cc: jto@u.arizona.edu, Valerie.Masson@cea.fr, olgasolomina@yandex.ru, ricardo@lab.cricyt.edu.ar, Eystein Jansen <eystein.jansen@geo.uib.no>
date: Thu, 23 Feb 2006 11:02:00 +0100
from: Valrie Masson-Delmotte <Valerie.Masson@cea.fr>
subject: Re: latest draft of 2000-year section text
to: Keith Briffa <k.briffa@uea.ac.uk>

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Dear Keith,

A few rapid comments on the section 6.6 revised text. I have enjoyed 
reading it, more concise, less defensive and key conclusions appear more 
solid. Sometimes the text is written in the past tense, sometimes in the 
present tense : it could be homogenised.

Please remove the sentence page 6-15 "The paleohydrologic record of 
North America is the most complete and diverse of any of the world in 
part due to the proximity to many well equipped labs but also due to the 
concern of the frequent change in drought, flood...". This has nothing 
to do in a scientific assesment (equipement versus motivation). The same 
motivation should hold true for all tropical areas!

It would be worth to discuss in one paragraph somewhere (possibly 
together with the text page 6-6 about the proxies) the methods of tree 
ring standardisation which seem to have changed over time and lead to 
larger low frequency signals in the tree ring width based reconstructions.

Comments on the structure :

6.6.1 I think that the italic question for the section does not work. I 
suggest to add sub questions such as :
What do early instrumental records tell us? (p6-2, lines 7 to 39)
What new reconstruction efforts have been conducted since TAR for NH 
temperatures (6-2 lines 41 to 6-6 25)
What are the main sources of uncertainties in large scale climate 
reconstructions (6-6 lines 27 to 49) - should refer to the section 
introduction / description of proxies
What do NH temperature reconstructions tell us (6-6 lines 51 to 6-8 line 5)

Regarding climate forcings and simulations (6.6.3 and 6.6.4) there must 
be a cross verification with chapter 9, have you looked at their revised 
text? The title 6.6.3 includes too much refereence to modelling. They 
have been also statistical efforts to relate forcings and respondes (not 
only physical models) which have to be mentioned. Then modelling should 
be in 6.6.4 only. Another way could be to combine both in one section : 
6.6.3 would be model-data comparisons with 1) forcings and 2) 
simulations versus reconstructions. Section 6.6.5 is too long compared 
to the # of studies conducted here.


Minor comments :

6-3 2 line 20 add "North European records"
line 27 and onwards I think that Boehm reconstruction should be cited 
around the Alps back to 1780 (it really deserves to be cited).
line 33 Chuine et al puts the French heat wave in a 700 perspective with 
grape harvest dates, which could be mentioned.
line 36 shorten to "detailed changes in various climate forcings"
line 44 : what are the documentary sources incorporated by Mann? I 
understand essentially early instrumental records.

6-3 line 49 : this paragraph is a bit vague. Maybe mention more clearly 
areas where no data are available. Goosse et al GRL 2004 used a 
synthesis of Antarctica data + simulations to discuss the pb of phase 
with Antarctica and could be mentioned. I suggest to replace 
"assimilated" which has a special meaning for meteorologists by "combined"
6-4 line 9 change"are" to "is"
line 16 : how many such long records are available (= what are "very few"?)

6-3 line 39 : is it the rapidity of the 20th c warming or the level of 
late 20th c temperatures that have to be discusssed?

6-5 line 8 use reconstruction, not "series". I understand that one 
series is one proxy record and a mixture of records with various 
statistical methods is a reconstruction.
Line 31 : add "many of the individual annually resolved proxy series".

6-6 line 30 change "over a fixed calendar based time window such as J-A 
or J-D" to "over a specific season"

6-8 line 29  : I propose to change the text about tropical ice cores.
There are few strongly temperature-sensitive proxies from tropical 
latitudes. Water stable isotope records from high latitude tropical 
glaciers where first used as temperature proxies but recent calibration 
and modelling studies have confirmed that tropical precipitation 
isotopic composition is mostly sensitive to precipitation changes 
("amount effect") at seasonal to decadal time scales both in south 
America and south Tibet.
References :
*Hoffmann G*, *Ramirez E*, Taupin JD, et al.
Coherent isotope history of Andean ice cores over the last century 
<http://wos.isiknowledge.com/?SID=W1hPnja@D7cM8l86jFa&Func=Abstract&doc=17/3> 
GEOPHYSICAL RESEARCH LETTERS 30 (4): Art. No. 1179 FEB 25 2003
*Vuille M*, Werner M, Bradley RS, et al.
Stable isotopes in precipitation in the Asian monsoon region 
<http://wos.isiknowledge.com/?SID=W1hPnja@D7cM8l86jFa&Func=Abstract&doc=19/1> 
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 110 (D23): Art. No. D23108 
DEC 8 2005


By the way, in the same paragraph, you cite tropical glacier retreat as 
caused by temperature changes. I suggest to refer to chapter 3 on this 
topic because many studies have also shown that precipitation / relative 
humidity / albedo effects can be very important for tropical glacier 
mass balance (see for instance Vincent et al, Comptes rendus Geosciences 
2005).

Page 6-8, ground surface temperatures : are there tropical records 
available that could be explicitely discussed?
The problem of calibration mentioned line 29 (lack of the last decades 
of the 20th century) also holds true for many of the long tree ring 
records... should it be explicitely highlighted here?

6-9 : line 9-10, what is a "much longer warm period", I do not 
understand. I think that this could be shortened. I still suffer that 
Antarctica is not mentioned at all. In Goosse et al 2004 I made a stack 
of 6 records from East Antarctica. There is also one good borehole 
record from Law Dome (Dahl Jensen Annals of Glacio 1998) showing the 
same features.

6-10 line 28 : I do not think that it is appropriate to discuss the 
Solanki paper here.

6-10 and 11 : why mix volcanic and anthropogenic sulface aerosols rather 
than 2 sections? Why not discuss changes in surface occupation (land 
use) in the forcings for the last millenium at least in one sentence?

6-12, lines 38 and onwards : it seems that this is attribution and 
detection and should be a summary of chapter 9 or just a cross reference 
to chapter 9.

Section 6.6.5 (6-12 and 13) is too long compared to the studies cited. 
Maybe Fortunat could help to make this section more punchy. Should the 
PhD thesis of MacFarling Meure be cited in this assessment?
Remove "the best known aspects of the records"
Refer to chapter XX for biogeochemical cycles
The last paragraph is  probably redondant with respect to the carbon 
cycle climate feedback discussed in that chapter.

Page 6-14 line 43 : redundancy in this paragraph. Does the coldest 
European winter have to be discussed in such detail? I would skip this 
(remove line mid 42 to beg of 45 and keep the last sentence of the 
paragraph which basically says the same thing.

The section on Asian monsoon variability is not focused on the last 2000 
years but on millenial variability => mix with 6.4? Why not cite the 
Tibet ice core records here (ex Dasuopu 18O which should be a local 
precip record). There are also high res speleothem records with high 
resolution. Ramesh should help on this paragraph.

I hope that you find this useful, congratulations for the large 
improvements of this section and taking into account a record number of 
comments...

Valrie.
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