The decadal mean temperature graph

Perhaps the most ridiculous graph in the IPCC AR5  SPM is this one showing “decadal mean” temperature.

A few points about this graph:

  • As far as I know, such a graph has not been used in any peer reviewed publication
  • The graph was not in the draft version of the SPM subjected to expert review
  • No such graph has been used in any of the previous IPCC reports.
  • I’m not aware of any such graph being used in any other field of science – any examples?

So why is the graph so bad? It’s hard to see why it is necessary to point this out.  Firstly, it takes a graph with about 160 data points on it, and reduces this to just 16, effectively throwing away most of the data.  Secondly, the appearance of the graph depends very much on how you choose to do the 10-year cuts. They seem to have chosen either 0-9 or 1-10 bins (it’s not clear which) so that the last two or three years aren’t included at all. But if we chose 5-4 bins, the picture would probably look quite different (has anybody done this?).  The introduction of this graph into AR5, with no such graph in the previous reports, leaves the IPCC open to accusations of trying to “hide the decline” in warming this decade,  though of course the levelling off is clear in the graph above, so the graph seems quite pointless.

In the draft version of the SPM reviewed by scientists, this graph was not there, perhaps because the authors were aware that it might be criticised.  This illustrates the point about the authors having carte blanche to insert whatever they like into the final version after the review.   The decadally averaged graph was there in the main section of the report, in chapter  2, Fig 2.20 (In the final draft version, it is Fig 2.19).  In my review comments, I was very critical of this graph (“Fig 2.20 – I am surprised to see this absurd figure still in the SOD. No such figure appears in the cited paper Morice et al, or in any other published paper I am aware of , or in previous IPCC reports. Such a figure would be widely and rightly ridiculed as an attempt disguise the recent slow-down of warming.”)

The IPCC responded to my criticism by putting the graph in the SPM.

I have not seen much comment on this graph.  But Reiner Grundmann tweeted “Summary for policymakers dodges issue of ‘pause’ in global warming. New fig.1 makes problem invisible” and “So SPM replaced the ‘dodgy sandwich’ graph with an ‘elevator’ graph of decadal temp rise. Good PR, but is it sustainable?” on the day the SPM was published.

This type of graph seems to have originated in a Met Office press release from 2009, although the IPCC version seems to be based on this one from 2012 from the EEA.

Update, October 2: Thanks to John Kennedy for pointing out that the decadal mean graph appeared in the 200+ page report, “State of the climate in 2009” (Fig 2.3).


22 thoughts on “The decadal mean temperature graph

  1. Is there any official body (the Statistical Society eg) which lays down rules of good conduct for graphical representation of statistics? It shouldn’t be difficult, I’d have thought, to get relevant professionals (scientific and economic journalists, market researchers, writers of official reports in government, think tanks, etc) to agree to some very simple basic principles.

  2. Hi Paul

    Is our very own Met Office contributing/lead authors,the ‘guilty’ party?
    see this Met Office Report July 2013 about “the Recent Pause In Warming”

    Report 1, pg 8, has a very similar looking graphic, labelled ‘source and methods as Hadcrut4 & Morice et al2012)

    all the reports here:

    or have others been using similar graphics before the Met Office?

  3. But the graph you show is panel (b) of Figure SPM-1, directly underneath panel (a) which shows year-by-year variability and shows the recent pause (see page SPM-7. In fact they are joined so closely that the labelling of the y-axis has been chopped in half in your cut-up version above.

    So it’s quite obviously not an attempt to hide something, as it would be impossible to see panel (b) without also seeing panel (a) – unless of course one was to deliberately cut it in half as you have done! Why did you do that?

    It’s valid to show the decade-by-decade changes, because these are the timescales on which long-lived GHGs have an effect. As long as it’s also accompanied by information on the year-to-year variability so that readers can see that there are other processes going on that affect things on shorter timescales, nothing is being hidden here.

    It’s a red herring to say that this graph wasn’t reviewed in the draft SPM, because (as you say) it was in the draft chapters that were subject to review, so it has been reviewed.

  4. So it’s quite obviously not an attempt to hide something, as it would be impossible to see panel (b) without also seeing panel (a)

    Except, of course, that the decadal version will be the one seen by the public, out of the context of the graph above. Sure enough that is exactly what Revkin did on Dot Earth 0n 27 September.

    Seriously Richard, don’t you think that the entire purpose of that graph is to obscure the offending halt in temperatures? What other purpose does it achieve? Are you so naive that you believe that everyone will go back to the SPM to check that it is reported correctly in context?

    The purpose of the new graph is to hide something. Only in the “black is actually white” world of climate science would a scientist not admit that.

  5. Of course, Richard is right about the two charts appearing together, but Mooloo is also right that they would not necessarily be reproduced together elsewhere. Having some experience in data viz training, it does seem a bit unusual to represent the same data in two different ways next to each other like this.

    The guru in these matters, Edward Tufte, emphasises information density as key to the success of any graphical representation of data. Panel (a) still seems to me like it is showing a recent upwards trend, but the decadal average chart loses a lot of the nuance.

    Also, what happens to the chart when you start the decades from a different year eg 1985-95, rather than 1980-1990?

    Geoff: I’m not aware of any ONS best practice, but this Tufte chapter on ‘corrupt evidence in data presentation’ is a winner on what not to do: There’s also a good guide from Local Gov Unit in Wales, but alas it does not cover decadal averages

  6. Richard, yes, I partly agree with you – in fact I did say ‘the levelling off is clear in the graph above’ (about which someone has just disagreed with me on twitter). Regarding the review process, we’ll have to wait and see whether any reviewers said ‘This is a really great graph, please put it in the SPM!’

