A Global Perspective on Local Sea Level Changes

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The research addresses the comparison between Global Perspective and Local Sea Level Change, which is indeed a very relevant and valuable topic. The applied methodology is appropriate and well-suited to the comparative nature of the study. Both the results and discussion sections are logically structured and reflect a coherent interpretation based on the local and comparative sea level analysis, while also taking into account the uncertainty in local measurements, which requires research limitations that should be presented in the study. The discussion, in particular, offers clear and insightful interpretations that add value to the study.

In addition, a few comments for improvement are as follows

The most important one is that the manuscript undergoes a thorough language revision and polishing to enhance the overall quality of scientific writing. Improving clarity, grammar, and sentence structure will significantly strengthen the presentation and readability of the research.

The abbreviation “appr” should be avoided in the abstract. It should be replaced with the full word “approximately”.

It appears that the last sentence in the abstract (lines 19–20) is repetitive. Kindly review and consider removing or rephrasing it to avoid redundancy.

In the Introduction section, please ensure that author names are followed by the publication year. In many instances, citations are missing the publication year and only the author's surname is mentioned, which should be corrected.

On pages 29–30, in the sentence starting with “Projection of future sea level are...”, it is unclear why approximately nine references were cited for what appears to be a relatively straightforward or commonly accepted statement.

Try to avoid the use of first-person pronouns such as “we” academic writing to maintain an objective and formal tone.

Regarding Figures 3 and 5, the caption could be improved for clarity and precision. 

It is not recommended to include comparisons or citations in the conclusion section. The conclusion should focus more on summarizing the key findings and outcomes of the research clearly and concisely, without introducing new information or referring extensively to previous studies. Citations should be minimized in this section, and the emphasis should be placed on presenting the final insights in a scientifically sound and synthesized manner.

Author Response

The research addresses the comparison between Global Perspective and Local Sea Level Change, which is indeed a very relevant and valuable topic. The applied methodology is appropriate and well-suited to the comparative nature of the study. Both the results and discussion sections are logically structured and reflect a coherent interpretation based on the local and comparative sea level analysis, while also taking into account the uncertainty in local measurements, which requires research limitations that should be presented in the study. The discussion, in particular, offers clear and insightful interpretations that add value to the study.

Thank you

In addition, a few comments for improvement are as follows

The most important one is that the manuscript undergoes a thorough language revision and polishing to enhance the overall quality of scientific writing. Improving clarity, grammar, and sentence structure will significantly strengthen the presentation and readability of the research.

We reviewed the manuscript regarding language, including the specific suggestions given below.

The abbreviation “appr” should be avoided in the abstract. It should be replaced with the full word “approximately”.

Done

It appears that the last sentence in the abstract (lines 19–20) is repetitive. Kindly review and consider removing or rephrasing it to avoid redundancy.

Corrected

In the Introduction section, please ensure that author names are followed by the publication year. In many instances, citations are missing the publication year and only the author's surname is mentioned, which should be corrected.

As we understand MDPI formatting rules, years should not be added to author names. The editors have confirmed this to us. However, we moved the numeric reference to the author name where authors are mentioned.

On pages 29–30, in the sentence starting with “Projection of future sea level are...”, it is unclear why approximately nine references were cited for what appears to be a relatively straightforward or commonly accepted statement.

Probably the reviewer means lines 29-30. The references were reviewed and superfluous references removed.

Try to avoid the use of first-person pronouns such as “we” academic writing to maintain an objective and formal tone.

Reviewed and corrected

Regarding Figures 3 and 5, the caption could be improved for clarity and precision. 

Reviewed and corrected

It is not recommended to include comparisons or citations in the conclusion section. The conclusion should focus more on summarizing the key findings and outcomes of the research clearly and concisely, without introducing new information or referring extensively to previous studies. Citations should be minimized in this section, and the emphasis should be placed on presenting the final insights in a scientifically sound and synthesized manner.

The conclusion section was re-written in view of this comment

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript examines the comparison between observed local sea level rise (SLR) and projections provided by the IPCC. Utilizing extensive datasets from PSMSL and GLOSS, the authors implement a regression framework that accounts for long-term trends, tidal cycles, and potential acceleration. The primary finding is that most tide gauge records do not exhibit statistically significant acceleration in SLR, and that IPCC projections generally overestimate local SLR.

The manuscript is well researched and has the potential to make a valuable contribution to the sea level science literature. However, I recommend major revision prior to consideration for publication.

 

Major comments:

• What is the impact on the results if the acceleration onset year is left unconstrained? This assumption could influence the detectability and magnitude of acceleration.
• How sensitive are the findings to the choice of model—specifically, using linear versus quadratic fits? A sensitivity analysis would strengthen the robustness of the conclusions.
• When discrepancies exist between PSMSL and GLOSS records (e.g., Honolulu), how are these resolved or reconciled? More methodological detail is needed to clarify this aspect.

