Are human beings causing the warming? My perspective on ‘climate change’ #5

We have come far enough along this road for a short recapitulation of the story so far. I came into reading, thinking and writing about AGW, or ‘climate change’, some ten years ago, and was doubtful from the beginning: too much speculation on too little real data. The AGW scare started about 1988, and quickly built up momentum, in part because temperatures were rising in apparent lockstep with carbon dioxide accumulations. Before long there was an IPCC, a precautionary principle, and lengthy assessment reports on what carbon dioxide was doing to our climate.

For a while politicians and electorates were obsessed by the scare, then the Global Financial Crisis took over the front pages, and the scare lost its way. It has never really recovered, but enough institutional inertia remains to cause ‘climate’ to remain both a media interest and an occasional political issue. The core argument inside the scare is that we humans are changing the climate through our own activities, principally in burning fossil fuels. Warming must increase, and in doing so will have dire effects on other aspects of climate, like precipitation and storms. We must act now, before it is too late.

Is the earth warming? Well, it depends on what timescale you are thinking of. On the evidence, which is admittedly scanty, we are in an interglacial period which is not as warm as some previous ones. In this interglacial, the Holocene (which some want to call the ‘Anthropocene’ because they think this is the first period where sentient beings have altered climate — but see below), it looks as though the warmest part is behind us, some thousands of years ago. On the evidence, again, it looks as though there has been some warming, in spurts, since about 1850. Before that temperatures seem to have been much cooler. In the Mediaval Warm Period temperatures seem to have been about the same as today, in the Roman and Minoan warm periods, perhaps a little hotter.

Now read on: Have human beings actually caused the warming — or, rather more usefully, how much of the warming since 1850 have they and we caused? The IPCC has no doubt at all. The Summary for Policymakers of the IPCC’s AR5 (2013) says, at D.3:

  • It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.

Readers should note that ‘extremely likely’ in this statement means that those who wrote the statement assert that the probability of their being right here is more than 95 per cent (not that the probability of their being right is 95 per cent). I object to this sort of language, which gives the impression that real data show this to be the cause, and that it is not simply the opinion of the writers. Readers might also note that the baseline is now 1951, during a cooling period. Why not 1900, or 1850? My explanation is that starting at 1951 removes the need to explain a similar warming period between 1910 and 1940, when carbon dioxide is not thought to be important.

The question of the ‘attribution’ of global warming is perhaps the clearest case of  the science not being settled. To begin with, there is no paper that clearly shows the link, despite the passing of nearly thirty years since James Hansen warned the US Senate of the doom to come. The scare picked up its momentum from the similar trends in carbon dioxide and average global temperature from 1975 to 1998. It’s best explored through the following graph, which shows carbon dioxide in the jagged red line, and global temperature anomaly in the blue. The graph runs from 1960 to the end of 2014.

GISS GlobalMonthlyTempSince1958 AndCO2

The details don’t really matter. The IPCC claims that the warming from 1951 is mostly due to human activity, and it may be. But if the IPCC is correct, then what caused the similar warming trend from 1910 to 1940 shown in the third graph in essay #4? And why, given the great expansion of industrial activity in the postwar period all over the world, was there cooling from 1940 to 1975? It was graphs like this that originally made me shake my head at the confident attribution of warming to human activity.

The general response from the IPCC in its Third Assessment Report (inasmuch as these questions were dealt with at all) was that something called ‘internal interactions between components of the climate system’ accounted for the wobbles you see in the graph, until carbon dioxide took over triumphantly in 1975. It was quite vague about the nature of these ‘interactions’, and especially vague about the timing issue. The most recent AR5 SPM simply ignored the whole issue. Human activity was stressed to the exclusion of all else.

Many sceptics think that the IPCC has dodged the issue completely and that everything that follows is thereby flawed.  There is a counter argument, put forward by John Nielsen-Gammon, the Texas State Climatologist. He has argued with Judith Curry that if the sources of natural variation are cycles of some kind they must in time cancel out, whereas the effects of increasing carbon dioxide will keep occurring, pushing the climate system out of its usual equilibrium into a new warmer one. Natural cycles, like the Pacific Decadal Oscillation and el Nino/la Nina fluctuations, have a cooling phase and warming phase. When they are over, nothing has changed.

Judith Curry and others have proposed a further hypothesis, that of the stadium wave, in which long-, medium- and short-term cycles interact with each other in unexpected ways (unexpected because we don’t know a great deal about any of them). And what if some of the forces are not cycles at all, but solar influences, like the ‘solar wind’? Her conclusion, which is also mine, is that the influence of anthropogenic effects cannot be as great as the IPCC makes out, which suggests that we should be spending much more time and effort in exploring what ‘natural variability’ is is all about.

My take on it all is that humans and their activities do have an effect on temperature, but it is by no means the be-all and end-all of ‘climate change’. If I had to guess, and it would only be my intuition, after some years of looking at the data, I would plump for a proportion less than half of the observed increase. Nor should the level of warming be especially worrying, an issue I’ll take up in a later essay. Human beings have been managing their environments for a very long time, in an effort to make life more enjoyable and productive for them, and their efforts have produced the planetary environment in which 7 billion people live and work, most of them decently fed. We humans do make mistakes, but we learn from them, and we will continue to do so.

Next: Should rising seas be a worry?

Further reading: There is a great deal about attribution in the blogosphere. Judith Curry has devoted a lot of her website to questions revolving around attribution and uncertainty, and she has certainly done so cogently. Her position is that we know much less than the IPCC pretends we know, and while that is the case, the IPCC’s confidence about everything should be taken with a lot of salt. The effect of warming through increased carbon dioxide is logarithmic, which means that significant temperature increases will take a very long time even if the IPCC is right about everything.

The graph above, and so much of the debate about the last 150 years, depend for their validity on the quality of the temperature data that we have. The regular adjustments to that data, very often unexplained to the general public, produced the following cartoon, another fine example of Josh’s pen.


Late Footnote: There is an interesting essay on WUWT which tries to quantify the human effect, and suggests that it amounts to about 80 per cent over the last century. It is nonetheless a correlation=causation argument.

Join the discussion 110 Comments

  • Alan Gould says:

    Thanks Don,
    Clear, useful, measured, as ever.

  • JohnM says:

    It’s true that an El Nino followed by a La Nina will leave things much as they were but a sustained pattern in the El Nino-Southern Oscillation (ENSO) system can have an impact on tempeerature trends. From 1950 to 1976 there were several La Nina events and very few El Nino events, and not surprisingly it was a time of coolish temperatures and plenty of rainfall. After 1976 the situation reversed, probably due to the Great Pacific Climate Shift, and we had very few La Nina events and quite a few El Nino’s, resulting in a sustain period of warmer and generally drier conditions. Together these sustained natural events produced in an upward trend in temperatures.
    Read the IPCC reports closely and you find references to temperature changes changes since the “mid-seventies” but the link to ENSO changes isn’t explicitly mentioned. Now we might not really know what drives the ENSO or whether the ENSO is a cause or a consequence, but we do know that the ENSO is natural and correlates closely to global average temperature anomaly from 1950 to 1987.
    The other factor that people forget is that from about the mid-1980’s Europe and Russia made deliberate efforts to reduce air pollution. This pollution carried with it tiny speck of matter called micro-particles. Water vapour condenses on these micro-particles to form cloud (and fog and mist), and it looks like a reduction in micro-particles meant less cloud, especially low level cloud, and therefore more sunshine and higher temperatures. (Think of London’s pea-soup fogs disappearing after the banning of burning coal in the capital’s houses.) We know that the Earth doesn’t warm during the day and lose all that heat overnight because if that was the case the hottest time would coincide with the summer solstice. The warmest period is in the following month as the impact of ground heat is felt. All this means that the change in cloud cover might account for the slight warming from 1987 to 1997.
    We are not surprised that when a window is cleaned more light comes through so why should climate scientists fail to see that reducing micro-particle emissions will likely change temperature patterns?

