Open letter across the barricade

Here I respond to a letter sent to The Listener by a former scientific colleague, Doug Edmeades. He is now a science spokesperson for local groups which attack the current scientific consensus on climate change as well as attacking local climate scientists.

Doug and I are old mates. In the past we fought together against commercial and bureaucratic attacks on our research. Now we find ourselves on opposite sides of the “barricade.” But I am sure there is enough mutual respect to enable a reasoned discussion of the claims made by Doug about climate change science in his letter.

I have invited him to respond in turn to my comments and hopefully he will be happy that I post his response, at least in part, here.


Hi Doug,

I am responding to claims you made in your recent letter to The NZ Listener reproduced on the Climate Conversation Group Blog (see In a climate of listening). Space limitations clearly prevented you from justifying these  five claims (your refer to them as “facts”). However they are, in my view, either not factual or misleading. I explain why below and welcome your response to my comments.

1: Claim of “no recent global warming” is misleading

Climate change is a multi-decadal phenomenon – short-term temperatures are strongly affected by natural variability. This is clear in a recent figure portraying five different global temperature records (Fig. 1).

Figure 1: From The Yale Forum on Climate Change & the Media. (Click on figure to see article)

Choosing short time periods (eg a decade) may give an entirely misleading impression as you can see from Figure 2 where I have plotted temperature trends of separate periods.

Figure 2: Uses GISTemp data

The most relevant comparison here is the 1998 – 2008 and the 1999 – 2010 periods (the dotted trend lines). The table makes it clear how incorporating 1998 in a short period like this distorts one’s conclusions – because it purposely includes a large variation which confuses the trend (see Table below). This is a classic ploy used by many people who attack the current scientific understanding of climate change.

Period Trend (°C/decade) 95% confidence range
1970-2010 0.20 0.16 – 0.23
1998-2008 0.16 -0.09 – 0.41
1999-2010 0.28 0.10 – 0.45

Comparison of trends for the  1970 – 2000 and 1970 – 2010 periods also suggests that  temperature increases over the last ten years probably have not declined. If anything they may have even increased (see Figure 3). This test was presented on the Yale Climate Media Forum – I realise it cannot be conclusive but would be interested in a statistician’s opinion of the test.

Figure 3: From The Yale Forum on Climate Change & the Media. (Click on figure to see article)

So Doug your claim may well be technically true, maybe even statistically “true” depending on which data set is used, especially if the data for 1998 is included. But it is clearly unwarranted. And misleading.

2: “Medieval warm period” regional, not global.

While contrarians, deniers and climate sceptics have sometimes made a big issue of the “medieval warm period” the conclusion has usually been that it is not a global effect. That is, it may have occurred for parts of the northern hemisphere but is not seen strongly in the global data. See Hemispheric Temperatures in the ‘Medieval Warm Period’ in Working Group I Report “The Physical Science Basis” (AR4).

3: All warming factors are considered

Yes, many factors are involved in driving global temperatures – both natural and human effects. But here is the fact which concerns climate scientists and governments around the world. We just can’t explain the observed temperature trends over the last 50 years without incorporating human inputs as well as natural ones. This is demonstrated in Figure 4 below.

Figure 4a included all the natural and anthropogenic influences.  The black line is the actual measured global temperature anomaly (obtained by subtracting the average temperature for 1901 to 1950).  The individual simulations are shown as thin yellow curves. The red line is the multi-model ensemble mean (see Figure 9.5 – AR4 WGI Chapter 9: Understanding and Attributing Climate Change).

Figure 4: From AR4 Working Group I Report "The Physical Science Basis"

Figure 4b is a similar plot using simulations which consider only the natural influences on climate. The individual simulations are shown as thin blue curves. The thick blue line is the multi-model ensemble mean.

So, climate scientist have considered both natural and anthropogenic influences. And they are unable to reproduce the global temperature changes since 1970 unless anthropogenic influences are included.

That is why the IPCC has concluded that there is a high probability (>90%) that human influences are contributing to the current observed global temperature increase.

