cc: Jonathan Overpeck <jto@u.arizona.edu>, Eystein Jansen <eystein.jansen@geo.uib.no>, cddhr@giss.nasa.gov, Fortunat Joos <joos@climate.unibe.ch>, joos <joos@climate.unibe.ch>, Ricardo Villalba <ricardo@lab.cricyt.edu.ar>, lean@demeter.nrl.navy.mil
date: Wed, 5 Jan 2005 21:17:41 -0500 (EST)
from: hegerl@duke.edu
subject: Re: Fwd: Re: [Wg1-ar4-ch06] IPCC last 2000 years data
to: Keith Briffa <k.briffa@uea.ac.uk>


Hi again, we have a figure with forcing and simulations
for last 1-2 millenia drafted by Pascale, but there is not a lot of
forcing discussion in the chapter for the last millenium apart from a
timeseries in pascales figure. Mostly, we are drawing on
you guys. Our section on the last millenium simulations not very detailed,
focusing more on the big picture (20th century sticks out) than the
individual episodes  (like medieval warm period/maunder minimum).
I think this was what we approximately decided how to slice it
but its been a while....

Gabi

On Wed, 5 Jan 2005, Keith Briffa wrote:

> Hi Peck (et al)
> I am considering comments (including David's) re last 2000 years - some are
> valid =  some are not . Will try to chop out bits but we need this
> consensus re the forcing and responses bit - I am for keeping the forcings
> in as much as they relate to the specific model runs done - and results for
> last 1000 years as I suspect that they will not be covered in the same way
> elsewhere . David makes couple good points - but extent to which forcings
> different (or implementation) perhaps need addressing here. The basic
> agreement I mean is that the recent warming is generally unprecedented in
> these simulations.
> It will take time and input from the tropical ice core /coral people to do
> the regional stuff well . I think the glaciological stuff is a real problem
> - other than just showing recent glacial states (also covered elsewhere) -
> of course difficult to interpret any past records without modelling
> responses (as in borehole data), but this requires considerable space . My
> executive decision would be to ask Olga to try to write a couple of
> papragraphs on limits of interpretation for inferring precisely timed
> global temperature changes? What do others think?  I only heaved Olga's
> stuff in at last moment rather than not include it - but of course it needs
> considerable shortening. The discussion of tree-ring stuff is problematic
> because it requires papers to be published eg direct criticism of Esper et
> al. We surely do not want to waste space HERE going into this esoteric
> topic?  All points on seasonality , I agree with , but the explicit stuff
> on M+M re hockey stick - where is this? ie the bit about normalisation base
> affecting redness in reconstructions - sounds nonsense to me ?
>
> I have to consider the comments in detail but am happy for hard direction
> re space and focus. If concensus is no forcings and model results here fine
> with me - Peck and Eystein to rule
> Keith
>
>
>

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Gabriele Hegerl
Dept. of Earth and Ocean Sciences, Nicholas School of the Environment
Duke University, Durham NC 27708
phone 919-684-6167, fax 919-684-5833
email: hegerl@duke.edu   http://www.eos.duke.edu/Faculty/hegerl.html
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