 

Minor comments:

In Table 1, please define the acronym "GIA" (presumably Glacial Isostatic Adjustment) and clarify how the “Extreme rate” threshold is determined or justified.

Author Response

This manuscript examines the comparison between observed local sea level rise (SLR) and projections provided by the IPCC. Utilizing extensive datasets from PSMSL and GLOSS, the authors implement a regression framework that accounts for long-term trends, tidal cycles, and potential acceleration. The primary finding is that most tide gauge records do not exhibit statistically significant acceleration in SLR, and that IPCC projections generally overestimate local SLR.

The manuscript is well researched and has the potential to make a valuable contribution to the sea level science literature. However, I recommend major revision prior to consideration for publication.

 

Major comments:

• What is the impact on the results if the acceleration onset year is left unconstrained? This assumption could influence the detectability and magnitude of acceleration.
  A valid research question. However, as stated in the paper we chose the bounds to reflect contemporary insights in the onset of acceleration published by other (referenced) authors. This was a conscious choice in our research and we therefore politely decline.
• How sensitive are the findings to the choice of model—specifically, using linear versus quadratic fits? A sensitivity analysis would strengthen the robustness of the conclusions.
  As explained in the paper, we do not make a choice but test both models and compare them statistically. The sensitivity analysis suggested by the reviewer is therefore already part of the present paper
• When discrepancies exist between PSMSL and GLOSS records (e.g., Honolulu), how are these resolved or reconciled? More methodological detail is needed to clarify this aspect.
  We did not combine the two datasets and therefore did not need to resolve the discrepancies. We clarified this aspect of our research in the last sentence of section 4.3

 

Minor comments:

In Table 1, please define the acronym "GIA" (presumably Glacial Isostatic Adjustment) and clarify how the “Extreme rate” threshold is determined or justified.

Done. A footnote was added to the first appearance of GIA in the table

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript is related to analysis of local aspects and conditions considering sea level changes in comparison to global perspective. This research deals with interesting topic, especially from the perspective of users and practitioners facing the challenge of relevant sea level selection during the design of different structures.

Manuscript is quite long, there is definitely some room for optimization and the structure of the manuscript should also be improved. Introduction section fails to give sufficient information considering the goal(s) of this manuscript. Introduction should be straightforward, explaining what is the research problem and hypothesis based on which this research is developed.

Although many researches and practitioners are facing challenges considering uncertainty about sea level rise projections, one can hardly rely on IPCC data during the design process of different structures. So my point is that authors should better explain the purpose of this research. Is it to show that IPCC projections are irrelevant and/or incorrect? Or to give better insights or guidelines for engineering design? IPCC projections are quite harsh, with large amount of uncertainty. And it is hard to believe that engineering could rely just on their inputs considering sea level changes.

Data selected for this analysis should be discussed as well. PSMSL yearly data could be, in theory, applicable for analysis of long-term changes and permanent sea level rise. But if you speak about local perspectives, than you should be aware that a lot of physical causes have impact of total sea level, some of which are also related to climate change and cause temporary flooding of coastal area (lines 253-255). Furthermore, it's a bit pretentious to draw conclusions about global trends and perspectives based on data used in the analysis. Large number of stations have insufficient data, excluding them from the analysis. Also, uncertainty analysis considering data and methodology at the end is missing. How can one be certain that the selected data is relevant and filtered from other effects?

Finally, analysis you performed based on yearly data will not provide general conclusions considering climate change impact and global sea level rise. It will give information considering local effects where the data is collected. And this should be the focus of this paper, giving guidelines to engineering and practitioners in interpretation of variable and often opposite information considering sea level changes.

Author Response

This manuscript is related to analysis of local aspects and conditions considering sea level changes in comparison to global perspective. This research deals with interesting topic, especially from the perspective of users and practitioners facing the challenge of relevant sea level selection during the design of different structures.

Manuscript is quite long, there is definitely some room for optimization and the structure of the manuscript should also be improved. Introduction section fails to give sufficient information considering the goal(s) of this manuscript. Introduction should be straightforward, explaining what is the research problem and hypothesis based on which this research is developed.

We re-wrote the introduction and reviewed the overall structure of the paper.

Although many researches and practitioners are facing challenges considering uncertainty about sea level rise projections, one can hardly rely on IPCC data during the design process of different structures. So my point is that authors should better explain the purpose of this research. Is it to show that IPCC projections are irrelevant and/or incorrect? Or to give better insights or guidelines for engineering design? IPCC projections are quite harsh, with large amount of uncertainty. And it is hard to believe that engineering could rely just on their inputs considering sea level changes.

We feel we covered the points made by the reviewer in line 35-58.

