Wednesday, December 21, 2011

1158153059.txt

From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@uea.ac.uk>
Subject: Re:
Date: Wed, 13 Sep 2006 09:10:59 -0600
Cc: rahmstorf@ozean-klima.de, Bette Otto-Bleisner <ottobli@ncar.ucar.edu>, cddhr@giss.nasa.gov, joos <joos@climate.unibe.ch>, Eystein Jansen <eystein.jansen@geo.uib.no>, "Ricardo Villalba" <ricardo@lab.cricyt.edu.ar>, t.osborn@uea.ac.uk

Keith - thanks for this and the earlier updates. Stefan is not around this week, but
hopefully the others on this email can weight in. My thoughts...

1) We MUST say something about individual years (and by extension the 1998 TAR statement) -
do we support it, or not, and why.

2) a paragraph would be nice, but I doubt we can do that, so..

3) I suggest putting the first sentence that Keith provides below as the last sentence, in
the last (summary) para of 6.6.1.1. To make a stand alone para seems like a bad way to end
the very meaty section.

4) I think the second sentence could be more controversial - I don't think our team feels
it is valid to say, as they did in TAR, that "It is also likely that, in the Northern
Hemisphere,... 1998 was the warmest year" in the last 1000 years. But, it you think about
it for a while, Keith has come up with a clever 2nd sentence (when you insert "Northern
Hemisphere" language as I suggest below). At first, my reaction was leave it out, but it
grows on you, especially if you acknowledge that many readers will want more explicit prose
on the 1998 (2005) issue.

Greater uncertainty associated with proxy-based temperature estimates for individual years
means that it is more difficult to gauge the significance, or precedence, of the extreme
warm years observed in the recent instrumental record. However, there is no new evidence to
challenge the statement made in the TAR that 1998 (or the subsequent near-equivalent 2005)
was likely the warmest of Northern Hemisphere year over the last 1000 years.

5) I strongly agree we can't add anything to the Exec Summary.

6) so, if no one disagrees or edits, I suggest we insert the above 2 sentences to end the
last (summary) para of 6.6.1.1. Or should we make it a separate, last para - see point #3
above why I don't favor that idea as much. But, it's not a clear cut issue.

Thoughts? Thanks all, Peck

Eystein and Peck
I have thought about this and spent some time discussing it with Tim. I have come up
with the following

Greater uncertainty associated with proxy-based temperature estimates for individual
years means that it is more difficult to gauge the significance, or precedence, of the
extreme warm years observed in the recent instrumental record. However, there is no new
evidence to challenge the statement made in the TAR that 1998 (or the subsequent
near-equivalent 2005) was likely the warmest in the last 1000 years.
This should best go after the paragraph that concludes section 6.6.1.1
I believe we might best omit the second sentence of the suggested new paragraph - but
you might consider this too subtle (or negative) then. I think the second sentence is
very subtle also though - because it does not exclude the possibility that the same old
evidence that challenges the veracity of the TAR statement exists now , as then!
I think this could go in the text where suggested , but I think it best NOT to have a
bullet about this point.We need to check exactly what was saidin the TAR . Perhaps a
reference to the Academy Report could also be inserted here?
Anyway, you asked for a straw-man statement for all to argue about so I suggest we send
this to Stefan, David , Betty and whoever else you think.
cheers
Keith

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784
http://www.cru.uea.ac.uk/cru/people/briffa/

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
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http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

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