from: Keith Briffa <k.briffaatXYZxyz.ac.uk>
subject: Re: your submission to THe Holocene
Dear Dr Gil-Alana
I am terribly sorry , but your email prompted me to check my files and I have now only just
realised that I did not communicate with you following my last message. Your file was put
in the wrong drawer.
I am sorry to say that we have decided not to publish your paper - the overwhelming reason
being , not a criticism of its general scientific content , but rather the relatively low
relevance weighting put on it by the referees, with specific regard to this journal. After
reading their reports , one of which ( ironically the one that took a long time to secure),
simply emphasised that the readership would not appreciate the significance of the work .
The other referee made potentially somewhat more substantive comments and these are copied
below, but the question of relevance was also to the fore. I discussed this with our main
editor, John Matthews, and we agreed that we would have to concur with this opinion,
particularly given the current heavy load of submissions.
Of course this decision should have been communicated to you many weeks (even months ) ago
, and for this I am truly sorry. I hope you accept this apology and will feel able to
submit the manuscript elsewhere.
referee 1 comments
Review of manuscript "A Global Warming in the Temperatures in the Northern Hemisphere Using
Fractionally Integrated Techniques",
author: L.A. Gil-Alana
This manuscript describes some interesting statistical modeling experiments with the CRU
instrumental 'Northern hemisphere mean temperature' series of 1854-1989, building on
previous work by Bloomfield and others.
The primary problem with this, and other similar past papers of this kind, however, is that
the wrong null hypothesis is assumed, creating somewhat of a 'straw man' for the argument
in favor of a long-range dependent noise process. The null hypothesis invoked is that the
observed NH mean temperature series is a realization of a stationary noise process, and
that null hypothesis is subsequently rejected in favor of a non-stationary noise process
(i.e., a fractionally-integrated noise process). The null hypothesis thusly assumed is
inappropriate however, leading to false conclusions regarding the statistical character of
the series. It is very likely that at least 50% of the low-frequency variability in the
series in question is externally forced (by volcanic, solar, and in particular in the 20th
century, anthropogenic radiative forcing). See e.g.:
Crowley, T.J., Causes of Climate Change Over the Past 1000 Years, Science, 289 (14 July),
The non-stationary (ie., the 20th century trends) in the series in large part arises from
the linear response of the climate to these forcings, and much of the apparent
'non-stationarity' is simply a result of the non-stationary nature of the forcings, not the
non-stationarity of the noise term. Moreover, this associated temporal dependence structure
is almost certain to change over time, as the emerging anthropogenic forcing increases the
relative importance of the forced vs. internal (noise) component of variance. See e.g.:
Wigley, T.M.L., R.L. .Smith, and B.D. Santer, Anthropogenic Influence on the
Autocorrelation Structure of Hemispheric-Mean Temperatures, Science, 282, 1676-1680, 1998.
The appropriate null hypothesis (and a challenging one to beat, in my opinion) would be
that the observed temperature series is the sum of an externally-forced component as
modeled e.g. by Crowley (the data is available here:
http://www.ngdc.noaa.gov/paleo/pubs/crowley.html) plus a simple autocorrelated AR(1)
internal noise process. This is the most physically-plausible model for the observed NH
mean temperature variations, so the fractionally-integrated process must at the very least
do better (in a statistical sense) than this model...
There are a number of other minor problems:
1) No account is taken of the obvious change in variance (and presumably, the temporal
dependence structure as well) back in time with increased sampling uncertainty (and
potentially, bias due to limited spatial representation in the underlying data network) in
the sparser early observations. For some purposes that isn't a problem. However, in this
study, where it is precisely the variance and temporal dependence structure of the series
that is being analyzed, I believe this is a problem.
2) It looks as if an unnecessarily outdated version of the CRU NH series has been used. A
revised, and updated version through 2001 is available online here:
The author should also reference more recent work:
Jones, P.D., M. New, D.E. Parker, S. Martin, and J.G. Rigor, Surface Air Temperature and
its Changes over the Past 150 Years, Reviews of Geophysics, 37 (2), 173-199, 1999.
see also the additional references and information in the website indicated above.
3) It seems to me that a number of other papers on long-range dependence in surface
temperature series have been published over the past 5 years (e.g. Smith, Nychka, others),
and the author needs to do a far more thorough literature review. The reviewers literature
review looks, on the average, to be about 5 years or so out of date...
I would thus suggest that the authors resubmit the paper for consideration after
appropriately dealing with the issues outlined above.
the short /late response
I have finally read this paper and since you are so anxious to get a quick answer my
opinion is that it is not the type of paper that paleo people would understand or be much
interested in. This sort of thing has been looked at before and I do not think there is
much to justify publishing it here. It would be better sent to a stats journal or climate
journal that publishes statistical analysis of climate series . I think journal of climate
would be a good option.
I do not see anything glaringly wrong but I would suggest it is not your kind of thing.
At 04:29 PM 9/24/03 +0000, you wrote:
Dear Prof. Briffa,
I am writing you in connection with a paper submitted to The Holocene
Research Papers a long time ago and titled: "A global warming in the
temperatures in the Northern hemisphere using fractionally integrated
On 02 May 2003 you replied to me saying that you were still waiting for
the comments of the second referee.
I would be very glad if you can inform me about the progress of the paper.
Dr. Luis A. Gil-Alana
On Fri, 02 May 2003 10:13:02 +0100 Keith Briffa wrote:
> Dear Dr Gil-Alana
> this is a brief note to say that I am still chasing up the second referee
> regarding your paper. I am away for a week now and hope to get some
> response by the time I return. Sorry about the delay but I will try
> to get
> a reply to you soon. Keith
> Professor Keith Briffa,
> Climatic Research Unit
> University of East Anglia
> Norwich, NR4 7TJ, U.K.
> Phone: +44-1603-593909
> Fax: +44-1603-507784
Este mensaje ha sido enviado con Buz�n - www.unav.es
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.