draw such strong conclusions before your ideas have been tested.

            Conceptually many of your arguments would be more relevant in the setting of a cross sectional data set, but not nearly so much with longitudinal data (see also your recent post on CO2 measurement) . Because data with repeated measures over time offers statisticians an opportunity to control for error not available with cross sectional data sets.

            IMO your commentary consistently reflects a lack of understanding of these statistical issues.

          • JimboR says:

            And those that don’t understand those techniques are often the first to cry foul when they witness them being used by real scientists, e.g. “the BOM is manipulating the data to make things appear warmer”.

            They’re happy to blindly accept signal processing when it brings them clear TV reception, high speed DSL, an ECG trace or even video from Mars, but apply those techniques to weather data and out come the conspiracy theorists. I’d be surprised if any of them have ever had a day job that involves sampling data from real life physical sensors.

          • Don Aitkin says:

            Jimbo, whom are you quoting here? Not me.

          • JimboR says:

            Who can say? Once the voices start bouncing around the chamber it’s kinda’ hard to pinpoint the source. I certainly was left with the impression that you believed it, but I’m encouraged to now learn that I was mistaken.

          • Don Aitkin says:

            Oh dear. The abstract says that the networks of stations ‘can reliably discern trends’. I agree. I have said many many times that I have no doubt that the planet has warmed up a bit over the last hundred years. What I don’t accept is that precision of the figures is valid. That is, whether or not 2015 will be the warmest year ever (since…..) is a futile claim, because the precision is not warranted by the error involved

            I wrote to Judith Curry about the paper, and she replied, in part, that ‘It is hardly the last word on this topic.’ I would agree with that, too.

          • David says:

            Don, you are exasperating 🙂

            ” …because the precision is not warranted by the error involved”

            The fundamental challenge that is faced by any statistician is not “error” it is “bias”! Issues surroundings error are managed by increasing the sample size. This is why researchers conduct power calculations as they design their studies.

            However bias is far more problematic statistical issue.

            Look at the way JC typically argues her case against AGW. Her fundamental criticism of AGW is that there maybe other factors, which if included in the AGW model, would affect affect the estimated coefficient of CO2 on temperature. JC is raising an issue of bias, not precision.

            Some of the concerns you raise against the AGW “scare” as you call it, are reasonable. But you tend to latch on to any argument that suits your conclusion. At times you appear to have no filter.

          • Don Aitkin says:


            I am a number-cruncher from way back. Temperature anomalies are given to one or more decimal points. I do not know what the error is in all this, and there are few estimates that I have seen. The error bars are wider in the past than they are in more recent years. Nonetheless I have to say that I can’t take at all seriously claims of the hottest year or month ever on the basis of a hundred years of data, when I am not told what the error is.

            I’ve been reading JC since she started in 2010, and have had a few essays published on her website. Yes, in the case you raise she is talking about missing variables, some unknown, some hard to provide estimates for. Yes, that is something else. So what? I agree.

          • bobo says:

            “I am not told what the error is.” If you want to find errors they are easy to find. If you look at the announcement by a particular agency you should always find the uncertainties stated.

            Data freely available online (e.g. HadCRUT4) has bounds for various confidence intervals for data listed.

          • Don Aitkin says:

            That’s true, but the anomalies are not usually presented that way to the public, and indeed the dataset people themselves don’t always do it. And even iff they do, the past data error bounds are estimates that themselves have to have errors!

          • bobo says:

            My recollection of the announcement that 2014 was the hottest year was that plenty of mainstream media outlets published discussion about the uncertainties, albeit mangled, such as the venerable Daily Mail:


            Many mainstream media outlets were publishing the same sorts of stories but did not clearly explain the uncertainties, the context or the point of the Monte Carlo simulations to determine the probability that 2014 was the hottest year. Rather, many articles implied that some dodgy analysis or dodgy announcements had taken place, written by journalists who were quick to believe their gap in understanding was a gap in the science. Many of these same journalists were clinging onto, and misinterpreting, probabilities obtained through climate models (the Monte Carlo models) despite their usual anti-climate model rhetoric.

            Regarding errors of errors, I’m not sure this is a significant issue? You’ll have to enlighten me how the data confidence intervals are significantly wrong.

          • JimboR says:

            I recall The Drum had a pretty good go at talking about the uncertainties, and even offered a few possibilities for why some of the mainstream media didn’t. Your ABC tax dollar at work Don!


