Wednesday, May 2, 2012

3734.txt

cc: Jonathan Overpeck <jto@u.arizona.edu>,David Rind <drindatXYZxyzs.nasa.gov>, rahmstorf@ozean-klima.de,Bette Otto-Bleisner <ottobliatXYZxyzr.ucar.edu>, cddhr@giss.nasa.gov,Ricardo Villalba <ricardoatXYZxyz.cricyt.edu.ar>
date: Fri Sep 15 12:57:13 2006
from: Tim Osborn <t.osbornatXYZxyz.ac.uk>
subject: Re: 1988/2005
to: Keith Briffa <k.briffaatXYZxyz.ac.uk>, Fortunat Joos <joosatXYZxyzmate.unibe.ch>, Eystein Jansen <Eystein.JansenatXYZxyz.uib.no>

Hi,
my view is also that Eystein's adaption of Keith's original wording (with the second
'individual' removed as Keith said) seems to be the best option so far, because it does not
attempt to re-assess the TAR's claim about 1998 but instead it just points out that such
claims are difficult to assess.
If the uncertainty were simply larger for individual years then we could still do the
assessment. The difficulty is that the uncertainty is not just larger but also harder to
quantify -- e.g. Wahl & Ammann, in press, do not attempt to verify the inter-annual
variability of the Mann et al. reconstruction, instead focussing on verification of decadal
timescales. Without such inter-annual verification, the assessment cannot be made. Yet it
is also difficult to 'withdraw' the previous statement, because it had only been made with
relatively low confidence (likely, 66-90% confidence).
Cheers
Tim
At 11:33 15/09/2006, Keith Briffa wrote:

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

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