From	Darrell Kaufman	Date	Sun, 6 Sep 2009 06:31:35 -0700
To	Bo Vinther
CC	Nick McKay, Caspar Ammann, David Schneider, Jonathan T. Overpeck, Bette Otto-Bliesner, ray bradley, Miller Giff, Keith Briffa, Michael E. Mann
Subject	Re: Arctic2k update?
Bo and others: Regarding the annual data: You're correct that we only use 10-year means throughout our calculations (Fig 2 shows annual values, but are not used in any calculation/conclusion). In his e-mail to me, McIntyre requested the annual data that we say are not publicly available as a footnote to Table S1. Unless anyone has another suggestion, I will reply and send him the 10-year data (which is already posted at NOAA-Paleoclimate) and explain that they were the basis for all of the calculations. He might want the annual data that the mean values were based on. I suppose we'll cross that bridge when we get to it. Darrell On Sep 6, 2009, at 5:42 AM, Bo Vinther wrote: Hi Darrell Sorry to hear that you are getting trouble for doing such a nice paper....I by the way agree completely with Peck that we should not be rushed and that a correction probably should go into Science. Anyway, let me answer the two questions you had for me: 2) Correcting ice core data for upstream effects should not be controversial (while not correcting in areas of flow should be highly controversial indeed!). Upstream correction of delta-18O was in fact already done 30 years ago for the Milcent ice core - a quick quote from Hammer et al. 1978, page 14: "The delta values are corrected for decreasing deltas up-slope at the site of formation of the individual layers" Hammer, C. U., H. B. Clausen, W. Dansgaard, N. Gundestrup, S. J. Johnsen and N. Reeh, Dating of Greenland ice cores by flow models, isotopes, volcanic debris, and continental dust, J. Glaciol., 20, 326, 1978. So upstream correction of delta data from ice cores 8using ice flow models9 has in fact been performed since the year I was born..... 5) I will suggest that we release the 1860-2000 section of the annually resolved ice core data, as these are the data that go into figure 2 in the paper. Such a limited release I can permit immediately. Releasing everything is something different and I can't see the need - as far as I rememver we are not presenting/using the 1-1859 part of the series in annual resolution anywhere in the paper - or am I wrong? Cheers........Bo Darrell Kaufman wrote: All: I received my first hate mail this AM, which helped me to realize that I shouldn't be wasting time reading the blogs. Regarding the "upside down man", as Nick's plot shows, when flipped, the Korttajarvi series has little impact on the overall reconstructions. Also, the series was not included in the calibration. Nonetheless, it's unfortunate that I flipped the Korttajarvi data. We used the density data as the temperature proxy, as recommended to me by Antii Ojala (co-author of the original work). It's weakly inversely related to organic matter content. I should have used the inverse of density as the temperature proxy. I probably got confused by the fact that the 20th century shows very high density values and I inadvertently equated that directly with temperature. This is new territory for me, but not acknowledging an error might come back to bite us. I suggest that we nip it in the bud and write a brief update showing the corrected composite (Nick's graph) and post it to RealClimate. Do you all agree? There's other criticisms that have come up by McIntyre's group: (1) We cherry-picked the tree-ring series in Eurasia. Apparently this is old ground, but do we need to address why we chose the Yamal record over the Polar Urals? Apparently, there's also a record from the Indigirka River region, which might not have been published and doesn't seem to be included in Keith's recent summary. If we overlooked any record that met our criteria, I suggest that we explain why. Keith: are you back? Can Ray or Mike provide some advise? (2) The correction for Dye-3 was criticized because the approach/rationale had not been reviewed independently on its own. Bo: has this procedure now been published anywhere? (3) We didn't publish any error analysis (e.g., leave-one-out ), but I recall that we did do some of that prior to publication. Would it be worthwhile including this in our update? The threshold-exceedence difference (O&B-style) does include a boot-strapped estimate of errors. That might suffice, but is not the record we use for the temperature calibration. (4) We selected records that showed 20th century warming. The only records that I know of that go back 1000 years that we left out were from the Gulf of Alaska that are known to be related strongly to precipitation, not temperature, and we stated this upfront. Do we want to clarify that it would be inappropriate to use a record of precip to reconstruct temperature? Or do we want to assume that precip should increase with temperature and add those records in and show that the primary signals remain? (5) McIntyre wrote to me to request the annual data series that we used to calculate the 10-year mean values (10-year means were up on the NOAA site the same AM as the paper was published). The only "non-published" data are the annual series from the ice cores (Agassiz, Dye-3, NGRIP, and Renland). We stated this in the footnote, but it does stretch our assertion that all of the data are available publicly. Bo: How do you want to proceed? Should I forward the annual data to McIntyre? Please let me -- better yet, the entire group -- know whether you think we should post a revision on RealScience, and whether we should include a reply to other criticism (1 through 5 above). I'm also thinking that I should write to Ojala and Tiljander directly to apologize for inadvertently reversing their data. Other thoughts or advise? Darrell On Sep 4, 2009, at 5:24 PM, Nick McKay wrote: The Korttajarvi record was oriented in the reconstruction in the way that McIntyre said. I took a look at the original reference - the temperature proxy we looked at is x-ray density, which the author interprets to be inversely related to temperature. We had higher values as warmer in the reconstruction, so it looks to me like we got it wrong, unless we decided to reinterpret the record which I don't remember. Darrell, does this sound right to you? This dataset is truncated at 1800, so it doesn't enter the calibration, nor does it affect the recent warming trend. The attached plot (same as before) shows the effect of re-orienting the record on the reconstruction. It doesn't change any of our major or minor interpretations of course. Nick On Thu, Sep 3, 2009 at 4:45 PM, Nick McKay <[1]nmckay@email.arizona.edu> wrote: Hi all, I haven't checked the original reference for it's interpretation, but I checked the code and we did use it in the orientation that he stated. He's also right that flipping doesn't affect any of the conclusions. Actually, flipping it makes it fit in better with the 1900-year trend. I've attached a plot of the original, and another with Korttajarvi flipped. Nick References 1. mailto:nmckay@email.arizona.edu