.

Saturday, October 24, 2015

The IPCC climate message is clear based on the evidence: The fundamental flaws of Hollin & Pearce

Sou | 3:17 PM Go to the first of 10 comments. Add a comment
In June this year I wrote about a paper in Nature Climate change concerning the press conference for the release of 2013 IPCC report WG1. In the paper, G. J. S. (Gregory) Hollin and Warren Pearce from the University of Nottingham claimed that the IPCC speakers at a press conference “threatened their (own) credibility” took an “an incoherently oscillating position”, and caused “confusion within the press conference and subsequent condemnation in the media”.

Hollin and Pearce were fundamentally wrong in all of these claims, and more:
  1. Clear message about different time contexts: A comment to the letter by Jacobs et al (Jacobs15) has just been published, which identifies major flaws in the paper. Not least of which is that Gregory and Warren do not understand the difference between the "hottest decade" since records began, and the recent short term slowdown in the ongoing rise in the global mean surface temperature. Jacobs15 and its supplement also identify some other flaws that should never have slipped through the review net, and which undermines their unsupported claims even further.
  2. The journalists were not confused: Arguably the biggest flaw in the NCC letter was that Warren and Gregory didn't bother to check for evidence to support their case. Their entire argument rests on their claim that the IPCC confused the press. But it didn't. Not at all. An examination of the articles subsequently written by the journalists who asked a question demonstrates that the IPCC’s message was clearly received. It did not confuse the journalists, nor was the IPCC's credibility eroded in any way. If anything it was enhanced. You can download the report about the media articles or open it directly.
  3. Only David Rose "condemned" (as usual): There was no general condemnation of the IPCC. The only condemnation from journalists who asked a question at the press conference, was from one single source: David Rose, who has a history of misrepresenting the IPCC and climate science. And David Rose's silly article was the entire sum total of the "evidence" that Gregory and Warren offered in support of their claim of "condemnation in the media". 
  4. It was also David Rose who provided "incoherence: Gregory and Warren spattered their article with the words "incoherent" and "incoherence". This word first appeared in the "condemnation" article by David Rose - it wasn't an original thought from Gregory and Warren. This lends further credence to the notion that Warren and Gregory penned their article with David Rose in mind. (See below).
  5. David Rose was not dismissed as scientifically illiterate: The authors were wrong when they said that David Rose was dismissed as being "scientifically illiterate". He wasn't. I covered this point in detail in my previous article on the subject. It's also covered, with references, in the supplement to Jacobs15. It's another case of Warren and Gregory not understanding something that most other people would understand.
  6. Questions on the recent slowdown were not ignored. The authors were also wrong when they claimed that the IPCC said the "pause" (as Warren and Gregory called the slowdown) was scientifically irrelevant. They didn't. Nor did they ignore any of the questions about it, contrary to what Warren and Gregory claimed. The supplement to Jacobs15 covers this point well, with references. (You can download the supplement here.)
  7. And the above doesn't even cover the many question marks around their main hypothesis, that the general public can only relate to events that are close in time to the present. What they loosely term "public meaning" and "temporal locality". 

When I wrote the first article, it seemed obvious to me that the letter from Warren and Gregory was a sop to David Rose. Since then I've done some more investigating, and so have others. It seems even more obvious to me that this was just two people seeking some payback on behalf of UK tabloid journalist David Rose for an imaginary grievance.


How David Rose provided "incoherence", borrowed from Richard Lindzen


For starters, Gregory and Warren took a liking to the word "incoherence". That was a curious word to adopt. Here is part of the opening paragraph from Gregory and Warren's paper:
However, when journalists enquired about the similarly short ‘pause’2 in global temperature increase, the speakers dismissed the relevance of such timescales, thus becoming incoherent as to ‘what counts’ as scientific evidence for AGW. We call this the ‘IPCC’s certainty trap’. This incoherence led to confusion within the press conference and subsequent condemnation in the media3.
Notice the words I've emphasised. I've figured out where the incoherence came from - it's from David Rose himself, via Richard Lindzen. It came straight out of the article that David Rose wrote following the IPCC press conference:
  • IPCC accused of sinking to 'hilarious level of incoherence' (source)
  • Prof Richard Lindzen, the Alfred P Sloan Professor of Meteorology at the Massachusetts Institute of Technology, said the IPCC had ‘truly sunk to a level of hilarious incoherence. (source)

So who came up with the notion that the IPCC was "incoherent"? It was David Rose, who got the idea from Richard Lindzen. Richard Lindzen in these his golden years, as you probably know, has taken to the speaking circuit where he hawks his science denial. That Warren and Gregory got the idea from David Rose is hardly a surprise. The main purpose of their article seems to have been to defend poor defenseless David Rose. But before we get to more evidence of that, what about the core premise of their paper?



