Climate Audit

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Climate Audit is a blog run by Stephen McIntyre devoted to auditing the statistical methods and data used in historical reconstructions of past climate, especially multiproxy reconstructions such as the 1998 reconstruction by Mann, Bradley and Hughes ("MBH98"), which was prominently featured in the 2001 IPCC Third Assessment Report.

McIntyre became interested in these issues after advocates of the Kyoto Protocol used the Hockey Stick graph from MBH98 in ways that he found similar to Bre-X and other stock frauds, leading him to try to audit the MBH98 data and analysis. He launched the blog in January 2005 just before Geophysical Research Letters published a paper by McIntyre and Ross McKitrick critiquing MBH98. The blog is largely concerned with McIntyre's efforts to audit current climate publications. It supports comments, but topics not related to auditing results in climate science are generally discouraged.

The ClimateAudit blog was credited with spurring two hearings on the Hockey Stick Graph, open documentation and the reliability of peer review in government-funded science research by the U.S. House of Representatives Energy and Commerce Committee in 2006 at which Stephen McIntyre testified. Of the role of the Climate Audit blog in inspiring the hearings, the Prometheus blog of the Center for Science and Technology Policy Research of the University of Colorado at Boulder said, referring to ClimateAudit, "[McIntyre and McKitrick] also have provided a case study in the power of blogs in today's worlds of science and politics".^[1] Climate Audit has been highlighted by the press including The Wall Street Journal^[2] and United Press International,^[3] and was co-winner of the 2007 Best Science Blog award.^[4]

In 2007, McIntyre started auditing the various corrections made to temperature records, in particular those relating to the Urban Heat Island effect. In the course of his analysis of the records for individual sites, he discovered a small discontinuity in some US records in the Goddard Institute for Space Studies (GISS) dataset starting in January 2000. He emailed^[5] GISS advising them of the problem and within a couple of days GISS issued a new, corrected set of data^[6] and "thank[ed] Stephen McIntyre for bringing to our attention that such an adjustment is necessary to prevent creating an artificial jump in year 2000". The adjustment caused the average temperatures for the continental United States to be reduced about 0.15°C during the years 2000-2006. Changes in other portions of the record did not exceed 0.03 °C, and it made no discernible difference to the global mean anomalies. However, this "micro-change"^[7] meant that 1998 was no longer the warmest year on record for the U.S. -- it is now 1934 -- which sparked some political commentary^[8]^[9]^[10] and analysis.^[11]

McIntyre later commented:^[12]

[M]y original interest in GISS adjustment procedures was not an abstract interest, but a specific interest in whether GISS adjustment procedures were equal to the challenge of “fixing” bad data. If one views the above assessment as a type of limited software audit (limited by lack of access to source code and operating manuals), one can say firmly that the GISS software had not only failed to pick up and correct fictitious steps of up to 1 deg C, but that GISS actually introduced this error in the course of their programming. According to any reasonable audit standards, one would conclude that the GISS software had failed this particular test. While GISS can (and has) patched the particular error that I reported to them, their patching hardly proves the merit of the GISS (and USHCN ^[13]) adjustment procedures. These need to be carefully examined.