Oh, for some real climate science!

A couple of weeks ago a great fuss was made about an article by Tom Karl and others, ‘Possible artifacts of data biases in the recent global surface warming hiatus.’ You can see the abstract and the whole paper here. At first only the abstract was available, with open access expected. I thought I’d wait until the paper was available before commenting, even though many others had already done so. Perhaps they had access through universities and other institutions, a benefit I don’t possess. It has been some time since such a lot of energy has been expended on a single article, and part of the reason is that the authors say that the supposed ‘hiatus’ in global warming, which even the IPCC accepts, is false: global warming has been there all the time. I’d better use the precise words of the article, which are that the results shown in the paper do not support the notion of a global warming “hiatus.” That take-home message was broadcast everywhere, even in the Antipodes.

Tom Karl is the Director of the US National Climate Data Center of the National Oceanic and Atmospheric Administration, and is a genuine big wheel. His Center’s work and indeed his own have been much used by the IPCC, and he has his own dataset as well. When you read the article closely, it is in fact largely about reconstructing ocean temperatures, on the ground that they need reconstructing. When the reconstruction has been done — Lo! His amended new dataset shows that the warming of the first fifteen years of the 21st century is at the same rate as that of the second half of the 20th century.

Well, on this occasion the proof is both in the pudding and in the eating. Why do we need reconstructed SSTs (sea surface temperatures)? The Karl explanation is that there is a difference between the results of temperature buoys and the temperatures calculated from ships. The buoys show a cooler temperature than the ships. I have also discussed the errors in SST measurement before, and in my view SSTs before the Argo buoys that came in 2003 are just about worthless in any time series. There are just so many different kinds of error that it is impossible to ‘correct’ for them all.

Nonetheless Mr Karl felt it had to be done, and what he did was to increase all the temperature data from the buoys to accord with the data from the ships. That of course makes the whole SST trend much warmer, and the 21st century is now apparently a much warmer period. Oh, and the so-called ‘hiatus’ seems to have disappeared. Because a ‘hiatus’ is a gap in a series (from Latin, hiare, to gape), there is now, at least according to Mr Karl, no gap, and warming has continued unabated. I’m not sending it all up. This is the argument I gained from reading the paper.

Now, if you were a serious scientist , what would your next move be? You have the new data series. Wouldn’t you now compare your results to all the other results that are built on SST measurements? There’ll be differences, of course, and you’ll need to have a plausible account of why yours are better (or theirs are worse). The five standard global climate datasets are well-known, and the accompanying graph shows what they say about global temperature anomalies in the last twenty years.


The datasets vary in terms of how high the anomaly trend is, but they show the same movements, by and large. So the Goddard Institute of Space Science’s gistemp shows the highest anomaly, and RSS (Remote Sensing Systems, a satellite system) probably the lowest. But they all show the same movements, up and down.The horizontal lines show how long there has been a zero trend (no warming or cooling), and the colours of the lines tell you which dataset is which. That applies also to the vertical lines. It’s a bit cramped, for which I apologise. There are many versions of this diagram, and they are all based on publicly available data, from those who prepare the statistics.

And what they all show is a lack of warming. I don’t like the ‘hiatus’ term because it implies a resumption of warming, which may or not occur for who knows how many years. Even gistemp shows the zero trend though only for ten years. Now it is true that all journal article are but contributions to the larger quest for knowledge, and that each paper’s results are not definitive — or if they are, then we will not know that until many years later, and if the paper is really important, and in the right field, then a Nobel Prize may well be on its way.

It seems to me that if you are going to tell the world that your work does not support the notion of a global warming hiatus you had better show not just that you have some fancy new reconstructed data, but that your data are just miles better than everyone else’s, if only because nobody else agrees with you, and they’ve been in the business for a long time. Not only that, despite the fact that the datasets are based on different techniques, there is a strong measure of agreement among them.