    • Don Aitkin says:


      These are excellent observations, and point once again to the fact that we know so little. What did happen in 1976? Something significant, because you can see the changes in temperature before and after, without there being any obvious cause. And the whole aerosol factor is mostly speculation, it seems to me. For the models to work with a 3x ECS parameter and a CO2 control knob there has to be a lot of aerosol matter.

      The Clean Air Act in the UK was 1963, I think, and changes occurred quite quickly there (I was in the UK 1964/5). When I returned in 1975 a great deal more had happened.

      And even a small amount of variation in cloud cover could explain all the warming‚ but again, we can’t measure clouds easily. I learned yesterday that nimbo-cumulus clouds last for about an hour — i.e. the shape that you see — there will be another formation later…

      The CO2-AGW link is based on correlation more than observation. And there is an even better correlation between warming and the growth of human population.

  • Aert Driessen says:

    Thanks Don, another lucid account which I find useful because it is argued by someone who understands what data is and how it should be used, and also, is rooted more in common sense logic than in climate science. I have always been a sceptic because, as a geologist, I’m fully aware of all all the climate changes that planet Earth has experienced, all adequately explained without recourse to CO2. And all geologists should know that in the time frame of multi-cellular life on Earth (say 550 million years) we now live in a CO2-deprived atmosphere — now around 400 ppm CO2 compared to around 7000 ppm then (in the Cambrian). That includes ice ages lasting tens of millions of years during which CO2 was many times higher than now. So when a politician with no understanding of science then calls you a ‘flat-earther’ because ‘you don’t believe in ‘climate change’ something is clearly amiss and another agenda is in play. And the insult got worse when the ABC’s resident scientist Dr Williams likened sceptical scientists to paedophiles. From that time I have become an ‘activist’ in the cause of Science and the Scientific Method.

    • dlb says:

      The BOM on 23 Feb 2016 reports
      “During the current wet season, only three tropical cyclones have developed in the Australian region, well below the long term average of eleven. ”

      And I thought your mob said global warming was going bring on the bad weather 🙂

      • bobo says:

        Climate projections re. tropical cyclones: fewer cyclones, but more cat 5 cyclones to make landfall; confidence in these projections is moderate. Trends are supposed to be multidecadal.

        If you bothered to look into why the cyclone average was down, you might have found this on the BOM site:
        “Tropical cyclones in the Australian region are influenced by a number of factors, and in particular variations in the El Niño – Southern Oscillation. In general, more tropical cyclones cross the coast during La Niña years, and fewer during El Niño years. ”
        This is intuitively obvious because the western Pacific is cooler during El Nino years.

        • dlb says:

          My comment was just parroting David, with his linking of every unusual weather event to “climate change”. Lighten up Bobo, most sceptics are well aware that ENSO is the driving force of much of our weather in Australia.

        • Don Aitkin says:

          Most would say that these hot days (which are not all that hot, just consistently around 32/33C) are what we call weather, and are linked to the current el Nino. We may have a hotter than usual April, too.

          But should I infer that you think, on the contrary, that these hot days are an example of ‘climate change’? If you do, why don’t you explain why, rather than toss off these little aphorisms with links that mean nothing?

          • David says:

            Yes Don you can infer that I think these “hot days” are caused by AGW. Record after record is being broken. You estimate the temperature to be around 32/33. How did you come to that estimate?

            The BoM reports that the average maximum temperature of 38.14 degrees on March 2 broke the previous record for the month by 0.98 degrees – a margin that has only been surpassed once before, in July 1975, the bureau said.

            Follow us: @smh on Twitter | sydneymorningherald on Facebook

            Exactly how should I construct an argument with a person who does not accept the concept of an average temperature. You cant have it both ways.

          • Don Aitkin says:

            Whoops! We were talking about Canberra, and you then move to Australia, shifting those old posts again…

            If you go back to the first strong warming period in the 20th century, 1910 to 1945, records were being broken then, too, but according to the IPCC AGW was not involved. Since temperature has been increasing in fits and starts since about 1850, records go on being broken, and will do so until warming stops, whenever that is.

            But you ‘think’ it’s caused by AGW, so how about you explain why you can pick out the difference between now and 1910-1945?

          • Don Aitkin says:

            Oh, I forgot to point out that the estimate of 32/33 degrees for Canberra in that period was the daily reports in the Canberra Times.

    • Mike says:

      So 97 years ago in Brisbane it was a dryer than now. Roundabout 1914 the Murray was so dry that I have photographs of camel trains on the riverbed, it was known as the Federation drought which went for about 25 years. If it is CO2 now what was it back then? CO2 was much lower back then so logic dictates that droughts are quite possible with low CO2 and this falsifies the hypothesis that CO2 causes droughts. I suggest looking at to dispel the ignorance expressed by the mainstream media. I have read much of the history of climate that we know very frequently climate is a bitch and in fact it is better now than it was in the past as to why I don’t know. I sure hope we do not go back to the climate at the time the Little ice age hit.

  • NameGlenM says:

    Perhaps David could read Hubert Lamb and get a perspective other than the misdirected and fallible track he is on at the moment.What confounds me is -with a modicum of evidence, AGWrs jump onto any disaster or elevated temperatures to call proof.None exists whatsoever that the signature of man is on any recent rise in temperature- albeit small.That is what science requires- and should demand.PROOF.

    • David says:

      Proofs are for mathematics. Science deals with evidence. And there is heaps of evidence which is consistent with the hypothesis of AGW.

      Thanks I will have a look at Hubert Lamb

      • Don Aitkin says:

        ‘Consistent with’, yes. But there is abundant evidence also that is consistent with natural changes, and plenty that is not consistent with the AGW hypothesis. I would agree that while AGW hasn’t been falsified completely, it is not looking as robust as it did twenty years ago.

        On what do you base your position?

    • Mike says:

      Lamb’s book was the first book when I became interested in the subject. What prompted me was watching a movie about Tuvalu. It reeked of con.

      • Bryan Roberts says:

        It always has been a con. The Prime Minister of Tuvalu, in Paris “We need a permanent mechanism for Loss and Damage anchored in the Paris Treaty to give us the assurance that the necessary response to climate change impacts will be forthcoming. This is important to Tuvalu and other low-lying small island developing states to safeguard their survival from increased sea level.”

        Given the BOM data for seal level at Tuvalu has not changed significantly for 23 years, it’s an unashamed dash for cash.

  • Malcolm says:

    The smoking debate back in the 1950s led to clear statements on the criteria needed to establish a cause and effect relationship between two variables, as opposed to mere association. The seminal paper was by Sir Austin Bradford Hill in about 1965. The debate has evolved a little since then but one of the key criteria is absence of other influencing factors. In the climate debate, “natural variation” has clearly been going on for many centuries but is still poorly understood .Unless climate scientists can clearly explain, list and quantify the factors causing natural variation, they are in no position to nominate carbon dioxide as a definite cause of variations of less than a degree or so over a number of decades. Their CO2 hypothesis simply does not meet the standards required to establish a cause and affects relationship, according to normal scientific criteria. Together with the total failure of their computer models to predict temperature trends, this means that their hypothesis is unproven. As Lomborg says, there are other more important priorities than attempting to stop the carbon dioxide concentration increasing from 0.03% to more than 0.04% of atmosphere.