Out of time (scales) - how another basic premise was wrong


The claim that the IPCC caused confusion seems to have been based on what you might call a confusion about climate on the part of Warren and Gregory (if you were feeling generous). They were confused about the difference between the hottest decade on record (since at least 1850, and almost certainly for many, many centuries) and the recent slowdown in surface temperature.

This pair wrote at length about "public meaning" and "temporal locality".  What they were arguing was that people don't relate ("public meaning") to anything much longer than a few years. And they relate to short term events in near time ("temporal locality") much better than to events in the distant past (or future).

That's fair enough for some people I suppose. Anyone planning their superannuation, or taking on a home mortgage, or building something to last for fifty years or more would be exempt, I expect. Likewise people who work for massive mining investment companies like BHP, people who design power plants, or hydro-electric schemes, or cathedrals. And older people are probably able to take a longer term perspective. If you can look back on 90 years you're probably capable of imagining 90 years hence.

However where their argument of "incoherence" completely fell apart was when they claimed that the "hottest decade" and what they called the "pause" were both on the same timescale. They weren't, and neither were they presented as such at the IPCC press conference.
  • The recent slowdown is only on a timescale of years - since 1998 if you go by the IPCC's discussion of the so-called "hiatus"
  • The "hottest decade" is on a timescale of generations - since at least 1850 when discussed at the IPCC press conference.
The period of the slowdown in global mean surface temperature is hardly comparable to the hottest decade in sixteen decades.

Figure 1 | Decadal surface temperatures from 1886-1905 to 2006-2015. The difference between the short period of the recent "slowdown" (shown by the small rectangle above the word "slowdown"), defined by the IPCC as being from 1998 to 2012, a period of 14 years - and the "hottest decades" (shown by the long rectangle below the words "hottest decades"), which are in relation to the entire record, going back to 1850 (earliest years not shown here), a period of 165 years. Data source: GISS NASA

Even in their reply to Jacobs15, Warren and Gregory insist that talking about the "hottest decade" (and presumably the series of hottest decades) is a misapplication of what they now term the "30 year rule". But it's not. In their original letter Warren and Gregory claimed that references to the hottest decade since records began are examples of "recent and shortterm climate changes", which is also nuts. The warming is is in the long term context, not the short term. It refers to a period much longer than 30 years. The hottest decades of the past 16 decades (and probably at least 100 decades) been "recent" now for at least forty years! Quite a lot longer than their "pause". And the time context is centuries to millenia - much longer than 30 years.

It's worse than that though. When Warren and Gregory listed quotes of IPCC people talking about the hottest decade, they claimed: "speakers attempted to make AGW meaningful by temporally localizing the terms of reference, focusing particularly on recent and short-term climate changes". Problem is, all the three quotes they referenced specifically talked about the "hottest decade" in the context of long-term climate changes, not short-term. Not one of them "focused particularly on recent and short-term climate changes. Here are the quotes they used to support their wrong claim:
  • The decade 2001-2010 was the warmest on record [ie since 1850], continuing the trend of global warming. Jarraud (L84-85) 
  • Each of the last three decades that you see at the right end of this graph has been successively warmer at the Earth’s surface than any preceding decade since eighteen fifty. Stocker (L418-420)
  • I also want to highlight the fact that each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. And this is something that Dr Michel Jarraud has talked about when he mentioned the decade 2001 onwards having been the hottest, the warmest that we have seen. Pachauri (L257-263)

The journalists knew the difference. I checked. The press conference was mainly attended by science and environmental journalists, who are clearly much better informed about climate science than are Warren and Gregory. I've prepared a synopsis listing each journalist who asked a question, their question, and where possible, the article they wrote following the press conference. The article that stood out like a sore thumb was the one from David Rose. All the others were pretty much consistent with the IPCC report and the press conference.


Do Warren and Gregory think it's cooling?


One thing you might deduce from their climate confusion is that Warren and Gregory "believe" that it's about to get colder. Perhaps an ice age is comething. How else can you explain the fact that they think the "hottest decade on record", the hottest decade in 160 years, where each of the last three decades is successively warmer - is merely a "recent and short-term" climate change, rather than the long term trend that it is?

