Wednesday, March 14, 2012


cc: Jean Claude Duplessy <>, Thomas Stocker <>, Keith Briffa <>, jean jouzel <>,
date: Thu, 20 Jul 2000 09:18:59 -0700
from: Jonathan Overpeck <>
subject: Re: Euresco conference "abrupt climate change dynamics" November
to: Keith Alverson <>

<x-flowed>Hi Keith and friends -

First, I'd be happy to help and serve on the org commitee.

Second, I appreciate/like comments from Jurgen and Jean-Claude.
Jurgen's suggestions would make the mtg much stronger on the CLIVAR
side. On the CLIVAR side, having Kevin there is a great asset, and
although I'd like to endorse Jurgen's recommended talk idea, I'd also
like to stir up some good debate by suggesting we invite either Mark
Cane or Amy Clement to talk about abrupt changes in ENSO/tropical
Pacific from a simple model point of view. If I'm right, this might
provoke some interesting discussion, particularly if Kevin is in the

Jansen and Keigwin both have new results, which would be a plus. I
also suspect that there is a good "new" perspective on the Nordic ice
core data, but the question is how to get it. Dave Fisher always
seems to be doing new and different work (also good) in terms of
synthesizing the northern Canada work with the Greenland work, and
I'm pretty sure he has new data in the mix as well. We could ask him,
and also check to see if he could bring in the older Greenland
(Dansgaard) data as Jean-Claude suggests. I agree that we're overdue
for a reconciliation of the old data (and interesting inferences,
like neoglacial cycles) with the new (lots more coverage and
variables).I could check with Fisher if you'd like - a good Canadian

One general comment about the speaker list is that I believe it is
the one created a year ago to get the funding. As such, it emphasizes
some talks that were "hot" a year ago, but are now published and "old
news." This includes the work on the 8.2 event - I suggest we find
one person to summarize the previous data-oriented work (either
Alley, Von Graffenstien or ?) and then have a matching data talk.

I'd follow the same tack with with the mid-holocene African change.
Each of the speakers we have - Claussen, deMenocal (note the small
d!), Gasse, Harrison and Joussaume - do not invite them all to talk
unless they have some substantial NEW material. Each has written some
great papers in the last few years, but it will be a bit boring to
hear what is already published. So, figure out who has new stuff,
and ask them to combine that with a summary of the already published.
Again, I'd try to get one or two data talks, and then one or two
model talks, but only if they all have SOME new stuff.

So, the question is, what is new and interesting. The Cane/Clement
stuff is good - it may be published by then, but not yet. More
Americans (I know this stuff best, and we need to consider a more
american balance to the mtg (see below - I think we can get $$ for
this). Anyhow, focusing on NEW science

- North American Holocene drought variability - there are new data
and a great summary emerging. Lots of abrupt change, moving dunes,
very long droughts, regime shifts - all in a region that is the
"breadbasket" of the US. There are several good potential speakers,
but right now, I'm guessing Steve Forman might be the best - he has a
new summary ms. just submitted somewhere. Thus, my guess is that it
would be published just about next fall - perfect timing. He talks
about dynamics too. Suggest you add Steve Forman.

- S. Asian (Indian) monsoon variability in the Holocene. - here the
person is Carrie Morrill. She''ll defend next fall, so a new face
that would be good to encourage. She has new data from Tibet that is
pretty impressive - century scale variabilty is much larger than I
would have guessed. Also, she's working on a new summary that brings
in a much improved Asian monsoon perspective on the Younger Dryas,
the 8/2 k even, the 4 k event, the Little Ice Age, etc. Again, the
paper probably won't be published in fall 2001, but it will be close.
NEW science. Only problem is that she's my student (just joking, but
you should know that this bright new paleo person is from the Univer.
of Arizona). I'd add her to the list. We need some new faces!

- ESNO and N. American drought over the last 200 years. There is an
emerging picture that ENSO variability was much more decadal during
the 19th century. This will be highlighted in a paper soon to appear
in Nature (Urban et al), supporting the tree-ring (teleconnection)
inferred perspective. This will be a bit old, then, by fall 2001.
However, there is going to be a pile of new work on the nature of
this "abrupt" shift (and others in the Holocene), and the
corresponding shifts in drought variablity over North America (and
perhaps further south too). Unfortunately, the person doing this
interesting work is my wife - Julie Cole. Needless to say, I think it
would be great to invite her, but will understand if you don't think
it is appropriate. The work will be NEW and of interest to CLIVAR
types for sure.

- Julio Betancourt has a paper coming out in Science that has a very
interesting new view of change in South America (Atacama desert).
This is just the tip of the story, however, and the group might
appreciate hearing from Julio - a story that is different from the
one we have heard for the last decade - quite possibly the most
interesting S. American perspective of recent years. There would be
NEW science for next fall, as they're actively working down there.

- as for volcanic forcing, we do have a new summary paper in press in
JGR as Jean-Claude mentioned. But, it only concerns the last 500
years. I propose you let me check in with Greg Zielinski (a co-author
on that JGR paper) to see if he has a new perspective on the role
volvanic eruptions may have played in generating abrupt shifts
farther back in time. Greg is the american expert on this, and I'm
always interested in his latest - he always has unpublished results
that make you think. Could be better than focusing on the last 500
years, when, frankly, I'm not sure the volcano story is all that
positive. My story (unpublished) is that I think proxies might not
have the ability to give a faithful record of the impacts of the
really big eruptions (eg Tambora).

In summary, I'd shift around things to ensure that each speaker has
exciting new results to present in a solid context of past work.
Paleo mtgs of late have tended to have too many "old news" talks. I'm
95% sure that we could get US NSF support for any US additional US
participants you wish to invite, so the ones I suggest above will
probably not cost a Euro. Let me know what to do.

Hope this helps, cheers, Peck

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
tel: +1 520 622-9062
direct tel: +1 520 622-9065
fax: +1 520 792-8795

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