cc: tcrowley@ocean.tamu.edu date: Tue, 1 Aug 2000 10:52:26 -0500 from: tom crowley subject: Briffa et al review JGRd2000R306 to: jgr@gaia.envsci.Rutgers.EDU Dear Roni, Below is my review of Briffa et al. (JGRd 2000R306). This is a very nice paper. The new analysis makes a good case that summer temperatures were colder than previously estimated - this is an important conclusion that is relevant both to the magnitude of climate change and mechanisms required to explain the changes. I recommend publication with only very minor changes, which I do not need to see. Tom Crowley Review of Briffa et al. (JGRd2000R306) I really liked this paper. It is a careful reanalysis of a large number of tree ring data that makes a good case for summer temperatures being colder in most regions than previously estimated. I recommend that the paper be published with only minor changes, which I do not need to see. Comments: - p. 6, second full para., line 9, I may have missed it but there seems to be no callout for Figure 5 - the text just says "This figure..." With respect to Fig 5 it would be helpful for those interested in gritty details to put larger tick marks at the mid-century points so that the reader can more easily narrow down the ages of certain events - p. 7, even though the authors restrict their summation to NH land summer half-season, it would be useful if they listed the correlation between this index and NH mean annual temperatures. In an earlier study Crowley and Kim (GRL, 3:359-362, 1996, Fig. 2 and text) obtained a 0.8 correlation for the interval ~1890-1990. How would the correlation change for the interval discussed by the authors? - p. 10, bottom, it would be nice if the authors expanded a little on possible circulation patterns that could account for the Siberian warming - AO? Their time series data are intriguing - in addition to the obvious ENSO peaks there is some indication from Pacific coral data for 14 AND 17 year peaks - not in the same corals but in different sites. This result has long puzzled me - maybe there are really two oscillations with different periods in different regions. The significance of these oscillations probably still needs testing. This is more of a comment for the authors rather than any recommendation to expand on the point. END OF REVIEW Thomas J. Crowley Dept. of Oceanography Texas A&M University College Station, TX 77843-3146 409-845-0795 409-847-8879 (fax) 409-845-6331 (alternate fax)