Alas, the Karl paper doesn’t even mention anyone else in the temperature-measuring field. I pressed on into Supplementary Materials attachment and found this gem: Previous versions of our SST analysis included satellite data, but it was dis-included in a later release because the satellite SSTs were not found to add appreciable value to a monthly  analysis on a 2° grid, and they actually introduced a small but abrupt cool bias at the global scale  starting in 1985 . Other observing systems, including satellites, and model simulations could  provide important insights that would enable the quantification of interpolation uncertainties in data-sparse regions, but haven’t been used in this study.

Why not, you ask, and then shrug. OK, Mr Karl only offered his work as a ‘possible’ explanation, but he did so with such hullabaloo that one can only conclude that the reason for the paper, whose account of reconciling ship SST measurements is awfully unconvincing (see Ross McKittrick’s offering here), is political, not scientific. By that I mean that the Karl paper is just another in the almost weekly production of ‘scientific’ work that seems intended to justify the whole world getting together in Paris at the end of the year, and at last producing a global agreement on curbing greenhouse gas emissions.

I notice that Graham Lloyd of The Australian is inspecting these productions with real critical skill. It would be lovely if the ABC and the Fairfax Press could do likewise. But, at least at the moment, that is to hope for too much.

Footnote: There are more than a dozen examinations of the Karl paper on the major climate websites, and they are all critical save for the one on RealClimate, which is nonetheless somewhat opaque. A summary can be found on Climate etc, here.

I have written about the sea-surface temperature-measurement problem here:

An Agnostic’s Guide to Global Temperature, part 2: Measuring Temperature


Join the discussion 42 Comments

  • Doug Hurst says:

    Thanks Don – Yours conclusions wrt Paris are hard to fault.

    My main job in the 1960s and 70s was flying over the ocean to find out if what was on it and in it belonged to the then fearsome Red Navy. One important tool was hydrophones (underwater microphones) attached to buoys we dropped from the aircraft that would radio the received sound up to us. Sea temperatures, especially vertical profiles, were key to us as they greatly influenced sound transmission.

    At the beginning of each sortie we dropped a ‘bathy buoy’ that measured temperatures down to hundreds of feet. This was done because in most cases we had inadequate knowledge of these temperatures and forecasts were, at best, guestimates. This and other experience tell me that until satellites began measuring surface temps in the 1970s, and Argo buoys temperature profiles this century, little accurate information about sea temperatures existed. I therefore treat any claims about changes to sea temperatures pre-Argo buoys with deep suspicion.

    The oceans are so much bigger than many people realise, and measurements from ships can never be a reliable sample of any area so vast as the water covering 70% of Earth.

  • Alan Gould says:

    Amen to the hope in your second last para, Don. The intransigence there makes one nostalgic for stocks and pillory.

  • Mike says:

    You have to wonder why someone wants to throw doubt on the hiatus at this point in time. If it is just a reworking of data I become very suspicious indeed surely to discredit the current thinking you need a very close technical examination on what is being used to measure it. You need to prove they are in error surely!

  • dlb says:

    Unless I have missed something I have yet to hear about this on the ABC. Usually they would be crowing about it from the rooftops, perhaps even they have reservations about the paper. But come to think of it, in their many broadcasts about climate change they have barely mentioned the “pause”, might be best to say nothing rather than draw attention to some very embarrassing science.

  • Andrew says:

    Don you have misunderstood Karl et al. It doesn’t increase Argo temps – it doesn’t use Argo data. Its supplementary material mentions than plan to use Argo data in ERSST v5.

    • Don Aitkin says:

      Andrew, I am always glad to be corrected on matters of fact. I took my inference from the section in the paper around this sentence:

      ‘In essence, the bias correction involved calculating the average difference between collocated buoy and ship SSTs. The average difference globally was ?0.12°C, a correction which is applied to the buoy SSTs at every grid cell in ERSST version 4.’

      I assumed that these were Argo buoys. Is that not the case? What other drifting buoys are we talking about? Certainly a number of other writers have made the same assumption. Glad to know where I’ve gone wrong.

      • Andrew says:

        As I understand the buoys are both drifting & moored, deployed by research organisations from various countries in recent decades & collated in the ICOADS datset – but if you read Karl et al & follow the cites you should get the exact details.