4: Models are not reliant on incorrect assumptions about clouds

You misrepresent the current understanding of the influence of clouds in climate models. The fact is that cloud effects are just not well understood yet – the IPCC reports acknowledge that. Figure 5, for example, is from the last IPCC report (Figure 2.20 – AR4 WGI Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing). It shows the estimated influences of several human caused effects and solar radiation since 1750. Notice the error bars. They are much bigger for clouds and aerosols than they are for the others. Notice the assessment of scientific understanding for these influences. The IPCC acknowledges the low understanding for clouds and aerosols.

Figure 5: From AR4 Working Group I Report "The Physical Science Basis"

Obviously this problem is getting attention in current and planned future research.

5: Criticism of NIWA temperature record wrong and malicious

New Zealand’s temperature record, being regional, has very little relevance to the overall global record. However, politically it has been contentious because of unwarranted attacks on the record, and on NIWA climate scientists, by the organisations you represent.

Richard Treadgold crudely attacked the previously published record, and NIWA scientists, in his article “Are we getting warmer yet?” Campaigning by the extreme right wing  ACT Party in parliament resulted in finance to repeat the calculations your organisations were claiming fraudulent. This produced a new temperature record, together with details of adjustment calculations and methodology which confirmed the previously published record.This would have settled any real, but misguided, concern about the data.

Of course, your Climate Science Coalition and The Climate Conversation Group have continued their campaign – probably not at all surprising because their purpose is political, not scientific. And they have adopted the common denier strategy of McCarthyist attacks on climate scientists we are seeing around the world. The promotion of Treadgold’s article at the very time the “climategate” email scandal erupted highlights the common strategy.

This raises the important question of scientific integrity – a subject that I know has concerned both of us over the years. In his article Treadgold made claims that were damaging, malicious and probably libellous. He said that:

NIWA scientists “created a warming effect where none existed.” That “the shocking truth is that the oldest readings were cranked way down and later readings artificially lifted to give a false impression of warming.” And “we have discovered that the warming in New Zealand over the past 156 years was indeed man-made, but it had nothing to do with emission of CO2 – it was created by man-made adjustments of the temperature. It’s a disgrace.”

At the same time he included his own “scientific” analysis which ignored completely effects due to inevitable changes in  recording station. (Obviously because erroneously using the uncorrected raw data fitted his picture better). At the time he claimed that his report was based on work done by scientists in his group – scientists which he refused to name, claiming they wished to remain anonymous!

You may remember I wrote to you at the time asking if you had been involved, or had reviewed the article before its release. This is still a relevant question to me. Despite scientific rubbishing of Treadgold’s article he refuses to withdraw those  malicious comments, or acknowledge the faulty, naive, analysis reported. And, his article still gets used to attack New Zealand scientists.

Well, I am not so naive as to expect politically motived people to be concerned with the truth. But I think this issue does present a problem for us because, unless we take a principled stand on it our scientific integrity is threatened. So, could you please comment on your position with respect to Treadgold’s article, his analysis and his malicious criticism of NIWA scientists? Do you support him? Or have you criticised them within your organisations and attempted to get their withdrawal?

Doug, I am sure you will take my comments and questions in the spirit they are intended and hope you will take the time to respond to this open letter. I certainly look forward to your response and any continuing discussion of these issues.

Ken Perrott.

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31 responses to “Open letter across the barricade

  1. Simon Arnold

    Some quick comments.

    First trying to stick linear trends through the global temp series is a nonsense – the time series series is well known to not be stationary. In any event the underlying processes are complex with cyclical and chaotic elements. This would require fitting multivariate nonlinear functions . The cycles are such that any 10-12 year base line is a joke.

    Anytime anyone talks about recent trends in the global temp record fall about the floor laughing.

    You might however say that the global temp hasn’t increased much in the last 10 years.

    On the medieval warm period the question of whether it was warmer than now or global falls into the category of unsettled science with the former being more settled than the latter (less direct evidence).

    Whether GCMs adequately model all factors, give unbiased results , or handle clouds adequately is settled science. They don’t . More work is required. Have a poke around in http://sms.cam.ac.uk/collection/870907. It isn’t clear whether the current approach to GCMs is the answer. This is a matter of debate.

