cc: <keith.alverson@pages.unibe.ch>, <jcole@geo.Arizona.EDU>, <sandy.tudhope@ed.ac.uk>, <mhughes@ltrr.arizona.edu>, <rbradley@geo.umass.edu>
date: Fri, 11 May 2001 09:13:10 -0700
from: "Malcolm K. Hughes" <mhughes@ltrr.arizona.edu>
subject: Re: IGBP piece
to: Keith Briffa <k.briffa@uea.ac.uk>

   I think Keith (Briffa's) rewording of the tree section is excellent. It's important to
   remember that the observing system being argued for has as much to do with monitoring
   future change in the context of the past, and understanding how proxies came to be, as it
   might be with conserving natural archives. In that spirit, I suggest a slight rewording of
   the sentence: "Whatever the cause, this phenomenon points toward the need for more
   integrated ecosystem studies , both data and model based, that involve the use of multiple
   archives capable of providing an understanding of the time-dependent interrelationships
   between different biological and physical processes." I suggest replacing "ecosystem" with
   "process" because "ecosystem studies" has, for many, a rather specific meaning that is not,
   I think, what Keith means. I also suggest inserting the words ", observations, models and
   experiments" after" "multiple archives", to give a flavor of the big campaign nature of
   what is involved. Finally, I do think that the loss of potential records in tropical
   forests is very real and certainly on a par with the ice cap and coral problems - teak
   offers the potential of (probably) dry-season reconstructions clear across its range from
   India to Indonesia. SO, I would urge you to include reference to the- loss of tropical
   tree-ring material and to use teak as an example. Note, until now, no snipes in this
   message. Is this a first between me and Keith? Cheers, Malcolm Quoting Keith Briffa : > >

   >
   > 11 May 2001
   > Keith,
   > Malcolm is quite right that you have seriously misinterpreted the > climate >
   > response change described in our (1998) Nature paper. Actually, I > do
   > think that you can use the "destruction of archives" line in > forest-related
   > research too, but to a limited extent.
   > Destruction of old growth forests in some areas of eastern Siberia and > even the
   > United States do constitute a loss of palaeoarchives (plus, of
   > course, the widespread destruction of tropical forests,including teak as > stated by
   Malcolm). This, though, is nothing to do with what > Malcolm calls the "Briffa effect",
   which cannot be interpreted > in any way as impugning the value of trees as palaeoarchives
   in the > specific density case (i.e. see our own continuing publications) or the > general
   case of dedro in other areas / variables. Rather it (the > relative > density decline)
   refers to a subtle decadal-scale *trend* divergence > between one tree-ring variable
   (Tree-Ring Density) and one specific > temperature window (April-Sept. mean). It does not
   affect many other > growth variables (e.g. Basal area increment, which shows a very >
   different > history) or even the high-frequency temperature/density relationship , > and is
   not geographically ubiquitous even in density data. All > high-latitude trees were, and
   still are, valuable indicators of > temperature variability. The interpretation of the
   climate 'signal' is > difficult in recent decades because of (I believe) non-climate
   changes. > This points to a different interpretational challenge (or you could even > say
   opportunity for better understanding). It is not a loss of an > archive.
   > Unlike Malcolm, I have always realised the inherent danger in assuming a > time-invariant
   response between some (albeit optimal and > objectively-defined) temperature variable and
   any tree-ring (or other) > climate proxy. There is a lot of work showing the time-dependent
   changes > in empirically-calibrated associations between proxies and climate data. >
   However, the effect we describe is ostensibly a 'new' and likely > unprecedented change. I
   do not believe it is adequately (i.e. fully) > explained by the
   > snow-lie theory (and I note Malcolm's snipe that theirs is the only > published
   evidence/explanation!) .
   > There is probably some justification for flagging the problem of
   > interpretational bias in proxies as introduced by anthropogenic effects > but
   > Malcolm is dead right that the way the piece reads now, over dramatises > and even
   misleads the reader by implying trees are now no good at > all.
   > I have suggested a minor rephrasing to set the record straight - but if > you
   > require the dramatic - I suggest you remove the tree section and > references altogether.
   > You may want to move the last sentence of mine down and incorporate it > where you talk
   again about transfer functions.
   >  My suggested replacement for the paragraph starting "Other > sources...." is as follows
   >
   >
   >

