The CRU hack: Context

  • HARRY_read_me.txt. This is a 4 year-long work log of Ian (Harry) Harris who was working to upgrade the documentation, metadata and databases associated with the legacy CRU TS 2.1 product, which is not the same as the HadCRUT data (see Mitchell and Jones, 2003 for details). The CSU TS 3.0 is available now (via ClimateExplorer for instance), and so presumably the database problems got fixed. Anyone who has ever worked on constructing a database from dozens of individual, sometimes contradictory and inconsistently formatted datasets will share his evident frustration with how tedious that can be.
  • “Redefine the peer-reviewed literature!” . Nobody actually gets to do that, and both papers discussed in that comment – McKitrick and Michaels (2004) and Kalnay and Cai (2003) were both cited and discussed in Chapter 2 of 3 the IPCC AR4 report. As an aside, neither has stood the test of time.
  • “Declines” in the MXD record. This decline was hidden written up in Nature in 1998 where the authors suggested not using the post 1960 data. Their actual programs (in IDL script), unsurprisingly warn against using post 1960 data. Added: Note that the ‘hide the decline’ comment was made in 1999 – 10 years ago, and has no connection whatsoever to more recent instrumental records.
  • CRU data accessibility. From the date of the first FOI request to CRU (in 2007), it has been made abundantly clear that the main impediment to releasing the whole CRU archive is the small % of it that was given to CRU on the understanding it wouldn’t be passed on to third parties. Those restrictions are in place because of the originating organisations (the various National Met. Services) around the world and are not CRU’s to break. As of Nov 13, the response to the umpteenth FOI request for the same data met with exactly the same response. This is an unfortunate situation, and pressure should be brought to bear on the National Met Services to release CRU from that obligation. It is not however the fault of CRU. The vast majority of the data in the HadCRU records is publicly available from GHCN (v2.mean.Z).
  • Suggestions that FOI-related material be deleted … are ill-advised even if not carried out. What is and is not responsive and deliverable to an FOI request is however a subject that it is very appropriate to discuss.
  • Fudge factors (update) IDL code in the some of the attached files calculates and applies an artificial ‘fudge factor’ to the MXD proxies to artificially eliminate the ‘divergence pattern’. This was done for a set of experiments reported in this submitted 2004 draft by Osborn and colleagues but which was never published. Section 4.3 explains the rationale very clearly which was to test the sensitivity of the calibration of the MXD proxies should the divergence end up being anthropogenic. It has nothing to do with any temperature record, has not been used in any published reconstruction and is not the source of any hockey stick blade anywhere.

Further update: This comment from Halldór Björnsson of the Icelandic Met. Service goes right to the heart of the accessibility issue:

Re: CRU data accessibility.

National Meteorological Services (NMSs) have different rules on data exchange. The World Meteorological Organization (WMO) organizes the exchange of “basic data”, i.e. data that are needed for weather forecasts. For details on these see WMO resolution number 40 (see

This document acknowledges that WMO member states can place restrictions on the dissemination of data to third parties “for reasons such as national laws or costs of production”. These restrictions are only supposed to apply to commercial use, the research and education community is supposed to have free access to all the data.

Now, for researchers this sounds open and fine. In practice it hasn’t proved to be so.

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