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  2. Simon, could you explain just what you mean by “the time series series is well known to not be stationary.”?

    Thanks.

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  3. On the medieval warm period the question of whether it was warmer than now or global falls into the category of unsettled science with the former being more settled than the latter (less direct evidence).

    Climate Denial Crock of the Week – “The Medieval Warming Crock”

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  4. Whether GCMs adequately model all factors, give unbiased results , or handle clouds adequately is settled science. They don’t . More work is required.

    This Year’s Model

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  5. Simon Arnold

    Ken, to do linear regression and correctly estimate the parameters you have to assume that things like the mean and variance don’t change in time (i.e. are stationary). Just what the exact characteristics of temp time series are is part of the unsettled science, but they generally fail hypothesis tests that they are stationary. This means that anyone sticking lines through the series and claiming confidence limits are skating on thin ice.

    The kind of issue that comes up (along with other issues around the nature of the temp time series) is just how much of the recent increase is simply due to long-term cycles or memory (i.e. the tendency for truly random processes to revert to the mean gets muted because today’s temp is influenced by last year’s, for example).

    Note that in this pure form time series analysis is trying to deduce underlying structure from the observations rather than fit models derived from first principles to the data. Both however need respect for the data and the assumption required for the statistical inferences being used.

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  6. Richard Christie

    Arnold, that was a pretty sciencey comment .

    Might you please translate into English these sentences, for laypersons such as me:

    Whether GCMs adequately model all factors, give unbiased results , or handle clouds adequately is settled science.

    Anytime anyone talks about recent trends in the global temp record fall about the floor laughing

    and

    First trying to stick linear trends through the global temp series is a nonsense – the time series series is well known to not be stationary.

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  7. GCM = global climate model (or perhaps atmospheric/oceanic “general circulation model”). NASA’s ModelE looks to be the premier resource.

    Anytime anyone talks about recent trends in the global temp record fall about the floor laughing
    A few decades of temp data may not be statistically convincing (the industrial revolution is very recent compared to the last Ice Age!) but there are noticeable trends, and a lot of other measures [Antarctic ice cores, ocean acidity, glacier retreat, rainfall, CO2 concentration,…] forming an incontrovertible picture of a drastic change in global climate.

    First trying to stick linear trends through the global temp series is a nonsense – the time series series is well known to not be stationary.
    Of course there are cyclic fluctuations such as the present “La Nina” system that is screwing up the NZ summer holiday but there is still an overall trend of “Up”. Not difficult to spot!

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  8. I’m still waiting for a comment about Dilithium crystals and how if we re-route the interface through the warp coils we might increase the sensor array efficiency by 15% thereby avoiding an overload. However, it’s important to note that the science on that isn’t settled and that to jump to conclusions is to skate on thin ice. There is less direct evidence for it and we should all have a deep respect for the data.
    However (and I would like to stress this part) this is a matter for debate.
    More work is required.

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  9. No, Simon. You are either going to have to explain yourself better or provide an online reference which explains for you.

    I suspect you are trying to make this issue more complicated than it is. No one is trying to “deduce underlying structure” (whatever you mean by that). There is simply the assertion being made by Doug and his organisations that global warming stopped in 1998. A fallacious interpretation relying on the variation in temperature making it impossible to see any statistically significant trend in such a short time period. Hence deniers use even Steve Jones comments to support their claims.

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  10. The Anti Global Warming movement owes a lot to US right-wing politics. There are disturbing parallels with the tobacco smoking and acid rain issues, where scientific scepticism and political naivety were manipulated by well-funded industry think tanks and PR firms.

    http://en.wikipedia.org/wiki/Merchants_of_Doubt

    Well worth a read, even as the wiki review above.

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  11. Richard Christie on climate models if you look at some of the other stuff from Cambridge http://www.newton.ac.uk/programmes/CLP/seminars/index.html particularly http://www.newton.ac.uk/programmes/CLP/seminars/112414059.html you see some of the issues. The ppt isn’t exactly able to be understood without watching the video, but it gives an indication where some of the problems are with GCMs.