      • Don Amoore says:

        Bobo, It would appear that you have not had the time or interest to read and review the papers by Dr David Evans on the Jonova blog. I was hoping you would join the critiques reviews and discussions there as you seem to have a good mind and a differing view. I am disappointed in you!!

        • bobo says:

          Hi Don, I have looked at some of the pages by David Evans, but I really do need to sit down for a few hours to go through them in detail. There is a problem with one of his assumptions: he seems to think that the current episode of global warming is primarily caused by increasing insolation; the issue with this is that the upper atmosphere is cooling, the opposite of what should be expected for increasing insolation.

          • Don Aitkin says:

            Good luck! Some of the maths is beyond me, so I am not in a position to give a reasoned response.

          • Bryan Roberts says:

            bobo, you may be interested in a discussion of insolation by the astrophysicist, Duncan Steel.


          • bobo says:

            Thanks for that.

          • JimboR says:

            There’s a very readable review (from the middle of last year) of David Evans’ notch filter theory here:


            The author (Luboš Motl) is quite critical of many warmist models as well, so I think his only motivation is good science, and he doesn’t find much of that in David Evans’ work.

            The comments section is well worth a read too.

          • Don Aitkin says:

            Yes, all that is true, But Evans has dealt with these criticisms in his new essays — indeed that is the point, as I understand it. There may still be errors, but I haven’t seen anything from Lubos about the new series yet (of course it’s not finished).

          • bobo says:

            Interesting, the comments do highlight how “factionalised” climate scepticism is.

            It’s reassuring to see that Lubos struggled a bit with it too – he has a strong mathematical physics background. I think David Evans could probably do a better job rewriting his ideas so they are a bit more readable.

          • Don Amoore says:

            I can not emphasise how much educated and constructive input is needed and appreciated. You will not be denigratated – and as this is pre peer review get in there and fix what is wrong – please??

          • bobo says:

            The biggest challenge for me is learning some of the signal processing stuff he’s trying to do – it will take time to get my head around as I don’t have an engineering background. The FFT stuff I’m fine with, but the work certainly needs time to digest.

      • Don Amoore says:

        Sorry Don, hit the wrong reply. Shoiuld have been to Bobo.

      • bobo says:

        Big questions Don.

        Your first question presumably is referring to equilibrium climate sensitivity (ECS). This is an interesting question that is very difficult to answer precisely. Most comprehensive studies determine a probability distribution for ECS. The question is, why is a precise value so difficult to determine? I suspect there is no precise value; rather ECS is best described by a function of several variables.

        I had never tried to estimate ECS previously but gave it a go when I saw your question. Examining some paleo records such as the following show how difficult a task it is:


        The following image is suspect, I am interested in the total solar irradiance though (yellow), I was unable to confirm this data through several searches online:


        What is apparent is that climate sensitivity varies depending on:

        – the specific forcing

        – the stage of glaciation.

        It’s apparent that in the advanced stages of an ice age the climate is extremely sensitive to high altitude insolation. This is not yet completely understood.

        So it’s reasonable to suggest that ECS is a non-trivial function of the major possible forcings (total insolation, insolation at specific latitudes, GHGs, …) as well as the extent of glaciation.

        The PETM seems to be a perfect paleo phenomenon which would enable a relatively precise calculation of ECS; yet even this yields a very broad probability distribution function; moreover there was far less glaciation in the Eocene than now, so sensitivity values may not necessarily apply to the current climate.

        There seem to be plenty of different ways to calculate ECS. One method that could be fruitful (if I can find some decent total solar insolation data going back several glacial cycles) is to examine the relation between temperature and CO2 for fixed total solar insolation values as CO2 declines in each glacial cycle. But again it is probably very difficult to separate out the confounding variables with such limited data sets.

        (Question 2 re ecosystems) I think Don that while you accept that some warming will continue to occur, you do think it is a lot lower than the various projections suggest. What rate of warming do you think is most likely over say the next 100 or more years?

        I personally think that global average surface air temp will continue along its multidecadal trend of roughly 0.11-0.16C per decade for a long time to come. This is at least ten times faster than the fastest glacial to interglacial warming, which is concerning from an ecological perspective. Will sensitive ecosystems be able to migrate fast enough with shifting climate zones? Will they be able to migrate at all (e.g. highly endemic montane environments)? If they can’t practically migrate, will they evolve fast enough? This will compound on top of the greatest current environmental crisis: loss of biodiversity. Simplified ecosystems will be less resilient to the effects of drifting climate zones.

