PCLM-D-24-00018

How climate models reproduce the observed increase in extreme precipitation over Europe.

PLOS Climate

Dear Dr. Steensen,

Thank you for submitting your manuscript to PLOS Climate, and first of all, apologies for the long time that it has taken in this case to reach a decision on your manuscript. Unfortunately, one of the reviewers was not able to submit a review on time, and this delayed the process. 

Regarding your manuscript, after careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by May 12 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Juan A. Añel

Academic Editor

PLOS Climate

Journal Requirements:

Additional Editor Comments (if provided):

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: There are several concerns that prevent me from recommending the paper for publication at this time. First and foremost, there is little novelty in the conclusions. The paper does not provide new insights into the subject. Another concern is the limited review of precedents and relevant literature on some of the key topics. For example, the authors state that "additional analysis is needed to understand the difference between the global and regional models". This question could easily be answered by a simple review of the issues raised against regional climate models in the last decade. The same goes for precipitation extremes and model validation. There is also a problem with applying statistical techniques to models that do not meet independence criteria. Many models in the list share parameterizations and physical cores, so the ensemble is not fully independent. More rigor is needed in the statistical treatment of the data. It is known that some CGMs and some RCMs do not compare well with observations - should they be discarded from the ensemble? Uncritical use of the CORDEX ensemble may lead to the inclusion of models that have not been shown to simulate the precipitation climatology at the appropriate spatial and temporal resolutions needed to capture extremes. All these issues will need to be addressed in a revised version.

Reviewer #2: Dear authors, I have read your manuscript entitled: How climate models reproduce the observed increase in extreme precipitation over Europe.

Major comments

In this study, an assessment is made of the ability of models and reanalysis to represent precipitation extremes. In the Introduction, the authors should highlight the novelty concerning previous studies, which is necessary in order not to be redundant and not to reproduce previous studies. Much of the explanation is devoted to the description of the results, however, the Discussion is very limited, with only 4 studies cited in this section, and lacking in-depth analysis. It would be mandatory, and I recommend you to better discuss the results not only based on themselves, but considering more previous studies as points of comparison. In lines 176-177 you argue that: ‘‘Results are calculated for each station or land grid cell, and then averaged over the European region’’. So I wonder why the authors do not present a spatial analysis, which would allow us to understand the changes/differences between the occurrence and representation of extremes and their trends in areas with higher and lower station density in Europe, and improve the discussion. Adding this analysis, if possible, would be a plus to increase the quality of the article. I believe that major revisions need to be made to improve the quality of this study and consider it for publishing in this journal.

Minor comments:

- In the Dataset section, you don’t inform the Scenarios, while in contrast, you do in the Methodology. I believe you should include this information in the datasets section.

- Figures don’t have captions

- Line 189. (8) proposed …. Check if this is the correct form to reference at the beginning of a sentence.

- Check the sentence on line 203.

- From lines 201 to 207 you reference ‘’8’’ three times. Please check if the way you did is correct or not.

- According to the text the only difference between Figure 1b and 1a is that the 99.97 threshold is added, so why not add this threshold in Figure 1a adding also a vertical line for limiting the 99.97 bin, and have only one figure?

- Why does ClimEx data have no change on extremes? In case of a mistake please check along all the manuscript the explanation of this dataset.

- Why do the values of the extremes in station data differ significantly from the rest of the data? Wouldn't you expect some overlap with EOBS data?

- Line 200. How did you define heavy and extreme precipitation?

- Line 201. What is the significance of saying this: illustrated in the same way as in (8)?

- Lines 335-337. ‘’In this study we show that when including a higher percentile of 99.97, which is around an event once per tenth year for the frequency bins presented in Fig1, most of the precipitation events that fall in the lower 99.9 bin also fall in the 99.97 bin’’. This is something normal.

- In lines 378-379 the authors mention that ‘extreme precipitation events over Europe have caused flooding and large damages’’; which events, which damages? or at least add a reference.

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6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PCLM-D-24-00018R1

How climate models reproduce the observed increase in extreme precipitation over Europe.

PLOS Climate

Dear Dr. Steensen,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

First, I would like to apologize because of the long time that it has taken to evaluate the current version of your manuscript. Several factors have contributed to it. First, your reviewed version obtained mixed recommendations from the reviewers in the first round. Because of it, I decided to secure a third reviewer to have an additional view. Then, unfortunately, a holidays period and personal issues of the third reviewer delayed the decision for five additional weeks.