    One apposite example is slide 15 that superimposes Ken’s fig 4a above upon the absolutes temp values the models produced rather than the anomalies. You’ll see the absolute temperatures being modeled range over 4 degrees C – at this basic level they are modelling different climates, and this is a real problem because much of the climate is non-linear with temp. The models are biased.

    As to the issue about “trend” (on which Ken remains unconvinced) I’d just perhaps use a simplification. If you are given a sine wave and someone said there there was a trend in it would you fall about on the floor laughing? Hopefully yes. However you might be potentially confused if you only were shown the bit going up or down, but you’d get it sorted once the rest of the curve was shown..

    So it is with any time series. You need to take into account of as much of the structure as you can deduce from it before you can talk too much about trends (whether in support of or against AGW). In this case the global temp series isn’t well enough behaved that you can start sticking trend lines through it (including short segments) and making pronouncements on what’s going on. Its not as bad as dissecting bits of a sine wave or circle for example and announcing what’s happening to the trends, but nearly.

    Ken it is a little bit complicated, but not that complicated..

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  12. Simon Arnold

    BTW that last comment was from me

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  13. @simon.

    I don’t really understand what you are talking about here. Surely the whole point with sticking a trend line in is to ignore the fine structure of the data to try and communicate some big picture info.

    Sure, you can use different methods to generate trend lines that may fit the data better. One downside in the more sophisticated methods however, is that you can lose the point of sticking a trend line in, which is surely to communicate some big picture information, or?

    I mean, at the extreme, lets say you can come up with some formulas that fit the data so closely as to nearly perfectly match the curve. Adding these to the graph is not going to communicate anything at all.

    As far as I know, nobody is making actual predictions using linear regressions, rather they are using a range of modelling techniques and including information abou the error ranges predictions etc..

    Or perhaps you are of the opinion that any simplification or summarisation is bad?

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  14. Simon I am sure this issue is not too complicated for me to understand as I am familiar with statistics at that level. My point is that you are not explaining your point clearly enough. Even in your last comment you say “much of the climate is non-linear with temp” – WTF does that mean. We are not measuring “climate”, or even modelling “climate” in these models. We are surely modelling and measuring temperature.

    All I can do is try to read into your comment what I think you might be saying, and seeing if it is relevant.

    No one has (knowingly) been given a sine wave. No structure has been assumed (even though of course it may well be there). This is always the situation when one obtains a whole collection of data like this.

    One can analyse data and notice trends – or lack of trends – for the data we have. And of course that conclusion may be meaningless when it comes to guessing mechanisms. We may of course speculate on mechanisms using other evidence. But here I am just talking about the temperature data. And recognition of variation is important if one is going to draw any conclusion about trends.

    But Doug has made an unwarranted statement on trends by ignoring variability.. He (or the particularly denier/sceptic/contrarian he relies on) has assured us that there is no (positive) trend in the global temperature since 1998. That the observed trend over the last 50 years has “stopped.”

    Getting back to your sine wave. Mechanistically, over the extremely long term the problem is not global warming but global cooling. The thinking is that eventually all life will die out on this planet (mammals before bacteria) because incorporation of carbon below the earth’s surface will cause the global temperatures to drop drastically. Then of course the sun will expand in its death throes.

    But come off it. Humanity today is concerned about the present, the next few decades and centuries. Mechanistically our global temperature may be riding something like a sine wave, and we can only see as yet a small part of it. But that is the relevant part! It helps us to estimate what the near future might be.

    We are not trying to get a long term (millions/billions of years) out of this short temperature record.

    So, I say your comment is irrelevant because the long-term structure you allude to may only be seen over a billion years of record. Are you suggesting that humanity should therefore ignore the trend it has seen over the last 50 years?

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  15. Richard Christie

    @Has
    i enjoyed the Newton Institute presentation.
    It served to increase my confidence that climate models are being responsibly used and interpreted by the scientific community.

    Mind you, I can see the attraction to AGC deniers of disseminating such a video to scientifically naive audiences. When terms such as bias and uncertainty appear they can alarm those who don’t appreciate their use in a scientific or mathematical context.
    Sort of akin to frightening the children and the terminally bewildered.

