IPCC Misrepresents the Instrument Temperature Record

OOPS! Corrected my errors in Figure 1 and 2 and in the text. (8 Oct 2013)

# # #

I included a copy of an illustration from the IPCC’s approved Summary for Policymakers for AR5 in my post IPCC Still Delusional about Carbon Dioxide, which was also cross posted at WattsUpWithThat.

Figure 1

Figure 1

The illustration was their Figure SPM.10.  I’ve included a close-up view of Figure SPM.10 as my Figure 1.  See the problem?

Blogger Dr. Burns commented at WUWT:

Dr Burns says:
October 8, 2013 at 12:19 am

Where did they find the temperature increase between 2000 and 2010?

Good question.  (Thanks, Dr. Burns.) The decade ending in 2010 appears to be more than 0.25 deg C warmer than the decade ending in 2000, according to the IPCC.  That’s about 0.05 deg C higher than reality.

My Figure 2 presents the average of GISS, HADCRUT4 and NCDC global land+sea surface temperature products from January 1979 to July 2013, using the base years of 1981-2010.  Also included are horizontal red lines indicating the decadal average temperatures for the periods ending in December of the 10th year: December 2010 for example.  As shown, the decade ending in 2010 was only about 0.2 deg C warmer than the decade ending in 2000.

Figure 2

Figure 2

[Note: Because I was bound to be asked, I also included the average global temperature anomaly for period beginning in January 2011 and ending in July 2013 as the dotted red line—though I would not get all excited about it because we’re only a couple of years into the decade.]

Additionally, Figure 3 presents annual HADCRUT4 global land+sea surface temperature anomalies from 1861 to year-to-date 2013. I’ve used the same base years (1861-1880) as the IPCC claims to have used for their Figure SPM.10. I’ve also included horizontal lines for the average temperature anomalies for the decades ending in 2000 and 2010. Note that, according to the HADCRUT4 data, with the base years of 1861-1880, it has an anomaly of 0.7 deg C for the decade ending 2010—not over 1.0 deg C, as shown in the IPCC’s Figure SPM.10.

Figure 3

Figure 3

Curiously, in the Second Order Draft of the Summary for Policymakers, a similar illustration was presented as the IPCC’s Figure SPM.9 (my Figure 4). The global surface temperature anomaly for the period of 2001-2010 is shown with a STAR.  It’s significantly lower than shown in the approved version (my Figure 1), but it’s still reading high.

Figure 4

Figure 4

The IPCC report is supposedly the most widely peer-reviewed scientific document ever.  Looks like the peer-reviewers missed the errors in the IPCC’s portrayal of something simple and widely known—the instrument temperature record.

About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
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2 Responses to IPCC Misrepresents the Instrument Temperature Record

  1. Scute says:


    The entire SPM.10 graph is modelled, all the way from 1860 to 2100. That means the black dotted line, labelled as “historical” in the legend, is make-believe and has been passed off as the actual instrumental record. They will simply say it’s pointless making comparisons with the instrument record, as you have done, because they never intended it to show the real historical temperature, just the modelled (and therefore conveniently inaccurate) historical temperature. Put another way, it has been explained to me personally as “the estimated history of past forcings”. Yes, I have that absurd statement on record from CRU. It wouldn’t be absurd if the estimated historical forcings hadn’t led inexorably to a false temperature record that was used by the IPCC to paint a doomsday scenario at their press conference. Whatever their explanation, it is clear they were doing their level-best to make us think it was the instrument record.

    In my researches, straight after the press conference, I only found the first version of the graph, SPM.10, in the SPM dated 7th July and ‘subject to copy editing’. It had no caption so there was absolutely no way of knowing the ‘historical’ trend was modelled. As for the SPM.9, it has a caption at least and it does say:

    “. Model results over the historical period (1860–2010) are indicated in black. ”

    At the WG1 SPM press conference, this graph (SPM.9, with the slightly lower 2000-2010 temperature value) was paraded as showing the temperature, with no mention of it being a modelled historical plot. There was no caption cited and on searching, I found only the ‘subject to copy editing’ version with the graph on p 36 and its caption languishing on p 20.
    I think the title of your post is still entirely justified. WG1 at the press conference were leading us up the garden path, hiding fig leaves at every bend to swipe out and cover themselves with:

    1) They can now say the caption explains it all but there was no caption at the time of the press conference or mention of its “model results over the historical period”. The SPM at that time was still awaiting copy editing because they had wrangled over it all night (or at least that is the only reasonable inference I can make- if your copy edited SPM, the second order draft, with properly placed SPM.9 caption came out before the conference I’d be happy to be corrected).

    2) to add insult to injury, there was no mention of the 2000 and 2010 dots being decadal means, leading Dr. Burns and a billion others, to think there was a gigantic hike in temperature between those two dates when in reality, it flatlined. This, all set against the backdrop of being asked to come clean on the ‘pause’. Again, the fig leaf is “read the caption” but there was no caption at that time and it certainly wasn’t read out by Stocker at the press conference.

    There’s a lot more to the way they presented this graph/ these graphs than I’ve said here, including Thomas Stocker’s use of language in introducing the graph and referring to the temperature scale without giving away the fact it’s not the instrument record but entirely fabricated. It’s a disgrace that he then used this false picture to describe a doomsday scenario.

    I left a comment on your WUWT “IPCC Still Delusional about CO2” thread which has more info, here:


    (Scute’s comment on WUWT on 8th Oct 2013 at 2:18)


  2. Bob Tisdale says:

    Thanks very much, Scute!

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