cc: "rbradley@geo.umass.edu" <rbradley@geo.umass.edu>
date: Mon, 9 Mar 2009 09:49:14 -0700
from: Darrell Kaufman <darrell.kaufman@nau.edu>
subject: Re: citations and comments on draft
to: Keith Briffa <k.briffa@uea.ac.uk>

   Keith:

   Thank you for your insights. I think I can deal with nearly all of your suggestions. You
   picked up on the plug for proxies from lakes at high latitudes. I'll try to tone that down,
   but do want to retain the message.

   I'll see whether our NCAR co-authors can address your suggestion about using an energy
   balance model to relate Milankovitch forcing to temperature. That will take some time, but
   I'd rather submit a manuscript with a high probability of success than to have to go back
   to the drawing board.

   Most importantly: You commented about the significance of the regression used to scale the
   proxy values to temperature. This is the weakest point of the paper, in my view. Because
   the focus is on the 20-year intervals, we only have 5 points for the regression, which is a
   serious limitation, and I doubt would hold up to statistical scrutiny. On the other hand, I
   am confident that the proxy values do correlate with temperature and the correlation is
   significant at even the annual scale (see Fig 2), and here I mean 'significant' even after
   accounting for autocorrelation effects on the df. Would it be valid to present the
   statistics for the annual correlation, then use this to support the scaling for the 20-year
   means, even though the n (= 5) for the 20-year means is too small to derive
   statistical significance? Or can you see another way around this issue? It's important to
   scale the proxy data to temperature, and I believe that our data can support this, I'm just
   not sure how best to make the case. I'll append the values for the five, 20-year intervals
   that I used to calculate the scaling in case you have some ideas to try.

   Also, could you please forward a pdf of your 1990 Nature paper? Our electronic subscription
   picks up at 2000 and I wanted to follow up on your suggestion that we place some
   probabilistic estimate on the significance of the recent warming.

   Thanks again; the paper will be much stronger with your input.

   Darrell

   JJA(C) Proxy
   0.26   1.66
   -0.05  1.35
   0.09   1.54
   0.11   1.32
   -0.31  0.29

   On Mar 9, 2009, at 8:44 AM, Keith Briffa wrote:

   Darell

   perhaps a short piece in the Supp. Inf. could give a little more
   detail on RCS , cite the original refs and show a Figure? but CAN NOT
   do for now , so let's go with it as is to make your deadline. This
   could be done later if referees say so. Attached is a tracked version
   with my comments (forwarded only to Ray also for hard-nosed comment!).

   Cheers

   Keith

   At 16:54 08/03/2009, you wrote:

   Also:

   Would it be important to cite the original sources for the tree-ring
   data, or do you think citing your new compilation would suffice?
   thanks.

   Darrell

   --
   Professor Keith Briffa,
   Climatic Research Unit
   University of East Anglia
   Norwich, NR4 7TJ, U.K.
   Phone: +44-1603-593909
   Fax: +44-1603-507784

   [1]http://www.cru.uea.ac.uk/cru/people/briffa/ <2k synthesis v6-KRB.doc>