        Here’s an interesting diagram pertaining to this question showing when the Sahara suddenly became a desert superimposed with insolation, and suggests that the Sahara has two stable states that depend on the extent of glaciation: vegetated and unvegetated:


        (Question 3 re sea level) The plots of sea level obtained by satellite altimetry do not exhibit significant acceleration; that’s not to say that no acceleration is present, just that if sea level rise is accelerating, it is sufficiently slow that longer time scales are required to characterise it, i.e. it is subtle. Thermal energy appears to be accumulating in the climate system at a roughly constant rate:


        Without major breakup of ice sheets it doesn’t seem unreasonable that ice melt would be adding to the oceans at a roughly constant rate.

        • Don Aitkin says:

          Bobo, I appreciate that you have done a lot of work here. I raised climate sensitivity because unless it exists in the real world and unless it is high, then doubling CO2 will produce an increase of around 1.1 degrees C, which is not a worry, given that the doubling takes place in a logarithmic fashion, and there has been very little warming over the last twenty years.

          You ask me what rate of warming I expect. And my response is that I don’t know at all. As will be clear to you, I think that CO2 is given much too much attention, and I am more interested in the other factors that account for warming and cooling. Since we don’t know a lot about those, I do not have an expectation. As to sea-level rise, I assume, given what we know, that it will go on rising very slowly for the next century, and that no island communities are threatened.

          • bobo says:

            1) Don, how do you justify an ECS of around 1.1? According to various comprehensive studies the probability of an ECS of less than or equal to 1.1 is very low. It’s worth noting that 2015 is predicted to have a global average surface air temp that is 1C higher than the pre-industrial average; if one is to accept that the warming since that time is mostly due to AGHGs (and it’s not entirely – e.g. the current El Nino provides something like a 0.1C lift in global average temp) then immediately you are faced with a problem: atmospheric CO2 has only increased about 40%, and even if there had been a doubling, ECS is higher still because the deep ocean is still a sink for thermal energy, so surface temps are cooler than they would be if the ECS equilibrium was allowed to eventuate over 2000+ years; the temperature response to doubling CO2 is monotonically increasing if all other external forcings are held constant.

            ECS determination requires the doubled concentration of CO2 to be maintained in the atmosphere for thousands of years until equilibrium ensues. If there had been a constant 560ppm concentration of CO2 since preindustrial times, I think even you would have to acknowledge that there’s a good chance that a 1.1C temp rise since preindustrial times would have been breached by now.

            2) You refer to the fact that CO2 forcing is logarithmically related to the addition of CO2. Sure, no arguments. But if you examine a plot of CO2 concentrations such as


            you see that there is a subtle acceleration – the trend seems to curve up gently with time. An exponential can be fitted to the data quite well, and the logarithm of an exponential is a linear function, hence a roughly linear forcing results. This agrees with the roughly linear increase in total thermal content graph that I’ve pasted in other comments. In other words, while CO2 concentrations increase exponentially, GHG radiative forcing will increase linearly. When short term natural variability is filtered out of the surface temp data you get correlations approaching 1 with total thermal energy in the climate system, so over multidecadal periods, we will continue to see roughly linear increases in global average surface temp.

            3) “there has been very little warming over the last twenty years.”

            I picked a global average surface temp monthly data set (HADCRUT4,



            and did a linear regression of the last 20 years, obtaining a slope of 0.0127C/year, (or 0.127C/decade) which is in close agreement with the multidecadal trend.

            The p-value for a significantly non-zero slope is 1.18e-17 (F-test). This means that the probability of a significantly nonzero slope being observed in that data if there was no actual warming occurring is extremely low.

          • Don Aitkin says:

            How do I justify it? Because the tendency of studies of ECS is that the more recent ones point to low sensitivity:

          • JimboR says:

            Don, I’m still not quite sure how you got to 1.1. The lowest point in that graph is Lewis 2013 at 1.6 right? Are you extrapolating the trend line or are you quoting the lower end of Lewis’s range? Either way, why?

          • JimboR says:

            More importantly I guess, is how did you test your hypothesis Don? What error bars do you associate with your 1.1 finding?

