Issues arising out of Paragraph 1.1

The terms of reference are as follows:

1.1 Examine the hacked e-mail exchanges, other relevant e-mail exchanges and any other information held at CRU to determine whether there is any evidence of the manipulation or suppression of data which is at odds with acceptable scientific practice and may therefore call into question any of the research outcomes.


1. The allegation of ignoring potential problems in deducing palaeotemperatures from tree ring data that might undermine the validity of the so-called “hockey-stick” curve. In the late 20th century, the correlation between the tree ring record and instrumental record of temperature change diverges from that for the earlier period. The cause of this divergence does not appear to be understood. If the method used to deduce temperatures from tree ring proxy metrics for the earlier tree ring record is applied to the late 20th century tree ring series, then declining temperatures would be deduced for the late 20th century. It is alleged that if the cause of divergence between the tree ring and instrumental temperature record is unknown, it may have existed in earlier periods.  Therefore if tree rings had similarly failed to reflect the warming of the early Middle Ages, they may significantly under- estimate the warming during the Medieval Warm Period, thus falsely enhancing the contrast between the recent warming and that earlier period.  (It is this contrast that has led to statements that the late 20th century warming is unprecedented during at least the last 1000 years.)


 What method do you use to deduce palaeotemperatures from tree ring data?

 Does not the problem of divergence for the late 20th century record

invalidate the deduction of tree ring palaeotemperatures for the period prior to the instrumental record?

 How open have you been about this issue?

 What attempts have you made to resolve it?

 What is the evidence that the amplitude of warming during the Medieval

Warm Period (MWP) is not underestimated by tree ring evidence?

 How does the tree ring evidence of the MWP compare with other proxy data?

Have you showed how data from different sources compare or have you conflated them? If the latter, what is the justification?

 If tree ring proxies are removed from reconstructions, what evidence remains of the MWP?

 Have you been selective in utilizing tree ring evidence from Yamal in Siberia; and if so, what is the justification for selectivity and does the selection influence the deduced pattern of hemispheric climate change during the last millennium?

2. The allegation that CRU has colluded in attempting to diminish the significance of data that might appear to conflict with the 20th century global warming hypothesis The CRU group, in consultation with Professor Michael Mann, is alleged to have systematically attempted to diminish the significance of the Medieval Warm Period, evidenced by an email from Mann 4th June 2003: “I think that trying to adopt a timeframe of 2K, rather than the usual 1K, addresses a good earlier point that Peck made w/ regard to the memo, that it would be nice to try to “contain” the putative “MWP”, even if we don’t yet have a hemispheric mean reconstruction available that far back [Phil and I have one in review–not sure it is kosher to show that yet though–I’ve put in an inquiry to Judy Jacobs at AGU about this].” The use of the words “contain” and “putative” are alleged to imply an improper intention to diminish the magnitude and significance of the MWP so as to emphasise the late 20th century warming.


 What does the word “contain” mean in this context?

 What involvement have you had in “containing” the MWP?

 How important is the assertion of “unprecedented late 20th century

warming” in the argument for anthropogenic forcing of climate?

3. It is alleged that proxy temperature deductions and instrumental temperature data have been improperly combined to conceal mismatch between the two data series An attempt to hide the difficulty of combining these two data series and to mislead is alleged to be revealed in the following sentence in a November 1999 email from Professor Phillip Jones which is alleged to imply a conscious attempt to mislead: “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (i.e. from 1981 onwards) and from 1961 for Keith’s to hide the decline”. 


 What is the meaning of the quotation from the 1999 email?

 How do you justify combining proxy and instrumental data in a single plotted line?

 What method do you use?

4. It is alleged that there has been an improper bias in selecting and adjusting data so as to favour the anthropogenic global warming hypothesis and details of sites and the data adjustments have not been made adequately available It is alleged that instrumental data has been selected preferentially to include data from warmer, urban in contrast to rural sites; that the rationale for the choice of high/low latitude sites is poor; and that the processes by which data has been corrected, accepted and rejected are complex and unclear.


 What is the rationale for the choice of data stations worldwide?

 How has this choice been tested as appropriate in generating a global or hemispheric mean temperature (both instrumental and proxy data)? 

 Describe as clearly as possible the protocols you have followed in selecting, correcting and rejecting data and stations.

 Has this been an orderly and objective process applied to all datasets? 

 To what extent have different procedures for data of different vintages and different sources been unified?

 What means do you use to test the coherence of the datasets?


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