cc: katie.farnsworth@iup.edu, lsmith@geog.ucla.edu, P.Jones@uea.ac.uk, kxu@vims.edu
date: Mon, 10 Sep 2007 22:02:58 -0400
from: John Milliman <milliman@vims.edu>
subject:  Nature manuscript 2007-07-07125
to: j.mossinger@nature.com

   Dear Dr. Mossinger:

           After several days of mulling over the two reviews of our paper, "Climatic and
   anthropogenic factors affecting river discharge to the global ocean, 1951-2000", it becomes
   increasingly clear that neither you nor my co-authors and I were well-served by one of your
   reviewers, and that, combined with some points of confusion by the other reviewer, resulted
   in your decision to reject the paper.

           We did submit an earlier version of manuscript to Science, which was rejected in
   part based on the comments of Reviewer #1.  Parenthetically, we saw no reason by inform
   Nature  of the manuscript's prior history nor changes we had made to the manuscript based
   on those reviews.  We did, however, take the Science reviews into account as we revised
   manuscript for Nature.

           As a single example, Reviewer #1 requested that we compare our trends with those
   obtained by Milly et al. (Nature, 438, p. 347) for a 100-yr period, something that a second
   reviewer also suggested.  In fact, there were several valid  reasons for not  initiallyl
   comparing  our results with either Milly et al. or those of Labat et al. (Adv. Water Res.,
   27, -p. 631), the most obvious being that their "100-yr" records were strongly biased
   towards North American and northern European rivers, compelling the authors to rely on
   questionable models to extrapolate long-term records for rivers from the less-developed
   countries (e.g., Asia, South America, Siberia and Africa).  Realizing, however, that other
   readers might also wonder why we did not refer to the Milly  or Labat papers, we added both
   new words and footnotes to p. 2 of the Nature manuscript; note particularly footnote (8):

   Although 50- to 100-yr discharge records are desirable, access to globally distributed
   long-term data remains problematic.   Of the ~650 rivers listed in the Global Runoff Data
   Center (GRDC) database that discharge directly to the ocean, for instance, only 20 records
   extend back to 1900, only two of which (Karun and Nile, both of whose accessible records
   cease in the mid-1980s) lie outside northern Europe or the USA.  Attempts to compensate for
   the lack of long-term empirical data include wavelet-based runoff reconstruction (6) and
   climate models to simulate regional discharge (7).  The lack of data (8), however, calls
   into question such reconstructions (9, 10).



   6) Labat, D., Godderis, Y., Probst, J.L. & Guyot, J.L. Evidence for global runoff increase
   related to climate warming.  Adv. Water Res. 27, 631-642 (2004).
   7) Milly, P.C.D., Dunne, K.A. & Veccchia, A.V. Global pattern of trends in streamflow and
   water availability in a changing climate. Nature 438, 347-350 (2005).
   8) The 100-yr trends for the 165 rivers in (7), for instance, are based on a median of 59
   years of observational data; the median record for Asian, African and South American rivers
   in that dataset may be closer to 50 years.
   9) Legates, D.R., Lins, H.F. & McCabe, G.J.  Comments on "Evidence for global runoff
   increase related to climate warming" by Labat et al. Adv. Water Res. 28, 1310-1315 (2005).

   10) Peel, M.C. & McMahon, T.A. A quality-controlled global runoff data set. Nature 444, E14
   (2006).

           That Reviewer #1 did not note these rather significant changes (which appeared in
   the second paragraph of the Nature manuscript) suggests that he did not read it
   ("Therefore, my review is the same, and if the authors in fact have made changes, they
   should indicate specifically what and why to the Nature editor.").  In my 40 years of
   publishing and 23 years editing (Deep-Sea Research) I have never come across a reviewer
   who  submits a review without reading the paper in question.  It may be a first for you
   also.

