Wednesday, December 21, 2011


From: Jonathan Overpeck <>
To: Tim Osborn <>
Subject: Re: Law Dome figure
Date: Tue, 18 Jul 2006 10:30:36 -0600
Cc: Ricardo Villalba <>, Keith Briffa <>, Valerie Masson-Delmotte <>, Eystein Jansen <>

Hi Tim, Ricardo and friends - your suggestion to
leave the figure unchanged makes sense to me. Of
course, we need to discuss the Law Dome ambiguity
clearly and BRIEFLY in the text, and also in the
response to "expert" review comments (sometimes,
it is hard to use that term "expert"...).

Ricardo, Tim and Keith - can you take care of
this please. Nice resolution, thanks.

best, Peck

>Hi all,
>(1) Jones/Mann showed (and Mann/Jones used in
>their reconstruction) an isotope record from Law
>Dome that is probably O18 (they say "oxygen
>isotopes"). This has a "cold" present-day and
>"warm" MWP (indeed relatively "warm" throughout
>the 1000-1750 period). The review comments from
>sceptics wanted us to show this for obvious
>reasons. But its interpretation is ambiguous
>and I think (though I'm not certain) that it has
>been used to indicate atmospheric circulation
>changes rather than temperature changes by some
>authors (Souney et al., JGR, 2002).
>(2) Goosse et al. showed Deuterium excess as an
>indicator of Southern Ocean SST (rather than
>local temperature). Goosse et al. also showed a
>composite of 4 Antarctic ice core records (3
>deuterium, 1 O18). Neither of these comes up to
>the 20th century making plotting on the same
>scale as observed temperature rather tricky!
>(3) Dahl-Jensen showed the temperatures obtained
>by inverting the borehole temperature profiles.
>This has a colder MWP relative to the recent
>period, which shows strong recent warming.
>I have data from (1) and now from (3) too, but
>not from (2) though I could ask Hugues Goosse
>for (2). Anyway, (1) and (2) aren't calibrated
>reconstructions like the others in the Southern
>Hemisphere figure, so plotting them would alter
>the nature of the figure.
>But if we show only (3) then we will be accused
>of (cherry-)picking that (and not showing (1) as
>used by Mann/Jones) because it showed what we
>Can I, therefore, leave the SH figure unchanged
>and can we just discuss the Law Dome ambiguities
>in the text?
>At 02:41 18/07/2006, Jonathan Overpeck wrote:
>>Hi Tim, Ricardo and Keith - Valerie just
>>reminded me that she sent this to us all (minus
>>Tim) back in June. There is plenty below for
>>discussion in the text, and the Law Dome
>>borehole data can be obtained at the site below
>>( This is
>>the record that should be added to the SH
>>Thanks, Peck
>>>X-Sieve: CMU Sieve 2.2
>>>Date: Wed, 28 Jun 2006 12:44:50 +0200
>>>From: Val�rie Masson-Delmotte <>
>>>Organization: LSCE
>>>To: Jonathan Overpeck <>,
>>> Ricardo Villalba <>,
>>> Keith Briffa <>
>>>Subject: (pas de sujet)
>>>Dear Ricardo and Peck,
>>>Here are the references for the Law Dome temperature discussion :
>>>* stack of Antarctic ice cores and Law Dome
>>>deuterium excess profile (showing large
>>>changes in moisture source)
>>>Title: *A late medieval warm period in the
>>>Southern Ocean as a delayed response to
>>>external forcing?*
>>>Author(s): *Goosse H*
>>>*Masson-Delmotte V*
>>>Renssen H
>>>Delmotte M
>>>Fichefet T
>>>Morgan V
>>>van Ommen T
>>>Khim BK
>>>Stenni B
>>>Source: GEOPHYSICAL RESEARCH LETTERS 31 (6): Art. No. L06203 MAR 17 2004
>>>Document Type: Article
>>>Language: English
>>>Abstract: On the basis of long simulations
>>>performed with a three-dimensional climate
>>>model, we propose an interhemispheric climate
>>>lag mechanism, involving the long-term memory
>>>of deepwater masses. Warm anomalies, formed in
>>>the North Atlantic when warm conditions
>>>prevail at surface, are transported by the
>>>deep ocean circulation towards the Southern
>>>Ocean. There, the heat is released because of
>>>large scale upwelling, maintaining warm
>>>conditions and inducing a lagged response of
>>>about 150 years compared to the Northern
>>>Hemisphere. Model results and observations
>>>covering the first half of the second
>>>millenium suggest a delay between the
>>>temperature evolution in the Northern
