date: Tue, 2 Sep 2003 11:18 -0400 from: jgr-atmospheres@agu.org subject: Review Received by Journal of Geophysical Research - Atmospheres to: K.Briffa@uea.ac.uk Dear Dr. Briffa: Thank you for your review of "On reconciliation of borehole and proxy based temperature reconstructions over the last five centuries" by Shaopeng Huang [Paper #2003JD003856], which we have safely received. A copy of this review is attached for your reference. Sincerely, Alan Robock Editor, JGR-Atmospheres ------------------------------------------------------------------------ Assessment: Category 5 Ranking: Poor Confidential Re-Review: No Annotated Manuscript: No Comments: My overall opinion of the Huang manuscript is that it is not suitable for publication either as a stand-alone contribution, or even as a critical commentary relating to the Mann et al. (2003) paper. This is unfortunate in the sense that the Mann et al. paper is not without some shortcomings, but my task here is to review the contribution to the global warming debate represented by this manuscript and, overall, I feel that there is insufficient new information or insight to justify publication. The title is a misrepresentation of the content and I must agree with referee 1 that there is no independent treatment of the borehole or any original paleoclimate data that results in any independent evidence of a better match between them. Rather, what the author has done is to combine the original Mann et al. (1999) final data composite series with the Huang et al. (2000) composite series, giving all weight to the former in the high-frequency domain and all weight to the latter in the low-frequency, and more equal weight to each in the mid-frequency range. This, in itself, tells us nothing new about the validity of the low-frequency components of either the Mann et al. or Huang et al. series. It certainly cannot be considered as in any way ‘reconciling’ them. The supposed evidence for the validity of the Huang et al. long-timescale trend is apparently the better (in comparison to Mann et al.) match achieved between this and one particular radiative forcing series (shown in Fig. 4), incorporating a combination of solar irradiance, anthropogenic aerosols and greenhouse gases only. The volcanic component is excluded on subjective and unconvincing grounds: namely that “the long term effects … on temperature change have not been well quantified”! The same can certainly be said of solar variability, and arguably also even CO2! What is sure is that if the volcanic component had been included, the shape of the forcing curve would differ. The early level of mean temperature indicated by the combined borehole-based estimates of multiple local temperature are significantly warmer in the 16th and 17th centuries when the data are gridded prior to averaging: much warmer than implied in Huang et al. (2000) and the hemispheric mean based on these previously gridded records could have been used with equal justification, instead of the Huang et al. series, and the results (in terms of linear regression with the forcing history used here) would likely have been as good as those achieved here (and the implied sensitivity to forcing change would have been less). I have problems with other aspects of the manuscript but there is no point going into further detail. In several areas the author criticises the Mann et al. methodology but does not provide sufficient or warranted detail. This is unfortunate in that the Mann et al. so-called optimal approach is not entirely convincing, but, be that as it may, it is largely irrelevant when judging the merits of the manuscript before me, and its fundamental shortcomings as regards providing a ‘reconciliation’ of the various proxy temperature evidence or any convincing case that the Huang long-timescale trend is nearer the “truth”. I must recommend rejection.