    • David says:

      Malcolm, I do not agree with a statement like this

      “Unless climate scientists can clearly explain, list and quantify the factors causing natural variation, they are in no position to nominate carbon dioxide as a definite cause of variations of less than a degree or so over a number of decades.”

      Road traffic crashes are the result of known underlying factors and unknown factors that we don’t yet fully understand. Despite our incomplete knowledge we can make statements like “alcohol causes road traffic crashes, without feeling compelled to fully understanding every other risk factor that may affect a road traffic crash. And of course it would be ridiculous to expect road safety researchers to explain every “natural variation” in road accident before we introduced laws against drink driving.

      • bryan roberts says:

        David, it may be useful to police or politicians to categorise road accidents as ‘speeding’ ‘alcohol’, ‘tiredness’, etc;; but the overriding factor is inattention. This is well understood, by everybody. Road safety researchers cannot advise regulation of inattention; hence the emphasis on speeding, drink, drugs, mobile phones, and so on. Don’t you understand jobs are at stake? How can you be a road safety researcher and not come up with recommendations to improve road safety? Exactly. How can you be a r searcher on CAGW without coming up with ‘recommendations’ to stabilise the climate?

        • David says:

          Bryan I agree there is a element of truth in what you say. The causes of accidents are complex and related to inattention. I also agree there are incentives in Research, as there are with any type of employment, for people to act in their self interest. Last time I checked Researchers were still classified as human.

          That said, Judith Curry is a good example of a celebrity septic who has carved out quite a nice living for herself appearing before Congress recommending that we do nothing for the time being. The climate scientists who quantify its effects are different from the social scientists who recommend strategies on how to deal with it.

          To use a health analogy; over servicing is a recognized problem in the health care system but that does not mean we should ignore all medical advice.

          • Don Aitkin says:

            I nearly let it go, but I hope you meant that JC was a ‘sceptic’ rather than a septic.

            JC does not make ‘a nice living’ out of appearing before Congress or the Senate, any more than I did when appearing before Parliamentary Committees. You are invited to appear because you have some standing in the area, which she has, and you are not paid for doing so. She says that there is too much uncertainty about AGW for governments to establish measures like carbon taxes, which will do almost nothing to reduce temperatures anyway, quite apart from the issue of whether an increased global temperature is a bad thing. If you think she is wrong about that you need to show why, not just to use tired and inappropriate analogies like going to the doctor.

  • David says:

    “I nearly let it go, but I hope you meant that JC was a ‘sceptic’ rather than a septic.
    JC does not make ‘a nice living’ out of appearing before Congress or the Senate, any more than I did when appearing before Parliamentary Committees.”

    But let us have a looksee, shall we.

    If you go to Judith Curry’s web site you will see she reports $12.6 million in successful grant applcations. Compare that to Michael Mann who reports $7 million in grants. You will also notice that both academics are heavily funded by NASA and NOAA. The argument that academics with a predisposition to publish research which questions the AGW hypothesis (aka “skeptics” or “a skeptic” take your pick) are at some sort of funding disadvantage is not supportable.

    And what does the US tax payer have for the $12 million they have forked over to Curry? A vague statement about a “possible unknown unknown” and a request for more funding. At least Mann can point to a p-value.

    • Don Aitkin says:

      David, you are a goal-post shifter. I point out to you that JC does not in fact make ‘quite a nice living’ out of appearing before Senate and House committees, and you ignore that correction in order to point out that she has won more grants than Michael Mann. What’s that got to do with the point? She is older than MM and has been a successful researcher for at least a score more years than Mann. And her research grants mostly precede any appearance of that kind. She is no longer a grant-seeker.

      And Mann has at least a p-value, you say. Have you read his paper (MBH 1998)? Have you read the critiques of it? You claim to know some statistics. How would you judge Mann’s use of principal components analysis in that paper? Let us see your reasoning, as well.

      Have a go at some real research, and leave the ad hominem stuff.

    • dasher says:

      I have to wonder whether David ever reads Judith Curry or anyone who does not share his view. If I want a good roundup of views Judith Curry’s blog is one place to go….many many viewpoints some she agrees with some she does not. I like her sensible approach, for example her views on scientist’s who write group letters trying to silence those who disagree or are sceptical of the orthodoxy. One of Curry’s points is that rather than railing against dissenters these scientists should be encouraging sceptics thus testing the theories. Presumable if what they say is junk then they are exposed as dopes. Oh and she also makes the very sensible observation that this approach also tends to reinforce groupthink…she has a special admonition for established players leaning on young vulnerable players who can’t afford to be ostracised and so are swept up into the this science?

      • David says:

        “I have to wonder whether David ever reads Judith Curry or anyone who does not share his view.” What an odd question. I read Don all the time. If I just want to read people I agreed with I would hang out at the Guardian.

        “One of Curry’s points is that rather than railing against dissenters these scientists should be encouraging skeptics thus testing the theories”

        Dasher don’t you think a comment like that from Professor Curry is just a little bit self serving. The US tax payer has flicked her $12.6 worth of “encouragement” to explore her ideas on climate. Twice as much as Mann. I have no problem with her winning these grants. I think it is good. But I tire of this idea that the academic system is gamed against skeptics.

        • Don Aitkin says:


          This is to me genuinely unpleasant stuff, and quite unnecessary. Would you say that the US taxpayer ‘had flicked’ $7 million to Dr Mann? You must know that these grants are fiercely competitive. I might disagree with some of the assumptions of the peer-review assessment system, about which I have written, but the notion that the US taxpayer has passed over $12.6 million to Professor Curry, as though in a plain brown envelope (yes I know you didn’t say that ‚ but what does ‘flicked’ mean? It just sounds bad) is both wrong and in extremely poor taste.

          Please stop it.

          • David says:

            Professors Curry’s CV reports she has been a member of these U.S. FEDERAL AGENCIES

            • Earth Science Subcommittee, NASA Advisory Council (2009-2013)
            • NOAA Climate Working Group (2004-2009)
            • Search Committee, NSF Director for Geoscience (2007)

            And has won these GRANTS
            • Integrated analysis of atmospheric water cycle in intense marine storms. NASA, $189K 11/1/12- 10/31/14. (PI)
            • Climatology of African Easterly Waves. NOAA, 8/1/10 – 7/31/13, $240K (PI)
            • Impact of Marine and Dust Aerosols on Atlantic Tropical Cyclone Development. NSF, $349,901, 4/1/11-3/31/14 (co-PI).
            • Estimating the tropospheric BrO budgets from satellite measurements. NASA, $50K, 1/12/11- 1/11/13 (PI)
            • Impact of storms on ocean surface turbulent fluxes, NOAA, 8/1/10 – 7/31/11, $100K, (PI)
            • Impact of Marine and Dust Aerosols on Atlantic Tropical Cyclone Development. NSF, $349,901, 4/1/11-3/31/14 (co-PI).
            • Impact of Aerosols on the Arctic Hydrological Cycle. NASA, 06/01/07-05/31/10, $480,000 (co-PI).
            • Spatio-temporal Variability of Aerosol Load in the Tropics: Interaction with Precipitation and the Radiation Budget. NOAA, 5/01/08-4/30/11, $366,000 (co-PI)
            • Global analysis of ocean surface fluxes of heat and freshwater: satellite products, NWP analyses, and CMIP simulations. NASA, 10/1/05-9/30/10, $1.4M (PI).
            • Parameterization of cloud particle activation and diffusional growth. NASA, 11/05-10/08, $450,000.
            • UAV Systems Analysis for Earth Observations: Education and Outreach. NASA, 3/05-3/08, $350,000 (PI)
            • Arctic Regional Climate Model Intercomparison Project: Evaluation and Interpretation Using Data Products from FIRE.ACE. NASA, 12/03-12/07, $525,000. (PI)
            • Applications of Aerosondes to long-term measurements of the atmosphere and sea ice surface in the Beaufort/Chukchi sector of the Arctic Ocean, NSF, 9/1/99-8/31/06, $3,997,402. (PI)
            • Climate variability of the Alaskan North Slope Coastal Region: Observations, simulations, and integrated assessment, NSF/NOAA, 1/1/01-1/1/05, $2,404,308 (Co-PI)

          • Don Aitkin says:

            Exactly what are you implying here, David?