        • tony thomas says:

          the first fifteen years of the 21st century is just like that of the second half of the both century.

      • David says:


        Andrew has not only corrected you on “some matters of fact”, as you put it. His comments shine a spot light on your total lack of objectivity. Every piece of climate science you examine, must first be passed through the Aitkin ideological prism.

        Then along comes someone like Andrew who actually knows something about climate science (unlike the rest of us) and he has shown you up.

        • DaveW says:

          Hi David – Maybe you should hold back on the shoot-from-the-hip ad hominems as it only makes your deep ideological biases more apparent. Andrew provided a direct and polite correction and Don took it on with thanks. I too would have assumed the authors had used the best data available and that would have been Argo. However, I don’t really have any interest in spending much time trying to digest the string of excuses for the lack of CAGW, like cars piling up into a massive highway crash. I’m waiting on the data and it doesn’t look very good for your cherished doomsday scenario.

          • David says:

            Don had no other choice. If he wants to write an acerbic critique, that’s fine, he just needs to get his facts correct. 🙂

          • David says:

            And just for the record I don’t think [C]AGW will result in a doomsday. My rationale for intervening is that the benefits would be greater than the costs. That is why I always use the acronym “AGW”, when discussing global warming.

  • Peter Kemmis says:

    I just find it amazing that for these scientists it is their day job, and they get paid for it. It’s a bit like grave-digging, unaware it is your own.

    This quality of data selection and analysis once would not have got through First Year Science.

  • Gordon Watson says:

    A timely article we should all share. Thank you,

  • Don Aitkin says:

    Andrew, below, and another correspondent by email, have pointed out that Karl et al did not use Argo buoys. I have checked, and they are right. My error, based on too quick an assumption. There are about 1250 drifting weather buoys in the world’s oceans, and these are the basis of the Karl ‘buoy’ data.

    My reading took me, among other sites, to the Wikipedia entry on weather buoys, which mentions that ship intake measurements of temperature are about 0.6 degrees C too high because of the warmth of the ship itself…

  • Don Aitkin says:

    I have now revised the text in the light of Andrew’s comments, and added a link or two.

  • Mike says:

    Don there you go http://hockeyschtick.blogspot.co.uk/2014/07/updated-list-of-29-excuses-for-18-year.html 63 reasons anyone thinks there is a pause must be wrong.

  • Andrew says:

    Don you seem to be critizing the wrong paper – you criticize Karl et al for a unconvincing account of the changes to ERSST v4 but it doesn’t seek to provide this – it only summarizes them because it uses ERSST v4.

    You’ll find full discussion of the changes in methodology in ERSST v4 & comparisons to other indices in the cited 2014 Huang et al paper. If your critcism extends beyond the sign of the ERSST v3 – v4 change you should be discussing Huang et al.

    • Don Aitkin says:

      Andrew, I agree that the methodology of Karl et al has been set out also in earlier papers. What my post was about is encapsulated in the abstract to Karl et al:

      ‘we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a “slowdown” in the increase of global surface temperature.’

      Yes, I could have delved further into the methodology, and others have so. Is there something in Karl et al that I should have appreciated more than I did?

      • Andrew says:

        Don above you criticize Karl et al at length for not comparing ERSST v4 to other SST indices and not justifying the changes ERSST v3-v4, as you now know this information is provided in the cited 2014 paper by Huang et al, shouldn’t you amend your post to remove this criticism of Karl et al.?

        Also, you plot above the one of UAH tropospheric indices above. The UAH indices underwent a change quite recently (v5/v6) of magnitude similar to the change ERSST v3/v4. Don’t you have similar concerns about the UAH indices?

        • David says:

          Andrew, I hope you continue to comment on this site!

        • Don Aitkin says:

          UAH v6 is not yet adopted; it is a beta version awaiting comment and criticism. I’ve read what the authors have to say on it, and, as usual, am awaiting discussion in the literature and elsewhere.

          Huang et al is not available to me in full text, but the abstract of the paper does not show the sorts of comparisons I suggested in my essay. In any case it is the Karl paper, not the Huang paper, that makes the claim about the end of the hiatus. If you have access to the full Huang paper and can send it to me, I’d be most grateful (donaitkin@grapevine.com.au).