>>>Hemisphere and in the Southern Ocean. The
>>>mechanism described here provides a reasonable
>>>hypothesis to explain such an interhemipsheric
>>>* borehole temperature profile from Law Dome :
>>>Title: *Monte Carlo inverse modelling of the
>>>Law Dome (Antarctica) temperature profile*
>>>Author(s): *DahlJensen D*
>>>Morgan VI
>>>Elcheikh A
>>>Source: ANNALS OF GLACIOLOGY, VOL 29, 1999
>>>ANNALS OF GLACIOLOGY 29: 145-150 1999
>>>Document Type: Article
>>>Language: English
>>>Abstract: The temperature profile in the 1200
>>>m deep Dome Summit South (DSS) borehole near
>>>the summit of Law Dome, Antarctica, was
>>>measured in 1996, 3 years after the
>>>termination of the deep drilling.
>>>The temperature profile contains information
>>>on past surface temperature over the last 4
>>>ka. This temperature history is determined by
>>>the use of a Monte Carlo inverse method in
>>>which no constraints are placed on the unknown
>>>temperature history and no solution is assumed
>>>to be unique. The temperature history is
>>>obtained from a selection of equally
>>>well-fitting solutions by a statistical
>>>The results show that solutions covering the
>>>last 4 ka have a well-developed central value,
>>>a most likely temperature history. The
>>>temperature record has two well-developed
>>>minima at: AD 1250 and 1850. From 1850 to the
>>>present, temperatures have gradually increased
>>>by 0.7 K. The reconstructed temperatures are
>>>compared with the stable oxygen isotope
>>>(delta(18)O) from the DSS ice core.
>>>=> The inversed temperature data are available on the GFY web site at :
>>>, go to "Dye
>>>3, GRIP, Law Dome temperature reconstructed
>>>from borehole measurements"
>>>* Regarding the calibration issue there are several publications :
>>>- seasonal calibration between 18O and T :
>>>[van Ommen and Morgan, 1997a]
>>>Tas D. van Ommen and Vin Morgan. Calibrating
>>>the ice core paleothermometer using
>>>seasonality. J. Geophys. Res.,
>>>102(D8):9351-9357, 1997, [AAD Cat. Ref. 7488].
>>>[van Ommen and Morgan, 1997b]
>>>Tas D. van Ommen and Vin Morgan. Correction to
>>>"Calibrating the ice core paleothermometer
>>>using seasonality". J. Geophys. Res.,
>>>102(D25):30,165, 1997, [AAD Cat. Ref. 8236].
>>>- decadal calibration from a high resolution
>>>ice core (using deuterium excess)
>>>*Recent southern Indian Ocean climate
>>>variability inferred from a Law Dome ice core:
>>>new insights for the interpretation of coastal
>>>Antarctic isotopic records*
>>>V. Masson-Delmotte ^A1 , M. Delmotte ^A1 A4 ,
>>>V. Morgan ^A2 , D. Etheridge ^A3 , T. van
>>>Ommen ^A2 , S. Tartarin ^A1 , G. Hoffmann
>>>Stable isotopes in water have been measured
>>>along a very high accumulation ice core from
>>>Law Dome on the east Antarctic coast. These
>>>enable a detailed comparison of the isotopic
>>>records over sixty years (1934-1992) with
>>>local (Antarctic station data) and remote
>>>meteorological observations (atmospheric
>>>reanalyses and sea-surface temperature
>>>estimates) on a seasonal to inter-annual time
>>>scale. Using both observations and isotopic
>>>atmospheric general circulation model (GCM)
>>>results, we quantify the relationships between
>>>stable isotopes (d ^18 O, dD and deuterium
>>>excess; /d/ = dD -8 � d ^18 O) with site and
>>>source temperature at seasonal and decadal
>>>time scales, showing the large imprint of
>>>source conditions on Law Dome isotopes. These
>>>calibrations provide new insights for the
>>>quantitative interpretation of temporal
>>>isotopic fluctuations from coastal Antarctic
>>>ice cores. An abrupt change in the local
>>>meridional atmospheric circulation is clearly
>>>identified from Law Dome deuterium excess
>>>during the 1970s and analysed using GCM
>>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
>Dr Timothy J Osborn, Academic Fellow
>Climatic Research Unit
>School of Environmental Sciences, University of East Anglia
>Norwich NR4 7TJ, UK
>phone: +44 1603 592089
>fax: +44 1603 507784
>**Norwich -- City for Science:
>**Hosting the BA Festival 2-9 September 2006

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

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