date: Thu, 28 Jun 2007 11:19:31 -0600
from: Kathreen Ruckstuhl <kruckstu@ucalgary.ca>
subject: Re: Philosophical transactions
to: Tom Melvin <t.m.melvin@uea.ac.uk>, Keith Briffa <k.briffa@uea.ac.uk>

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Dear Keith and Tom,

Please find below the last reviewer's comments on your paper. Please 
also make sure that you deal with them and send me a list of the changes 
you made. This also applies to the minor changes suggested by the first 
reviewer.

Best wishes and thanks again for this excellent contribution!

Kathreen

Review of `Trends in recent Temperature and Radial Tree Growth spanning 
2000 years across Northwest Eurasia`, by Keith R. Briffa et al.

General Comments

Overall, I liked the paper. I value the findind that the strenght of 
climate-tree growth relationships has not declined during the 20th 
century, as this has been the cause of debate in the last years since a 
paper published ironically by the same author in 1998 (Briffa et al. 
1998). This gives tree-ring-based temperature reconstructions in the 
area credibility and enables the authors to state that the 20th century 
has been unprecedented in terms of high temperatures in the last 2 
millenia in NW Eurasia. The analyses are easy to understand, practical 
and useful in getting to the point of the paper.

I have no major comments in a general sense. Sometimes the text might be 
a bit confusing, the sentences too long and grammatically complex, with 
some commas missing that make things difficult to understand, and the 
structure of the paper not pertfectly fluid, but I would not say it 
represents a problem overall. My only comments are punctual and come here:

Particular comments

*1.* Page 3. Lines 10-12. This sentences refer to the Arctic 
Amplification: the Arctic amplification has caused a great debate in the 
last decade which does not appear in here. Whereas many authors claim 
that temperatures in Northern latitudes will increase more than in the 
temperate areas due to the ice-albedo feedback (e.g. Serreze and Francis 
2006), some others claim that this is not the case in observed values 
(e.g. Polyakov et al. 2002). A reference to this debate could be useful.

*2.* Page 5. Line 2. Erase the word that or else the sentence is not 
comprehensible.

*3.* Page 6. Lines 1-8. The RCS method was termed this way by Briffa 
et al. 1992, but the same method had been applied by other authors way 
before (Erlandsson 1936; Fritts 1976). I would appreciate the earlier 
references in the text.

*4.* Page 7. Line 33. Id add a comma between millenia and two.

*5.* Page 7. Line 35 and lines 8-10. After stating that regional 
chronologies have practically nothing to do with each other, the authors 
built a NW-Eurasian chronology, which they will only use once and in a 
minor analysis which unnecessary for the papers main conclusion. I do 
not see the point in using that chronology, as it represents the average 
of three chronologies that have very little in common.

*6.* Page 9. Line 17. lower than instead of lower that.

*References*

    * Briffa, K.R., Jones, P.D., Bartholin, T.S., Eckstein, D.,
      Schweingruber, F.H., Karlen, W., Zetterberg, P., & Eronen, M.
      (1992) Fennoscandian summers from AD-500 - Temperature-changes on
      short and long timescales. Climate Dynamics, 7, 111-119.
    * Briffa, K.R., Schweingruber, F.H., Jones, P.D., Osborn, T.J.,
      Shiyatov, S.G., & Vaganov, E.A. (1998) Reduced sensitivity of
      recent tree-growth to temperature at high northern latitudes.
      Nature, 391, 678-682.

 Erlandsson, S. (1936) Dendrochronological studies. Report 23. Uppsala, 
Sweden. Stockholms Hgskolas Geokronological Institute.

 Fritts, H. (1976) Tree rings and climate. London: Academic Press 567 pp.

 Polyakov, I. Et al. (2002) Observationally based assessment of polar 
amplification of global waring. Geophysical Research Letters 29(18): 
1878. doi 10.1029/2001GL011111

 Serreze, M. And J.A. Francis. (2006) The Arctic Amplification Debate. 
Climatic Change 76: 241-264.



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