          • Andrew says:

            Don, its good you are considering UAH v6 carefully – why aren’t you doing the same for ERSST v4? You have made some serious criticisms of the work on ERSSTv4 and in particular some unpleasant speculation as to the motivations of Boyin Huang and his co-authors.

            Shouldn’t you retract these criticisms and wait to pass judgement on ERSST v4 until you’ve read the papers by Huang et al. and Liu et al, and the discussion in the literature?

          • Don Aitkin says:

            Thank you for sending the links. I have to say, after having read Huang et al carefully, that my reservations are unaltered‚ if anything hardened.

            First, with reference to a remark you make above, I cannot find where I made ‘unpleasant speculation as to the motivations of Boyin Huang and his co-authors’. I made no mention of the author in my essay.

            Second, there is no comparison in the Huang et al paper of the sort of comparisons I argued for in my essay.

            Third, the methodology of adjusting for shifts in the way temperature measurements were done on ships, averaging the results to a two by two degrees grid, and then using high-quality statistics to show trend lines, brings back all the misgivings I have about the whole temperature anomaly business. The SST data are rough and ready, and polishing them in this way seems to me a pretence. They cannot be better, realistically, then the original, and the sort of work that Karl and Huang are doing is ingenious, but to me a form of scientific fairy floss.

            In conclusion, no, I do not retract my criticisms of Karl’s paper, and I do not find in the Huang paper a justification for its sweeping, and to me unjustified, conclusions about the hiatus.

          • Don Aitkin says:

            I ought to have added that I appreciate your contributions, and that I would really appreciate an extended account of why you find all this important and powerful

          • Andrew says:

            You mis-attribute Huang’s work to Karl here: “Nonetheless Mr Karl felt it had to be done, and what he did was to
            increase all the temperature data from the buoys to accord with the data
            from the ships.”

            The preceding paragraphs speculate that this has been done with political motivations – essentially that Huang et al have committed scientific fraud. Allegation not withdrawn despite your gross misunderstanding of the work.

            Huang et al. doesn’t seem an important paper – just a incremental & logical step forward of their work. Part 2 (Liu et al) with its characterization of uncertainty seems the most useful improvement. My (very uninformed) understanding is that HADSST is a bit ahead of them.

            The small change ERSSTv3/v4 would suggest modest systemic uncertainty and consequently a degree of caution in using ERSST – as would the modest differences between ERSST, HADSST & COBE.

          • Don Aitkin says:

            Mr Karl is the head of the Division where all this is done, and there is no necessary inference that ‘essentially that Huang et al have committed scientific fraud’.

          • Andrew says:

            Don, are you aware ERSST adjustments reduce the global SST trend (v4 slightly less than v3)?

            When you say the original data is better than ERSST, you are arguing ERSST under-estimates the rise in SST.

            Did you see Figure 8 in Huang et al. it compares EERST v4 & V3b with the other major SST indices HADSST3 & COBE-SST2 – the comparison you complain above is absent.

            No you didn’t mention Boyin Huang by name, you made unpleasant speculations about his and his co-authors work and you mis-attributed this work to Tom Karl.

          • Don Aitkin says:

            I didn’t say that the original data are better. I said that the adjusted data cannot be better than the original. I could add that those data were not collected for the purposes of climate science, and the attempt to make these data fit that purpose is an almost worthless exercise, something akin to pretence.

            You say ‘you made unpleasant speculations about his and his co-authors work and you mis-attributed this work to Tom Karl.’ Where did I do this? What are these ‘unpleasant speculations’?

  • Margaret says:

    You see, when David says “And just for the record I don’t think [C]AGW will result in a doomsday. My rationale for intervening is that the benefits would be greater than the costs. That is why I always use the acronym “AGW”, when discussing global warming.” …
    I grasp that principle even if I don’t grasp the factoids. If the benefits are greater than the costs we’ll all be dead in a matter of decades but future generations won’t wear the burden of men who are unwilling to bend from their unhelpful position because they must have proof of something that cannot maybe ever deliver the sort of proof they desire – and yes it is about desire and power.

