Friday, April 13, 2012

3414.txt

date: Sun, 15 Jan 2006 16:12:45 -0500
from: "W.R Peltier" <peltieratXYZxyzosp.physics.utoronto.ca>
subject: [Wg1-ar4-ch06] Emailing: IPCCsealevelgraphic.eps
to: Wg1-ar4-ch06atXYZxyzs.ucar.edu

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Dear Colleagues,

Attached is the next draft of the graphic describing the variation of
sea level through the most recent ice age cycle. I have modified it in the
way suggested during our meeting in Christchurch. This has involved
incorporating the data assembled in the paper by Waelbroeck et al
(2002) into an inset for the entire last glacial interglacial cycle.
Claire very kindly sent me the original data plotted in this paper. For the
last 30,000 years, however, I've shown the complete set of data that is now
available from the Barbados location at a sufficiently high resolution
that one can appreciate the importance of the new samples that have become
available . In particular, the complete set of U/Th dated coral samples
enables us to refine our understanding of the period extending from pre-
to post-LGM in an important way. the new data have also provided better
resolution of the post-Younger Dryas event called meltwater pulse 1b.
Suggestions for further improvements of this Figure will be welcome. The
caption for this revised version of the Figure is as follows:

Figure 6.4. In (a) the range of allowed variations of eustatic sea level
that have occurred over the last glacial-interglacial cycle is depicted
according to the data assembled by Waelbroeck et al.(2002). These data
included both dated coral assemblages from the tropics as well as oxygen
isotope records from deep sea sedimentary cores that have been corrected in
order to optimally remove the influence of temperature variations in the
abyssal ocean that contaminate what is otherwise an excellent proxy for the
volume of continental ice on the continents and therefor eustatic sea
level. Superimposed upon the Waelbroeck et al. record is the eustatic sea
level record corresponding to the ICE-5G model of this cycle ( shown in
red) of Peltier (2004) for which the global distribution of time dependent
ice thickness is available from
http://www.sbl.statkart.no/projects/pgs/ice_models/. The black curve on the
insert is the SPECMAP oxygen isotope record of Imbrie et al. (1984) scaled
so as to deliver the same sea level as that observed at Barbados at 30 ka.
In (b) is shown the complete set of U/Th dated coral derived sea level
index points now available from the Barbados location (Fairbanks 1989,
Peltier and Fairbanks 2006). The acropora palmata samples, which provide
the tightest constraint on sea level, are shown with an error bar of 5m
extending upwards from the depth at which they were sampled as is
appropriate given that this is the greatest depth below sea level at which
this species is found in the modern ecology. The data with the 20m
intermediate length error bars attached are samples of the species
monastrea annularis. Although they do not provide a tight constraint on sea
level they are nevertheless useful as they provide a upper bound upon the
sea level depression where such samples are available. The other samples
for which the data are also shown provide similar information. The red
curve superimposed upon the data, as in (a), is the theoretical prediction
for the sea level history at this site based upon the ICE-4G(VM2) model of
Peltier (2004). As noted directly on the Figure, the net eustatic sea level
depression at the conventional age of the LGM ( 21 ka) according to the
ICE-5G(VM2) model, which accurately fits the observations, is 118.7m. This
is very close to the conventional oxygen isotope derived estimate of
Shackleton (eg. 2000) and to the temperature corrected oxygen isotope
records shown in Waelbroeck et al.(2002).

Cheers
Dick
PS. The font employed for the lettering on this Figure will be reduced in
size in the next edition of the graphic.

IPCCsealevelgraphic.eps

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Prof W.R Peltier
Dept of Physics, University of Toronto
60 St. George Street, Toronto, Ontario, CANADA, M5S 1A7
Tel (416)-978-2938 Fax (416)-978-8905
email peltieratXYZxyzosp.physics.utoronto.ca
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