Tuesday, December 20, 2011


From: Val�rie Masson-Delmotte <Valerie.Masson@cea.fr>
To: Keith Briffa <k.briffa@uea.ac.uk>
Subject: warning - more reviews for you
Date: Fri, 30 Jun 2006 13:46:45 +0200
Reply-to: Valerie.Masson@cea.fr

Dear Keith,

I hope that you had a good trip back from Bergen.

Some of the review comments which appeared to be relevant for the
Holocene section are yours. I copy them here so that you can take there
of them.

All the best,






Replace "limiting the vallue" on line 18 to "review as a" on line 19 by
"which means there is no legitimate"

[VINCENT GRAY (Reviewer�s comment ID #: 88-774)]






Section (on 2000-yr proxy reconstructions) is a little too long.
It can be either shortened or reorganized into 2 or more shorter
sections, say on reconstruction history, debate, and new development.

[Govt. of United States of America (Reviewer�s comment ID #: 2023-407)]




Fig. 6.10a. Rather than showing the average of 4 European stations I
suggest to plot the available averaged European mean land temperature
(using much more than just 4 stations) from Luterbacher et al. 2004 and
Xoplaki et al. 2005. This continental scale average would provide a more
appropriate overview for the last 250 years. The first lead author has
the data or they can be obtained prepared from xoplaki@giub.unibe.ch or
juerg@giub.unibe.ch. Xoplaki, E., Luterbacher, J., Paeth, H., Dietrich,
D., Steiner N., Grosjean, M., and Wanner, H., 2005: European spring and
autumn temperature variability and change of extremes over the last half
millennium, Geophys. Res. Lett., 32, L15713. Luterbacher, J., Dietrich,
D., Xoplaki, E., Grosjean, M., and H. Wanner, 2004: European seasonal
and annual temperature variability, trends and extremes since 1500,
Science, 303, 1499-1503.

[J�rg Luterbacher (Reviewer�s comment ID #: 151-8)]




Fig 6.10. I here repeat a point made in my comments on the FOD. It is
statistically invalid and visually misleading to overlay the black
instrumental line on this diagram. The coloured graph lines show proxy
records that end at 1980. If you want a line that continues up to more
recent years that then you must use the proxy records that continue past
1980, not switch to a different type of series. There are up to date
proxy records available, but as I'm sure the authors of this chapter are
aware, they depart from the surface instrumental record, many of them
declining after 1980. By failing to show this, and including the surface
temperature data in black, it constitutes a misrepresentation, since the
black line is an invalid forward extrapolation of the proxy data. If the
reason for not showing the updated proxies is that they are not
considered to be good representatives of temperature anymore, then by
what right does the Figure insinuate that they were good proxies 8-10
centuries ago? It is no defence to claim that MBH99 established a
statistically skillful relationship between the proxy network and the
instrumental data, since that claim has been refuted, as discussed
above. McIntyre and McKitrick (2005a,d) showed that the pre-1450 RE
statistic was incorrectly benchmarked, yielding a spurious inference,
and the r2 stat calculated by MB&H themselves, which showed the lack of
skill, was simply not reported. The failure of the r2 and CE stats is
confirmed by Wahl and Ammann. The squared correlation between the MBH
long proxies and the instrumental record is nearly zero (MM05a,c). The
mean correlation between the long NOAMER proxies and gridcell
temperatures in the MBH98 data set (which dominate the pre-AD1450
portion) is -0.08 (McIntyre and McKitrick 2005c), and the RE
significance benchmark is above the MBH98 RE score, using all available
implementation of the Mann code (McIntyre and McKitrick 2005d). The
surface instrumental record cannot be used as a statistically valid
extrapolation for the proxies after 1980.

[Ross McKitrick (Reviewer�s comment ID #: 174-35)]


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