           Many points raised by Reviewer #2  seem valid; his insights are greatly appreciated
   and will be addressed fully in a revised manuscript - no matter where it is eventually
   published.  However, several of his  points, we feel, are off-base, four of which I cite
   below four (in blue), together with our responses in brackets:

           1) The reviewer has some problem to understand why the authors discuss the increase
   and decrease of trends for rivers without statistical significance. In Table S2, only half
   of the river basins show statistically significant increases or decreases. Therefore the
   reviewer is puzzled to see a sentence like "local and regional changes were significant" at
   line 3, page 5. The reviewer recommends discussing the long term trends only for
   statistically significant river basins. [With the exception of the Yana River all deficit
   and excess rivers showed a statistically significant change in runoff and/or
   precipitation.  In contrast,  21(out of the 31 normal rivers show no statistically
   significant change in either runoff or precipitation.  But this should not be surprising:
   if normal rivers are defined as rivers in which DR reflects DP, is it not logical to assume
   that temporal trends for either both or neither should be statistically significant?  To
   discuss long-term trends based for statistically significant river basins , as suggested by
   the reviewer, necessarily negates all those rivers (including, for example, the Amazon,
   Yangtze, Rhine, etc.) for which there was no statistically significant trend in either DP
   or DR.   To that extent we may have added to the reviewer's confusion by using the word
   "significant" in both a statistical sense and a non-statistical sense; substituting, where
   appropriate, a word like "relevant" might help eliminate this confusion.]

           2) It is also strange to compare the linear relationship between DP and DQ by
   percentage, as Fig.2 or the text at the middle of page 5. As far as the reviewer knows,
   there is no geophysical theory that DP and DQ are equal in long term trend under natural
   condition. Recalling the Budyko's empirical curve of the water balance considering the
   available radiative energy, the relationship between DP and DQ is non-linear. Of course,
   any functional relationship may be able to be approximated as linear, the changes discussed
   here is more than a few tens of percent and applying perturbation concept would not be
   appropriate. [Nowhere did we infer that DP and DQ are equal (the DP and DQ axes in Fig. 2
   are not equal) or that they correlate linearly; the purpose of Fig. 2 is simply to show
   global and latitudinal similarities in the two trends, the notable exceptions being the
   deficit and excess rivers identified and discussed in the paper.  (Parenthetically, this
   figure may not be as essential to the paper as the other figures; if space is a problem and
   if the editor were insistent, we might be "persuaded" to eliminate it.)]

           3) Since global river discharge from land to ocean is estimated to be approximately
   40,000km3/y or more, the article covers less than half of it. Moreover, most of the
   findings and discussions in the article are changes in individual river basins, and the
   title "To The Global Ocean" seems not appropriate. [As Fig. 1a clearly shows, our 135
   rivers represent a global distribution of temporal trends. Moreover, global basin areas are
   more or less equally apportioned, cumulative African, Arctic, Australasian, North American
   and South American rivers each ranging between 8-11 x 10^6 km^2.   With the data at hand,
   this represents just about the best that one can hope for in terms of a global picture -
   and the task grows almost exponentially more difficult as one attempts to increase the
   coverage.  To achieve 75% global coverage, for instance, would require long-term temporal
   trends for >250 rivers, including from at least 25 Indonesia and the Philippines, for which
   there may be no long-term data.]

           4) Secondly, there should be longer river discharge record for Arctic rivers, and
   the authors will be able to show more robust long term trend and would be able to discuss
   the reason of negative DP and positive DR.  [Extending our record for Arctic rivers further
   back in time, which Peterson, McCllelland and others have done with Siberian rivers (whose
   records date back to the 1930s), would compromise our synthetic global approach, as the
   records for many rivers (e.g., Chinese, Brahmaputra, etc.) only extend back to the early
   1950s -  the reason that we chose the 1951-2000 interval for this study.]



           We are somewhat perplexed as to our next step with Nature - if, in fact, there is a
   next step.  Your rejection letter seems to have left the door opened for your re-evaluation
   of a revised manuscript.  Any revision obviously would address the reviewers' points (the
   manuscript that we submitted to Nature, in fact, already had addressed many of the points
   raised by Reviewer #1). We must wonder, however, whether Reviewer #1 would/could give us an
   impartial review; I suspect not.  On the other hand, we think that we can respond to all of
   Reviewer #2's comments to his satisfaction.  Assuming that you will need a new reviewer,
   Des Walling (Exeter) read an early draft of this paper, but would serve as an excellent
   reviewer in terms of his global perspective on temporal trends in fluvial discharge.

           I might add that I/we never have nor never would submit a manuscript simultaneously
   to more than one journal.  We hope that this manuscript will published in Nature.

           Sincerely,

           John Milliman
