Assessing Environmental Sustainability: A National-Level Life Cycle Assessment of the Icelandic Cattle System

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a life cycle assessment study of beef and dairy production from cattle in Iceland. The work identifies the main hotspots in the process. The reviewer considers the manuscript to present coherent and sufficiently high-quality information for potential citation in future work. However, the reviewer also believes that the information is presented in lengthy paragraphs, which limits its comprehension. Comments and suggestions are provided in the attached file.

Comments for author File: Comments.pdf

Author Response

General Comments

The manuscript presents a life cycle assessment study of beef and dairy production from cattle in Iceland. The work identifies the main hotspots in the process. The reviewer considers the manuscript to present coherent and sufficiently high-quality information for potential citation in future work. However, the reviewer also believes that the information is presented in lengthy paragraphs, which limits its comprehension. Comments and suggestions are provided in the attached file.

Answer and Action: We thank the reviewer for a detailed review and their valuable feedback on the manuscript. We have addressed the comments made, please find the individual reply below.

 

1. Page 1 Please use the same font type and size throughout the document

Answer and Action: In accordance with the reviewer’s comment, we have adjusted the font type and size.

 

2. Page 2 Please include quantitative values for emissions, not just the percentage.

Answer and Action: In accordance with the reviewer’s comment, we have added the quantitative value as per FAO report and highlighted the changes in yellow in Section 1 page 2 line 51.

 

3 Page 2 Please include quantitative values for emissions.

Answer and Action: In accordance with the reviewer’s comment, we have added the quantitative value and highlighted the changes in yellow in Section 1 page 2 line 58-61.

 

 

4. Page 2 Please clarify what those categories are.

Answer and Action: In accordance with the reviewer’s comment we have added the categories, this includes biodiversity and water quality and highlighted the changes in yellow in Section 1 page 2 line 70-72.

 

 

5. Page 3 and 6 The paragraphs are too long. Please shorten them.

Answer and Action: We agree with the reviewer comments that the paragraphs are long. On page 3 the paragraphs include the literature review. Considering a wider audience in Iceland and abroad from universities, students for educational purpose, farming community and policymakers. We believe as a first study in the country it is required to set the stage for the cattle system and would like to keep detailed literature review.

For the second paragraph on page three which sets the stage for research goals, we agree with reviewer, and we have divided the paragraph into two parts for clarity.

 

On page 6 the section includes life cycle inventory description. These two paragraphs provide an overview of the inventory formulation, and we would like to keep them as it is. We keep most of the detailed information on inventory in Supplementary Material 1 and 2 and these paragraphs guide the reader towards more information and provide an overview of the system.

 

 

6. Page 24 Do the authors share the viewpoint on biophysical allocation?

Answer and Action: Explanations in accordance with the reviewer’s comments, in discussion section 4.2-page 24 line 874-909, we elaborate on the implications of the different allocations method utilized in this study. In the conclusion section, we also provide that "the biophysical allocation method provides the most balanced allocation between meat and milk products and is best suited for livestock systems compared to the mass and economic allocation methods." Our viewpoint is that different allocation methods should be utilized to address multifunctionality and given that economic (market fluctuations and subsidies) and mass allocation (larger milk output than meat) skew the results, biophysical allocation provides a balanced approach. By employing different allocation methods, the study provides a range of possible environmental impacts in the dairy cattle system. This has been added to section 4.2-page 25 line 935-937 and highlighted in yellow.

 

10. Page 24 What factors do the authors consider critical for allocation? From the authors' perspective, do the geography and economic characteristics of the region influence allocation? Do they recommend biophysical allocation for a similar study in a region with limited financial resources, where farmers prioritize products based on their economic value?

Answer and Action: As stated in the above comment, we recommend using a wide range of allocation methods to illustrate the potential environmental impacts. In regions with limited financial resources, where farmers prioritize products based on their economic value, it is crucial to show the sensitivity in the results, as market fluctuations in costs, government subsidies, and support can significantly affect allocation factors and overall results.

 

11. Page 28 Were the transport distances of livestock feed and their effect on the environmental impact outcome considered? From the authors' point of view, it is possible to quantify this effect in an LCA of the magnitude presented in the manuscript.

