Friday, December 16, 2011


From: Eystein Jansen <>
Subject: Re: [Wg1-ar4-ch06] abrupt and Important thoughts on References
Date: Tue, 28 Jun 2005 23:13:56 +0200

Hi all,

Two things:

1. Concerning the 1470k pacing of DO-events.
There are revisions underway in the
layer-counting of the Greenland Ice Cores. A
meeting in Copenhagen in August co-ordinated by
Sigfus Johnsen will discuss the issue at length,
but there may not be many papers out from the
meeting that are citeable for IPCC. There is
already the Shackleton paper which indicate that
Greenland Ice Cores in MIS3 have an age model
that are off by some millennia, and the
preliminary data on the new age models indicate
substantial revisions as far as I hear from talks
given at various meetings. My thinking is that
we neither can ignore the fact that current data
indicate a 1470 pacing for some time interval of
the ice cores if one apply the existing age
scales. I think it would be foolish not not refer
to it, I think the possibility that the system
has the ability to enter into specific cycles is
intriguing, and is a result that is well known
and IPCC should not pretend we haven�t heard
about it. But we should make it less blunt than
in the current version of the Abrupt Change
subchapter, perhaps stating that the result is
highly dependant on age models and we need time
to absorb new research in order to verify the

2. Having the fortune of not being that close to
the darker sides of US politics, I have the
feeling that Peck�s comment concerning
referencing perhaps is a bit too "paranoic". I
think the advice is well taken not to overcite
our own research, and make sure not to overlook
other important contributions, but we should do
our best to cite what we think are key results.
In any case we will have the FOD review and have
the opportunity to have all our good colleagues
keeping us honest on this issue.


>Hi all - thanks Fortunat and Stefan for more
>debate on the 1470. Sounds like the final
>decision is up to Eystein, but I can guess the
>way he's thinking.
>With regard to refs - remember that our goal is
>to cut the number of references significantly.
>Since this is an assessment and not a review, we
>can delete all but the most recent and
>comprehensive references. I don't like cutting
>out the original refs any more than you, but we
>just don't have room, and its more important to
>have text than exhaustive references. Our
>colleagues will hopefully understand, and if
>they don't then they need to do an ego check.
>It's more important that we make an impact with
>policy makers rather than with citation indices.
>Does this make sense?
>In any case, please help make sure we trim the
>total references DOWN in number by a significant
>number. This is not happening the to degree it
>Also, please not that in the US, the US Congress
>is questioning whether it is ethical for IPCC
>authors to be using the IPCC to champion their
>own work/opinions. Obviously, this is wrong and
>scary, but if our goal is to get policy makers
>(liberal and conservative alike) to take our
>chapter seriously, it will only hurt our effort
>if we cite too many of our own papers
>(perception is often reality). PLEASE do not
>cite anything that is not absolutely needed, and
>please do not cite your papers unless they are
>absolutely needed. Common sense, but it isn't
>happening. Please be more critical with your
>citations so we save needed space, and also so
>we don't get perceived as self serving or worse.
>Again, we can debate this if anyone thinks I've gone off the deep end.
>Thanks, peck
>PS - this is not to say anything critical of the
>refs Fortunat is suggesting - we must cite the
>most relevant papers, and we must be as up to
>date as possible.
>>Peck and all,
>>Fully agree. This '1470' yr periodicity is highly controversial and I
>>was never convinced.
>>We can use the space for better things that are relevant in the context
>>of the anthropogenic GHG perturbation.
>>I miss the recent and relevant literature. Examples are Pahnke and Zahn,
>>Science, 2005 and Stocker and Johnsen, Paleoceanography 18, 2003, and
>>Knutti et al., Nature, 2004
>>Hemitt et al., Rev Geophysics, 2004 might be a good reference for
>>Heinrich events.
>>Jonathan Overpeck wrote:
>>> Hi guys - I'm not aware of the age model changes that Eystein is
>>> talking about (however, I'm not in the Euro meeting circles, and
>>> trust he's right), but I know of several studies (e.g., U/Th dated
>>> (well dated) spelothem studies (plus C14 Cariaco) that indicate that
>>> the GISP/GRIP age models are off by quite a bit pre 40kish. The other
>>> studies agree, so it makes sense to me that the ice core gangs are
>>> revising their age models. Regardless of the probabilities (note that
>>> one finds evidence in quasi-periodic variance most all paleo
>>> records), this significant age model change means that the "1470
>>> beat" has to be off/wrong or something else other than we've been led
>>> to believe. For the sake of playing it safe, we should play this beat
>>> way down until there is new evidence that is more convincing that it
>>> is for real. We can mention it, but we make it clear that the
>>> evidence for it is not all that strong - at best.
>>> I'll cc this to Fortunat and Valerie too - we don't want to rush to
>>> conclusions w/o good discussion.
>>> Thanks, Peck
>>> >Hi Eystein,
>>> >
>>> >concerning your comment on the 1470-year beat: I'm aware that in the
>>> >new time scale, it is less regular (at least I heard this, have not
>>> >tested myself yet).
>>> >
>>> >If you have two time scales, one showing a regularity and one not,
>>> >then there are two possibilities.
>>> >(1) The regular one is correct, in the other one the regularity got
>>> >wiped out by random dating errors.
>>> >(2) The one without regularity is correct, in the other one a
>>> >regularity arose by chance due to random dating errors.
>> > >
>>> >The likelyhood of the regularity found with the original GISP2 time
>>> >scale occuring by chance is minute - I've done some more
>>> >calculations, they are not complete yet but the likelyhood is in the
>> > >permil range. I think hypothesis (2) can be exluded at least at 99%
>>> >confidence level.
>>> >
>>> >Stefan
>>> >
>>> >--
>>> >To reach me directly please use:
>>> >(My former addresses are read by my assistant Brigitta.)
>>> >
>>> >Stefan Rahmstorf
>>> >
>>> >
>>> --
>>> 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
>>Climate and Environmental Physics, Physics Institute, University of Bern
>>Sidlerstr. 5, CH-3012 Bern
>>Phone: ++41(0)31 631 44 61 Fax: ++41(0)31 631 87 42
>>e-mail:; Internet:
>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
>Wg1-ar4-ch06 mailing list

Eystein Jansen
Bjerknes Centre for Climate Research and
Dep. of Earth Science, Univ. of Bergen
All�gaten 55
N-5007 Bergen
Phone: +47-55-583491 - Home: +47-55-910661
Fax: +47-55-584330

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