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  16. Nick, the two protagonists here are arguing about whether or not there has been “global warming in the last 10 years”. If this is narrowly interpreted as the global temp hasn’t gone up you can probably get away with asserting that. This is different from saying there is a trend in the data. To counter the assertion that temp hasn’t gone up Ken goes onto fit a series of trend lines going back over the past and showing confidence levels.

    The problem is that this data set isn’t suitable for using linear regression on. It violates the necessary assumptions. It needs to be processed to make it stable. Now you might find this rigour somewhat tedious, but it generally leads to less certainty about what is happening (confidence limits expand particularly with short baseline periods). Understanding that and communicating it is the “big picture”.

    And BTW you say “As far as I know, nobody is making actual predictions using linear regressions, … ” but that is exactly what Ken is doing above and Zeke Hausfather is doing at the piece Ken cross references.

    Ken I had assumed that you were making the point that temperature changes were an artifact of changing climate. If not then ignore any comments about the relationship between the temperature series and climate. However the point about the temp series remains. When you stick lines through bits of the temp series and calculate confidence limits you are assuming the series has a structure it doesn’t.

    On the issue of time frames for forecasts I’d agree that its the generational time frame that is important, and that is where better understanding of the uncertainties and how they propagate in time is important. We have the choice of GCMs that were developed from weather models to provide virtual labs to study climate rather than forecast on these time frames, or stochastic models (of which time series analysis is a rudimentary example). The Newton Institute stuff in part talks about combining both approaches to improve our ability to forecast on these time frames because neither current approach is satisfactory.

    There is as far as I can see a real debate to be had about attribution issue i.e. how much of the warming is the result of lags, natural variation etc. This is really the argument you are having with Doug. IMHO what you are doing is over estimating the attribution by ascribing recent increases to GHG and ignoring the chances that what we are seeing might be natural fluctuations, Doug is understating it by saying “look its all gone away”.

    Neither of you are correct.

    Richard Christie I’m sure you didn’t really mean to say that only the elite should understand the uncertainty in the science. IMHO the political problem has been created by the exaggeration of the certainty in all this, and like Y2K people are now just quietly moving on. Better that people understand it is complex and uncertain.

    But then respect for ex-cathedra wasn’t part of my upbringing.

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  17. Perhaps Simon you can make your point understandable by explaining this ” It needs to be processed to make it stable.”

    What “processing” of the basic data being analyses are you requiring?

    Please be specific – it is a simple set of data and you can ignore its origins.

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  18. Simon, I did not provide the plot and trend lines to “counter the assertion that temp hasn’t gone up.” Their sole purpose was to show how such an approach can be misleading because selecting data and short periods enables one to say anything. Despite the fact that the overall trend since 1970 is one of a temperature increase.

    Global temperature increases may well have stopped in 1999. The point is such short term trend analysis cannot show one way or the other.

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  19. Simon Arnold

    Ken found http://www.esrl.noaa.gov/psd/people/brant.liebmann/papers/global_change/global.change-final.pdf that deals with this issue. If you look at fig 5c you will see that there are really no segments of 10 or even 20 years where the trend is greater then chance taking account of the structure of the time series (you should adjust the probabilities to take account of the argument being over whether there has been a positive trend i.e. use a one tailed test). The tongue is an interesting artifact of the data set. That aside there hasn’t been any significant trends in the series for any segments that didn’t include the post 1970 observations.

    Note the caveats even here about how well this represents the data, and note also this doesn’t tell you anything about causality.

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  20. Richard Christie

    ‘m sure you didn’t really mean to say that only the elite should understand the uncertainty in the science.

    (shrug) perhaps you are sure of that because I didn’t say that.

    Climate scientists are well aware of model uncertainties, biases and predictive limitations.

    Less clear is why you emphasized that CM results are “biased”.?

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  21. Simon, who the hell is claiming it does say anything about causality? The issue with Doug is whether he is justified in saying that the positive global warming trend stopped in 1998. That’s about the data – not mechanisms.