            You show that Professor Curry has won not quite $11m in grants from three funding agencies, between 1999 and 2014. She was the principal investigator in eight and the co-PI in four (you have repeated one grant, and the name of the PI is not mentioned for one grant).

            She has no current grants.

            She served on a peer review panel for NASA, on a climate advisory group for NASA, and was asked to help in finding a panel director for NSF. None of these is a salaried position; the first two, from my past acquaintance with the US, would have provided fares and a sitting fee. The last might well have been done by email and correspondence, with one meeting in Washington.

            What are you suggesting? I have reproved you for commenting that the US taxpayer ‘flicked’ money to her. What you have provided is evidence of a first-class researcher who has won grants in her own right, and with other well-regarded researchers. She has said that she is no longer a funded researcher in this way, and you have not shown otherwise. It is standard practice for well-regarded researchers to sit on peer review panels in Australia and the USA, as everywhere else where competitive research funding exists. What alternative are you suggesting, if any?

            Altogether, what you have done is to show that Professor Curry has been an eminent practitioner in her field of climate science. I ask, again, that you stop providing what seem to me to be malicious ad hominem remarks that have no foundation in fact.

        • dasher says:

          David ..the Guardian?…………oh and do you read Curry?

          • David says:



            I have read her a little. But I have to confess Curry’s research is not on my bed side reading table. As far as I can tell I think Professor Curry has published some high quality research on climate . As I have mentioned before on this blog I find the paper she wrote with Lewis (?) on ECS interesting in particular their use of Bayesian approach. It is something I would like to learn.

            If you read a bit more Curry you would realize that when I used the expression “a possible unknown unknown” at various times on this blog I am quoting Curry . As she used this expression when she gave evidence to the US Senate. Which brings me to my main point of disagreement. I don’t think it is reasonable to put public policy on hold while she farts around for another 15 years and $12 m looking for her “possible unknown unknown.”

            But I really don’t understand what you think you are trying to achieve. If you are trying to imply that I have some bias let me help you out. Yes I do. I think that is fairly obvious that I have a Green take on AGW.

          • Damodar says:

            My goodness. “farts around for another 15 years and 12m “. You really are an angry zealot aren’t you. I can imagine you, in another time , being at the front of the mob screaming to burn the witch. I notice you have different standards about where public funds are spent . Where is your outrage at the billions of tax funds pouring down the throats of multi nationals for those monstrous abominations called wind farms.

  • David says:

    Don you have jumped in the middle of my response to Bryan who asked,

    “How can you be a researcher on CAGW without coming up with ‘recommendations’ to stabilize the climate?”

    This type of comment is very common on this blog. And I make the point that it is not necessary “come up with recommendations” to develop a career as climate scientist. e.g. Judith Curry, who has done very well for herself, grants, tenured Professorial Chair and a fat 401K, no doubt.

    But yes Don I will concede that Curry does not get paid pro rata for appearing before the US Congress.

    • Bryan Roberts says:

      Of course it is not necessary to “come up with recommendations” to be a climate scientist, if you are, like Judith Curry, objectively studying factors that influence the climate. However, if you are convinced of the reality of CAGW, it is very hard to avoid being an advocate for some measures (typically reductions in carbon dioxide) to reduce ‘warming’. For example, in a discussion of coral beaching broadcast on the ABC recently, Professor Hughes asserted that, despite these events having occurred with varying severity in previous years, the current episode was unquestionably due to ‘global warming’, that should be addressed as a matter of urgency – a quite unnecessary scare tactic.

      Re “Don I will concede”; it might pay you to check your facts before making all these silly assertions. JC not only does not get paid ‘pro rata’, she does not get paid at all.

    • dasher says:

      I don’t think it is reasonable to put public policy on hold while she farts around for another 15 years and $12 m looking for her “possible unknown unknown.” This seems to me the “just do something approach” ( I digress but there is a great book called ” The Psychology of military incompetence”, which cites numerous example of military leaders “just doing something” because they did not have the wit or self confidence to think it through) Just doing something whether or not it makes a scintilla of difference..for example spending trillions on wind and solar which simple does not have the heft to do the job seems reckless madness particularly when there is serious contestability about is really happening with the climate I think a little hasten slowly might be a smart move…the Blomberg approach.

  • David says:

    “Of course it is not necessary to “come up with recommendations” to be a climate scientist, …. ” And that’s my point.

    • Bryan Roberts says:

      It might help if you read to the end of the sentence before replying. There was a qualification: “if you are, like Judith Curry, objectively studying factors that influence the climate.”

      Unfortunately, David, you are moe interested in scoring points than in discussion.

      • David says:

        Bryan here is your original sentence, in full, from your post above.

        “How can you be a researcher on CAGW without coming up with ‘recommendations’ to stabilize the climate?”

        Exactly where is the qualifier?

  • bobo says:

    Don, any thoughts on the GHG “fingerprints” that are being observed? These qualitatively rule out many of the forcings that climate contrarians like to cling onto, but are consistent with GHG global warming (e.g. upper stratosphere, mesosphere, thermosphere cooling rules out increasing solar irradation; increase in downward thermal IR but decrease in upward thermal IR from atmosphere is exactly consistent with increasing atmospheric GHG concentration, what other forcings would do this?)

    The Skeptical Science website has a good list of some of these “fingerprints”:

    I’d be interested to know if some climate sceptic has put together a similar list of what they think should be observed if GHG warming was occurring.

    • Ross Handsaker says:

      The article you refer to in Skeptical Science was written in 2010. If you look at the up-to-date NOAA data for troposphere/stratosphere/ OLR at top of the atmosphere, the trend lines have changed over the past 10-15 years and are no longer “consistent with increasing atmospheric GHG concentration”. The trend line for the stratosphere is nearly flat while OLR has increased.

      • bobo says:

        According to your references, how’s the mesosphere going? Stratosphere has ozone effects as well, but mesosphere doesn’t.

        “OLR has increased”
        How is the radiative budget looking? i.e. is more radiative energy entering than leaving the climate system?

        It’d be great if you pasted links to support your claims, Ross.

    • Don Aitkin says:

      Not on my current agenda for essays, Bobo.

      • bobo says:

        Don, I don’t think there is a more relevant or important topic in an essay about attribution of global warming than GHG fingerprints.