That said, given the opinion by the reviewers and my own assessment, I have decided to send you back the manuscript for Major Revisions. Your manuscript is far from what I consider would be necessary to make it useful for the community and, therefore, publish it. I agree with the view of reviewers #1 and #3 regarding the lack of references in your work. Despite the wealth of literature on extreme precipitation in Europe, your manuscript barely contains 40 references. I think it is necessary to provide much more context in the Introduction, and comparison to published works after the results. As reviewer#3 notes, bulk numbers or scatter plots do not add to much to the current state-of-the-art. In this regard, the paper would be much more useful and benefit from some comparisons and discussion at the regional level, and I think you should include them, including illustrative plots.

I understand that the idea behind your manuscript was probably to publish a brief text with some key figures. Notwithstanding, adding the mentioned improvements, I think that it is possible to keep a direct, brief and informative text while increasing its quality, value and usefulness.

Please submit your revised manuscript by Nov 28 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Juan A. Añel

Academic Editor

PLOS Climate

Journal Requirements:

Additional Editor Comments (if provided):

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

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2. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: N/A

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4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have not properly addressed the reviewers' comments. "We choose to treat each model statistically independently, even though the models themselves are not independent" is not a proper scientific response to the criticism. The novelty of the paper is still not justified. Sentences in the abstract such as "This inter-model diversity is found to be stronger than the intra-model spread represented by different ensemble members." are not justified in the paper (in fact, such a finding is not original and must be referenced). The paper is redundant and simply reproduces the results of other studies (which are not referenced). The paper lacks in-depth analysis and does not reference previous research on the limitations of RCMs, thus ignoring the precedents. Previous work on precipitation validation is also ignored, resulting in an incomplete approach to a problem that has been addressed before. The conclusions are therefore not new, and the authors are not the first to report such findings.

Reviewer #2: (No Response)

Reviewer #3: Review of PLOS Climate article:

How climate models reproduce the observed increase in extreme precipitation over Europe

By Birthe Marie Steensen, Gunnar Myhre, Øivind Hodnebrog, Kari Alterskjær

I have been asked to review the revised version of this paper. I have not been a reviewer of the submitted version. Thus, I follow the general review instructions and assess the value of this paper for the scientific community.

The paper provides an analysis of a large number of climate simulations. The paper considers European mean changes, but no assessment is provided of geographical variations of the climate change signal. The main result is that changes at high percentiles are more pronounced than at lower percentiles.

It is evident that there is significant overlap with a previous publication of the same group (Myhre et al, 2019) in terms of methodology. However, the current study considers CMIP6 instead of CMIP5 simulations.

Major comments

(1) The method section should be improved to better discuss how the methodology is applied to the different data sets. Relevant issues not addressed are the following: (a) I understand that the analysis is done over the land-portion of a European subdomain. Is this done on the original grids of the respective models and observational data sets? (b) The text states that the “results are calculated for each station or land grid cell, and then averaged over the European region”. You should explicitly state what quantities are averaged. Are you averaging the climate changes, or are you averaging the precipitation intensity and frequency, and then compute the averaged changes?

(2) The main thrust of the paper is to use a European-wide summary assessment, i.e. all data is averaged over a large area with substantial differences in regional climates. In principle this is a nice idea; if it works this would simplify the argumentation. However, this point requires justification. To do so, you need to show geographical maps, showing both absolute values for the current climate and relative values for climate changes. More specifically, for instance: median intensity for some percentile for the three data sets (observations, CMIP6 and CORDEX). And respective relative changes for the same data sets. Unless you demonstrate that the geographical pattern of changes is consistent across data sets, there is no justification to using a single bulk assessment.

(3) I wonder: what are the implications of this study for a hydrologist, located somewhere in Europe, that needs to adapt his area to climate change effects? Your text sounds like he/she can use curves such as shown in Fig. 5. You should discuss this in the last section. May be comment (2) helps in making this discussion.

(4) The conclusions state (L376-379): “Even with the large model spread, results presented here show that GCMs part of the CMIP6 historical simulations manage to reproduce the increase in heavy-to extreme precipitation observed since 1955 over Europe with around a 20% increase for the 99.9th percentile.” I think this statement is misleading. It is well known in our modelling communities that GCMs dramatically underestimate precipitation extremes and their geographical variations are not realistic. It is not enough that the relative changes appear ok, also the absolute values should be fine. The sentence should be revised considering these concerns.

