From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@uea.ac.uk>
Subject: Re: 1988/2005
Date: Fri, 15 Sep 2006 08:55:58 -0600
Cc: David Rind <drind@giss.nasa.gov>, rahmstorf@ozean-klima.de, Bette Otto-Bleisner <ottobli@ncar.ucar.edu>, cddhr@giss.nasa.gov, Ricardo Villalba <ricardo@lab.cricyt.edu.ar>, t.osborn@uea.ac.uk, joos <joos@climate.unibe.ch>, Eystein Jansen <eystein.jansen@geo.uib.no>, <oyvind.paasche@bjerknes.uib.no>

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Thanks Keith, Tim and Fortunat for your input. 
We'll go with what we have then - Eystein's 
suggestion minus the second "individual".

Eystein and Řyvind - just want to double check 
that you've deleted that 2nd "individual" in the 
all important 1998 sentence??

Thanks, Peck

>I do not disagree either - in fact I preferred 
>not to make the "too clever" second statement in 
>my "straw man" as I said at the time. If this is 
>the consensus (and I believe it is the 
>scientifically correct one) then I would be 
>happy with Eystein's sentence. The worry is that 
>we have inserted this late with no refereeing 
>and no justification in the text. I would also 
>suggest dropping the second "!individual" in the 
>sentence.
>
>At 10:50 15/09/2006, Fortunat Joos wrote:
>>Hi,
>>
>>I support Eystein's suggestion and agree with David.
>>
>>If there is not sufficient evidence to support 
>>or dismis claims whether 1998 or
>>2005 was the warmest year of the millennium than we should indeed say so.
>>It is the nature and the strenght of the IPCC 
>>process that points from the TAR
>>and earlier reports get reconsidered and 
>>reassessed. It is normal that earlier
>>statements get revised. Often statements can be strenghtened, but sometimes
>>statements can not be supported anymore. Our job is to present the current
>>understanding of science as balanced as possible.
>>
>>With best wishes,
>>
>>Fortunat
>>
>>Quoting Eystein Jansen <Eystein.Jansen@geo.uib.no>:
>>
>>>  Hi all,
>>>  My take on this is similar to what Peck wrote.  My suggestion is to write:
>>>
>>>  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
>>>  individual years observed in the recent
>>>  instrumental record, such as 1998 and 2005, in
>>>  the context of the last millennium.
>>>
>>>  I  think this is scientifically correct, and in
>>>  essence means that we, as did the NAS panel say,
>>>  feel the TAR statement was not what we would have
>>>  said. I sympatise with those who say that it is
>>>  not likely that any individual  years were
>>>  warmer, as Stefan has stated, but I don´t think
>>>  we have enough data to qualify this on the
>>>  hemispheric mean.
>>>
>>>  Best wishes,
>>>  Eystein
>>>
>>>
>>>  If this is interpreted as a critisim of the TAR, then I think we
>>>  At 14:09 -0600 13-09-06, Jonathan Overpeck wrote:
>>>  >thanks David - lets see what others think. I
>>>  >agree, that we don't want to be seen as being
>>>  >too clever or defensive. Note however, that all
>>>  >the TAR said was "likely" the warmest in the
>>>  >last 1000 years. Our chapter and figs (including
>>>  >6.10) make it clear that it is unlikely any
>>>  >multi-decadal period was as warm as the last 50
>>>  >years. But, that said, I do feel your are right
>>>  >that our team would not have said what the TAR
>>>  >said about 1998, and thus, we should delete that
>>>  >second sentence.
>>>  >
>>>  >any other thoughts team?
>>>  >
>>>  >thx, peck
>>>  >
>>>  >
>>>  >>Leaving aside for the moment the resolution
>>>  >>issue, the statement should at least be
>>>  >>consistent with our figures. Fig. 6-10 looks
>>>  >>like there were years around 1000 AD that could
>>>  >>have been just as warm  - if one wants to make
>>>  >>this statement, one needs to expand the
>>>  >>vertical scale in Fig. 6-10 to show that the
>>>  >>current warm period is 'warmer'.
>>>  >>
>>>  >>Now getting back to the resolution issue: given
>>>  >>what we know about the ability to reconstruct
>>>  >>global or NH temperatures in the past - could
>>>  >>we really in good conscience say we have the
>>>  >>precision from tree rings and the very sparse
>>>  >>other data to make any definitive statement of
>>>  >>this nature (let alone accuracy)? While I
>>>  >>appreciate the cleverness of the second
>>>  >>sentence, the problem is everybody will
>>>  >>recognize that we are 'being clever' - at what
>>  > >>point does one come out looking aggressively
>>>  >>defensive?
>>>  >>
>>>  >>  I agree that leaving the first sentence as the
>>>  >>only sentence suggests that one is somehow
>>>  >>doubting the significance of the recent warm
>>>  >>years, which is probably not something we want
>>>  >>to do. What I would suggest is to forget about
>>>  >>making 'one year' assessments; what Fig. 6-10
>>>  >>shows is that the recent warm period is highly
>>>  >>anomalous with respect to the record of the
>>>  >>last 1000 years. That would be what I think we
>>>  >>can safely conclude the last 1000 years really
>>>  >>tells us.
>>>  >>
>>>  >>David
>>>  >>
>>>  >>At 9:10 AM -0600 9/13/06, Jonathan Overpeck wrote:
>>>  >>>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
>>>  >>>direct tel: +1 520 622-9065
>>>  >>>fax: +1 520 792-8795
>>>  >>>http://www.geo.arizona.edu/
>>>  >>>http://www.ispe.arizona.edu/
>>>  >>
>>>  >>
>>>  >>--
>>>  >>//////////////////////////////////////////// 
>>>///////////////////////////////
>>>  >>
>>>  >>//////////////////////////////////////////// 
>>>///////////////////////////////
>>>  >
>>>  >
>>>  >--
>>>  >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
>>>  >direct tel: +1 520 622-9065
>>>  >fax: +1 520 792-8795
>>>  >http://www.geo.arizona.edu/
>>>  >http://www.ispe.arizona.edu/
>>>
>>>
>>>  --
>>>  ______________________________________________________________
>>>  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
>>
>>
>>--
>>   Climate and Environmental Physics
>>   Sidlerstr. 5, CH-3012 Bern
>>   Phone:    ++41(0)31 631 44 61      Fax:      ++41(0)31 631 87 42
>>   Internet: http://www.climate.unibe.ch/~joos/
>
>--
>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
direct tel: +1 520 622-9065
fax: +1 520 792-8795
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
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