Answer and Action: In accordance with the reviewer comments, we have added a limitation in Section 2.2 (life cycle inventory) and highlighted the changes in yellow on page 8 line 290-294. In our LCA model, we consider market activities for imported livestock feed; these are global (GLO) or rest-of-the-world (ROW) processes in ecoinvent and include an average transportation distance. The reason for including these activities with average transportation distances is that the feed source (import country) was unavailable. The farmers generally buy feed from feed companies in Iceland, but despite our attempts to reach out to these companies to gather specific data, we were unsuccessful. Therefore, we utilize the GLO/ROW market process for feed concentrate. In the case of hay production, which is a locally grown feed, the transport distance is also not considered, as 1) hay is grown close to the farm or on farm, 2) it would not have been possible to estimate total or average distance from hay field to farm in Iceland for the whole country and therefore not included in this study.

12. page 28: Consider shortening the conclusions or restructuring them into shorter paragraphs to enhance clarity.

Answer and Action: In accordance with the reviewer comments, we have restructured the conclusion section and made it shorter with bullet points.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study diagnoses and defines the baseline of the Icelandic cattle system. The authors use Life-Cycle Analysis to conduct a cradle-to-farm-gate assessment of cattle production in Iceland. Therefore, it is of enormous importance to determine and monitor Iceland's climate-related policies, as this is the first work undertaken for Iceland in this field. The authors made a remarkable effort to compile all the data considered in this paper.

The research problem is clearly stated. The overall approach is sound. The results are detailed and compared with other studies. The conclusions relate to the results. Overall, the paper is quite fine.

However, we recommend some aspects to the authors:

• A primary limitation of the study, as recognized by the authors, is the lack of nationwide data standardization, with no further details provided for different cattle categories. If data is available, it would be helpful to provide more detail. But even as an aggregate analysis, it represents a significant contribution to literature and to the country’s climate policies.
• The references included are appropriate. However, I would like to recommend one additional source that used similar approaches in Brazil: Barros, M. V., Salvador, R., Maciel, A. M., Ferreira, M. B., de Paula, V. R., de Francisco, A. C., ... & Piekarski, C. M. (2022). An analysis of Brazilian raw cow milk production systems and environmental product declarations of whole milk. Journal of Cleaner Production, 367, 133067. https://doi.org/10.1016/j.jclepro.2022.133067
• Regarding methodology, how are veterinary products considered in the analysis? Are they counted? Or are they neglected?
• How is the trade of inputs and outputs considered in the LCA? Are they relevant for the Icelandic case?

We believe that these aspects may improve the overall paper quality and thus make it a citable reference for researchers in this field.

Author Response

The study diagnoses and defines the baseline of the Icelandic cattle system. The authors use Life-Cycle Analysis to conduct a cradle-to-farm-gate assessment of cattle production in Iceland. Therefore, it is of enormous importance to determine and monitor Iceland's climate-related policies, as this is the first work undertaken for Iceland in this field. The authors made a remarkable effort to compile all the data considered in this paper.

The research problem is clearly stated. The overall approach is sound. The results are detailed and compared with other studies. The conclusions relate to the results. Overall, the paper is quite fine.

However, we recommend some aspects to the authors:

• A primary limitation of the study, as recognized by the authors, is the lack of nationwide data standardization, with no further details provided for different cattle categories. If data is available, it would be helpful to provide more detail. But even as an aggregate analysis, it represents a significant contribution to literature and to the country’s climate policies.
• The references included are appropriate. However, I would like to recommend one additional source that used similar approaches in Brazil: Barros, M. V., Salvador, R., Maciel, A. M., Ferreira, M. B., de Paula, V. R., de Francisco, A. C., ... & Piekarski, C. M. (2022). An analysis of Brazilian raw cow milk production systems and environmental product declarations of whole milk. Journal of Cleaner Production, 367, 133067. https://doi.org/10.1016/j.jclepro.2022.133067
• Regarding methodology, how are veterinary products considered in the analysis? Are they counted? Or are they neglected?
• How is the trade of inputs and outputs considered in the LCA? Are they relevant for the Icelandic case?

We believe that these aspects may improve the overall paper quality and thus make it a citable reference for researchers in this field.

 

Answer and Action: We thank the reviewer for a detailed review and their valuable feedback on the manuscript. We have addressed the comments made, please find the individual reply below.

1. A primary limitation of the study, as recognized by the authors, is the lack of nationwide data standardization, with no further details provided for different cattle categories. If data is available, it would be helpful to provide more detail. But even as an aggregate analysis, it represents a significant contribution to literature and to the country’s climate policies.

Answer and Action: We agree that there is a lack of standardization, which led us to utilize national databases in their current form to formulate the inventory. However, in our assessment, we calculate the material, energy, and feed inputs for each animal in the study (dairy and beef cattle classes) as described in section 2.2 line 209-268 and the calculations and estimates are provided in Supplementary Material 1, section S1 table S2-S3, which are then used to formulate the national-level inventory.

