cc: "Raymond S. Bradley" , mhughes@ltrr.arizona.edu, k.briffa@uea.ac.uk, tom@ocean.tamu.edu, p.jones@uea.ac.uk, td@gfdl.noaa.gov, hpollack@geo.lsa.umich.edu date: Fri, 2 Mar 2001 10:53:01 -0600 from: tom crowley subject: Re: Science letter to: "Michael E. Mann" Dear All, A few more comments re Mikes note - Mike and I thought that if we cannot make a case to our colleagues, why muddy the waters further (as either Keith, Malcolm, or Ray said)? That said, I don't think this has been wasted time. I still think a thoughtful short paper on the subject of Holocene climate change wold be useful, this time stating it from OUR perspective (i.e., not focusing exculsively on Broeckers message). By broadening this it may be more interesting; we could also include a couple of figures and maybe add some input from Tom Delworth and Henry Pollack. I would be willing to take a crack at this, and if anyone wants to CONDITIONALLY sign on, I would be more than happy to include you. I probably would not begin this until late April, after our trip to Germany and the meeting in Virginia. Tom ps fyi I counted the average spacing between the warm and cold oscillations in the iron oscillations illustrated by Broecker. Regardless of whether warm or cold are used, the mean spacing is indeed 1.5 k, although the s.d. is 0.4k HOWEVER, the mean spacing between the four main warm phases illustrated by Broecker on the same figure is, believe it or not, 2.15! much closer to the solar peak. This calls to mind the interesting (and clever) Wigley and Raper paper in Proc. Roy. Soc. (1990) indicating that, given the uncertainties in chronology, solar forcing plays a role i n Holocenn climate change. It therefore seems that the conveyor is indeed oscillating but the time scale of the larger scale CLIMATE shifts may be more regulated by solar, with volcanism adding some stochastic contribution. Something like this is worth adding to the proposed Eos piece. Tom Thomas J. Crowley Dept. of Oceanography Texas A&M University College Station, TX 77843-3146 979-845-0795 979-847-8879 (fax) 979-845-6331 (alternate fax)