Gregory and Warren called the recent slowdown in surface warming a "pause". The IPCC called it a "hiatus". In a blog article on the subject, Warren even let slip that he thought global surface temperature had decreased, writing "the short-term decrease in temperature witnessed during the 15-year ‘pause’."

What "short-term decrease" could he be talking about? There was none. The world continued to warm, even though at the surface, after the late 1990s it didn't warm as quickly as it had been in the years immediately prior. It still warmed. 2005 and 2010 were the hottest years on record until 2014.
Not only was the "hottest decade" in the context of long term climate time frames, "hottest decades" are likely to keep on coming. They are with us for the long haul. We have been having "hottest decades" now for about forty years, and barring a massive volcanic eruption, we're likely to keep having them for quite a few more decades.

The journalists at the press conference understood that. I'd say that David Rose understood that. The only people who don't seem to have understood that were Warren Pearce and Gregory Hollin - and maybe the people who reviewed their original paper before it was published at Nature Climate Change.

Only one person was "incoherent" in his messaging: David Rose


There's more.  The main point that Gregory and Warren were wanting to make was that the IPCC was "incoherent". That they didn't convey their messages clearly. That's wrong, and I can show it.

In complete contradiction to this main premise, of all the journalists who asked a question at the IPCC press conference, the only journalist who misrepresented the IPCC presentation afterwards, was David Rose himself. I checked. Of all the 18 journalists who asked a question at the IPCC presentation, David Rose was the only person who distorted the message. You can check for yourself. I've drawn up a list of the journalists who asked a question, the question(s) they each asked, and the articles they published after the press conference. You can access it here - or download the pdf directly.

The only person who made a mess of things was David Rose. So that hits on the head the main argument that Warren and Gregory made, which was that the IPCC was "incoherent" and confused people. The IPCC might have confused David Rose, but I doubt it. He has form in misrepresenting climate (read on).


One of many misrepresentations from David Rose 


Let's take a step back.

In the weeks leading up to the release of the IPCC's AR5 report, on the science of climate change, David Rose had written a number of articles in the Mail, utterly misrepresenting climate change and including misleading claims about the IPCC. For example:

And now it's global COOLING! Record return of Arctic ice cap as it grows by 60% in a year - David Rose's very silly and misleading article on the 8 September 2013 (HotWhopper article).  In that article, David Rose even wrote that "The continuing furore caused by The Mail on Sunday’s revelations – which will now be amplified by the return of the Arctic ice sheet – has forced the UN’s climate change body to hold a crisis meeting." That prompted the IPCC to issue a statement confirming that there was no crisis meeting being held. David was misrepresenting a regular IPCC meeting as a "crisis". Twenty days later, David Rose or his editor subsequently changed his Daily Mail article, with the slightly less raucous but still misleading headline "And now it's global COOLING! Return of Arctic ice cap as it grows by 29% in a year". And got rid of the wrong claim about the IPCC meeting.


Global warming is just HALF what we said: World's top climate scientists admit computers got the effects of greenhouse gases wrong - another wrong David Rose article in the Mail on 14 September 2013 (HotWhopper article).  It wasn't just the fact that he didn't cite any of the world's top climate scientists, but he was, of course, wrong about his computer claim as well. In fact you'd be hard pressed to find an accurate sentence in the entire article. This time it was the UK Met Office that published a statement correcting some of David Rose's wrong claims. (A later version of the article had the headline: "World's top climate scientists confess: Global warming is just QUARTER what we thought - and computers got the effects of greenhouse gases wrong")

David Rose subsequently attended the IPCC meeting. Despite his attacks on science and his scurrilous misrepresentation of the IPCC, he was treated in the same manner as the other more responsible journalists who asked questions. Following the meeting he was the only journalist who misrepresented the meeting and the reports.


Warren and Gregory leap to the defense of David Rose


Gregory and Warren didn't seem to be hiding the fact that their paper was a defense of David Rose. In fact, David Rose was the only journalist they mentioned in their paper, writing:
This `temporal segmentation' enabled the pause to be dismissed as scientifically irrelevant, suggesting that journalists' questions on the matter could be ignored. Jarraud offered just such a dismissal to Rose's question, which he claimed was 'from a scientific point of view...what we would call an ill-posed question’ (L827-828), essentially dismissing Rose as scientifically illiterate....
...When Rose3 published his article the following day, the quote "your question is ill-posed!'' was given headline status, and derided as a misjudged response to ``a simple question''. 
And who decided that the IPCC panel members dismissed David Rose as scientifically illiterate? Only Warren and Gregory. Who decided that David Rose's portrayal of the response was derision? Warren and Gregory. Here is how David Rose presented it:

Figure 2 | David Rose's reaction to his question being recognised as "ill-posed".
Source: David Rose, Mail article, September 2013.


