Monday, December 19, 2011


From: Keith Briffa <>
To: Eystein Jansen <>, Jonathan Overpeck <>
Subject: Re: Bullet debate number 1
Date: Thu, 16 Feb 2006 17:49:58 +0000

Dear Peck and Eystein

I have to come back again on this.


Happy with first sentence.
Then following largely on a suggestion made by Tim , I suggest

The additional variability implies mainly cooler
temperatures (predominantly in the 12th-14th,
17th and 19th centuries) and only one new
reconstruction suggests slightly warmer
conditions (in the 11th century), but well within
the uncertainty range indicated in the TAR.

Failing this, I suggest we omit everything after the first closing bracket.


Now suggest insert the bit about our work (Tim
and I) in the second point - after the sentence ending "1300 years." That is..

The regional extent of Northern Hemisphere warmth
was very likely greater during the 20th century
than in any other century during the last 1300 years.

Will finish corrections to my text tomorrow - but
hope Fortunat has checked it all, and is doing a
paragraph on the EMICS still?


At 23:19 15/02/2006, Eystein Jansen wrote:
>I think we should avoid discussing the Moberg et
>al results in the exec. bullet. I also think we
>need to have a statement about the MWP in the
>bullet, and I cannot really understand why the
>most central conclusion from the very nice
>recent Osborn et al. Science paper cannot be
>highlighted in the first bullet. My suggestion is:
>o Some of the post-TAR studies indicate
>greater multi-centennial Northern Hemisphere
>temperature variability than was shown in the
>TAR, due to the particular proxies used, and the
>specific statistical methods of processing
>and/or scaling them to represent past
>temperatures. The additional variability implies
>cooler temperatures, predominantly during the
>12th to 14th, the 17th, and the 19th centuries.
>The warmer period in the 11th century is in
>general agreement with the results shown in the
>TAR. Consideration of the regional records of
>temperature for the 11th century indicate that
>it is unlikely that the spatial extent of
>warming during this time period was as
>significant as in the second half of the 20th century.
>At 11:46 -0700 15-02-06, Jonathan Overpeck wrote:
>>Hi Keith (and Eystein - we need your opinion) -
>>thanks for the quick response. I think it
>>easier (imagining the mess of email that could
>>result) if we focus on one bullet/email. So
>>I'll start w/ the first, and hope that Eystein can also weigh in.
>>With regard to the first one below, I agree
>>that we can leave statistics out of it. Good point.
>>But, I think we must at least address Susan's
>>concern. To do otherwise would be
>>counterproductive. She makes sense. I think
>>your MWP results is quite appropriate - they
>>were published in Science, and in my reading of
>>the paper, you are convincing. If it's in the
>>chapter, it makes sense to draw on it for the
>>exec summary. Please defend more convincingly,
>>or suggest an alternative way to deal with
>>Susan's concern - what is the significance (not
>>statistical) of this one record being warmer? We need to say it.
>>If you really want to leave as is, please write
>>your response in a way that I can forward to
>>Susan - we can't ignore he comment in this
>>case, because other (me, at least) think it
>>makes sense. So we have to convince her too -
>>this is big stuff for the AR4, and will be in
>>the TS/SPM. We can't be as vague as the current bullet is.
>>And as for the MWP box fig, I think it should
>>be as you suggest - combine the existing fig w/
>>the new one from Tim and your paper. I think
>>Tim might already be working on it?
>>Sorry to be a tough guy, but this bullet needs to be more clear.
>>Thanks, peck
>>>do not think you will like what I say here ,
>>>but I am going to give straight answers to your questions.
>>>The new draft says enough in the text now
>>>about "far-less-accurately dated" and
>>>"low-resolution proxy records that can not be
>>>rigorously calibrated" in relation to this
>>>paper (Moberg et al.) . It is not appropriate
>>>to single the one series out for specific
>>>criticism in the summary . The use of the word
>>>"only" implies we do not believe it. Mike
>>>Mann's suggestion begs a lot of questions
>>>about what constitutes "significantly warmer".
>>>You need to have a Null Hypothesis to test .
>>>If you mean would the estimates in Moberg and
>>>the other reconstructions (during medieval
>>>time) show significantly different means using
>>>a t-test - then of course not , but this tells
>>>us nothing other than they are not likely
>>>samples from totally different populations -
>>>an almost impossible test to pass given the
>>>wide uncertainties on all reconstructions .
>>>Incidentally, we do not have formal
>>>(calibration ) uncertainties for Moberg anyway
>>>(just boot-strapped uncertainty on the average low-frequency curve).
>>>I think the vagueness is necessary -
>>>"suggests slightly" and is appropriate.
>>>I would not call out The results of Tim and my
>>>paper either. It is just an aside in the
>>>Medieval box at present , perhaps with a
>>>Figure to accompany the original if you agree,
>>>but without more text in the Chapter , which I
>>>do not consider appropriate, it should not be highlighted as a bullet.
>>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
>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

Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784


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