From	Jonathan T. Overpeck	Date	Fri, 15 Sep 2006 08:55:58 -0600
To	Keith Briffa
CC	David Rind, Stefan Rahmstorf, Bette Otto-Bleisner, cddhr@giss.nasa.gov, Ricardo Villalba, Tim Osborn, Fortunat Joos, Eystein Jansen, Øyvind Paasche
Subject	Re: 1988/2005
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 Øyvind - 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 : >> >>> 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/