        Comparing two time series as a method of attribution is very unsophisticated relative to a discussion of GHG fingerprints. You are making an erroneous implicit assumption that if CO2 is causing global warming, the surface temperature plot should have the same shape as the plot of CO2 concentration. You don’t explain at all why you think this should be.

        • Don Aitkin says:

          To repeat, Bobo, I have my own agenda, because it is my website. I write about things I think are interesting. As I’ve suggested before, you are at liberty to write such a piece and submit it for publication. If it is well-written, well-argued and not longer than 1200 words I’ll run it. I had seen that stuff in SkS, and it is neither well-written nor well-argued, and I’m sure you can do better. I wouldn’t use SkS as a reference, however. Argue from the papers it points to. John Cook is at the bottom of any list of persuasive science writers, just a tad below his colleague Lewandowsky.

          • bobo says:

            Appreciate the offer. A little bit time poor at the moment, but I am hoping to take you up on the offer.

        • JimboR says:

          “You are making an erroneous implicit assumption that if CO2 is causing global warming, the surface temperature plot should have the same shape as the plot of CO2 concentration. You don’t explain at all why you think this should be.”

          Perhaps that’s another example of what the late Professor Stephen Schneider referred to as the “false god of falsification” when he reviewed Don’s work a few years back:


          • Don Aitkin says:

            Well, as to the first, if James Hansen could do so, why can’t anyone else?

            As to the late Stephen Schneider, you provide a wonderful opportunity for me to post my response to him, after he tried to monster me on the ABC. He didn’t, of course, reposed, but I hardly expected it. People like him on the whole do not debate — they just speak from the pulpit and leave, as he did then. But this is what I wrote:

            ‘Dear Dr Schneider,

            My Ockham’s razor talks were not addressed to you, nor yours to me. We were both trying to reach an educated, interested audience. But I thought it might be worth my commenting on some of the things you said. I am increasingly struck by the similarity of the AGW debate to the struggle between the Church of Rome and the Protestant dissenters in the 16th century and afterwards. The Church claimed the right to mediate between the believer and God, while the Protestants argued that each of us could establish a personal communication with God. Throughout your talk I could hear someone talking in the tones of ‘received wisdom’. My sceptical, protestant mind begins to object as soon as I hear anyone talk like this, no matter how many years they have worked in a field, no matter how many peer-reviewed papers they have published, no matter what their title. They are claiming authority. I don’t accept it.

            And as soon as I began to read I started to shake my head. You must know that the way you describe the IPCC process is a form of ‘wall-papering’. The numbers you quote are not accurate measures of what actually happens. For me the notion of ‘consensus’ in this debate is intellectual bunk, and you know why. Phrases like ‘the vast bulk of knowledgeable climate scientists’ (you like ‘vast’) cut no ice with me at all. I think I have spent as long as you in the world of peer review, and as I have written elsewhere, it gets only two cheers from me. The defence of ‘peer review’ in this domain is a poor one, and again, you know why. The notion that the IPCC’s use of numbers to describe its sense of the probability that statements are true is again a form of wall-papering. These numbers have no basis in measurement at all, and you know that.

            You spend some time in showing that the earth has been warming, and there we have no real argument, for I said so too. But you still use 1998 as the hottest year, though GISS has now conceded that it was not. You don’t mention the problem of argument — that if natural variations like El Nino can cause higher temperatures than expected, what is then the contribution of AGW? Like many others, who have written to me about what they think I have said or written, you jump too quickly to what you think I said, rather than to what I did say. I did not, as you say, ‘claim that the few years from 1998 until now falsifies global warming…’ I mentioned that period twice — from the first talk: ‘If we look at the last century, then it warmed from about 1910 to 1940, when it stopped warming, It warmed again from 1975 to 1998, and then it stopped warming again.’ From the second talk: ‘After a peak in 1998, the result apparently of an El Nino episode, temperature has not increased, though carbon dioxide has gone on doing so.’ Where is the ‘false contrarian science’ in that? You say that thermometers don’t lie, but you don’t say that there are many thermometers, and they don’t all show the same things. The central England thermometers, perhaps the longest continuous and supposedly accurate set in the world, don’t show any particular trend since the middle 17th century. HadCRUT3v shows a clear decline from 1998. Most of the warming seems to have occurred in the northern hemisphere, where most of the people are. And so on. I think you have an obligation to deal with these inconvenient data, and I’ll go on being someone who thinks Popper got it right, and that Feyerabend had some insight too.
            My approach is to ask what I think are central, sensible questions, and go on doing so until I get good answers, or discover that there aren’t any. I haven’t published any peer-reviewed papers in climate science (which doesn’t make me at all unusual, since neither has Al Gore) but I have spent a long time in science policy and in helping to reach decisions about the spending of large amounts of money on scientific research proposals, both in Australia and Canada.

            At the end you dismiss people who ask questions, like me, as someone who belongs to ‘a small band of people who represent only themselves’. Whom do you represent? As an academic I have been a ‘public intellectual’ for forty years, and in that time I have tried to explain to readers of newspapers what I think the important issues of the day are and how they might engage with them. In doing so I am always trespassing on other people’s patches, and I make no apology for doing so. My interest is in a better democracy, whose citizens are concerned about problems and their solution. But I try not to engage in polemics, or to get into the ad hominem style, which is so much part of any political debate. I believe that my position is an honourable and essential one, and when I read a transcript like yours, I feel even more positive about the virtue of what I am doing. To return to where I began, your talk sounds like the high priest in action. I’m not much into high priests, especially when they preach global salvation. If you want to be taken seriously as a scientist in this debate, it seems to me, you have to deal with the problems of measurements and argument, not to brush them aside because you think you have a ‘vast consensus’ on your side. You haven’t, and you know it.’

            That was eight years ago, and I would say exactly the same today.

          • Don Aitkin says:

            Oh dear, ‘respond’ not ‘reposed’.

  • David says:

    “Exactly what are you implying here, David?

    Don in response Bryan’s question,
    “How can you be a researcher on CAGW without coming up with ‘recommendations’ to stabilize the climate?”

    I copied and pasted extracts from Professor Curry’s CV to show that it is possible to publish research on AGW, without coming up with ‘recommendations’ and still have a successful academic career as evidence by Professor Curry’s invitation to professional boards and winning grants.

    PS you are correct the grant

    “Impact of Marine and Dust Aerosols on Atlantic Tropical Cyclone Development. NSF, $349,901, 4/1/11-3/31/14 (co-PI).”
    was repeated, well spotted. If you feel strongly about it, I suggest you take it up with Professor Curry as she repeats herself in her CV.

    • Bryan Roberts says:

      Your claim:
      “Bryan here is your original sentence, in full, from your post above.
      “How can you be a researcher on CAGW without coming up with ‘recommendations’ to stabilize the climate?”
      Exactly where is the qualifier?”

      It is not the relevant sentence, as I pointed out. The relevant sentence is:
      Of course it is not necessary to “come up with recommendations” to be a climate scientist, IF you are, like Judith Curry, objectively studying factors that influence the climate.” The qualifier is in caps, in case you are as deficient in English grammar as you are in intelligence.

    • Bryan Roberts says:

      …and, David, please be careful about inferring that I am an idiot, or do not understand what I am writing. If you do not understand it, that is actually your problem.

      • David says:


        I don’t think you are an idiot.

        “Of course it is not necessary to “come up with recommendations” to be a climate scientist, IF you are, like Judith Curry, objectively studying factors that influence the climate.”

        Yes I agree with this sentence.

