Thursday, April 12, 2012


date: Thu Jul 24 13:57:44 2003
from: Keith Briffa <>
subject: Re: Holocene manuscript- sorry
to: Phil Camill <>

I am really sorry for the delay , that was a result of initially tardy reviewers, my
subsequent illness, and then a delay while John is away while I wished to consult with him
. The reason for the last wish will be clear when you read the reviews below.
The referees are not enthusiastic and in their private comments to me one is strongly
negative and the other ambivalent. The pressure on space means that this would normally be
a rejection (and we have, since your submission ,developed new , stricter rules regarding
possible re-submission.)
However, in the circumstances (the delay that is down to me) , I am overruling these and
(despite not discussing it with John) asking you to read these reviews and come back with a
frank opinion of whether you consider them fair and the paper publishable with some work .
I am doing this because I believe it is. If you can answer these remarks and feel you can
submit a valid manuscript that accounts for them - I will review your argument (without
recourse to the reviewers) and if I agree , I guarantee speedy process through the last
publication phase.
Again , you and I are well aware that this manuscript could have been dealt with much
better and I am really sorry for it.
Referee 1
Review of David Hunzicker and Phil Camill: "Using a new 672-year tree-ring drought
reconstruction from westcentral Montana" submitted to the Holocene.
This is a well written, well executed paper that I would unfortunately not recommend for
publication in the Holocene. It's a shame to read a paper like this. It is very well
informed, well referenced, places the work in a good scientific context, and includes
strong statistical analyses. However, the attention paid to the analyses and interpretation
of the reconstruction was evidently not paid so carefully to the fundamental tree-ring
chronology development. They call it "crossdating," but the best I can tell from the
limited discussion it was simply computerized correlation matching of measured time series,
with a massive culling of the data to pare down to those time series that produced
straightforward correlations in a COFECHA analysis. I was astounded to read that their
final chronology used only 61 out of the 152 trees sampled for the study. The 60% of the
trees not included apparently suffered from "complacency, unresolvable sections of missing
rings, or low interseries correlation values." This appears to be the first penalty for not
applying rigorous dendrochronological methods to the chronology development. I find it
incredible that over half of the Ponderosa pine samples would not be useful. I can't help
but suspect that by relying on COFECHA output, without any hard-nosed microscope work and
rigorous crossdating with the wood samples themselves, you at best default to the simple,
straightforward trees without missing rings. That is, you default to a less climatically
sensitive subset of trees. This appears to be the second penalty for the seemingly
inexpert, quick and dirty chronology development.
These authors have obviously worked hard on this study and bring excellent analytical
skills and knowledge of the literature. The paper itself is exceptionally well written
(with a minor complaint concerning the over use, and at times incorrect use of the term
"teleconnection"). But the calibration and validation reported in the paper are clearly
awful, and that surely ought not be the case for Ponderosa pine on moisture-stressed sites
in Montana. One hates to be non-supportive of their work, so much of which is high quality,
but it seems to come down to fundamentals, and here the fundamental dendrochronology and
chronology development are in question. And I also do not think it advisable to publish a
reconstruction that explains maybe 21% of the variance in the instrumental climate data,
when using an arid site conifer as the predictor (the persistence in the standard
chronology may be inflating even that figure). I just can't believe the calibration could
be so weak. It seems they need to revisit their chronology development work, and dig deeper
into the climate response of their chronology. Then look very carefully at climate data
itself. These climate data are not guaranteed to be homogeneous, especially in the mountain
West during the early 20th century. If all this could be done, and if the variance
explained in both the calibration and verification periods could be improved, then
publication in the Holocene would be well justified.
Referee 2
Review of "Using a New 672-Year Tree-Ring Drought Reconstruction from West-Central Montana
to Evaluate Severe Drought Teleconnections in the Western U.S. and Possible Climatic
Forcing by the Pacific Decadal Oscillation" by D.A. Hunzicker and P. Camill
This paper is reasonably well written, but has some problems in it that bother me. The
first issue relates to the tree-ring chronology that was developed at Lindberg Lake.
Anytime less than half of the core samples (61 or 152) are used in developing a chronology,
this is cause for concern. The fact that there are "unresolvable sections of missing rings"
(p. 10) can mean a lot of things. However, ponderosa pine is known to cross-date well,
which includes "locating" locally-absent rings during the cross-dating phase, so it is
surprising that the authors have chosen not to work through these problems. Presumably, the
trees with missing rings are also those most sensitive to drought, so isn't there a chance
that the chronology being analyzed in this paper is less sensitive to drought than it ought
to be? I also wonder how much their chronology is truly contributing to the overall stated
goal of this paper, i.e. evaluating "Severe Drought Teleconnections in the Western U.S. and
Possible Climatic Forcing by the Pacific Decadal Oscillation". The authors extensively use
the PDSI reconstructions of Cook et al. (1999) in their analyses. Aside from the increased
length of their new tree-ring chronology, what does it contribute that was not possible
simply by using the Cook et al. reconstructions to test for teleconnections and forcing.
None of the indices of forcing (ENSO, PDO, sunspots) extend back before the beginning of
the Cook et al. reconstructions, so there is little to be gained in using one longer series
from west-central Montana in this analysis. One could point to Fig. 3, which compares the
MT reconstruction vs the SWDI series. But even this comparison is limited in its overall
contribution to the paper. I also don't like the use of the FFT for estimating power
spectra, even if the confidence limits are determined by bootstrapping. The power spectra
calculated by the FFT are still inconsistent estimates. A more contemporary and consistent
method of spectral estimation, like the Multi-Taper Method, should be used.
For the reasons stated above, I do not consider this paper to be ready for publication as
is. I will leave it to the Editor to decide how to proceed with it past this point.
At 10:33 PM 7/23/03 -0500, you wrote:

Dear Keith,
I have not yet received an editorial response or reviews for the manuscript
entitied "Using a new 672-year tree-ring drought reconstruction from
west-central Montana to evaluate severe drought teleconnections in the
western US and possible climatic forcing by the Pacific Decadal Oscillation"
by Hunzicker and Camill. This manuscript has been in review for 14 months.
Can you indicate when I can expect these materials?
Many thanks,

Dr. Phil Camill
Assistant Professor of Biology and Environmental Studies
Carleton College, Department of Biology
One North College St.
Northfield, MN 55057
phone: (507) 646-5643
fax: (507) 646-5757

Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784

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