cc: Eystein Jansen , trond.dokken@bjerknes.uib.no, Valerie Masson-Delmotte , r.ramesh@prl.ernet.in, Keith Briffa date: Fri, 7 Jan 2005 17:23:47 -0700 from: Jonathan Overpeck subject: Re: Holocene masterpiece to: ricardo@lab.cricyt.edu.ar Hi Ricardo - ah, you lucky dog - fieldwork. Thanks for taking time out for the IPCC stuff, however. I was hoping to provide more today, but other LA's kept me hoping with constant email (all good, but time consuming). I will give more feedback soon. In the meantime, it would help if you did three things (in order of importance): 1) for section 6.5.4 (Modes of Variability - your lead): ** it would be good if you could see if Julie's new prose helps, and integrate it if it does. Keith is going to leave out variability changes, and in the end, I think Valerie might too (not decided). So this makes your section even more important. ** we'd like to ask if you could create Executive Summary type bullets for each of this section. See the TAR (e.g., chapter 2) for what I mean. The reason I ask is that we're starting to work on the Exec Summ, but also that space limits on our chapter mean that we can only afford to focus section text/figs on the most important policy relevant paleoscience. By generating the bullets, you will help us, but also make it clear what points your sections support. This might help in the editing, since material that doesn't support these points can be left out. 2) please read and edit/strengthen what Valerie just sent out a few minutes ago - the next version of 6.3.2.2. Last 10,000 years. Please use track changes, and send to her, me and Eystein 3) see if you can help Ramesh (and Dan, although we haven't heard from Dan - hope he wasn't impacted by the Tsunami...) with section 6.5.9. Ramesh agreed to help take over the lead, but I haven't heard from him since then (early in the week). Pls contact him with offer to help if you have time - we need a southern hem perspective!! We'll need your editing help with Keith's material too - but that won't be available until Monday or so. Will you be able to work next week? Limited time, or unlimited? Many Thanks! Peck PS - when we're all done in 2007, we should have a LA party in Chile! Enjoy. >Dear Peck, > >Thanks for your messages. Presently, I am doing fielwork with Antonio Lara >in Valdivia, Chile. I will take a break in my fieldwork during this >weekend to interact with you and Eystein. Cheers, >ricardo > >> the following is also attached as a word file... >> >> Hi Valerie and Ricardo - Here is some detailed feedback that Eystein >> and I developed for you to use in creating the next draft of section >> 6.3.2.2. Valerie, as section lead, should do this, but hopefully >> Ricardo can help editing/improving. As noted below, you should make >> decision about what previously received input to use or not to use. >> Fortunat and Dick both provide some useful still (especially F), but >> you should only use what fits and omit the rest (remember or keep >> notes why you make the choices you did, so you can discuss with them >> later if needbe). >> >> This is a big job, but you have most of the pieces. The section has >> many important policy-relevant points to make, so focus on them (you >> can add/delete from the list below, but be ready to argue if you >> delete ;) - ). >> >> Feel free to ask questions, etc. I will try to call tomorrow morning >> (my time, but with the baby, things are unpredictable - best give me >> your home phone number if I don't get you in the office). Feel free >> to contact us both by email or phone too. >> >> Thanks! Peck and Eystein >> >> January 6, 2005 >> Holocene Section 6.3.2.2 >> Feeback from CLAs >> >> A. Preamble/Introduction - >> >> 1) off to good start - lots of useful prose in hand. One reason for >> the delay is that this section, thanks to Valerie, had one of best >> first draft starts >> 2) Need to use available input where appropriate (and only where >> appropriate) - e.g., from Dick, Fortunat, Eystein (edits in Dec 30 >> doc) and David (see his comments sent separately from Eystein's Dec >> 30 compiled chapter document >> 3) sections should be 5 pages single spaced long (2.5 in IPCC pages) > > 4) can have 2-3 figures - like your ideas and what to see more >> 5) info related to glaciers is to be mostly in the new Box 6.1 (see >> previous email) >> 6) paleoclimates of the post-glacial Holocene (e.g., 8ka to present) >> are the best studied and understood of any warm interglacial earth >> period. This stems from wide applicability of radiocarbon and U/Th >> radiometric age models, as well as those developed using annual >> layers, bands and rings. After ca. 8ka, Holocene climate change was >> dominated by orbital forcing. Before ca. 8ka., glacial boundary >> conditions, particularly glacial meltwater also played a significant >> role. Mention (with citations to keep folks happy) the 8.2 event for >> example. Primary focus is thus on the post-glacial Holocene. Need to >> stress this in intro even more clearly. >> >> B. Section focus - need to stick to making policy relevant points. >> These include, but are not limited to the following. If you think >> there are additional