The scientific relevance of the recent slowdown in surface warming


Warren and Gregory said that the IPCC said on the one hand that the recent slowdown in surface warming (which they kept calling the "pause") was scientifically irrelevant, but on the other hand talked about the hottest decade being very relevant to human-caused global warming. They ignored the fact that the IPCC representatives said the slowdown was scientifically of interest, but that it wasn't significant in the context of long term global warming.

Either Gregory and Warren didn't realise that the hottest decade in the context of long term temperature trends, or they were playing games. What made the decade to 2010 the hottest, were all sixteen or so decades before it that were cooler. In other words, the hottest decade was in the context of climate change of at least the past 160 years or so of the instrumental record - the long term not the short term. And as is now known, it's in the context of at least the past 1,000 years.

The recent slowdown on the other hand can be regarded as short term variability. As the IPCC panel members explained, the period between around 1998 and 2012 was interesting in the manner any short term variability is interesting. It helps scientists tease out more details of weather and climate.

Below are some charts of surface temperature over recent times. If you click the to the first chart (bottom left-most button) - the period 1998-2012 -  and there was no temperature decrease. The other charts go back in time to 1990. The final chart is from 1990 to 2015 (year to date). I've kept the vertical scale the same for all the charts, so you can see that as you go back in time the chart gets steeper. However even what Warren and Gregory call the "pause" (and the IPCC calls the "hiatus") the surface temperature wasn't decreasing. It was getting warmer. 2005 and 2010 were the hottest years on record until 2014.

Figure 3 | Slideshow of recent temperature trends.. The slides show temperature trends going back progressively from 1998-2012 to 1990-2012, with the final slide being from 1990 to 2015 year to date.
Data source: GISS NASA


There was no dismissal


Warren and Gregory claimed that the IPCC dismissed the so-called "pause" as "scientifically irrelevant, suggesting that journalists' questions on the matter could be ignored". That's just plain wrong. First of all, the IPCC didn't dismiss the recent slowdown in surface warming as irrelevant. In fact, Michel Jarraud at one point (L1052-1055 of the transcript - see Supplementary Information A here) said about this period that:
...let’s be careful not to interpret that in terms of trend, but very interesting work is being done by the assessment to try to understand the elements of these variability and to do a bit of attribution, which is a tricky issue.
Neither did the IPCC panel members ignore any questions about recent surface temperatures. Warren and Gregory were a bit sloppy and said six journalists asked a question about it. However an examination of the transcript and video only finds five questions ( including some for which it was only a minor part of a longer question). None of these questions were ignored. A lot of time was spent answering them. (This is detailed in the supplementary information to Jacobs15.)


The IPCC Press Conference


The video below shows the IPCC press conference. The report I prepared has links to the video, which opens at the point at which each journalist asked the question. So you can check for yourself quite easily.




Warren and Gregory provided a transcript of the conference, with line numbers. The HotWhopper report also shows the line numbers where each journalist asked the question, so you can read the question and response. (You can do a search of the transcript for the relevant line numbers.)


More incoherence from Warren and Gregory: Global warming is "Abstract Knowledge"!


Jacobs15 points out much of what I've written here. In reply, Warren and Gregory seem to have themselves become incoherent, writing:
That Jacobs et al. critique our recent Letter about public meanings attached to abstract scientific knowledge by using even more abstract scientific knowledge reaffirms this central point: that scientific knowledge alone, no matter how certain, is poorly suited to meaningfully communicate climate change5.
What? Their reply suggests that they still don't know the difference between the hottest decade since records began, and the recent slowdown in warming. And wow! It's hardly "abstract scientific knowledge". It's been observed and quantified and there is sound and clear theory explaining the warming. You can see it in the rising sea levels, and melting ice, and hotter heat waves, and hotter droughts, and shifting plant zones, and more and fiercer floods and downpours.

Warren and Gregory are still confused by the certainty that temperatures keep rising. They wrote:
Continuing this misplaced focus on certainty, much of the correspondence from Jacobs et al. gives supporting scientific evidence for the claims of certainty made by speakers during the press conference for the Working Group 1 contribution to the Fifth Assessment Report of the IPCC.

