cc: mmanning@al.noaa.gov, wg1-ar4-ch06@joss.ucar.edu, Marquis@ucar.edu, v.ramaswamy@noaa.gov, Valerie.Masson@cea.fr, p.m.forster@reading.ac.uk, spahni@climate.unibe.ch date: Fri, 10 Feb 2006 08:46:44 +0100 from: Dominique Raynaud subject: Re: [Wg1-ar4-ch06] [Fwd: Greenhouse Gas Figure for IPCC] to: Jonathan Overpeck Dear all, Sorry to get on the moving train (in Brussels last week and a lot of commitments this week). If it is still time to comment on the last figure provided by Renato. I believe that the figure showing also the recent increase is appropriate for TS. As I mentioned in NZ last december I am not convinced that the discontinuous N2O record add values to the figure. It seems to me that it carries a lot of questions and, in my point of view, should not appear in TS. The figure presents another difficulty, which can probably be solved in the caption: why we don't see a recent decrease of the deuterium? In any case I think that the amplitude of the deuterium variability should be scaled with that of CO2 for instance. On the other hand, for chapter 6, I think we need a figure showing the three GG together with the deuterium record. This figure should not squeeze the amplitude of the CH4 variations (the CH4 record of the last figure of Renato looks nearly like a background noise record). We need to show clearly in chapter 6 the glacial-interglacial and millenial variability. So we could have a figure similar of one of the several figures that Renato prepared for NZ, without the continuous vertical lines for the recent increases, in order to scale properly the past variations. We could probably add only the present-day levels. Sorry for these late propositions. Dom >Hi Renato and friends - this looks really nice to me, and if all >agree, it would be good to get an eps version. > >All - pls send comments asap if you want to update the figure again. > >We need a updated caption - I suggest Renato, Fortunat and Dominique >work to do this. It would be nice to have soon, since this figure >has potential TS status as well as chap 6. In the caption, we should >state that (in your words) that there is clearly evidence for >earlier interglacial periods prior to 430 kyrs, but that these were >apparently cooler than the typical interglacials of the latest >Quaternary. Please let me know when you'll be able to send the >caption. > >Again, many thanks, Peck > >>Dear all, >> >>Thank you very much for including me as a contributer to this >>important report. I changed the EPICA/VOSTOK (CO2 also from Taylor >>Dome) figure accordingly: >> >>- figure with N2O and antropogenic increase >>- no shaded areas before MIS 11 >>- isotopes are shown as step plot with highest resolution published >>( 0-390kyr: EPICA Community Memebers, 2004; 390-650kyr: >>Siegenthaler et al. 2005, Spahni et al. 2005) >>- for visibility reasons the line widths are smaller now >>- the delta D label has probably a font problem, I converted it as >>a pdf this time >> >>Let me know if I can be of further assistance. >> >>All the best, >>Renato >> >> >>Jonathan Overpeck wrote: >> >>>Hi Valerie et al. - let's all weigh in before Renato generates the >>>final SOD graphic. My thoughts >>> >>>1) I don't feel strongly about the delta D data being smoothed or >>>not (it makes sense, but will it make a difference? - go ahead if >>>others agree), but I think we should keep isotopic data, rather >>>than temperature - to avoid the confusion with the most recent >>>data not being the warmest - or even close. It's regional temp, I >>>know, but some readers might realize this. We can say in the >>>caption that delta D is a regional temp record. I'm just one vote, >>>here... >>> >>>2) I agree with the vert grey shaded areas, and will go one step >>>farther for a compromise. I vote we keep the shading on the real >>>interglacials of the last 450kyrs, and delete the grey shading on >>>the earlier "interglacials" - they are different, clearly, and we >>>can make that point in the caption. Valerie's reasoning then works >>>the other way - the grey shading helps readers get the point about >>>how the length of interglacials comparable to the Holocene have >>>varied, with MIS 11 being the phattest. >>> >>>Thanks, Peck >>> >>>>Jonathan Overpeck a écrit : >>>> >>>>>Hi Fortunat, Renato and friends: Here's my thoughts on what you >>>>>have sent wrt to chap 6: >>>>> >>>>>1) for the EPICA/VOSTOK figure, I agree we should go with the >>>>>version WITH N2O and WITH the anthropogenic increase >>>>>(ipcc_ghg650kyr_v1ant) Renato - would you please resend with the >>>>>delta D label fixed. Thanks - otherwise, nice job. >>>>> >>>>I have a few comments on the figure ipcc_ghg650kyr_v1ant. >>>> >>>>- the deuterium data should be smoothed to appear with a >>>>resolution similar to the GHG records (we usually use step >>>>functions for deuterium plots because the measurements are >>>>conducted as averages for bag samples => not single points). >>>> >>>>- it is possible to show temperature fluctuations rather than >>>>deuterium, if you prefer. >>>> >>>>- I am worried about the vertical grey lines on this figure, >>>>assumed to define "interglacial periods". It is tricky and >>>>depends on some hypothesis (thresholds on deuterium or GHG). For >>>>instance stage 7.5, 7.3 should also appear as interglacials with >>>>the thresholds used for the other warm periods. >>>>As we are aware of (preliminar) Dome C age scale problems for >>>>stages 13-15, the grey bars may give false impressions regarding >>>>the duration of the oldest warm episodes. >>>> >>>>Valérie. >>> >>> >>> >> >>-- >>______________________________ >> >>Renato Spahni >> >>Climate and Environmental Physics >>Physics Institute, University of Bern >>Sidlerstrasse 5 >>CH-3012 Bern, Switzerland >> >>Phone: ++41 (0)31 631 44 76 >>Fax: ++41 (0)31 631 87 42 >>spahni@climate.unibe.ch >>www.climate.unibe.ch/~spahni >>______________________________ >> >> >>Attachment converted: Macintosh HD:ipcc_ghg650kyr.pdf (PDF /«IC») (0011236F) > > >-- >Jonathan T. Overpeck >Director, Institute for the Study of Planet Earth >Professor, Department of Geosciences >Professor, Department of Atmospheric Sciences > >Mail and Fedex Address: > >Institute for the Study of Planet Earth >715 N. Park Ave. 2nd Floor >University of Arizona >Tucson, AZ 85721 >direct tel: +1 520 622-9065 >fax: +1 520 792-8795 >http://www.geo.arizona.edu/ >http://www.ispe.arizona.edu/ -- Dominique Raynaud Research Director at CNRS Laboratoire de Glaciologie et Géophysique de l'Environnement BP 96 38402 Saint Martin d'Heres Cedex, France raynaud@lgge.obs.ujf-grenoble.fr PH: +33 4 76 82 42 52 FAX: +33 4 76 82 42 01 _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06