    • Margaret says:

      That was poorly expressed and this is a forum for well expressed points of view. To reiterate in a better way – my pov is that Australia should have an emissions trading scheme to mitigate AGW. I recommend Elizabeth Farrelly’s June 17 article in the SMH.

      • dlb says:

        Margaret, that whole article is on aesthetics and emotion. That is the trouble with the climate debate too much about feelings and wishful thinking (truthiness) and less to do with cold hard facts. About the only cold hard facts the alarmists can provide are the increasingly discredited predictions of computer models.

        Going to a emissions trading scheme will increase the price of energy, who do you think will be hit hardest by that? certainly not the big end of town. With renewables it is only the relatively well off that can afford roof top solar or own enough land to install wind turbines. They are the ones that will benefit from such investments.

        • margaret says:

          I know it was dlb – she’s an architect by profession – but writes on a wide range of topics because she isn’t narrowly focused on ‘climate change’. But as another commentator said wind farms are a sign of human progress – (and coal is not, not anymore – the days of being a miner in an industrial town and dying a death caused by your daily work are hopefully coming to an end).

      • Peter Kemmis says:

        Hi Margaret

        The nub of the issue is whether there is a significant effect from AGW about which we should be concerned, and whether the warming of the latter part of last century is due rather than mostly to human causes, but to ‘natural variation’ (a term which really means “we don’t know all the factors or their relative contributions to these variations”). Further, is there any global warming that is outside the cooling trend of the last 18,000 years?

        The UK Met Office, one of four primary bodies on whom the IPCC relies, has recently issued a paper on “Regional climate impacts of a possible future grand solar minimum”. (http://www.nature.com/ncomms/2015/150623/ncomms8535/full/ncomms8535.html). In 2010 the chance of a return to a Maunder Minimum was rated at 8% – that’s like the Little Ice Age around the latter part of the 17th Century. That likelihood has now been raised to between 15-20%.

        Here is the abstract of the paper:

        “The past few decades have been characterized by a period of relatively high solar activity. However, the recent prolonged solar minimum and subsequent weak solar cycle 24 have led to suggestions that the grand solar maximum may be at an end. Using past variations of solar activity measured by cosmogenic isotope abundance changes, analogue forecasts for possible future solar output have been calculated. An 8% chance of a return to Maunder Minimum-like conditions within the next 40 years was estimated in 2010 (ref. 2). The decline in solar activity has continued, to the time of writing, and is faster than any other such decline in the 9,300 years covered by the cosmogenic isotope data1. If this recent rate of decline is added to the analysis, the 8% probability estimate is now raised to between 15 and 20%.”

        Now I’m surprised that the UK Met Office has released such a paper, comparatively early. Various climate scientists have been drawing attention for some few years to the decline in sunspot activity and the significance of our solar cycles whose lengths range from 11 to 2300 years. It appears that this time the Met Office has decided it can’t afford to be late to the party again.

        However, the Met Office also states that any reprieve from global warming will be temporary, so I guess it’s wisely having two bob each way. But even if it’s temporary (a mere 40 years), where does that leave the climate models, on which the pro-AGW case depends?

        So do you and David want an ETS, as another two bob each way bet?

        • margaret says:

          Yes. In terms of hedging our bets I think the planet and its inhabitants are worth putting a hedge around.

          • Don Aitkin says:


            When you use a metaphor like ‘hedging our bets’ the inference is that one horse has to win, and you need to place your bets carefully, or that the benefits and costs trade-off is more or less even, so it’s worth going down the RET/carbon tax path. But the point of the RET/carbpn tax path is to reduce greenhouse gas emissions, in the hope that doing so will reduce temperature. But, on the evidence, nothing at all we do will have any effect on temperature. I wrote about this some time ago, at: http://donaitkin.com/if-we-do-all-this-by-how-much-will-we-reduce-temperature/

            Since the data and model belong to the IPCC and its scientific supporters they must be the best that we have, and they show that even if we stopped all industrial activity, the reduction in global temperature would be trifling. In short, if you are worried about ‘the planet and its inhabitants’ the way to go is adaptation, surely, not mitigation.