To what "focus on certainty" are they referring? They don't say. Could it be the certainty that global warming is happening that upsets them so? They introduce mention of a "30 year rule"(in their original paper they mentioned "30 years" a few times, but in a way that showed they didn't understand what it meant). It certainly seems to me that they still don't understand that the hottest decade is in the context of a much longer period than 30 years. They wrote:
Emphasizing the past decade, as IPCC speakers do, may well help to make anthropogenic global warming meaningful and potentially motivational for action. However, this emphasis on the decadal scale also seems to makes journalists’ questions about ‘the pause’ both reasonable (because it is also decadal in scale) and meaningful (for it might seem to demotivate action). If asking about the decade-long pause is an “ill-posed scientific question”, as asserted by Michel Jarraud during the press conference, then using the past decade of heat and extremes to emphasize the meaningfulness of anthropogenic global warming is not scientifically appropriate. It is the resulting confusion among journalists, caused by the flexible application of the ‘30-year rule’, that illuminates the tension between certainty and meaning faced by climate communicators. 

They still don't get it. Or pretend they don't.
  • It's wasn't the fact it was about the warming slowdown that made David Rose's question ill-posed. Warren and Gregory would know that by now (they would have read my blog article on the subject). It was the way David Rose framed the question.  Ill-posed is a term used in science and mathematics, meaning that as framed there is no possibility of a meaningful answer. (In mathematics it means that a problem has not been stated in such a way that there is an unambiguous and unique solution (refer Hadamard's definition).
  • Global warming can be readily seen on decadal time scales. That is, over multiple decades. Warren and Gregory are feigning ignorance here. They are confusing decades and decadal. Even using the IPCC's "hiatus" period (1998-2012), that's only fourteen years. You need several decades if you are going to determine a decadal trend, not barely one and a half decades. (Look again at Figure 1 up top.)
  • There was little evidence of any "resulting confusion" among journalists, as the articles that were written after the press conference demonstrate.


The sad, not sorry, last word


Oh, and when a duo who've never written a climate science paper in their lives and don't seem to understand the first thing about it, write the word "sadly" in their closing sentence, referring to world-renowned scientists who hold arguably the most senior positions in their field - I call "presumptuous insolence", or "hubris". These are the last words in their reply to Jacobs15.
but, sadly, the press conference in question was not such an example.

What's "sad" is that Nature Climate Change published their original letter full of misunderstanding of climate, and that their reply shows that Gregory and Warren don't understand much about climate.

What's even sadder is that "pauses" still seep into science journals, and the world still isn't doing enough to stop global warming.


References and further reading


Peter Jacobs, Hunter Cutting, Stephan Lewandowsky, Miriam O’Brien, Ken Rice and Bart Verheggen. "Clarity of meaning in IPCC press conference." Nature Climate Change 5, 961–962 (2015) doi:10.1038/nclimate2845 with supplementary information (pdf here)

G. J. S. Hollin & W. Pearce. "Reply to 'Clarity of meaning in IPCC press conference'." Nature Climate Change 5, 963 (2015) doi:10.1038/nclimate2846 (pdf here)

G. J. S. Hollin & W. Pearce. "Tension between scientific certainty and meaning complicates communication of IPCC reports." Nature Climate Change 5, 753–756 (2015)  doi:10.1038/nclimate2672 - Supplementary Information A has the transcript
The IPCC climate message is clear: Evidence from media reports from journalists who asked a question at the IPCC press conference, September 2013 - compiled by HotWhopper (Download or open the pdf)

IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp. (download here)

    Humiliating mistakes by 'The Mail on Sunday' - article by Bob Ward


    From other blogs



    From the HotWhopper archives

    10 comments:

    Marco said...

    Unsurprising to see Warren Pearce doubling down when shown wrong. I remember how he called Watts a genuine skeptic, because he put some articles on WUWT that questioned some really way-out-there 'skeptical' arguments (the sky dragons were specifically targeted), ignoring that a few days later those exacts same faux-arguments were used again in another article he put up on his homepage - by Tim Ball of course.

    It looks like Nottingham is deliberately hiring these kind of confusionist social scientists (Reiner Grundmann is there now, too).

    Everett F Sargent said...

    Sou,

    I'm Ethan Allen over at ATTP's.

    I'm sort of guessing this subject is the reason for less frequent posts lately.

    Your post is a good one, however there is some repetition and it is rather lengthy.