    Warren, that’s what I meant when I said ‘5-4 bins’, though I didn’t express it very clearly.

  7. It’s very interesting Richard that you point out the juxtaposition of the two graphs in the SPM, but not yet having had time to read that document yet I was not aware of that. I have however seen the decadal mean temperature graph produced several times, often by enviro organisations, who obviously thought it was not worthwhile producing the year by year temperature graph.

    If you, or anyone else at the IPCC, didn’t realise this graph would not be exploited, even if we were to accept that was not its main purpose, then you are naïve.

  8. I am of the opinion that this type of chart spins out of the meaningless statement “the warmest decade on record”. A statement favoured by Prof Slingo and the UKMO.

    Meaningless because it is possible for each successive decade of this century to be “the warmest on record” and yet the planet to have warmed by no more than +0.10C. A near zero rate of warming can produce a series of “warmest decades on record” .

    This issue is about the real world (observed) rate of warming, which I am sure it hasn’t gone unnoticed has been reducing since 2003. That is according to the WMO 30 year rate of warming and if the 60 year cycle, which is becoming more and more evident with every month that passes is to play out then were are faced with a reducing rate of warming for a further 20 years.

    Can’t find any mention of the 60 year cycle in AR5 but it stands out starkly in the much vaunted WMO 30 year rate of warming chart.

  9. Well done on the blog!

    Like almost everything else in the report this graph was chosen to hide the decline (pause) and to exaggerate the warming.

    And like so much they have shot themselves in the foot by doing this because when everyone knows about the pause and it is all too obvious that this graph was chosen to hide it.

    And the result is very obvious. I have been searching all day – on what were once “alarmist” forums, and it is becoming increasingly difficult to find any where there are alarmists contributing.

    Speaking with my MBA hat on, I have to say that in terms of engagement with the public, AR5 has been a PR disaster. It has done nothing to improve the IPCC credibility and a lot to enhance the stereotype of a group trying to hide the facts about the climate.

  10. I’m so glad someone else picked up on this. If you change the time ranges to 5 years, and include years 2011 and 2012, and replot, then we end up with two 5-year bands (2003-2007 and 2008-2012) that would be at about the same temperature level which re-establishes the “pause”. However, I think 1998-2002 would still be lower than those two later bands which would still mask the full 15-16 years of the pause. There’s also no excuse for selectively choosing conventional calendar “decade” periods in order to purge data from 2011 and 2012 out of the graph. It’s clearly a case of “Purge the Pause”.

  11. The economic version of using decadal temperature would presumably be the calculation of GDP over 2001-2010 for example. This would raise the question of why there has been so much fuss about recession and hard times. After all, real GDP for 2001-2010 is considerably above that for 1991-2000 in the US, UK and indeed most other western countries. As climatologists would say, get over it!

  12. There is a visual effect here. Although the gradients of the 1910 – 1940 warming period is the same as the recent one, the smaller error bars in the recent warming period makes the graph look far “worse”

  13. I think the point is this (and it’s a sign of how desperate the warmists are to keep the gravy train going a while longer):
    -The satellite record cannot be tampered with
    -The 1998 record has not been equalled; slight decline
    -The terrestrial record, however, can be fiddled; is being fiddled

    Oh to have been a fly on the wall when they met up to draft the SPM. “Looks like we’re screwed, boys. How can we keep peddling Global Warming if the fecking globe refuses to warm?” “Hang on… I have an idea. This may just work….” “We’ll never get away with it.” “Oh yeah? This scam is good for another ten years….”

  14. Interesting tweet on this graph from climate scientist Eric Steig (notorious for his Nature cover showing a big chunk of Antarctica red, as a result of smearing the peninsula warming over half the continent):

    If there was a “pause” then HOW did 2000s wind up warmer than 1990s? Look at bottom graph. Sheesh!

  15. Why do we compare October’s temp to September? Why do we compare the year 2013 to the year 2012? Why do we compare thee to a summer’s day? The same reason we compare the 00’s to the 90’s or the 90’s to the 80’s. They are clearly defined ranges. You can’t pick arbitrary ranges in the data just to prove a point. This decadal average graph does indeed blow all the “pause” nonsense out of the water.

  16. “effectively throwing away most of the data”

    Seriously? FYI they haven’t thrown away any data, they have just compressed it.

  17. Hilary Ostrov has a blog post of Thomas Stocker presenting the results of the IPCC at Stockholm. In that presentation he only shows the decadally averaged graph!

    I hope that Richard Betts will criticise Stocker as he did me.

  18. Attention all CAGW alarmists – I am currently pretending to be a Marine Biologist to impress my new girlfriend. What is the current price I should charge for commiting/transmitting scientific fraud regarding global warming in exchange for any remaining ethics I may or may not possess? $100K/yr, $200K/yr, more? It would be helpful to get input from someone in the water quality field that has a solid track record – perhaps chief climate ethicist Peter H. Gleick would advise. Thank you in advance for your help.

  19. I am not a scientist, (some career experience with statistics/mathematical models)- in light of the recent data showing no global warming- I have decided to review the evidence/arguments as objectively as possible. I was curious if anyone can tell me why the deviation from the mean over an arbitrary point in time means ANYTHING? If the IPCC wants to convince me that global average temperature is going up, why don’t they simply plot average temperature? Does anyone know how I can get the data points in their graph in order to regraph it in different ways, to make the point, that averaging the means from any particular starting point is meaningless? And I’d like to know, what is the average temperature actually doing?

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