cc: Eystein Jansen , rahmstorf@pik-potsdam.de, drind@giss.nasa.gov, Valerie Masson-Delmotte , joos date: Thu, 13 Jan 2005 11:05:09 -0700 from: Jonathan Overpeck subject: comments for 6.4.3.2 and 6.5.6 to: t.osborn@uea.ac.uk, Keith Briffa All - I guess it is David's job to lead the incorporation of these comments into these two sections which he leads, but others may want to discuss too. What do you think about a general bullet along the lines of Commonly cited warm periods, including the Medieval Warm Period, Holocene Climate Optimum, Altithermal, Hypsithermal and others appear to have been distinct only regionally, and in a time-transgressive manner. They should not be cited as globally warm intervals comparable to the late 20th century, and are usually too poorly defined to be of use in the literature. There will soon be a box on the Medieval Warm Period that makes this case for the MWP. Tim and Keith - when drafting, perhaps you should change the box's emphasis slightly to include these other periods. Title it "Box 6.1: The Medieval Warm Period and other Poorly Defined Periods of Regional Warmth." Use the MWP as the in-depth example, and then we can mention the other terms only in the intro. After the ZOD, we can make sure we got it all perfect. Lets put an end to some myths that have been around longer than we have! Thanks all, especially David for updating these two sections as appropriate. cheers, peck X-Sieve: CMU Sieve 2.2 X-Sender: f055@pop.uea.ac.uk (Unverified) Date: Thu, 13 Jan 2005 16:19:31 +0000 To: Jonathan Overpeck , Keith Briffa From: Tim Osborn Subject: Re: Need your help on something important Cc: Eystein Jansen , rahmstorf@pik-potsdam.de, drind@giss.nasa.gov, FortunatJoos@email.arizona.edu X-UEA-MailScanner-Information: Please contact the ISP for more information X-UEA-MailScanner: Found to be clean X-Virus-Scanned: amavisd-new at email.arizona.edu X-Spam-Status: No, hits=-2.599 required=7 tests=BAYES_00 X-Spam-Level: At 23:50 12/01/2005, Jonathan Overpeck wrote: Toward that end, I wonder if you two (or maybe just Tim if Keith is working more on 6.3.2.1) could read and comment/edit on: Section 6.4.3.2 -evaluation of transient model runs of the last millennium and Section 6.5.8 - synthesis of climate sensitivity issues Eystein and I are asking that you do this FAST because these sections must be compatible with your section 6.3.2.1 (and because you guys know as much as any about the material in these two other sections!). Dear Peck (plus cc to others - have I sent it to the appropriate people?), Keith and I have looked at these sections and the attached documents contain my tracked changes. They seem to be compatible with Keith's section and the figures. We've put in a couple of simple cross-references to the figures from Keith's section. Plus some minor changes. Plus some comments, particularly about the section(d) of the climate sensitivity section. Keith expands upon these latter comments with the following: -------------------- It would be wise NOT to refer to the Maunder Minimum time period. Anyway, 1675-1715 is (by most opinions) the LATE Maunder Minimum (an accidental name that derives from the random non-availability of documentary/paleo data for the earlier part of the period in some [Swiss] study by Pfister and people). Up to then, MM was taken to be 1645/50 to 1715. By using this terminology you divert objective analysis of TOTAL forcing change (particularly given volcanic uncertainty). The definition of "today" is also crucial as it affects (albeit not precise) estimation of forcing changes from the earlier period. The wider the comparison base, the more imprecise the estimates. The narrower the base, the more you could argue about likely non-equilibrium (see Tim's comment in attached document). The volcanic forcing likely means that the LMM is likely not in equilibrium either! Nice if base period for estimates of changes (forcings and temperatures) could be compatible with the base period used in Figure 1). We will cross reference this section from ours. -------------------- Cheers Tim and Keith Dr Timothy J Osborn Climatic Research Unit School of Environmental Sciences, University of East Anglia Norwich NR4 7TJ, UK e-mail: t.osborn@uea.ac.uk phone: +44 1603 592089 fax: +44 1603 507784 web: http://www.cru.uea.ac.uk/~timo/ sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm -- 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/ Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\6.4.3.2_osborncomments.doc" Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\6.5.8_osborncomments.doc"