     Though their existence may > not > be directly under threat, the interpretation of
     > other palaeodata may also be increasingly complicated by the activities > of
     > humans.  The relationships between tree-ring properties and > regional > climate
     > parameters, for example, are widely used for reconstructing past > climate.  At
     > high northern latitudes, tree-ring densities show a strong correlation > with
     > summer temperature.  Transfer function based estimates of > temperature from
     > trees in this region are accurate recorders of large-scale temperature > on > short
     > (interannual and decadal) and long (multidecadal) timescales: > demonstrably
     > during the early part of the twentieth century.
     >
     > During the second half of the twentieth century, tree density averaged > around
     > the Northern Hemisphere, still mirrors the year-to-year change in > hemispheric
     > temperatures accurately, but the density and temperature trends > have
     > increasingly diverged (Briffa et al., 1998).  The evidence on more > local
     > geographic scales is varied but ,at least in subarctic Eurasia, might be > linked
     > to an increase in winter precipitation that delays the onset of tree > growth
     > (Vaganov et al., 1999).  Other speculative possibilities include > some link with
     > a general fertilization effect seen in other tree-growth parameters, > possibly  due
     to high atmospheric CO2 concentrations or
     > nitrogen-bearing precipitation, or the effects of acid rain or enhanced >
     > ultraviolet radiation (Briffa, 2000

   >

       Whatever the cause, > this > phenomenon
     > points toward the need for more integrated ecosystem studies , both data > and model
     based, that involve the use of
     > multiple archives capable of providing an understanding of the > time-dependent
     > interrelationships between different biological and physical processes. > These
     studies may require a major effort to update many important > palaeoclimate and
     environmental archives. During recent decades,  > the combination of different
     environmental changes ,many the result of > human activities, may well be
     unprecedentedly > complex.

   > Cheers,
   > Keith
   >
   >
   >
   >
   >
   > At 01:44 PM 5/10/01 -0700, Malcolm K. Hughes wrote:
   >
   >

     Dear Ray and all other > recipients > of Ray's recent e-mail,
     > When I tried to open the attachemnt to Ray's message, my virus screen > warned me
     > that it contained the virus W97M/Marker.gen. Therefore I deleted it. I > suggest
     > you do the same, and run a virus scan. Ray or Keith - could you re-send > a > clean
     > version of the file, or include it as ascii text in an e-mail message? > Thanks,
     > Malcolm
     > Quoting "Raymond S. Bradley" > <rbradley@geo.umass.edu>:
     >
     > > I suggest you get input from Julie Cole or Sandy Tudhope on the > coral
     > > business, (what about blowing up reefs?) and Keith Briffa or > Malcolm
     > > Hughes
     > > on the tree ring section.  I'm not sure that it is quite as > you > state,
     > > but
     > > better that they fix it. I'll cc this to all concerned for a > hoefully)
     > > quick response.
     > >
     > > Note I think it's cladocerans, and either speleothems or use > stalactites
     > > --these are most often sampled.
     > > ray
     > >
     > > At 02:31 PM 05/09/2001 +0200, you wrote:
     > > >Dear Ray and Tom,
     > > >
     > > > Attached is the draft PAGES contribution to the next IGBP > newsletter
     > > which
     > > >will highlight each of the core projects with a few pages. This > issue
     > > will
     > > >appear shortly before the Amsterdam congress and will be > stuffed > in the
     > > >conference bags. Our submission is due Friday. If you have > any
     > > comments>  they
     > > >would be appreciated.
     > > >
     > > >Keith
     > > >
     > > >--
     > > >Keith Alverson
     > > >Executive Director
     > > >PAGES International Project Office
     > > >Brenplatz 2, 3011 Bern
     > > >Switzerland
     > > > >[1] eudora="autourl">http://www.pages-igbp.org
     > > >Tel: +41 31 312 31 33
     > > >Mobile: (+41) 079 641 9220
     > > >Fax: +41 31 312 31 68
     > > >
     > > >
     > > >Attachment Converted: > "C:\EUDORA\Attach\IGBPnews.doc"
     > > >
     >
     >
     >
     > Professor Malcolm K. Hughes
     > Laboratory of Tree-Ring Research
     > W.Stadium 105
     > University of Arizona
     > Tucson, AZ 85721
     > phone 520-621-6470
     > fax 520-621-8229

   >

   > --
   > Dr. Keith Briffa, Climatic Research Unit, University of East Anglia, >
   > Norwich, NR4 7TJ, United Kingdom
   > Phone: +44-1603-593909    Fax: +44-1603-507784
   >
   > > Professor Malcolm K. Hughes Laboratory of Tree-Ring Research W.Stadium 105 University
   of Arizona Tucson, AZ 85721 phone 520-621-6470 fax 520-621-8229