          • Don Aitkin says:

            The general assumption throughout these debates is that a doubling of CO2 will, other things being equal, lead to a temperature rise of 1 degree C or a little more. That rise occurs within a logarithmic process. Unless there is good evidence to the contrary, I will take the position that that is what has occurred, will occur, and is occurring now.

            I have read a lot and written a bit on climate sensitivity, and my reading of the literature is that (i) climate sensitivity is a hypothetical construct, not an observed reality; (ii) it is based on the assumption that a warming climate will lead to increased evaporation from the oceans leading to more clouds and therefore to a more powerful ‘greenhouse effect’; (iii) a contrary position would be that increased clouds will lead to a higher albedo and therefore to cooling; (iv) very many scientists have tried to work out what the observations tell us; (v) there are various papers, and some are in the graph above; (vi) their increasing tendency is to find the if climate sensitivity exists, it is not very much, or negative; (vii) the IPCC has given up trying to settle on an approved and likely ECS, and still quotes 1.5 to 4.5, despite the tendency referred to in the graph above; (viii) I don’t have any hypothesis (your comment below) other than the acceptance set out in the first paragraph above.

            That is, climate sensitivity may exist, and if it does the evidence and argument in some paper yet to be published will convince me. Otherwise, I will stick with 1 or 1.1 degree C for a doubling.

            I hope this make sense to you.

          • JimboR says:

            hmmm… I guess that translates to quite big error bars on the 1.1 then.

          • David says:

            crossing zero I suspect. 🙂

          • David says:

            Its an interesting approach to a systematic review.

            1. Search the literature

            2. Identify the lowest estimate

            3. Then reduce said result by another 30% based on the “vibe”

            To put your estimate into some perspective, the Curry-Lewis result suggests that there is approximately a 2.5% to 5% chance that the real ECS is 1.1 instead of 1.6.

          • Don Aitkin says:


            That is not at all what I wrote above. Do some work!

          • David says:

            Do you disagree with the last sentence?

            “To put your estimate into some perspective, the Curry-Lewis result suggests that there is approximately a 2.5% to 5% chance that the real ECS is 1.1 instead of 1.6.”

            If so, why?

          • David says:


            Here is C&L paper. To my reading an ECS estimate of 1 to 1.1 is very much at the lower bound of the C&L estimate of 1.64.

          • Don Aitkin says:

            I have read the paper, and commented on it at the time, too, I think. You need to read my summary again.

          • Don Aitkin says:

            You’ll see my discussion of that paper at


          • JimboR says:

            Thanks for that pointer to your earlier essay Don. It doesn’t read like a damning critique of the Curry-Lewis paper; I’d characterise it more as a semi-warm embrace.

            It’s left me more confused about how you arrived at your 1.1 number. I’ve re-read your 8 part summary above several times and am still struggling. If I had to paraphrase your summary, I’d say:

            “There is a lot of uncertainty in ECS modelling/measurments therefore I’m going to choose a number that all the literature agrees is very unlikely”.

            Do you think that’s a scientific approach? If one of your social science students handed in a paper with that approach how would you respond?

          • Don Aitkin says:

            You simply go on missing the point. Does climate sensitivity exist at all? What I think I know is that if the amount of CO2 is doubled, there will be an increase of around 1 to 1.1 degrees C on consequence, all other things being equal. Why will it be higher? Ah, some people think that (go back and re-read my summary). What is the evidence? Well, there really isn’t anything really hard you can point to. The climate models say this… (but climate models aren’t really good at temperature anyway). The people who try to use observations (and that means they are relying on measurements of SST based on buckets, inlet manifolds and the like) tend to suggest much lower measures than the IPCC’s 3 degree range, which is the same as it was in the IPCC’s TAR all those years ago. Nothing seems to have been learned.

            Ah, but unless there is a high climate sensitivity there won’t be a scary future for humanity, so it must be high.

            If one of my students handed in a paper saying that there must be high climate sensitivity, because the theories said so, I’d ask him/her what the evidence was. No evidence? No theory.

            To persist in theory when the evidence is slight or non-existent is simply objectionable — unless you are besotted with theories, and I am not.

            Until something is learned, I suggest that we rely on the doubling. Climate sensitivity has yet to be shown to exist. Of course, it is absolutely necessary if there is to be scary future for us and kurt children. But that’s not

          • Don Aitkin says:

            ‘at the low end of the IPCC’s range’ would have been better.

