The disclosure of climate data from the Climatic Research Unit at the University of East Anglia - Science and Technology Committee Contents

Memorandum submitted by John Graham-Cumming (CRU 55)

  I am writing at this late juncture regarding this matter because I have now seen that two separate pieces of written evidence to your committee mention me (without using my name) and I feel it is appropriate to provide you with some further information. I am a professional computer programmer who started programming almost 30 years ago. I have a BA in Mathematics and Computation from Oxford University and a DPhil in Computer Security also from Oxford. My entire career has been spent in computer software in the UK, US and France.

  I am also a frequent blogger on science topics (my blog was recently named by The Times as one of its top 30 science blogs). Shortly after the release of emails from UEA/CRU I looked at them out of curiosity and found that there was a large amount of software along with the messages. Looking at the software itself I was surprised to see that it was of poor quality. This resulted in my appearance on BBC Newsnight criticizing the quality of the UEA/CRU code in early December 2009 (see

  That appearance and subsequent errors I have found in both the data provided by the Met Office and the code used to process that data are referenced in two submissions. I had not previously planned to submit anything to your committee, as I felt that I had nothing relevant to say, but the two submissions which reference me warrant some clarification directly from me, the source.

  I have never been a climate change skeptic and until the release of emails from UEA/CRU I had paid little attention to the science surrounding it.

In the written submission by Professor Hans von Storch and Dr Myles R Allen there are three paragraphs that concern me:

    "3.1  An allegation aired on BBC's "Newsnight" that software used in the production of this dataset was unreliable. It emerged on investigation that the neither of the two pieces of software produced in support of this allegation was anything to do with the HadCRUT instrumental temperature record. Newsnight have declined to answer the question of whether they were aware of this at the time their allegations were made.

    3.2  A problem identified by an amateur computer analyst with estimates of average climate (not climate trends) affecting less than 1% of the HadCRUT data, mostly in Australasia, and some station identifiers being incorrect. These, it appears, were genuine issues with some of the input data (not analysis software) of HadCRUT which have been acknowledged by the Met Office and corrected. They do not affect trends estimated from the data, and hence have no bearing on conclusions regarding the detection and attribution of external influence on climate.

    4.  It is possible, of course, that further scrutiny will reveal more serious problems, but given the intensity of the scrutiny to date, we do not think this is particularly likely. The close correspondence between the HadCRUT data and the other two internationally recognised surface temperature datasets suggests that key conclusions, such as the unequivocal warming over the past century, are not sensitive to the analysis procedure."

  I am the "computer analyst" mentioned in 3.2 who found the errors mentioned. I am also the person mentioned in 3.1 who looked at the code on Newsnight.

  In paragraph 4 the authors write "It is possible, of course, that further scrutiny will reveal more serious problems, but given the intensity of the scrutiny to date, we do not think this is particularly likely." This has turned out to be incorrect. On February 7, 2010 I emailed the Met Office to tell them that I believed that I had found a wide ranging problem in the data (and by extension the code used to generate the data) concerning error estimates surrounding the global warming trend. On 24 February 2010 the Met Office confirmed via their press office to Newsnight that I had found a genuine problem with the generation of "station errors" (part of the global warming error estimate).

  In the written submission by Sir Edward Acton there are two paragraphs that concern the things I have looked at:

    "3.4.7  CRU has been accused of the effective, if not deliberate, falsification of findings through deployment of "substandard" computer programs and documentation. But the criticized computer programs were not used to produce CRUTEM3 data, nor were they written for third-party users. They were written for/by researchers who understand their limitations and who inspect intermediate results to identify and solve errors.

    3.4.8  The different computer program used to produce the CRUTEM3 dataset has now been released by the MOHC with the support of CRU."

  My points:

    1. Although the code I criticized on Newsnight was not the CRUTEM3 code the fact that the other code written at CRU was of low standard is relevant. My point on Newsnight was that it appeared that the organization writing the code did not adhere to standards one might find in professional software engineering. The code had easily identified bugs, no visible test mechanism, was not apparently under version control and was poorly documented. It would not be surprising to find that other code written at the same organization was of similar quality. And given that I subsequently found a bug in the actual CRUTEM3 code only reinforces my opinion.

    2. I would urge the committee to look into whether statement 3.4.8 is accurate. The Met Office has released code for calculating CRUTEM3 but they have not released everything (for example, they have not released the code for "station errors" in which I identified a wide-ranging bug, or the code for generating the error range based on the station coverage), and when they released the code they did not indicate that it was the program normally used for CRUTEM3 (as implied by 3.4.8) but stated "[the code] takes the station data files and makes gridded fields in the same way as used in CRUTEM3." Whether 3.4.8 is accurate or not probably rests on the interpretation of "in the same way as". My reading is that this implies that the released code is not the actual code used for CRUTEM3. It would be worrying to discover that 3.4.8 is inaccurate, but I believe it should be clarified.

  I rest at your disposition for further information, or to appear personally if necessary.

March 2010

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