2. The references included are appropriate. However, I would like to recommend one additional source that used similar approaches in Brazil: Barros, M. V., Salvador, R., Maciel, A. M., Ferreira, M. B., de Paula, V. R., de Francisco, A. C., ... & Piekarski, C. M. (2022). An analysis of Brazilian raw cow milk production systems and environmental product declarations of whole milk. Journal of Cleaner Production, 367, 133067. https://doi.org/10.1016/j.jclepro.2022.133067

 

Answer and Action: We thank the reviewer for directing us to an important study; this is a very comprehensive assessment similar to ours. However, our research focuses on Iceland and the broader Nordic region. Comparing results with a study from Brazil would not yield additional insights, as the production systems and emission factors differ. Therefore, we would not like to include this reference.

 

3.Regarding methodology, how are veterinary products considered in the analysis? Are they counted? Or are they neglected?

 

Answer and Action: The veterinary products are not included in the analysis due to insufficient information on their use. We have added this limitation in Section 2.1 and highlighted the text in yellow Page 4 line 186.

 4. How is the trade of inputs and outputs considered in the LCA? Are they relevant for the Icelandic case?

 

Answer and Action: As we understand from the comment, the trade of inputs and outputs as production output, as the study focuses on the environmental impacts of the cattle production, we consider the national output. Additionally, the imported feed and fertilizers are modelled as market activities (global and the rest of the world) we have added a description in section 2.2 line 290-294.

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

Your manuscript presents the first comprehensive LCA-based assessment of Icelandic cattle production systems, offering valuable insights into the environmental impacts of both milk and beef at the national level. The application of a wide range of impact categories, along with robust sensitivity and uncertainty analysis, significantly contributes to the scientific value of the work.

However, despite the high technical quality of the assessment, the discussion lacks a set of practical, management-oriented recommendations that would benefit both producers and policymakers. In its current form, the manuscript is largely analytical, with limited translation of the hotspot analysis into concrete strategies for environmental impact mitigation. For example, based on your findings, it would be helpful to provide specific suggestions regarding:

- Optimization of fertilizer (especially nitrogen) use in hay production;

- Adoption of methane-reducing interventions in feeding or animal management;

- Strategies to reduce reliance on imported feed concentrates, or to monitor heavy metal and pesticide residues more closely;

- Identification of priority areas for further research or policy intervention in Iceland’s livestock sector.

Adding even a brief section outlining such targeted recommendations in the Discussion or Conclusion would considerably enhance the manuscript’s practical relevance and utility. I recommend this as a minor revision.

Sincerely,

Comments on the Quality of English Language

The language is generally clear, though a light professional editing of the English would not only improve clarity and flow, but would also help to reduce the overall length of the manuscript, making it more concise and accessible to readers.

Author Response

Your manuscript presents the first comprehensive LCA-based assessment of Icelandic cattle production systems, offering valuable insights into the environmental impacts of both milk and beef at the national level. The application of a wide range of impact categories, along with robust sensitivity and uncertainty analysis, significantly contributes to the scientific value of the work.

However, despite the high technical quality of the assessment, the discussion lacks a set of practical, management-oriented recommendations that would benefit both producers and policymakers. In its current form, the manuscript is largely analytical, with limited translation of the hotspot analysis into concrete strategies for environmental impact mitigation. For example, based on your findings, it would be helpful to provide specific suggestions regarding:

- Optimization of fertilizer (especially nitrogen) use in hay production;

- Adoption of methane-reducing interventions in feeding or animal management;

- Strategies to reduce reliance on imported feed concentrates, or to monitor heavy metal and pesticide residues more closely;

- Identification of priority areas for further research or policy intervention in Iceland’s livestock sector.

Adding even a brief section outlining such targeted recommendations in the Discussion or Conclusion would considerably enhance the manuscript’s practical relevance and utility. I recommend this as a minor revision.

Sincerely,

 

Answer and Action: We thank the reviewer for a detailed review and their valuable feedback on the manuscript. We have addressed the comments made, please find the individual reply below.

 

In accordance with the reviewer’s comments, we have restructured the conclusion section and made it shorter with bullet points and additionally added the following comments (page 30).

 

 

1. Optimization of fertilizer (especially nitrogen) use in hay production;

 

Answer and Action:: We have added the point, optimizing fertilizer application (such as nitrogen) in hay production can reduce the overall environmental impacts of the cattle system.