        • Bryan Roberts says:

          Then obviously, you recognise that your entire argument has been based on a misreading of my post, and a waste of everybody’s time. As, I suggest, are most of your ‘interventions’.

          • David says:

            No Bryan. To re-cap. Your original post finished with this rhetorical question

            “How can you be a researcher on CAGW without coming up with ‘recommendations’ to stabilize the climate?”

            I explained why I disagreed with its implications. So you change your position to this statement.

            “Of course it is not necessary to “come up with recommendations” to be a climate scientist, IF you are, like Judith Curry, objectively studying factors that influence the climate.”

            Yes, I agree with your revised statement. And said so. But I certainly don’t think that Judith Curry in the ONLY “objective” climate scientist out there. There are many others for example Professor Mann and Muller are both excellent. Most of whom have published research which supports AGW. And as far as I am aware there is no requirement that “recommendations” be published with scientific research.

  • bobo says:

    There’s an interesting update regarding Roy Spencer’s personal unverified beta version of the UAH TLT dataset. As a bit of background, this is a dataset that looks pretty similar to the officially published UAH dataset pre-1998, but has a higher peak at 1998, and the post-1998 warming trend observed in the official data set has been deleted to give Spencer’s set.

    Despite these changes, February 2016 ranks as the having the highest monthly temperature on record (I think the record is about 30 years). General freak-out is occurring on WUWT and Spencer’s comments section.

    • Don Aitkin says:

      Yes, February’s is the highest ever, but apparently only in the Northern hemisphere — tropics and the south were ordinary. Seems to be unusual Arctic warming. Ole Humlum will have the good data for us in a few days. I don’t know what to make of it.

      Roy Spencer’s v.6 is about to be peer-reveiwed (see his website).

      • bobo says:

        “Roy Spencer’s v.6 is about to be peer-reveiwed”
        That’s very good news. However if it falters in the review process there will be a lot of analyses he’s done based on that set that may be worthless, and such a scenario will raise all sorts of awkward questions about motives. Fundamentally though the TLT construction is a “synthetic” procedure which produces a very wide uncertainty band, which gives more wiggle room.

        There is a fair bit of confidence that TLT temperature maxima lag El Nino surface temp maxima, so these results aren’t unusual; all that is happening is that heat in the ocean has been flowing into the atmosphere at a large rate over a sufficiently long period of time (from El Nino surface hotspot) and this heat is being dissipated to high latitudes and high altitudes . It’s fascinating that TLT doesn’t pick up surface temp warming at all, nor does it pick up the heat released from storm cloud systems generated by the El Nino hotspot, it only really seems to pick up really large thick regions of atmospheric warming.

        It will be fascinating to see the climate system’s total heat content plots for this period (because the Argo data is so smooth), I suppose that there should be a drop in the rate of accumulation of total heat content because extra heat in the atmosphere should lead to additional outgoing longwave radiation, potentially leading to a short period on the order of a year of global cooling (negative trend in heat content accumulation).

  • Neville says:

    Let’s look at some of the icons of their CAGW.
    Dr Goklany has shown that deaths from extreme events have dropped by 97% since the 1920s, NOAA global SLR shows about 1.5 to 2 mm a year and Sydney 0.65mm rise, plus Brisbane 0.09mm rise a year. Just 4,000 years ago Sydney SL was at least 1.5 metres higher than today. Also Le Clercq study found that glacier retreat has slowed since 1950. There is no sign of the Trop hot spot. Many PR ice core studies etc show that droughts were much worse over the last 1,000 years than today.
    Satellite data shows no warming over Antarctica for 37 years.
    In 1900 2 bn people lived in much poorer circumstances than the 7 bn people today and all underpinned by the use of fossil fuels. And the 7 bn people today live much longer easier lives than people just a century ago. In fact obesity is a major problem for wealthy first world countries. To finish, the planet has been greening for at least 40- years because of the extra co2 plant food in our atmosphere. Oh and those poor polar bear numbers have increased by 400 to 500% since the 1950s. What’s not to like?

    • bobo says:

      “There is no sign of the Trop hot spot.”

      That’s completely false, according to the following paper:
      Steven C Sherwood and Nidhi Nishant. Atmospheric changes through 2012 as shown by iteratively homogenized radiosonde temperature and wind data (IUKv2)
      Published 11 May 2015
      Environmental Research Letters

      Here’s an extract from the abstract:
      “tropical warming is equally strong over both the 1959–2012 and 1979–2012 periods, increasing smoothly and almost moist-adiabatically from the surface (where it is roughly 0.14 K/decade) to 300 hPa (where it is about 0.25 K/decade over both periods), a pattern very close to that in climate model predictions.”

      The troposphere is exactly what is expected from (unattributed) global warming (which we already know is occurring). The troposphere hot spot is caused by increased evaporation in response to warming, not some mechanism specifically restricted to GHGs (i.e. it’s not a GHG fingerprint).

      As for the rest of your post, you’re getting lost in a forest of details, I recommend that you clarify to yourself what global warming actually is.

      • Don Aitkin says:

        ‘completely false’ is a bit strong. This is a paper that suggests that if you do all the massaging he did with the radiosonde data you can see signs of a hot spot. The fact that no one, including the IPC C people, had been able to find it in the past is glossed over. Roy Spencer wasn’t much impressed with the work

        Being an agnostic I’ll wait and see. At the moment I think the paper is OTT. But there will be other work over the next year or two, and that will give us all a better guide.

        • David says:

          You repeatably have asked Bobo to post some high quality analysis of climate on your blog. Then when Bobo does you tend disengage from the debate.

          • Don Aitkin says:


            I didn’t disengage. I’ve read the paper, and have referred Bobo to Roy Spencer’s critique of it. I think it works much too hard to find something somewhere in the data. That is disengagement?

            Re Bobo, I have offered him space on the website to publish a developed response to something I have written. He has twice told me that he is grateful for the offer, but a bit busy. I accept that. What I don’t do is run off to respond to something that is tangential to what I am writing about. People who want me to do that should set up their own website, and I’ll comment there if I think I have something useful to say.

        • bobo says:


          Here’s Roy Spencer’s rationale for rejecting the paper:

          “I’ve looked through the paper and find the statistical black box approach they used to be unconvincing. I’ll leave it to others to examine the details of their statistical adjustments, what what the physical reasons for those adjustments might be.”

          It’s a completely superficial claim; zero detail has been given. He has not found a flaw in the paper’s methodology.

          • JimboR says:

            “I had a quick glance and I’m unpersuaded”… where have I heard that approach before?

          • Don Aitkin says:

            Bobo, you could have gone on to read Spencer’s quite straightforward account of why he prefers his own methodology. As it happens, I think ‘black box’ is a good summary of the Sherwood and Nishant paper. I assume you haven’t read it, so I am giving you the link:


            I couldn’t make much sense out of what has been done other than (i) the process is based on more than one model, (ii) it is not clear at all how winds were measured (by using ruffles on the surface of the ocean as proxies for wind speed and direction?), (iii) it involves kriging, but no details are given, and (iv) while the authors refer to uncertainties in the text there is no indication of what they are or how they affect the result.

            And their results are suggestive, not decisive. Since the paper has been about for a year, and has not led to continual discussion, my reading is that is not an important pale. But there may be more to come, and perhaps the black box will have been opened by someone.

            Jo Nova has a lengthy critique of the paper, which you can read by going to her site and searching for the authors

          • Don Aitkin says:

            This happens all too frequently:

            ‘is not an important paper’


          • JimboR says:

            ” (ii) it is not clear at all how winds were measured ”

            The radiosondes record wind speed and direction.

