From	Michael E. Mann	Date	Thu, 09 Oct 2003 14:16:31 -0400
To	Tom Crowley
CC	Caspar Ammann, ray bradley, Keith Briffa, Tom Crowley, Malcolm K. Hughes, Michael Oppenheimer, Tim Osborn, Jonathan T. Overpeck, Scott Rutherford, Kevin Trenberth, Tom Wigley, Michael E. Mann
Subject	Re: draft
HI Tom, My understanding of the papers from the borehole community ever since the 1997 GRL article by Huang et al is that they no longer believe that the data has proper sensitivity to variations prior to about AD 1500--in fact, I don't believe anyone in that community now feels they can meaningfully go farther back that that. Huang contributed the section on boreholes in chapter 2 for IPCC (2001), and wrote the very words to that effect... Now, the possible influences on boreholes might lead to inferred trends in GST that are different from those in SAT is a different one. A number of independent recently published papers by (Beltrami et al; Stiglitz et al; Mann and Schmidt) and others have demonstrated that there should be expectations for significant differences between past SAT (what we care about) and GST variations (what boreholes in the best case scenario see) due to snowcover influences, etc. We don't have time to discuss that in this very short piece, so I tried, as briefly as possible, to cover our bases on this issue, in a way that doesn't really stir up the pot w/ the borehole folks... I'm interested in any further thoughts on the above, mike At 12:38 PM 10/9/03 -0400, Tom Crowley wrote: Hi, I don't understand why we cannot cite the borehole data for the MWP - that in a sense is the only legitimate data set that shows a ~1 C cooling from the MWP to the LIA - forget the deforestation problem for the moment, that is later in time - if the borehole data for the MWP are legitimate then there is still a case for concluding that the MWP was significantly warmer than the LIA tom Thanks Phil, a few brief responses and inquiries below... cheers, mike At 04:17 PM 10/9/03 +0100, Phil Jones wrote: Mike, Away Oct 11-16, so here are a few comments. A few times the tone could be a little less antagonistic. We don't want to inflame things any further. So remove the word laundry. fair enough. You *should* have seen the first draft I wrote. This is quite toned down now... 1. With the boreholes do we want to get one of the borehole group to sign up, eg Henry Pollack? Would add a lot of weight to the last 500 year argument. this has merit. unfortunately though I think it might open up a hornets nest of the author list is not identical to the original list of authors on the Eos article. Other thoughts on this... 2. On the UHI, there was a paper in a very recent issue of J. Climate by Tom Peterson, arguing for the USA that this is non-existent. Issue with UHI is one of large versus local scale. One station doesn't influence large-scale averages. All studies which look at the UHI comprehensively find very little effect (an order of magnitude smaller than the warming). Also the warming in the 20th century is very similar between the NH and SH and between the land and ocean components. let me see if I can fit one or two sentences in on this and keep the article under the length. Also, if we can't estimate temperature histories accurately, then SB can't say it was warmer in their MWP period. They believe the 20th century instrumental data when they want to. yes, one of a large number of amazing contradictions in their reasoning... 3. Keith is away till next week. I doubt we will have the space to do the 'tree issues' justice. Best just to say that there are an (equal) number of non tree-based proxy series?? I do think we need to address their spurious description of the putative biological effects. Any way that you can get in touch w/ Keith for a response, perhaps just to this one point? Also, Malcolm might want to comment on the current wording? 4. Ray, Malcolm and Henry Diaz have a Science Perspectives piece coming out in the next couple of weeks on the MWP/E. This is also relevant. good! 5. Don't think we will get away with the last paragraph. Whether we want it is an issue ?? Shouldn't we be sticking to the science. ok, I wasn't sure myself--yet it is a powerful rebuke, and reminds people that the objection to the validity of their work goes beyond just our article--and that's important. Does someone want to try to rephrase this paragraph, maybe reducing it to a couple sentences? Cheers Phil At 21:37 08/10/2003 -0400, Michael E. Mann wrote: Dear co-authors, Attached is a draft response, incorporating suggestions Kevin, Tom W, and Michael. I've aimed to be as brief as possible, but hard to go much lower than 750 words and still address all the key issues. 750 words, by the way, is our allotted limit. Looking forward to any comments. Feel free to send an edited version if you prefer, and I'll try to assimilate all of the suggested edits and suggestions into a single revised draft. If you can get comments to me within the next couple days, that would be very helpful as we're working on a late October deadline for the final version. Thanks for your continued help, mike ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [1]http://www.evsc.virginia.edu/faculty/people/mann.shtml Prof. Phil Jones Climatic Research Unit Telephone +44 (0) 1603 592090 School of Environmental Sciences Fax +44 (0) 1603 507784 University of East Anglia Norwich Email p.jones@uea.ac.uk NR4 7TJ UK ---------------------------------------------------------------------------- _______________________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [2]http://www.evsc.virginia.edu/faculty/people/mann.shtml -- Thomas J. Crowley Nicholas Professor of Earth Systems Science Dept. of Earth and Ocean Sciences Nicholas School of the Environment and Earth Sciences Box 90227 103 Old Chem Building Duke University Durham, NC 27708 tcrowley@duke.edu 919-681-8228 919-684-5833 fax _______________________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [3]http://www.evsc.virginia.edu/faculty/people/mann.[4]shtml References 1. http://www.evsc.virginia.edu/faculty/people/mann.shtml 2. http://www.evsc.virginia.edu/faculty/people/mann.shtml 3. http://www.evsc.virginia.edu/faculty/people/mann.shtml 4. http://www.evsc.virginia.edu/faculty/people/mann.shtml