    As to the GISS data (you've shown above), is that the current GISS dataset or the GISS dataset circa before the NOAA revision (I'm sort of thinking that GISS incorporated the NOAA update but I'm not sure)? I'm thinking one would need whatever SAT (and UAH/RSS) datasets were used in the IPCC reports say circa through 2012. (per Figure 1 of your reply).

    I'm also thinking that W&H may have been listening to the Deniers too much, as in the UAH/RSS datasets. Anyways, whatever Deniersville was claiming back then, say negative temperature trends circa 1998-2012 is likely to still be in existence, if so, that's a dead giveaway that W&H were reading Deniersville stuff back then (or even right up to submission of their draft paper) IMHO.

    The "is very different from the short-term decrease in temperature witnessed during the 15-year" in their original blog post suggests 1998-2012 era, so which blog/newspaper/Monkers and which temperature dataset(s) showed a "short term decrease" I wonder? I smell a potential rat.

    You refer to Gregory and Warren which are their 1st names, that one confused me for a bit.

    Everett F Sargent said...

    Yup, I ran across some of his (Reiner Grundmann) droppings a few years ago.

    Sou said...

    Fair comment(s), Everett. Esp re me being a bit of a windbag :( (The NCC comment appeared a few days earlier than I expected, so this HW article wasn't edited as well as it could have been. No excuse, I know.)

    I've linked to pretty well everything relevant in the article. The chart showing the trends as used at the presentation are in the video (eg see here), and in the comment and supplementary info. Same thing.

    I've no idea where they got their "decrease" from. (Their original article and blog post were only published in June this year - after the "hottest year" of 2014, and well into the hottest year of 2015.)

    IanR said...

    Sou, now we know why you're been AWOL these past few days. That is a helluva lot of work you've put. Thank you.

    Everett F Sargent said...

    I've posted some dates at ATTP's 01 December 2014 was the original submission date, we can only see the final paper though and revisions up to potentially Accepted 01 May 2015. Their blog post is dated June 8, 2015.

    So does the "downward" or "negative" or language of that sort appear anywhere in the as published paper (I'm assuming you have a copy)?

    They do say "downward" in their blog post and I really don't think they bothered doing their own trendline analysis of the 5 known temperature datasets.

    Ergo, they saw that "downward" description elsewhere's and ran with it.

    I'm pretty sure that the RSS dataset is the only dataset that has been promoted with a downward (and still not statistically significant) trend.

    I'm sort of playing the part of The Auditor (their ruleZ not mine).

    Seriously, do W&H have any stats training at all? If they look at a graph with no error bars for the trendline (like what you always see at WUWT?), it stands to reason that W&H are effin' idiots.

    I'm sorry for venting like this but stuff like this just makes my blood boil so to speak.

    Sou said...

    No - this pair only talked about a "temperature decrease" in their blog article about their original paper. It's not in the paper itself.

    I think of it as "doing a Curry". (Judith Curry writes a lot of denier nonsense on her blog and in her government testimony, which she doesn't put into published papers.)

    Cugel said...

    Thanks from me too.

    "What made the decade to 2010 the hottest, were all sixteen or so decades before it that were cooler."

    Simply brilliant.

    Victor Venema said...

    The 30-year rule of the thumb is for station data. Station data has a year to year variability of about 1°C (it depends on the local climate, naturally). Thus an average over 30 year has a confidence interval of about 1°C/sqrt(30) = 0.18°C.

    The variability of global averages is much smaller. From the graph shown above you can estimate that it is about 0.1°C; let's be generous and say: 0.2°C. Thus the confidence interval for a decadal mean of the global temperature is 0.2°C/sqrt(10) = 0.06°C.

    A decadal average of the global mean temperature is thus more certain than the 30-year average of the temperature measured at a station.

    Thus even without seeing the decadal average temperature in context of the last 150 years, the decadal temperature is perfectly well defined.

    To add to this tragedy, computing a trend needs much more data than an average. It is a bit comparing apples with oranges (an ill-posed question), but you can imagine that you need at least 2 reliable averages to see a change.

    Joshua said...

    Nice work, Sou.

    It would be good to see P&H address this post (hmmm. I think I won't hold my breath)...in particular your treatment of whether or not journalists were "confused" by the press conference.

    It was hard to understand how they could have made their argument about the resulting "confusion" simply by assertion and still get the paper published.

    But at this point, with your work in establishing that not only was evidence in support of their claims lacking, but that the evidence that exists is actually in direct contradiction to their assertions....well, I'll just say they've really got some 'splaining to do.