            “(iii) it involves kriging, but no details are given”

            Source code available here:

            “(iv) while the authors refer to uncertainties in the text there is no indication of what they are or how they affect the result.”

            Structural uncertainties for each data point can be found with the data here:

  • Neville says:

    Gee bobo I’m sorry if I provided you with too much detail, but I was never one to believe in silly religious dogma. That study is a joke and it is generally accepted ( even by the IPCC) that there is no hot spot.
    Don’t forget that Phil Jones listed 3 warming periods from 1860 to 2009 that only differed by about two hundredths of a degree C. Two of those were before 1950 when co2 levels couldn’t be a factor in your CAGW. That’s according to the IPCC. In his BBC interview Jones also admitted that if more studies could be found from the SH showing a Med WP it would cast doubt that our modern warming was unusual or unprecedented. Remember our slight modern warming comes at the end of one of the coldest periods for thousands of years.
    There are many PR studies that show a warm Med WP from the SH including Antarctic ice cores . Just a few more details for you to think about.

  • bobo says:

    Roy Spencer actually acknowledged some likely flaws in his own analysis, the fact that the vertical temperature resolution of the weighting functions is poor and that the weighting function maxima are at the wrong altitudes:
    “It has been also been pointed out, with some justification, that our lower tropospheric temperature product really can’t be used to find the hotspot since it peaks too low in the troposphere, and our mid-troposphere product might have too much contamination from cooling in the lower stratosphere to detect the hotspot.”

    • Don Aitkin says:

      Yes, Bobo, I know that. It was me that suggested his website to you.

      • David says:

        “…But there may be more to come, and perhaps the black box will have been opened by someone.”

        Don according to your previous posts the concept of an arithmetic mean temperature is a conceptual “black box” also. Too impenetrable to have any meaning etc. I agree with Bobo’s comment above. It seems to me that “black boxes” are invented by dogmas that are in full intellectual retreat.

        • Don Aitkin says:

          Your turn, David. The link to the paper is there above. Why don’t you go and read it, and distill its methodology for us. You may be able to do something that lesser mortals cannot.

  • David says:

    Don you try to hide behind semantics, like you the third speaker on the high school debating team. The second sentence:

    “This method, in effect, performs a multiple linear regression of the data onto a structural …”

    Linear regression, is a statistical technique. And statistics is a branch of mathematics. FYI this is what maths looks like.

    • Don Aitkin says:

      Again, ‘methodology, David…’

      Here is the preceding sentence:

      ‘This new radiosonde dataset Iterative Universal Kriging (IUKv2) was produced via a process of IUKv2, using the same methodology as an earlier version (Sherwood et al 2008, hereafter S08) with a few modifications.’

      Section 2.2 then summarises a lot of changes to whatever IUKv2 is. Do you understand what they are saying? If you do, you might explain to the rest of us. That is what Spencer was calling the black box — methodology’, David, not mathematics.

      • JimboR says:

        Don, I’m struggling to understand what you’re asking for. The original authors appear to go into great detail as to their methodology. Are you disputing that, or are you asking someone to explain it to you without the maths?

        • Don Aitkin says:

          Are you happy with Kriging, both in principle and as used here? Do you understand what the missing data area is relative to the placement of radiosonde balloons? I don’t like filling in missing data by extrapolation anyway, but I defy you to find what the authors have done with respect to the oceans, where balloons are relatively sparse.

          Re winds: since winds are not constant in either direction or velocity as altitude increases, how are values for winds produced for the equations?

          Since Sherwood and his co-author claim to have discovered something that had eluded everybody until them, and everybody over twenty years or so, don’t you think this paper might be more accessible to everyone?

          If you want a dissection of it, Jo Nova has done a couple. Just go to her website and type in ‘Sherwood’. She is unpersuaded too. As I said earlier, the paper seems to have fallen into the ‘Oh, yes, that one’ box, notwithstanding Sherwood’s attempt to revive it.

          • JimboR says:

            His 2008 paper seems well cited and entirely uncontroversial (except maybe in skeptic circles):


            His latest contribution pretty much reads as “yep, made some improvements and found it’s 10% worse”. This might all be shocking news to you skeptics, but the real climate scientists are just getting on with it.

            As for turning to Jo Nova for science… isn’t that the site that gave us ForceX?

          • Don Aitkin says:

            Ah, no questions answered. Oh well.

            My general rule is to read what is made a fuss of, and in RealClimate as well as Climate Audit. Look at my blog roll. I almost draw the line at SkS, though I have been to it a few times. It is intellectually dishonest too often. So, I offer you the same rule. You will get good stuff from Jo Nova, and even if you don’t agree, it’s worth working out why you don’t.

          • JimboR says:

            Call me old fashioned but I always think climate science is best done by climate scientists. Get your critique of their work published(*) in the American Meteorological Society Journal and I’ll be first in line to read it. Meanwhile, simply declaring you don’t understand the maths doesn’t advance the field.

            (*) with that in mind may I offer a small nit-pick before you submit: “winds are not constant in either direction or velocity” perhaps “direction or speed” would be better. Velocity is already a vector.

          • David says:

            “I don’t like filling in missing data by extrapolation anyway”

            This is a silly comment. Of course we would all prefer to have data. But what should we do when we don’t?

          • Don Aitkin says:

            David, you should think before you write. It is not at all a silly statement. Extrapolation, or better, in this case, interpolation, is a fancy word for making it up, or guessing, assisted by assumptions. There are very few measuring stations in Antarctic. Should you assume that the missing area (virtually all of Antarctica) has the average temperature of the few temperatures you have measured? Or something else? Why are you doing this, in the first place? The data are what you have. Oh, you want to have a measure for the whole continent. Why? Now answer that question.

            Kriging is a form of interpolation, and I don’t like it, because (i) it is making up data for areas that don’t have any and (ii) I don’t see any need for it. What should we do when we don’t have data? Unless there is an absolutely compelling reason to do something, accept that you don’t have data! Kriging was invented to help find more gold when there were only a few samples from bore holes. Someone had to decide whether or not it was worth digging more holes. In the case of measuring temperatures above the the oceans there seems to me no compelling reason to do what S&N have been doing, and there is nothing in what they have published that persuades me that they did. Moreover, it is very difficult indeed to work out what they have done.

            A great deal of all the mucking about with temperature data that has gone on has been in aid of the AGW message, trying to make the data say more than they are capable of. This is yet another example.

      • David says:

        Sceptics are forever asking for the complexities of the relationship between CO2 and temperature to be explained to them. So researchers such as Sherwood and Nishant have begun to model some of the complexities of AGW by accounting for variations in temperature across different parts of atmosphere. Then, because your empirical skills are not up to speed, your fall-back position is that they “are working the data too hard”. FYI a model that does fully captured all the complexities of our climatic system will be working hard.

        For me, the main take away message from Sherwood and Nishant paper was that original Iterative Universal Kriging model was quite good as they state that the over-all trend did not change much.

  • Don Aitkin says:

    Do you mean that no one who is not a climate scientist should be allowed to comment on anything in climate science, unless the critique is published in a peer-reviewed journal?

    • JimboR says:

      Not at all, go your hardest. I’m just stating where I prefer to get my climate science from. I don’t have time to pour through all the unreviewed ForceX stuff. If any of it turns out to be good, I’m sure I’ll hear about it eventually.

  • Don Aitkin says:

    I guess we won’t see you here any more, then, since I’m not a climate scientist.

