Following are some remarks about my report "Grape harvest dates are poor indicators of summer warmth", as well as about scientific publication generally.
On 18 November 2004, Isabelle Chuine and co-workers published a research paper on global warming. The paper appeared in Nature, the world's most highly-regarded scientific journal. (UPDATE - Online here http://www.ipsl.jussieu.fr/~ypsce/papers/chuine432289.pdf) And it gathered some publicity. Chuine et al. claimed to have developed a method for estimating the summer temperature in Burgundy, France, in any given year back to 1370 (based on the harvest dates of grapes). Using their method, the authors asserted that the summer of 2003 was the warmest summer since 1370, in Burgundy.
I had been following global warming studies only as a disinterested outside spectator (and only occasionally). Someone sent me the paper of Chuine et al., though, and wondered what I thought of it from a mathematical perspective. So I had a look.
To study the paper properly, I needed to have the authors' data. (UPDATE - ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/france/burgundy2004.txt ) So I e-mailed Dr. Chuine, asking for this. The authors, though, were very reluctant to let me have the data. It me took eight months, tens of e-mails exchanged with the authors, and two formal complaints to Nature, before I got the data. (Some data was purchased from Météo France.) It is obviously inappropriate that such a large effort was necessary.
Looking at the data made it manifest that there are serious problems with the work of Chuine et al. In particular, the authors' estimate for the summer temperature of 2003 was higher than the actual temperature by 2.4 °C (about 4.3 °F). This is the primary reason that 2003 seemed, according to the authors, to be extremely warm.
There is also another reason. The three warmest years on record, prior to 2003, were 1945, 1947, and 1952. (The instrumental record goes back to 1922, or even 1883 if we accept some inaccuracies.) The estimate of Chuine et al. for the summer temperature in each of those years was much lower than the actual temperature.
That is, the authors had developed a method that gave a falsely-high estimate of temperature in 2003 and falsely-low estimates of temperatures in other very warm years. They then used those false estimates to proclaim that 2003 was tremendously warmer than other years.
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