          • JimboR says:

            “I’d ask him/her what the evidence was. No evidence? No theory.”

            Wow, probably a good thing you weren’t supervising Peter Higgs in the 1960s then.

          • Don says:

            Don you can be your own worst enemy at times. Instead of writing all this convoluted prose with supporting graphs, you should simply state that you don’t accept the current evidence for Climate Sensitivity.

            I note that this is now the second pier review publication published by Professor Curry that you reject.

          • JimboR says:

            Indeed. I now realise the reason I kept missing Don’s point was because it was so well obfuscated by references that didn’t support it.

            With regards that paper, Don even wrote an essay on it that seemed to embrace their findings. Now that he realises it doesn’t support his 1.05 number he accuses Lewis and Curry (and presumably all the other scientists represented by the dots on his ECS trend graph) of making it all up so ensure a “scary future for humanity”.

            And here’s just some of the scientific theories that would have been scuttled had Don been the supervising professor with his unimaginative “no evidence then no theory” rule:

            Atoms, photons, quarks, black holes, Higgs boson, relativity, Neptune’s existence, the Big Bang.

          • David says:

            I agree with JimboR. I went back and had another look at your previous post, as you suggested. Your article supports the Curry-Lewis estimate of 1.64. Which is fine. So why plug for a ECS of 1 to 1.1?

            That’s a pretty big re-adjustment on the basis that ” the estimates are trending down” (aka the vibe). So what, by 2020 we can expect to see published estimates of 1. And what of 2050, < 0?

            This argument is really just another version of "an unknown unknown" affecting temperature estimates. Its all very speculative.

          • JimboR says:

            In fact I think the Curry-Lewis paper tells us it’s just as likely to be 4.05 as it is Don’s 1.05. Given the Curry-Lewis paper is on the low side of all the others, if Don really wants to live on the edge of these 95% confidence intervals, then the high edge seems a more reasonable choice.

          • David says:

            I agree with that. The consequences of ECS =1.05 might mean we had wasted a lot of money decarbonising the economy not to mention lost pride for a lot of scientists. But all quite recoverable losses. Coal still in ground waiting to be used etc. But ECS = 4.05 is an existential threat.

          • JimboR says:

            It’s certainly a high risk game, and as you point out the downside seems to be extremely biased towards one outcome Vs the other.

            It’s curious that Don repeatedly calls out for people to justify their belief in an ECS of 3 and yet feels no requirement to justify his ECS of 1.05…. other than some vague “the science is too hard, so I’ve deemed it to be 1.05”.

            On the upside, if my mental picture of the Curry-Lewis PDF is correct, those defending 3 can simply reply “because it’s more probable than your 1.05, so you go first”.

          • David says:

            Agree. Don has asked me a number of times to provide my estimate of ECS. I am not a climate scientist, at all. So what would be the point? All I would do is end up selecting some papers that supported my “greenish” outlook on the whole AGW debate. I cant see that playing dress-ups and pretending to be something I am not is very constructive.

          • JimboR says:

            I’ve always had a chuckle over that game. He might as well ask you what your favorite colour is, or who you think is going to win the Melbourne Cup. It’s almost as if ECS can be determined by popular vote.

            I suspect it’s the social scientist in him. I think they’re much more at home asking people for opinions than they are studying hard data from physical sensor readings.

          • Don Aitkin says:

            Indeed. So is climate sensitivity itself.

          • bobo says:

            Just to nitpick Don, I presume in point (ii) you mean that the increasing water vapour content of the atmosphere results in increased GHG forcing and also leads to the formation of clouds.

            Not all clouds counteract warming via higher albedo – typically the lower altitude clouds do, but very high fine cirrus-like clouds actually trap heat – you may have observed this directly by noticing that on some of the very hottest days there appears to be a very high, very fine veil of cloud cover or haze (not smoke which filters sunlight a distinctive yellowish colour).

          • Don Aitkin says:

            Yes, indeed. I did know that.

          • bobo says:

            First thing I noticed with this plot is that the lowest ECS is purportedly 1.7 (Aldrin 2012). This lies inside the IPCC 66% probability range 1.5 – 4.5 (high confidence).

