Subject: No Subject
Date: Thu, 17 Sep 1998 10:35:12 -0400 (EDT)
Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org
Thanks for your message. I've chosen to "expand" the distribution
list to include a few other individuals who can better address some
of the key points you raise.
A meeting in January built around the AMS meeting (which should
bring people into the Boulder vicinity) sounds like a good tentative
plan. Peck? I'm assuming everyone on this list is a potential
As for your general comments, they get to some essential points.
The modeling community leaders are probably about as skeptical about
our paleo-reconstructions as we are of their sulphate aerosol
parameterizations, flux corrections (or more worrying, supposed
lack thereof in some cases!), and handling of the oh-so-important
tropical Pacific ocean-atmosphere interface...
So my personal philosophy is that more than one side here can
benefit from extending the olive branch, and there are a few
individuals in the modeling community who could benefit from slowing
down on the stone throwing from their fragile glass tower :)
More to the point, though, I strongly believe the paleo community
needs to present an honest but unified front regarding what we all
agree we can definitely, probably, and simply not yet say about
the climate of the past several centuries, and plan strategies
that will allow us all to work towards improved reconstructions
without stepping on each others toes. There's a challenge there,
but one I'm sure we can all rise to. I am grateful to Peck for
realizing that the time is ripe for a workshop in which we all
strategize as a group towards these ends. I believe we all go
into this in "good faith", and I'm very excited about what the
workshop might produce, in particular, in terms of effective
I share Phil's concern about getting things "straightened out"
before the IPCC report. As one of the lead authors on the
"observed climate variation and change" chapter for the 3rd assessment
report, a key goal of mine will
be to present fairly and accurately all of our different efforts,
and the common denominator amongst them...
I also understand all-to-well Phil's concerns about free data
exchange. In fact, we've been working closely w/ Peck to get
every aspect of our reconstructions, including calibration/verification
statistics, etc., available on-line at NGDC. The one catch w/ the
paleo network is that a few of the indicators we used were provided
us under conditions that they not yet be passed along (this includes,
I believe, the Morrocan tree rings, and some others. And at least
one important indicator--Malcolm's Yakutia record--was as yet
unpublished. Not myself knowing the details of the propietary
issues involved here, I have resisted simply putting our entire
multiproxy network out their for public consumption. But working
w/ Peck and Malcolm, I'm sure we can do this appropriately and
quickly. That's an example of a key issue that would be on the
table at the workshop in question.
--------------------PHIL'S MESSAGE TO PECK------------------------
Thanks for the comments on the paper in The Holocene !
The paper stems from work Keith and I have been doing with the
Climate Change Detection group headed by Tim Barnett. It is
much toned down from some of the things about paleo data that
Tim and Simon Tett wanted to say. Long paleo series (either the
individual ones or regional/hemispheric averages) have got to
be good before these sorts of people will begin to use them and
believe they tell us something about variability in the past -
something that cannot be got from long control runs of GCMs.
A small meeting would be a good idea, therefore. Mike Mann
knows the next few times I'll be in the US. The first possible
date for him is the AMS annual meeting in Dallas in Jan 99 -
maybe we can tag something onto the end of this for a day or two.
I'll let you and Mike work something out on this. I'm also
in the US for a meeting on Climate Extremes which is tentatively
scheduled for March 9-13 in Asheville.
Prsentation of the paleo data is the key in all this. Tim
Barnett was somewhat horrified by the coherency diagrams he
produced (fig 9). He then produced Fig 10 from the GCM and
that was not much better. Hidden between the lines of the
paper is the theme that a number of us have been saying for
years ( especially Ray and Malcolm) that the LIA and MWE
were not that global and not that different from today's
temperatures. Mike's paper in Nature reiterates this. Keith
and I have been thinking of writing a forum piece for The
Holocene addressing in somewhat provocative terms what
paleoclimatologists should be doing with regard the detection
issue and to some extent with respect to science in general -
should be continue using terms like LIA and MWE for example.
We hope to address many of the issues you make in your email -
seasonality, consistency of the proxy through time, goodness
of the proxy etc. We need to come up with some agreed strategy
on this especially with IPCC coming up.
What we did in the paper was one way of assessing proxy
quality. Something like Tables 2 and 4 are what is required
though to inform the uninitiated (modellers) about proxy data.
For use in detection at the moment a paleo series has to be a
proxy for temperature. I know proxies tell us about other aspects
of the climate as well, but a clear, unambiguous temperature
signal is what is needed.
Some other quick answers -
1) Happy to send to you all the series and the hemispheric values.
I hope Mike will send all his as well, but the last time we
discussed this he said that some could not be made freely
available. This isn't Mike's fault but there are still
some stumbling blocks to free exchange of data within the
various paleo communities.
2) We all know the quality of proxies changes with time. Trees
don't have dating problems but do have the reduction in
sample depths you talk about. Dendro people are much more
open about this though than the coral and especially the
ice core communitites.
3) Trees may not grow everywhere but they are more global in extent
than the others. There are also many more chronologies
available and this is a factor. We had much more choice there
than in the other paleo groups.
4) Whilst we are taking bets, proxies will never be better than
instrumental data. Corals will eventually extend the SOI
series but never be better than it for the years after 1850.
Similarly with the NAO. Instrumental data exists to extend
this to about 1750 and the fact that such data is sitting
out there is only just begining to be realised. A great NAO
reconstruction could be produced if the real data extended
over nearly 200 years, enabling the low-frequency aspects
to be considered in much more detail than ever before
( a la Stahle with the SOI).
That's enough for now.
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784 University of
Norwich Email email@example.com
Michael E. Mann
Adjunct Assistant Professor, Department of Geosciences
Morrill Science Center
University of Massachusetts
Amherst, MA 01003
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