 

2. Adoption of methane-reducing interventions in feeding or animal management;

 

Answer and Action: We have added the point, adoption of methane reducing interventions in feeding, animal husbandry and manure management (utilization of manure for biogas production) could reduce climate change related impacts.

 

3. Strategies to reduce reliance on imported feed concentrates, or to monitor heavy metal and pesticide residues more closely

 

Answer and Action: We have added the point, in dairy systems, strategies are needed to reduce reliance on imported feed concentrates and to enhance domestic feed production, such as barley.

 

4. Identification of priority areas for further research or policy intervention in Iceland’s livestock sector.

 

Answer and Action: We have added the points:

 

• The results of this study could enable policymakers to formulate quantifiable targets for the Climate Action Plan 2020 objectives, with key interventions in fertilizer, feed, manure management, and data harmonization and quality.

 

• Additionally, future studies should focus on evaluating the water scarcity footprint of imported feed and its associated biodiversity impacts.

 

5. Adding even a brief section outlining such targeted recommendations in the Discussion or Conclusion would considerably enhance the manuscript’s practical relevance and utility. I recommend this as a minor revision

 

Answer and Action: Several changes have been made to the conclusion section in agreement with the reviewer’s comments as provided above.

 

 

6. The language is generally clear, though a light professional editing of the English would not only improve clarity and flow, but would also help to reduce the overall length of the manuscript, making it more concise and accessible to readers.

 

Answer and Action: In accordance with reviewer’s comments, we have made editing of the English throughout the manuscript.

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

1- Please, authors, mark the lines and pages just to facilitate the revision

2-Do not start your sentence with an abbreviation, please, like (LCA is a methodology to evaluate a product’s environmental impact) 

3-In general, the introduction is too long; please try to shorten it 

4- Lack of a clear hypothesis in the introduction? 

5-Some references are colored in blue; others are not. ?

6-In my point of view, the authors did not represent any of the equations of his calculations, even though he depended on using TIAR2 

7-Figure 3 section beef meat, the  Y-axis is not clear 

8- The results section is too long. Please, needs to be more focused without any discussion in this part  

9-The discussion looks fine, but  the Conclusions are so long 

 

Author Response

We thank the reviewer for a detailed review and their valuable feedback on the manuscript. We have addressed the comments made. Please find the individual reply below.
1- Please, authors, mark the lines and pages just to facilitate the revision
Answer and Action: In accordance with the reviewer's comment, we submit the manuscript marked with lines. In our original submission, we added line numbers to the manuscript. Which MDPI later converted into their format and did not include.
2-Do not start your sentence with an abbreviation, please, like (LCA is a methodology to evaluate a product's environmental impact)
Answer and Action: In accordance with the reviewer's comment, we have made changes to the text and highlighted them in yellow on Page 2, line 75.
3-In general, the introduction is too long; please try to shorten it
Answer and Action: We agree with the reviewer's comment that the Introduction is long, as it sets the research goal and provides a literature review. Considering a broader audience in Iceland and abroad, including universities, students for educational purposes, the farming community, and policymakers. As the first study in the country, we need to set the stage for the cattle system, and we would like to include a detailed introduction.
4- Lack of a clear hypothesis in the introduction?
Answer and Action: We have made clarity improvements and added quantitative information in the introduction. In its current form, the introduction provides a clear research goal and hypothesis of conducting the first LCA of the Icelandic cattle system.
5-Some references are colored in blue; others are not. ?
Answer and Action: We have updated the referencing style and adopted the MDPI style, as requested by the Editor.
6-In my point of view, the authors did not represent any of the equations of his calculations, even though he depended on using TIAR2
Answer and Action: We have provided all the equations and their calculations in SM 1, along with an explanation and summary in SM 2. In SM1 Section 2: Table S2: Enteric methane emission estimate using IPCC (2019); Table S3: Manure methane emission estimate using IPCC (2019); Table S4: Dinitrogen monoxide emission estimate using IPCC (2019); Table S5: Ammonia emissions estimate using EMEP/ EEA 3. B manure management (2019); Table S6: Heavy metal estimate.
7-Figure 3 section beef meat, the Y-axis is not clear
Answer and Action: We have updated with higher quality figure in this submission.
8- The results section is too long. Please, needs to be more focused without any discussion in this part
Answer and Action: We agree with the reviewer that the result section is long. We are providing results for 18 environmental categories and two systems, along with uncertainty information. We have tried our best to make the results as concise as possible and would like to keep them in their current form.
9-The discussion looks fine, but the Conclusions are so long
Answer and Action: In accordance with the reviewer's comment, we have shortened the conclusion.