    My point about Doug’s claim that “1) There has been no global warming for 13 years despite increasing emissions of carbon dioxide.”

    This may or may not be factually true but his statement is misleading because such short time periods cannot reveal an overall temperature trend. Or support the claim that global warming stopped in 1998.

    Do you disagree with that?

    Do you support Doug’s statement.

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  22. Simon, have read the paper and still cannot see why you are quibbling. The authors make similar conclusions to mine although their analysis has enabled them to be more quantitative.

    Sometimes one can fool oneself by using over sophisticated techniques when simply eyeballing the data gives you a sufficiently accurate picture.

    As you say short time periods of the order of a decade or so will not show any statistically significant trend. However they will show either a positive or negative trend which, while not statistically significant, can be used, and are used, for dishonest political purposes.

    Those authors confirm my point that “trend estimates can change dramatically by including or excluding a few years at either end of the time series.” my point exactly and one can see why Doug has included the 1998 data.

    They specifically say of the so-called recent cooling period deniers claim that it is “well within the range of historical variability. Short-term trends of such magnitude (of either sign), therefore, are far from unusual.”

    Finally, the conclude that “the positive changes of long duration (several decades and longer) ending in recent years ate determined to be extremely unlikely to have occurred by chance”. Well, we knew that and this is why the IPCC concluded that evidence for recent warming is unequivocal. So why do you quibble? Do you think Doug’s assertions are correct or not?

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  23. Richard Christie I’m sure you didn’t really mean to say that only the elite should understand the uncertainty in the science.

    I’m sure he didn’t mean that either. Perhaps you should read what he wrote as opposed to putting words in his mouth in an attempt to build a strawman?
    Scientists are not “elites”. Not unless you define elites as being people with specialised training and experience to understand and do very complicated stuff in science.

    IMHO the political problem has been created by the exaggeration of the certainty in all this…

    The science has been clear for decades and uses multiple independent lines of evidence covering all the Earth Sciences. If you have found a flaw then write up a paper and claim your Nobel Prize. Don’t waste your time on the intertubes.

    …and like Y2K people are now just quietly moving on. Better that people understand it is complex and uncertain.

    Science is hard. It’s really, really hard. Super hard.
    Um, yeah, we know.
    It’s like medical science researching the link between smoking and lung cancer. It’s very, very hard.
    (yawn)

    But then respect for ex-cathedra wasn’t part of my upbringing.

    We have a new record!
    This one managed to avoid making spurious references to religion to denigrate science for four comments before surrendering to the dark side.

    (…Polite applause from the audience…)

    No that won’t do. Science is not a religion. Don’t be a tool. Science and religion are two different things. There are no high priests, no churches, no dogma and no popes.

    Well, we knew that and this is why the IPCC concluded that evidence for recent warming is unequivocal. So why do you quibble? Do you think Doug’s assertions are correct or not?

    Global Warming: It’s Not About the Hockey Stick

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  24. Simon Arnold

    Richard Christie, how then did you intend readers to interpret your comment equating non-scientists with children and the terminally bewildered? As to bias, it seemed relevant to Ken’s attribution arguments in respect of Q3.

    Ken, my comment about causality was not directed at anyone in particular or any argument. It is just the kind of comment one makes when being careful about what the evidence shows. As to whether Doug was correct in his statement 1. I’ve already said that on a literal interpretation of the term “global warming” you could make that claim.

    Equally I don’t think that the literal interpretation is what would be taken out of it by the man in the street. “Global warming” is these days taken as short hand for AGW.

    The reason I am quibbling is because you and Doug were both fitting straight lines to the data and arguing about who was right and who was wrong. This was and still is a nonsense.

    And unfortunately eyeballing the data doesn’t give a sufficiently accurate picture. You’ll get the wrong answer to whether what you are looking at occurred by chance, and worse you won’t know when.

    The thing you should reflect on is this. Just as you accuse Doug of cherry picking a short-period when temp is flat as evidence that global warming (aka AGW) has stopped, so too I hope you appreciate that when temp is going up this may be a consequence of chance not external forcings (and given the nature of the temp time series, more likely than if it were a simple linear process).