Minor comment:

Abstract: I think the abstract does not include all relevant information needed and leaves room for misunderstandings. A few specific comments: (a) The abstract does not point towards the main thrust of the paper, namely the use of an overall European-averaged precipitation frequency-intensity distribution. I consider this to be the main goal of the study, which should be exposed explicitly. (b) Likely many meteorologists will misinterpret the term “frequency”, as they have the precipitation frequency in mind. If you say that “frequency increases more than intensity”, please make sure to say, “frequency of heavy events”. (c) If you refer to percentiles, make sure you explain which percentiles you are meaning (there are many different percentiles used in our community). Similarly, you should explain / justify your choice in the methods section.

L347: “once per ten years”, and ”Fig. 2”

L388: The references selected here (33-36) appear a bit stochastic. The most comprehensive data sets about km-scale models in Europe were presented in Ban et al. (2021) and Pichelli et al. (2021), and are not referenced.

L417: The reference is incomplete

References:

Ban et al. al. 2021, https://doi.org/10.1007/s00382-021-05708-w

Pichelli et al. 2021, https://doi.org/10.1007/s00382-021-05657-4 (

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

How climate models reproduce the observed increase in extreme precipitation over Europe.

PCLM-D-24-00018R2

Dear Dr. Steensen,

We are pleased to inform you that your manuscript 'How climate models reproduce the observed increase in extreme precipitation over Europe.' has been provisionally accepted for publication in PLOS Climate.

At the same time, we would like to apologize for the long time that has taken to reach a decision on your manuscript. Unfortunately, securing reviewers for it, and reaching an agreement on your work, has been very challenging on this ocassion.

Before your manuscript can be formally accepted you will need to complete some formatting changes, which you will receive in a follow-up email from a member of our team. 

Please note that your manuscript will not be scheduled for publication until you have made the required changes, so a swift response is appreciated.

IMPORTANT: The editorial review process is now complete. PLOS will only permit corrections to spelling, formatting or significant scientific errors from this point onwards. Requests for major changes, or any which affect the scientific understanding of your work, will cause delays to the publication date of your manuscript.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they'll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact climate@plos.org.

Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Climate.

Best regards,

Juan A. Añel

Academic Editor

PLOS Climate

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Additional Editor Comments (if provided):

Please note that I have acted as a reviewer for this manuscript, and you will find my comments below, under Reviewer 4.

Reviewer Comments (if any, and for reference):

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #4: All comments have been addressed

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2. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Partly

Reviewer #4: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #4: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #4: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #4: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have still not adequately addressed the reviewers' comments in this new round. The novelty of the paper is still not justified and the authors have not adequately addressed the criticisms. The new version of the paper is still redundant and simply reproduces the results of other studies.

Previous work on precipitation validation is also ignored, resulting in an incomplete approach to a problem that has already been addressed. The results of the paper have been discussed elsewhere by others. In particular, the reasons why the models respond differently to climate change and how they respond to future global warming have already been explained by other scientists. The authors claim novelties that are not their own. I cannot find any new results.

Reviewer #4: Review of "How climate models reproduce the observed increase in extreme precipitation over Europe" by Rødssæteren Steensen et al.

I have reviewed this reviewed manuscript. Based on the previous reviews and my own assessment, and the replies provided by the authors, I consider that the manuscript can be published as is. Previous reviewers have raised serious concerns on the applicability of the results, lack of novelty, and even the statistical independence during the analysis. All of them are reasons that probably make this work of little use. The authors claim that the main novelty is the study of the most extreme percentiles of precipitation. Somebody with some knowledge of GCMs and RCMs, and their well know limitations to represent extreme precipitations, is expected to know that any result on so extreme values is doubtful and should be used very carefully.

I think that the authors have acknowledged the limitations of their work in their conclusions. This does not totally solves the question about if a manuscript that advances little the existing scientific corpus of knowledge, and with great limitations in the science presented should be published or not. However, doing it, has become a normal practice nowadays, initially done in good faith to try to advance science. Therefore, in this sense the science presented here is fair, and seems to be honest, and my recommendation is to publish it. It can serve to inform the research community (again) on the need to study extreme precipitation and all the limitations we face on it.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #4: No

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