Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model–data comparison

Peyron, Odile; Combourieu-Nebout, Nathalie; Brayshaw, David; Goring, Simon; Andrieu-Ponel, Valérie; Desprat, Stéphanie; Fletcher, Will; Gambin, Belinda; Ioakim, Chryssanthi; Joannin, Sébastien; Kotthoff, Ulrich; Kouli, Katerina; Montade, Vincent; Pross, Jörg; Sadori, Laura; Magny, Michel

doi:https://doi.org/10.5194/cp-13-249-2017

Articles | Volume 13, issue 3

https://doi.org/10.5194/cp-13-249-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

Human–land–sea interactions in the Mediterranean...

https://doi.org/10.5194/cp-13-249-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 13, issue 3

Research article

|

24 Mar 2017

Research article |

| 24 Mar 2017

Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model–data comparison

Odile Peyron, Nathalie Combourieu-Nebout, David Brayshaw, Simon Goring, Valérie Andrieu-Ponel, Stéphanie Desprat, Will Fletcher, Belinda Gambin, Chryssanthi Ioakim, Sébastien Joannin, Ulrich Kotthoff, Katerina Kouli, Vincent Montade, Jörg Pross, Laura Sadori, and Michel Magny

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Final revised paper (published on 24 Mar 2017)
Supplement to the final revised paper
Preprint (discussion started on 28 Jun 2016)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'a rather descriptive manuscript, could be more in-depth', Anonymous Referee #1, 21 Jul 2016
RC2: 'Requires better framing of questions and goals', Anonymous Referee #2, 06 Aug 2016
EC1: 'Editor's conclusions', Joel Guiot, 28 Aug 2016
- AC1: 'editor reply', Odile Peyron, 18 Nov 2016
  - EC2: 'Clearer replies are needed', Joel Guiot, 21 Nov 2016
    - AC2: 'reply to editor comments', Odile Peyron, 28 Nov 2016

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Publish as is (29 Nov 2016) by Joel Guiot

ED: Reconsider after major revisions (01 Dec 2016) by Joel Guiot

AR by Odile Peyron on behalf of the Authors (05 Dec 2016) Manuscript

ED: Referee Nomination & Report Request started (05 Dec 2016) by Joel Guiot

RR by Anonymous Referee #1 (23 Dec 2016)

Suggestions for revision or reasons for rejection

I think this version does represent an improvement with respect to the initial submission, and i principle the manuscript is close to a publication stage. This being said, I also think that the authors could have done more to produce a more innovative contribution, but this is to some extent a matter of taste. I do not see anything clearly wrong in this study, but without a more detailed analysis of the model runs, the manuscript is, to large part, a conformation of the results obtained by Mauri et al (2015). I acknowledge that this study contains marine proxies, which Mauri et al did not, but it is difficult to recognizee what these new proxies additionally tell us. Reading the manuscript again, it is clear that the authors use very often the expression ' ..which confirms previous studies...'. This is per se not bad, but perhaps a bit too conservative. In this sense, I was a somewhat disappointed, but I also recognise that conformation studies are also necessary.

I would, however, suggest to pay attention to three points that would strike the reader. The first point is the abstract. It is too long and some sentences /paragraph are repetitive (particular comment below). I think it should be tightened and shortened, maybe by 1/3 or so. It is written very 'generoulsy' and certainly the sentences can be shortened and the whole abstract written more to the point. The second point, in the introduction, is related to the discussions of previous proxy studies. The introduction sets off by explaining all what is known about the evolution of precipitation in Europe over the Holocene, which reads to be quite a lot (early Holocene, Midholocene, north-south, east-west dipoles), but then, a bit surprisingly, when highlighting the innovations of this study the authors point out that most previous studies are focused on the Midholocene (lines 147). The reader will wonder how we could know so much if most studied are limited to the Mid-Holocene.
Regarding the modelling side, I think that the authors do not do a favour themselves. They present results from a regional simulation backed by the reasoning that a high-resolution model is necessary to better simulate precipitation, but on the other hand also discuss that the results of the regional model cannot deviate much from the driving global model, for instance considering the question of the extension of the African Monsoon in the Mid-Holocene. Again, the reader would wonder why is a regional model necessary in the first place, and why the authors could not look into global coupled simulations.