    But I do agree with your last sentence. Knowledge advances slowly, with steps backwards and steps forward. It takes some time before the chaff gets blown away. If papers are really important, I’ll know because other people build on them, and they survive real critique. That was my point about S&N. They work really hard to try to show that there really is a hot spot. But the effort is so contrived that science so far has just shrugged. If they really have shown the hot spot there will have to be some further apparently confirming work, and a lot of previous data will have to be re-examined. I’ll wait and see.

    • JimboR says:

      Fear not, my expectations for learning any climate science here are very low. Occasionally I’m pleasantly surprised though, with a pointer to some paper/field I hadn’t heard of.

  • bobo says:

    “Kriging is a form of interpolation, and I don’t like it, because (i) it is making up data for areas that don’t have any and (ii) I don’t see any need for it…A great deal of all the mucking about with temperature data that has gone on has been in aid of the AGW message, trying to make the data say more than they are capable of. This is yet another example.”

    Don, with all due respect, that sounds like pseudoscience. You don’t just reject a method because you “don’t like it”. Kriging is a way of estimating, and all that matters from a scientific perspective is whether an estimate is good enough. What does “good enough” mean? Simply that the error of estimation is sufficiently small so that the conclusions drawn from the data are sound. In other words, instead of saying you “don’t like it”, you need to establish that the error of the estimation is so large that the claims based on the data can’t actually be deduced.

    “I don’t see a need for it”
    How do you propose to do the analysis ?

  • David says:

    “David, you should think before you write. It is not at all a silly statement. Extrapolation, or better, in this case, interpolation, is a fancy word for making it up, or guessing, assisted by assumptions….”

    Don it is very a silly argument. Your friends at the Planning Institute would make recommendations with incomplete information all the time. I am sure that they would always prefer more complete data, but they make do.

    • Don Aitkin says:

      Well, Bobo, you stick with it. My interest in all of this has been the basis for government policies, and what I see here is someone’s felt need for policy-based evidence. The arguments for a carbon tax or an ETS rest on data and scientific arguments. They seem weak to me,and are weaker now then they were in 2005; I have explained why for several years, in what seems to me a cool and rational way, When I see data massaged to produce yet another warming result, as with what is now being called the ‘Karlization’ of data, as with S&N, I just shake my head. What are these guys trying to achieve, and why are they trying to achieve it?

      You see nothing wrong. So be it.

      • JImboR says:

        ” I have explained why for several years, in what seems to me a cool and rational way”

        But never in a scientific way, which I think is what most of us are waiting for. The folks making these adjustments to the data go to great lengths to estimate errors and uncertainties in their techniques and you simply shrug all that effort away with a casual “I am not persuaded”.

        “What are these guys trying to achieve”

        They’re trying to correct for measurement errors.

        “why are they trying to achieve it”

        Because ignoring the measurement errors and pretending the raw readings are a genuine reflection of the underlying signal of interest would be negligent. Imagine you’re trying to measure a physical parameter with a physical sensor over a 50 or 100 year timespan. Equipment will get replaced and moved, technology will get improved. If engineering designs a radiosonde that is less sensitive to radiant heating from the sun are you really going to knock it back just because you have 10 years of measurements made by the old model? Are you going to throw out all your old data and restart your time series every time the technology improves?

        One of the great features of time-series measurements of a slow moving signal is that jumps caused by instrumentation changes stick out like dogs’ balls, and are easily corrected for, complete with error and uncertainty measurements when you do.

        “I just shake my head”

        Instead of doing that, why not take a course? Then you could either embrace their techniques with enthusiasm (like many of us that use similar techniques in our own fields do), or show us where they went wrong. Don, do you seriously believe your current approach to “analysing” these techniques is in any way scientific?

        • David says:

          Don JimboR gives good advice. You are too close to AGW, to maintain objectivity. You should go and look at how these techniques are used in other fields. You could see how contemporary time series analysis is analysed in research that has nothing to do with AGW. You will see climate science is not inventing its own empirical techniques.

      • bobo says:

        “The arguments for a carbon tax or an ETS rest on data and scientific arguments. They seem weak to me,and are weaker now then they were in 2005; I have explained why for several years, in what seems to me a cool and rational way,”

        Don, I get the impression that when you don’t understand some method or analysis (there is no shame in that; this is really difficult stuff) your instinct is to automatically assume that there is something fatally wrong. Indeed this is a universal mindset among climate sceptics, many of whom seem to be so quick to accuse some study as being error riddled or fraudulent when they really don’t understand what has been done and why. The confidence they have that something must be wrong is so high that they never bother to work through the detail to find precisely what is wrong with the study. Rationally if you don’t understand the reasoning used in the study or you can’t present a compelling counterexample you aren’t in a position to take an opposing point of view with a high degree of confidence. A clear indication of a cognitive bias among climate sceptics is that nearly every finding and piece of data in this broad discipline is apparently wrong according to them.

        You obviously find carbon pricing extremely distasteful; I suspect this might affect your rationality, so that you aren’t strictly objective about evaluating the science. Here’s an interestingly candid comment from another website which would be in line with this sort of thinking:

        “A lot of people doubt this science, not necessarily for the sciences sake but because what is coming with it – lots of government controls, taxation and a reduced standard of living. Those of us who are old enough to remember, see the faces of the old left, the Marxist extreme left, poking their faces up in the green movement”

        I’m not really sure why people who don’t want taxpayer’s money spent on mitigating global warming bother with poorly formed arguments against the science. What would be more intellectually honest for many climate sceptics would be to say, “I have no specific disagreements with the climate science but I don’t want any government policy to try to mitigate global warming, it is best left to the markets”. I have encountered ultra free marketeers with this perspective, and it is refreshingly honest and much more respectable than pretending they can see a problem with the science when they simply don’t understand what the science is saying.

    • Don Aitkin says:

      David, you like saying this, and of course you are right (as you always are). See my response to Bobo above.

      • David says:


        You really want it both ways. There is a correlation between CO2 and temperature. You and other skeptics then want the variance removed from the trend so that we can have more certainty. So when someone obliges you scream about data being massaged. Both the simple and more sophisticated models report the same average trend, which is the central point of relevance for policy.

        • Don Aitkin says:

          Yes, you can provide a statistic that shows what the relationship is between CO2 and temperature over a time period. But should you infer from the figure that temperature just keeps rising, when other data seems to show phases or a cyclical pattern? You are too wedded to what you think of as statistics, it seems to me.

          • David says:

            Yes, agree. I need to keep an open mind about whether temperature keeps rising. But, when you say “the data seems to show phases…” you are in effect introducing an interesting hypothesis that requires further testing. Different researchers will look at different variables. Sherwood et al added a couple of variables, which resulted in some minor improvement in their model. One day Curry may find her Factor X, etc. But until then I can only go with what is published.

  • […] In fact, despite Al Gore, the science of global warming is not at all settled, and over nearly three decades the core CAGW proposition (#3) — that current warming is unprecedented, and catastrophes of all kinds will be visited on humanity unless it abandons fossil fuels, NOW — has become less and less plausible. The Earth is warmer than it was 150 years ago, but it may have been appreciably warmer during the Middle Ages, the Roman period and the Minoan period, when greenhouse gases, so far as we know, were not as concentrated as they now are (#4). We still  don’t know how much of the present warming has been caused by human activity, and no paper has been published that shows the link decisively, even after thirty years and the expenditure of billions of dollars on climate research and computer model-building (#5). […]

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