date: Fri Mar  3 16:57:36 2006
from: Keith Briffa <k.briffa@uea.ac.uk>
subject: Re: photographs and other visuals for Science
to: Jonathan Overpeck <jto@u.arizona.edu>

   Peck
   we do need to say something , but as I said in an earlier message , not  without more
   consideration. We should not write something curt on this - ditto the Co2 possible
   fertilisation . In the push to do all this other stuff , we have had to leave it - to
   discuss later how to include an uncertainty issues bit about recent environmental mess ups
   . The D'arrigo paper is not convincing , but we have to do some work to show why , instead
   of just saying this . The divergence issue is NOT universal  , and not unrelated to very
   recent period bias arising from processing methods . It is VERY LIKELY not the threshold
   problem D'Arrigo thinks  it is. We need money here to work on this and losing our last
   application to Europe has messed us up. For now we  can not include anything. I will work
   on text for the next iteration.
   At 16:05 03/03/2006, you wrote:

     Hi Richard - this issue is one that we refer to in our key uncertainty table. I believe
     Keith Briffa was one of the first to write about it, and it is an important issue. I
     haven't seen R's paper or results myself, but I bet Keith has. I'm cc'ing this to him to
     see what he thinks.
     thanks, peck

     Know anything about the "divergence problem" in tree rings?  R D'arrigo
     talked to the NRC yesterday.  I didn't get to talk to her afterward, but
     it looked to me that they have redrilled a bunch of the high-latitude tree
     rings that underlie almost all of the high-res reconstructions, and the
     tree rings are simply missing the post-1970s warming, with reasonably high
     confidence.  She didn't seem too worried, but she apparently has a paper
     just out in JGR.  It looked to me like she had pretty well killed the
     hockey stick in public forum--they go out and look for the most-sensitive
     trees at the edge of the treeline, flying over lots and lots of trees that are
     lesss sensitive but quite nearby, and when things get a little warmer, the
     most-sensitive trees aren't anymore, and so the trees miss the extreme
     warming of the recent times, and can't reliably be counted as catching
     the extreme warmth of the MWP if there was extreme warmth then. Because as far as I can
     tell the hockey stick really was a tree-ring
     record, regardless of how it was labelled as multiproxy, this looks to me
     to be a really big deal.  And, a big deal that may bite your chapter...
     --Richard

     --
     Jonathan T. Overpeck
     Director, Institute for the Study of Planet Earth
     Professor, Department of Geosciences
     Professor, Department of Atmospheric Sciences
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   --
   Professor Keith Briffa,
   Climatic Research Unit
   University of East Anglia
   Norwich, NR4 7TJ, U.K.

   Phone: +44-1603-593909
   Fax: +44-1603-507784
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