            I’ve wondered before, and wonder now, why the orthodox don’t take any notice of these figures, and my current conclusion is that ‘feeling good by doing something, even if it is inconsequential’ is more important that considering the issue coolly. And that takes us away from science into policy and society…

          • margaret says:

            I recently heard the term virtue alert – it’s when a person flags their supposed virtue in an opinion on a public medium, simply by saying something like ‘when will this (insert outrageous situation) stop? It shows the world how caring they are (and yet how powerless they feel).
            I don’t think I’m sending a virtue alert though, mere mortal that I am. All the science in the world won’t be effective when used in a battle of I’m right you’re wrong. Most of the population can’t understand/isn’t interested enough in the detail that’s provided by experts to convince us.
            They are busy little beavers on the economic treadmill..

          • Peter Kemmis says:


            From Wikipedia: “A factoid is a neologism
            originally described by Norman Mailer in 1974 which describes a questionable or spurious (unverified, false, or fabricated) statement presented as a fact, but without supporting evidence”.

            You have previously stated that you don’t understand the scientific data and argument presented on both sides of the AGW debate. You are dismissing these generally as “factoids”.

            Now you have previously stated you have been a teacher (which I think is an admirable and fundamental profession). What would you think if one of your intelligent pupils who had been too lazy to do the simple research homework you had set, dismissed it as unnecessary to your requested small written assignment, on the grounds that they were all just factoids?

            Are all the failed climate predictions just factoids? Is the failure of the climate models to predict the current “pause”, let alone the prospect of a significant cooling, just factoids? What’s so difficult to understand about that simple information?

            My update on a definition of “a factoid’ is that it is “an inconvenient fact”, and so the term is used in an attempt to belittle or dismiss a view with which one does not agree.

            Those who are not sufficiently interested in climate science, or believe it is too difficult for them to understand, can hardly be relied upon for sound policy advice. They are but echoes in the ravines.

          • margaret says:

            Yes as a former teacher (and it was excellent training and broadly based but not deeply scientific obviously), of years K-6 I was very invested in literacy as first priority. The importance of critical thinking comes too late in the curriculum and I would say is not really encouraged within the education system as a whole.
            I just find the debate about facts or factoids from either side boring – I’m sorry.
            However many children are literate and have the foundation for critical thinking because of me and people like me – yay!!

  • dlb says:

    Norwegian Prof Ole Humlum who runs the excellent climate reference site “Climate for You” calls the latest sea temperature adjustments by NCDC (i.e. Huang et al.) “administrative changes”. Whether he meant “administrative” to mean “methodology”, or whether he was being ironic I’m not sure.

    Quote: “June 18, 2015: NCDC has introduced a number of rather large administrative changes to their sea surface temperature record. The overall result is to produce a record giving the impression of a continuous temperature increase, also in the 21st century. As the oceans cover about 71% of the entire surface of planet Earth, the effect of this administrative change is clearly seen in the NCDC record for global surface air temperature” (i.e. Karl et al.)

    When you look at what Karl et al. have done, (Fig 1.) it is not much, but it is in addition to other adjustments NCDC have made over recent years, all leaning the same way. Prof. Hulum explains:

    “The net result of the adjustments made are becoming substantial, and
    adjustments since May 2006 occasionally exceeds 0.1oC. Before 1945 global
    temperatures are generally changed toward lower values, and toward higher
    values after 1945, resulting in a more pronounced 20th century warming (about
    0.15oC) compared to the NCDC temperature record published in May 2008.” (see
    Fig 2.)

    Is it uncharitable to say Karl et al. put this paper out for the forthcoming conference in Paris? I don’t think so judging by the tone of their abstract. Phrases like “Here we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC” and “These results do not support the
    notion of a “slowdown” in the increase of global surface temperature” sound rather provocative to me.

    Fig 1. NCDC temperature anomaly time series, blue line after Karl et
    al. adjustments.

    Fig 2. Adjustments made by NCDC to their temperature record over the
    last 7 years.

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