From: Jonathan Overpeck <jto@u.arizona.edu>
To: Eystein Jansen <Eystein.Jansen@geo.uib.no>
Subject: Re: urgent IPCC need
Date: Fri, 1 Sep 2006 15:25:20 -0600
Cc: Keith Briffa <k.briffa@uea.ac.uk>, Stefan Rahmstorf <rahmstorf@ozean-klima.de>, Bette Otto-Bleisner <ottobli@ncar.ucar.edu>, david.adelman@law.arizona.edu

   Hi all - today has been a hectic one, with lots of good input from multiple folks. In the
   end, we agreed to stick with our existing bullets, which changes only where they would
   improve the clarity of what we were saying. Please check the attached - need Fortunat's
   detailed look in particular. Changes are all in yellow highlight. Two special issues:

   1) There is still concern that this bullet is too vague to be as useful as it could be:

   o       It is very likely that the global warming of 4 to 7 °C since the Last Glacial
   Maximum (ca. 21,000 years ago) occurred at an average rate about ten times slower than the
   warming of the 20th century.

   but, perhaps the safest thing would be to leave as is.

   2) As for the 1998/2005 warmest in last 1000 years issue, we suggest adding nothing new to
   the ES, in line with our chapter policy from Bergen, BUT adding something in the chapter
   along the lines of: " There is currently insufficient knowledge to form a consensus on the
   issue of how the warmth of individual years of the last 100 years compare with individual
   years of the last 1000 years" Keith, would you like to make a suggestion on the wording and
   placement?

   The reasoning expressed by Stefan on this issue is undoubtedly shared by others outside our
   team, and perhaps a paper be written on this key topic to help the community reach better
   consensus.

   Thanks for your continued dialog and work! Have a good weekend.

   best, Peck and Eystein

     dear All, thanks for being alert.
     I think we have an agreement that Martin´s comments are useful, but that we should
     change only those sentences where they clarify. Otherwise i agree with Stefan and
     Keith´s statements below.
     Eystein
     At 15:45 +0100 01-09-06, Keith Briffa wrote:

     I forgot to say that I too disagree with removing the first sentence re simulations
     being consistent with reconstructed NH temps. As Sefan says we need the context , and
     our results are independent of Chapter 9 in this regard.
     Keith
     At 15:37 01/09/2006, Stefan Rahmstorf wrote:

     Hi Peck,
     Martin as in Manning? I have found his feedback very useful so far, so we should
     definitely look at what he suggests - he mostly tends to look for whether our sentences
     are clear. Obviously, he cannot suggest real changes in meaning, only issues of clarity,
     but the latter I would take very seriously. Mostly I find his small rewordings good, I
     comment on the larger points and exceptions below.
     - I am against deleting the bullet on speed of deglacial change. This point is extremely
     effective. Just two days ago an oil industry person told me that there have been big
     natural climate changes like ice ages in the past, hence we need not worry. I responded
     that the biggest warming in recent climate history was the end of the last Ice Age - but
     that warming by about 5 ºC took about 5,000 years, not a hundred. "Oh" he said, "Really
     so long? I didn't know that." I think it is a very important point, we need to make it.
     Maybe not in term of "average rate", may we should just say: the warming of 4-7 ºC took
     about 5,000 years, as compared to a future change of up to the same magnitude within a
     century.
     - Next ice age bullet in 30k seems fine to me.
     - exceptional warmth: the SPM said:
     20th C T increase likely the largest in a millennium - that is strengthened (perhaps
     very likely now?)
     1990s likely the warmest decade in a millennium - that again is strengthened
     1998 likely the warmest year - I'd say this is unchanged (except for 2005 challenging
     it), likely is only 66%! Even though the annual proxy data may be uncertain, as a
     physicist I would find it unlikely that there is a mechanism to cause a big warm outlier
     year that beats 1998 from a much cooler background state. How would that work - where
     would the heat come from?
     So in my view we could actually say that these past SPM statements held up or were
     strengthened - but in fact I also like the bullet as it is.

     - Paleoclimate model simulations are broadly consistent with the reconstructed NH
     temperatures over the past 1000 years. The rise in surface temperatures since 1950 very
     likely cannot be reproduced without including anthropogenic greenhouse gases in the
     model forcings, and it is very unlikely that this warming was merely a recovery from the
     pre-20th century cold period.
     On this I disagree with deleting the first sentence, as the second one needs it to
     follow logically. And why should the paleo chapter suddenly make a statement on
     post-1950 warming, if it is not in the context of the past millennium?
     Cheers, Stefan
     --
     To reach me directly please use:
     <mailto:rahmstorf@ozean-klima.de>rahmstorf@ozean-klima.de

     (My former addresses @pik-potsdam.de are read by my assistant Brigitta.)
     Stefan Rahmstorf
     <http://www.ozean-klima.de>www.ozean-klima.de
     www.realclimate.org

     --
     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/

     --
     ______________________________________________________________
     Eystein Jansen
     Professor/Director
     Bjerknes Centre for Climate Research and
     Dep. of Earth Science, Univ. of Bergen
     Allégaten 55
     N-5007 Bergen
     NORWAY
     e-mail: eystein.jansen@geo.uib.no
     Phone:    +47-55-583491  -  Home: +47-55-910661
     Fax:       +47-55-584330

--

   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
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