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  25. Simon – sure “you could make that claim” but don’t be disingenuous. I am asking if you think Doug is justified or is he misrepresenting the situation by selecting a short time period and a high temperature start?

    Perhaps you should read Doug’s letter (I have provided aink above). He was not fitting a straight line to the data – he just made the bald statement. Plenty of people do though and then go on to make the claim he did.

    I was not drawing any quantitative conclusion from the trends I showed – just attempting to demonstrate that short term trend fitting like this is meaningless because they don’t represent anything statistically significant. The paper you referred confirmed this in more detail using the entire data set.

    Why are you so concerned that “”Global warming” is these days taken as short hand for AGW”? Are you worried that the public accepts what the IPCC has been saying? But anyway, why here – that particular difference with Doug is not related to any cause?

    As for this – ” I hope you appreciate that when temp is going up this may be a consequence of chance not external forcings” – didn’t I say as much? My comments, as those in the paper you referred, apply to both positive and negative trends over short time periods.

    The fact remains though, either one uses a simple regression on the anomaly data or does a more complex statistical analysis the conclusion is the same as the paper you refer shows. There has been a statistically significant trend of increasing temperature since 1970.

    Do you wish to dispute that – or just confuse the issue?

    I suspect the later as you seem to want to cast suspicion on the current scientific consensus as reported by the IPCC – you have chosen to bring in a meaningless, or at least irrelevant, reference to complex statistical procedures when these result in exactly the same conclusion.

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  26. Equally I don’t think that the literal interpretation is what would be taken out of it by the man in the street. “Global warming” is these days taken as short hand for AGW.

    Then ignore the man in the street.
    Focus on NASA.
    They are happy to tell you that global warming and climate change is man-made.
    They have a website and everything.

    NASA: Climate Change; A Warming World (HD)

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  27. Richard Christie

    how then did you intend readers to interpret your comment equating non-scientists with children and the terminally bewildered?

    I noted similar modus operandi as used in frightening children or fleecing the righteous.

    Here’s more

    The climate denier buzzes in and immediately starts laying its eggs;

    blah blah blah, UNSETTLED SCIENCE, blah blah blah, BIASED METHODOLOGY, blah blah PRATT blah blah PRATT blah blah FLAWED MODELS (and at some stage, usually later … ABUSE OF PEER REVIEW …DESTROYING THE ECONOMY..blah blah HIGH PRIESTS OF ALARMISM blah blah )

    Include links to Wattsupwiththat, Fox News and The Sunday Telegraph, or, if the troll is unusually clever, links to a bona fide science articles using alarming words such as “uncertainty” or maybe even “biases”.

    Doesn’t matter if the readers even understand the terms in such contexts, hearing them is all that’s required as doubt is the denier’s product.

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  28. Simon Arnold

    Ken, relax. I’m not concerned about whether people these days equate the term “AGW” with “global warming”. The meaning of terms change over time. Rather Doug made a claim that is technically correct, but exploited this change in meaning (and no doubt he did it with with malice aforethought). I simply drew attention to it.

    I’m being what is called evenhanded. You should try it.

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  29. Merchants of Doubt. Well worth a read.

    That book is an amazing read. I even sent a few copies to some deniers I know. Who knows? Maybe they will read it?

    Naomi Oreskes is an incredible science historian. The rewards and acclaim she has won from the scientific community are richly deserved. Her research is exhaustive and disturbing. The tobacco companies have a lot to answer for. Those who forget history are doomed to repeat it.

    Answering Climate Change Skeptics, Naomi Oreskes

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  30. Simon, when you claimed to be even handed I ran off to check Doug’s post at the Climate Conversation Blog.

    Nope, your even handedness hasn’t stretched to raising these issues with Doug via a comment on his post.

    Perhaps you are still getting around to it?

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  31. Simon Arnold

    Nope, I commented here because you cross post at Sciblogs and I follow that blog. Never heard of the Climate Conversation Blog before today.

    I don’t mind you mentioning the stuff I’ve raised here with Doug if that helps.

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