            I dug up the Aldrin et al paper – you can read it free at


            and noticed that Aldrin et al actually use the posterior mean of 2.0 as their ECS. So the graph above is misleading.

            The relevant probability distribution function is in figure 6a.

            Here’s some relevant discussion from p261:
            “The posterior mean is 2.0C (see also Table 2), which is lower than the IPCC estimate from the IPCC Fourth Assessment Report (IPCC, 2007), but this estimate increases if an extra forcing component is added, see the following text. The 95% credible interval (CI) ranges from 1.1C to 4.3C, whereas the 90% CI ranges from 1.2C to 3.5C. There is a small probability for S being larger than 10C (posterior estimate 0.001).”

            From their p.d.f. your claimed ECS of less than or equal to 1.1 is very low after considering that their p.d.f. has a very long tail and that there is a less than 5% chance of ECS being in the union of intervals (0,1.1) U (4.3, infty).

            I’m not sure what your position is on using climate models to estimate ECS, but the paper provides details on the climate model built to estimate ECS, as well as details of the validation procedure of the model with GCMs and data.

            To summarise I don’t think the graph, nor the seemingly most favourable study above presents a compelling case for rationally picking an ECS less than or equal to 1.1.

          • bobo says:

            Correction there is an Aldrin 2012 ECS marker at 2.0 in Don’s plot, though I’m not sure where the Aldrin 2012 plot ECS marker at 1.7 comes from.

            There is a high res pdf version of Don’s plot at


          • bobo says:

            Just looked into this further, it appears that the 1.6/1.7C ECS value for Aldrin 2012 was erroneously claimed by News Corp journalist Matt Ridley who obviously didn’t bother to read the paper, as the following exchange makes clear:


            Why did that data point subsequently appear in the plot above? who knows.

          • David says:

            Interesting post bobo.

            Even Nic Lewis who is at the skeptical end of the spectrum posts estimates 1.0 – 3.0 with a most likely estimate of 1.6. So 1.1 does seem quite low.

            It will be interesting to read Don’s response. My expectation is something non-technical, and tangential. But I hope this does not discourage you from making further posts.

          • bobo says:

            Rest assured I’m under no illusions that Don will change his mind. I think even if the probability of Don’s favoured hypothesis according to the science was 0.001, he’d still not discard his hypothesis, instead he’d be sure that the science was somehow broken without being able to put a finger on specifically what was wrong.

            That said Don seems a bit different to the run of the mill climate sceptic; climate sceptics so often seem to be pretty hardline political hacks.

      • bobo says:

        Further to add to my comment, it’s worth noting that ECS is not an explicit parameter in GCMs.

  • Dasher says:

    I worry when I hear the President of the United States making a speech that would have the uninformed believe that we have run away warming now. Mind you he was happy to leave the impression without blushing that the barrier reef was toast and his daughter was an asthmatic due to climate change. The world is on the cusp of spending obscene amounts of treasure on this issue which I suspect will have no material affect on the climate. Imagine how the 100 billion dollar fund(if it ever gets up) will be rorted ..an absolutely normal hurricane will attract even more hysteria and the victims will no doubt cry climate change and bank a motza. Hopefully it doesn’t find it’s way into the pockets of despots….not confident. Nuts.

    • David says:

      Is a $100 billion a big number, Dasher? Sounds like it.

      The IMF reports that world wide subsidies for fossil fuels are 5 Trillion $US per year. That’s 50 times the $100 billion you are hyperventilating about.

      The fossil fuel industry could loses $100 billion down the couch and they would not miss it. 🙂

  • GSR says:

    I remember Don Aitkin when he was a reasonable and thoughtful guy. What happened? He now spends his time writing fan mail to Judy Curry for fucks sake.

    • Don Aitkin says:

      You’ve won a zero prize for the first f— word in several thousand comments.

      • GSR says:

        I’m not here for prizes Don, I honestly want to know how a bloke with a good mind ends up sending Judy fan mail for displaying pig ignorance. Perhaps the fact that she just phones it in appeals to your latterly acquired lazy thinking.

        You once had credibility. What the fuck happened mate?
        (BTW I only discovered that you had embraced the crazies tonight. I was reading Judy’s fan mail re her winge at Ted Cruz’s flaccid iteration of HUAC (yes I do know he’s a Senator) and saw your fawning fan mail. Sweet Jesus Don. what happened to you?

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