points, please run them by CLAs before spending >> too much time on them. PLEASE alter the points to be accurate and >> unbiased - we think we're close, but you're the lead on this section. >> Also, you have to demonstrate that each point is supported by the >> evidence. >> >> 1. there were significant changes in climate forcing during the Holocene. >> >> 1a. trace-gas: these changes, including shifts of CO2 and CH4, are >> well known and understood to be due toŠ (use Fortunat text; deal with >> Ruddiman's hypothesis that changes were due to humans) - the point is >> that there are no known natural processes that altered atm trace gas >> concentrations in the Holocene that could be causing the much more >> significant post-industrial increases. >> >> 1b. the dominant forcing of Holocene change was orbital - explain > > briefly as you do >> >> 1c. there is evidence (not necessarily clear?) that both volcanic and >> solar forcing caused some perturbations of climates, that while >> significant regionally and over short periods of time, were smaller >> than those now taking place. There is no evidence that these >> mechanisms could be generating all or most of the change seen since >> the industrial revolution. Volc caused short term perturbations, and >> perhaps periods of increase volc activity caused longer periods of >> net cooling (any really convincing papers? Don't know of any). >> Evidence for solar exists (as you say), but it is not strong - or at >> least evidence is not strong that the sun can do that much on a >> global basis. Need to discuss Bond hypoth here (with Eystein >> text/comments). >> >> 1d. there is also some evidence (crappy, since some of the best - >> e.g., Bond - are only seen to be present in only a few select locals, >> rather than clear global signals) that there are natural >> multi-decadal to millennial-scale quasi-periodic "modes" (cycle is >> not the term to use!) of variability. Some, such as the Bond "mode" >> have been cited as contributing to the Little Ice Age and subsequent >> post-industrial warming. Evidence for this is weak at best, and there >> is no evidence that any natural cycle could be driving a significant >> part of the post-industrial warming. Need to carefully make this case >> if possible - but be careful to avoid bias - case has to be clear. >> >> 2. the evidence is clear (briefly summarize, lots of citations) that >> significant changes in climate forcing in the Holocene caused >> significant changes in climate response - including changes in >> temperature, precipitation (including periods of megadrought?), >> changes in monsoon strength ENSO (I will send prose from Julie Cole), >> ice sheet melting and growth (Dick's prose), sea level rise/fall >> (Dick again - note only need deal with sea level in highly focused >> manner in this section - bulk will go in to later sea level section) >> etc. (list major ones, include paleo oceanographic changes. The >> record makes it clear that the climate system, from global scale >> temperature and processes, down to local scale phenomenon, is quite >> sensitive to changes in climate forcing. >> >> 3. the evidence is clear (briefly summarize, lots of citations) that > > there are places and periods in the Holocene when temperature was >> likely as warm as parts of the 20th century (say what parts - >> late??), but Holocene warm periods were not global in nature like >> post-industrial warmth, nor were they characterized by warmer >> temperatures in all seasons. Plus, we have a good understanding of >> where, when and WHY these earlier warm anomalies existed. In addition >> to backing this all up with evidence, we like your: >> >> 3a. Figure idea - the one following the Bradley et al MWP approach - >> you need to draft such a figure fast, but we can finalize, add more >> data, etc. after ZOD - need a good demonstration of concept for the >> ZOD, however. >> >> 3b. dealing with the inappropriateness of terms like Holocene Thermal >> Maximum or Optimum or Altithermal or Hypsithermal (although, you >> probably have to point out that there was no synchronous Neoglacial >> either). >> >> 4. the evidence is clear (briefly summarize, lots of citations) that >> certain climate system feedbacks were positive and strong in >> amplifying the externally (e.g., orbitally) forced change. Thinking >> primarily biospheric (see Fortunat prose and oceanographic (see >> Sahel/Sahara papers - for good discussion (??) see also Overpeck et >> al in PAGES synthesis volumn - you can cite/ steal from there easily. >> Note that we are only focused on climate change (and feedbacks), but >> not impacts of climate change - can avoid saying much about veg >> change this way. >> >> 5. the evidence is clear (briefly summarize, lots of citations) that >> gradual changes in climate forcing (e.g., orbital) can drive the >> climate system to change abruptly - for the SW Asian monsoon, see >> Morrill et al - Holocene. Neoglaciation shifts, Africa ppt shifts - > > you have lots of good stuff here, but need focus. >> >> -- >> 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/ -- 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/