date: Thu Sep 25 07:59:46 2003 from: Keith Briffa subject: Re: your submission to THe Holocene to: alana@unav.es 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. Yours sincerely Keith Briffa 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), 270-277, 2000. 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: [1]http://www.cru.uea.ac.uk/cru/data/temperature/ 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 techniques". 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. Sincerely 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 > > [2]http://www.cru.uea.ac.uk/cru/people/briffa/ Este mensaje ha sido enviado con Buzón - [3]www.unav.es -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [4]http://www.cru.uea.ac.uk/cru/people/briffa[5]/