Data selected for this analysis should be discussed as well. PSMSL yearly data could be, in theory, applicable for analysis of long-term changes and permanent sea level rise. But if you speak about local perspectives, than you should be aware that a lot of physical causes have impact of total sea level, some of which are also related to climate change and cause temporary flooding of coastal area (lines 253-255).

Furthermore, it's a bit pretentious to draw conclusions about global trends and perspectives based on data used in the analysis. Large number of stations have insufficient data, excluding them from the analysis. Also, uncertainty analysis considering data and methodology at the end is missing. How can one be certain that the selected data is relevant and filtered from other effects?

No conclusions were drawn regarding global trends. Rather, trends in 200 distinct locations were analysed. The paper explains this. To avoid confusion, a few instances of the word “global” were removed. Data quality and potential human influences on observed level are explained in lines 100-119 of the manuscript

Finally, analysis you performed based on yearly data will not provide general conclusions considering climate change impact and global sea level rise. It will give information considering local effects where the data is collected.

We agree and where we unintentionally suggested something else we modified the text.

And this should be the focus of this paper, giving guidelines to engineering and practitioners in interpretation of variable and often opposite information considering sea level changes.

The difference between observed and projected sea level rise is the focus of the paper. We gave some guidelines for practitioners in the conclusions

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed my comments and questions.

 

Author Response

The authors have addressed my comments and questions.

Thank you for taking time to review our manuscript.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

thank you for your replies and improved manuscript. I believe that the manuscript is now improved and better explains the research goal.

My recommendation would still be to improve the Introduction, in my opinion you are missing to point out the importance of this topic and your motivation especially from the practitioner's point of view. I believe that by improving the Introduction you could strengthen your hypothesis and promote this research even more.

I strongly support your data-driven approach, which is more familiar with engineering needs and requirements. However, every day numerous engineers and practitioners are facing challenges in decision making and choosing appropriate input data and/or sea level projection for designing different coastal structures, weirs, breakwaters etc. Since these structures are designed to be mostly permanent, it is quite challenging to select optimal height or elevation to avoid flooding in the long period of time.

This leads to my final comment. I believe that you should provide stronger recommendations in the conclusion part. You are writing that practitioners should be aware of conservative projections. I agree with your conclusion. But what I am missing here is actually how can a practitioner perform or replicate similar analysis? Should someone rely on yearly or maybe hourly data when performing similar analyses and why? Is it just related to the length of time series? Or is it different from case to case? How can a practitioner identify the cause of sea level signal as demonstrated in Table 1?

 

Author Response

Dear Authors,

thank you for your replies and improved manuscript. I believe that the manuscript is now improved and better explains the research goal.

Thank you.

My recommendation would still be to improve the Introduction, in my opinion you are missing to point out the importance of this topic and your motivation especially from the practitioner's point of view. I believe that by improving the Introduction you could strengthen your hypothesis and promote this research even more.

Thank you for your encouragement. We re-visited our introduction and made a few additional remarks. Specifics are given in our response to your last comment.

I strongly support your data-driven approach, which is more familiar with engineering needs and requirements. However, every day numerous engineers and practitioners are facing challenges in decision making and choosing appropriate input data and/or sea level projection for designing different coastal structures, weirs, breakwaters etc. Since these structures are designed to be mostly permanent, it is quite challenging to select optimal height or elevation to avoid flooding in the long period of time.

Certainly a familiar conundrum. The remainder of our response is given in our response to your last comment.

This leads to my final comment. I believe that you should provide stronger recommendations in the conclusion part. You are writing that practitioners should be aware of conservative projections. I agree with your conclusion. But what I am missing here is actually how can a practitioner perform or replicate similar analysis? Should someone rely on yearly or maybe hourly data when performing similar analyses and why? Is it just related to the length of time series? Or is it different from case to case? How can a practitioner identify the cause of sea level signal as demonstrated in Table 1?

We appreciate your clear and concrete comments, but feel that it puts us in a difficult position. In the first review round we shortened the conclusion in view of a comment by another reviewer who stated (justly) that the conclusion should not contain new information and that references have no place in a conclusion. We feel we can not violate accepted comments from the first round in this second round.

Your comments invite to give guidance on the choice of sea level rise to account for in design. That is a related topic to which we certainly hope to contribute. But as it is not part of the research as such, we feel it does not belong in the conclusion. We chose to revisit the introduction and specifically look for how we dealt with the papers Voortman & Van der Kolk (2013), Voortman & Veendorp (2011) and Voortman & Vrijling (2004) as these  papers deal with the topic of your comment and do so from a practitioner’s point of view. With our modified introduction we hope to strengthen the relation between this research and the all-important matter of decision-making brought up in your comment.

Regarding guidance on how to run a similar analysis, we feel this is within the scope of the paper and therefore can be dealt with in the conclusions. We expanded our guidance in that respect.