I understand that the authors are trying to balance the new aspects of their work, and their intention of not going into a detailed analysis of the runs, but the present solution to this balance does not read very well. It can be, however, my own perspective.

Particular points

Abstract , line 38. Just an example, I think that the paragraph ' in order to test the above mentioned
hypotheses on a Mediterranean-wide scale, and we compare the results with model outputs from
a high-resolution regional climate model. Spatially, we focus on transects across the
Mediterranean basin from north to south and from west to east...' is repetitive. The same has been said before in the abstract-

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RR by Anonymous Referee #2 (08 Jan 2017)

Suggestions for revision or reasons for rejection

Review of “The climate of the Mediterranean basin during the Holocene from terrestrial and marine pollen records: A model/data comparison” by Peyron et al.

I thank the authors for their detailed reply to my original comments and for the changes that they have made to the manuscript. The aims of the study are more clearly stated, and it is easier to follow these to the conclusions reached. While the paper has improved, I have a few further comments that I would like to see addressed prior to publication:

Line 33 (and elsewhere): “regional/local level”. Please define what is meant by these terms – I’m not convinced that a regional GCM can really inform local scale processes.

Line 57: “general drying trend”. This is not really a trend, as it is based on two points in time.

Lines 171-172. This seems like a small number of sites, and checking against the EPD records, suggest that there should be several more in both time periods. Clearly there has been some selection – please state what the criteria were. Further, what are the time windows used to select samples? How much variation is there at sites within these windows? Is this bigger than the simulated changes? If so, it is going to be difficult to argue for any significant comparison.

Lines 188-190: I don’t really follow this justification for the MAT method. If you are using a non-robust statistic such as the mean, then I would think it is more susceptible to bias from higher noise. Please add some more detail here.

Line 197: What about the winter precipitation reconstructions?

Line 203: Did the authors merge the simulations for 2000 and 4000, and those for 6000 and 8000? Wouldn’t it have been easier to choose 2000 and 8000 to maximize the differences? Please justify this choice.

Line 212. What is HadSM3?

Line 228: What is being tested? The difference between simulations?

Section 3 Results and Discussion. While the maps show some apparently convincing matches between the reconstructions and simulations, it is very difficult to judge these. It would really help to have a figure that shows the reconstructed and simulated values perhaps as a function of longitude. This could also include the model and reconstruction uncertainty, and would make it easier to follow the points made in the discussion, as well as the assertion of “a remarkable qualitative agreement”

Line 403. The author mention here (and elsewhere) that many of the changes are small and of marginal significance. However, even these null changes are of interest if found in both data and model. Again, a figure displaying the actual values would help.

Line 409. What is a level of significance of 70%. A p-value of 0.7?

Line 479. Data limitations. Thank you for including this section, which provides a great overview of some of the limitations. There are a couple of phrases that should be reviewed by an native English speaker (“it may be highlighting commenting on some limitations” and “All of these points may seem very picky on the ecology side”)

Figures. Figures 2 and 3 carry much of the same data. Do the authors really need both?

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ED: Publish subject to minor revisions (review by Editor) (10 Jan 2017) by Joel Guiot

AR by Odile Peyron on behalf of the Authors (20 Jan 2017)

ED: Publish subject to technical corrections (25 Jan 2017) by Joel Guiot

AR by Odile Peyron on behalf of the Authors (20 Feb 2017) Manuscript

Short summary

This study aims to reconstruct the climate evolution of the Mediterranean region during the Holocene from pollen data and model outputs. The model- and pollen-inferred precipitation estimates show overall agreement: the eastern Medit. experienced wetter-than-present summer conditions during the early–late Holocene. This regional climate model highlights how the patchy nature of climate signals and data in the Medit. may lead to stronger local signals than the large-scale pattern suggests.