Data Discrepancies in Solar-Climate Link

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Contrary to the impression given in J. Pasotti's News of the Week story (“Daggers are drawn over revived cosmic ray-climate link,” 11 January, p. [144][1]), neither I nor any of the other climate scientists quoted in the story seek “to strangle the hypothesized climate-geomagnetism connection in its crib.” However, it is not unreasonable to expect that a hypothesis that neglects well-established greenhouse gas and aerosol radiative forcings should at least be based on appropriate and accurately described data. Courtillot and co-workers ([1][2]) made two errors that exaggerate the solar-climate correlation ([2][3], [3][4]). First, they showed only the most recent 50 years of a solar irradiance proxy; application of the same data analysis to the readily available full-century record causes the apparent correlation to fall apart. Second, the temperature record used as a basis of comparison was not a global mean temperature or any of the other temperature curves discussed in the paper ([4][5]) cited as a data source. In ([1][2]), this temperature curve was labeled “Tglobe,” and it was described explicitly as giving a “global temperature trend” at two places in the paper. Furthermore, when Bard and Delaygue raised questions about the data source, the original publicly posted version of Courtillot's response gave the name of a global land and ocean data set. It was only after a further challenge by Bard and Delaygue that the actual data set was revealed, and it turned out to be a record of growing season temperature for Northern Hemisphere extratropical land alone, derived originally for calibrating tree ring proxies, unambiguously described in the data set header as such. The corrected version of the erroneous figure reproduced in Pasotti's article can be found in ([2][3]), or compared side by side with the original in ([3][4]). 1. 1.[↵][6]1. V. Courtillot 2. et al. , Earth Planet. Sci. Lett. 253, 328 (2007). [OpenUrl][7][CrossRef][8] 2. 2.[↵][9]1. E. Bard, 2. G. Delaygue , Earth Planet. Sci. Lett. 265, 302 (2007). [OpenUrl][10] 3. 3.[↵][11]Real Climate ([http://www.realclimate.org/index.php/archives/2007/12/les-chevaliers-de-l’ordre-de-la-terre-plate-part-ii-courtillots-geomagnetic-excursion/][12]). 4. 4.[↵][13]1. P. D. Jones 2. et al. , Rev. Geophys. 37, 173 (1999). [OpenUrl][14][CrossRef][15] [1]: /lookup/doi/10.1126/science.319.5860.144 [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #xref-ref-1-1 View reference 1. in text [7]: {openurl}?query=rft.jtitle%253DEarth%2BPlanet.%2BSci.%2BLett.%26rft.volume%253D253%26rft.spage%253D328%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.epsl.2006.10.032%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [8]: /lookup/external-ref?access_num=10.1016/j.epsl.2006.10.032&link_type=DOI [9]: #xref-ref-2-1 View reference 2. in text [10]: {openurl}?query=rft.jtitle%253DEarth%2BPlanet.%2BSci.%2BLett.%26rft.volume%253D265%26rft.spage%253D302%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [11]: #xref-ref-3-1 View reference 3. in text [12]: http://www.realclimate.org/index.php/archives/2007/12/les-chevaliers-de-l%C3%A2%E2%82%AC%E2%84%A2ordre-de-la-terre-plate-part-ii-courtillots-geomagnetic-excursion/) [13]: #xref-ref-4-1 View reference 4. in text [14]: {openurl}?query=rft.jtitle%253DRev.%2BGeophys.%26rft.volume%253D37%26rft.spage%253D173%26rft_id%253Dinfo%253Adoi%252F10.1029%252F1999RG900002%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [15]: /lookup/external-ref?access_num=10.1029/1999RG900002&link_type=DOI