MOST scientific sceptics have been dismissive of the various reconstructions of temperature which suggest 1998 is the warmest year of the past millennium. Our case has been significantly bolstered over the last week with statistician Steve McIntyre finally getting access to data used by Keith Briffa, Tim Osborn and Phil Jones to support the idea that there has been an unprecedented upswing in temperatures over the last hundred years – the infamous hockey stick graph.
Mr McIntyre’s analysis of the data – which he had been asking for since 2003 – suggests that scientists at the Climate Research Unit of the Hadley Centre associated with the UK Met. Office have been using only a small subset of the available data to make their claims that recent years have been the hottest of the last millennium. When the entire data set is used, Mr McIntyre claims that the hockey stick shape disappears completely. 
Mr McIntyre has previously showed problems with the mathematics behind the ‘hockey stick’. But scientists at the Climate Research Centre (CRU), in particular Dr Briffa, have continuously republished claiming the upswing in temperatures over the last 100 years is real and not an artifact of the methodology used – as claimed by Mr McIntyre. However, these same scientists have denied Mr McIntyre access to all the data. Recently they were forced to make more data available to Mr McIntyre after they published in the Philosophical Transactions of the Royal Society – a journal which unlike Nature and Science has strict policies on data archiving which it enforces.
This week’s claims by Steve McInyre that scientists associated with the UK Met. Office have been less than diligent are serious and suggest some of the most defended building blocks of the case for anthropogenic global warming are based on the indefensible when the methodology is laid bare.
This sorry saga also raises issues associated with how data is archived at the UK Met. Office with incomplete data sets that spuriously support the case for global warming being promoted while complete data sets are kept hidden from the public – including from scientific sceptics like Steve McIntyre.
It is indeed time leading scientists at the Climate Research Centre associated with the UK Met. Office explain how Mr McIntyre is in error or resign.
Notes and Links
 Yamal: A “Divergence” Problem, by Steve McIntyre, 27 September 2009
The above chart shows the difference when the entire data set (black line) as opposed to a subset (red line) is used to reconstruct temperature. The chart is accompanied by the following comment from Mr McIntyre: “The next graphic compares the RCS chronologies from the two slightly different data sets: red – the RCS chronology calculated from the CRU archive (with the 12 picked cores); black – the RCS chronology calculated using the Schweingruber Yamal sample of living trees instead of the 12 picked trees used in the CRU archive [leaving the rest of the data set unchanged i.e. all the subfossil data prior to the 19th century]. The difference is breathtaking.”
Mann, Michael E.; Bradley, Raymond S.; Hughes, Malcolm K. (1998), “Global-scale temperature patterns and climate forcing over the past six centuries” (PDF), Nature 392: 779–787, doi:10.1038/33859, http://www.caenvirothon.com/Resources/Mann,%20et%20al.%20Global%20scale%20temp%20patterns.pdf
CRU Refuses Data Once Again