How Compatible Are Western European Dietary Patterns to Climate Targets? Accounting for Uncertainty of Life Cycle Assessments by Applying a Probabilistic Approach

Round 1

Reviewer 1 Report

The article shows an interesting study about diet and climate targets. However, the article could be shortened in some paragraphs and include some discusión about the pros/contras of different data sources as source of uncertain.

Author Response

Response Reviewer #1

We are very pleased to have the opportunity to resubmit the manuscript “How compatible are western European dietary patterns to climate targets? – Accounting for uncertainty of life cycle assessments by applying a probabilistic approach” after major revisions. We are grateful to the three reviewers for their feedback and suggestions.

The revised manuscript contains several revisions following the suggestions of the reviewers. We feel that the manuscript has improved after these changes. Our detailed responses to your statements are bulleted and italicized below for each of the individual points raised.

In addition to the comments to your remarks below, you also find the response letter to all reviewers attached.

Reviewer #1

The article shows an interesting study about diet and climate targets. However, the article could be shortened in some paragraphs and include some discusión about the pros/contras of different data sources as source of uncertain.

• We have refined the limitations section (ll.544, Table 2) to consider the impact of using different data sources on uncertainty and variability. Also, we added expert judgements (Table 2) as another potential improvement to this limitation. As applied in decision analysis approaches [1-4], expert judgement can both refine and narrow down existing data ranges, but also serve as a method to estimate value ranges from the ground up.
• We have shortened the manuscript by making some sections (ll. 104, 127-128, 136, 139, 156-158, 228-231, 254, 262, 348-350, 359-362, 425, 467-471, 475-476, 492-498, 529-533, 550-552, 618-622) more concise. Since we have added some further elaborations and restructured some paragraphs based on the proposed revisions of other reviewers, the total extent of the manuscript may be similar to our initial version.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study calculates probabilistic distributions for western European dietary pattern CFs by using ranges of animal-based food GHGEs in the modelling process. The results show that all dietary pattern carbon footprints overshoot the 1.5 degrees thresholds. Moreover, the vegan, vegetarian and the diet with low animal-based food intake were predominantly below the 2 degrees thresholds. I appreciate a lot the efforts of the authors. However, some problems should be addressed below:

 

1. As the industrial CFs reduce (i.e., using green energy, improving technology, etc.) in the future, will the food CFs also reduce? IF YES, how does this abatement affect the results?

 

2. Although consider the uncertainty is closer to reality, what is the brand-new finding of this study?

 

3. The contribution of this study should be summarized in the introduction.

 

4. The managerial applications of this study should be further discussed.

 

Author Response

Response Reviewer #2

We are very pleased to have the opportunity to resubmit the manuscript “How compatible are western European dietary patterns to climate targets? – Accounting for uncertainty of life cycle assessments by applying a probabilistic approach” after major revisions. We are grateful to the three reviewers for their feedback and suggestions.

The revised manuscript contains several revisions following the suggestions of the reviewers. We feel that the manuscript has improved after these changes. Our detailed responses to your statements are bulleted and italicized below for each of the individual points raised.

In addition to the comments to your remarks below, you also find the response letter to all reviewers attached.

Reviewer #2

This study calculates probabilistic distributions for western European dietary pattern CFs by using ranges of animal-based food GHGEs in the modelling process. The results show that all dietary pattern carbon footprints overshoot the 1.5 degrees thresholds. Moreover, the vegan, vegetarian and the diet with low animal-based food intake were predominantly below the 2 degrees thresholds. I appreciate a lot the efforts of the authors. However, some problems should be addressed below:

 

1. As the industrial CFs reduce (i.e., using green energy, improving technology, etc.) in the future, will the food CFs also reduce? IF YES, how does this abatement affect the results?

• We have added a section that discusses the impact of different greenhouse gas mitigation methods on the dietary pattern carbon footprints (ll. 501-513). Next to dietary changes, reducing food waste and adapting agronomical practices are expected to have a large impact on food-related greenhouse gas emissions [5]. Measures to reduce emissions in industry, like receiving energy from renewable sources and improved efficiency in electricity and (fossil) fuel consumption mainly reduce carbon dioxide emissions. In agricultural production, however, the majority of emissions arise from other gases than carbon dioxide [6]. Therefore, greenhouse gas emission abatement in industry is expected to only have minor effects on the dietary pattern carbon footprints examined in our study. 
• We regarded greenhouse gas emissions from cradle-to-farmgate. If the system boundaries were extended beyond the farmgate (e.g., taking transport, retail, cooking into account), emission reductions from carbon dioxide intensive processes, as we find them in the industry sector, would have a slightly larger impact. However, mitigation measures in post-farmgate life cycle stages only have a limited impact on food carbon footprints since approximately 80% of most food products’ greenhouse gas emissions arise at the farm stage and from land use change [7]. We revised a section (ll. 226-231) of our method chapter to further substantiate our system boundary choice and added the option of extending the system boundaries to reduce this limitation (Table 2).

 

2. Although consider the uncertainty is closer to reality, what is the brand-new finding of this study?

• We restructured and edited the first paragraph of discussion chapter 5.2 (ll. 429-443) as well as revised parts of the conclusion (ll. 563-600) to better highlight the novel findings of our study.

 

3. The contribution of this study should be summarized in the introduction.

• We have refined the sections on the research gaps our study addresses and further elaborated on the contribution of this study to research, both regarding the evaluation against climate targets (ll. 77-89) as well as the calculation of diet carbon footprints under consideration of uncertainty (ll. 156-158).

 

4. The managerial applications of this study should be further discussed.

• We have added and more clearly emphasized the managerial applications in various sections of the manuscript: In the discussion (ll. 500-515), we made it more clear that our results show that action needs to be taken on both the consumption side (dietary changes, reducing food waste) and the production side (e.g., increasing yields and agricultural efficiency by technological improvements). Diversified applications can accomplish the climate targets in the food sector, as also stated in the conclusion. There we also included some specifics of production-side measures (ll. 602-615). Since the consumption side is the focus of our work, we have edited and added specific applications in the conclusion section (ll. 569-600) that can drive the realization of GHG abatement on the consumption side. Here we address dietary guidelines, education, as well as information and also touch on the nutritional environment. We also have restructured this paragraph to clarify our line of argumentation.
• We also added a sentence highlighting the importance of assessing to what extent applied mitigation measures can abate GHGEs in future research (ll. 513-515).

 

Author Response File: Author Response.pdf

Reviewer 3 Report

1. Good representative of survey studies on food security issues. 

2. I have no issue with endorsing this article to be published as it would be a good indication of the current food security issues with regard to climate change.

3. Is there any possibility of having any 4.0IR element in the studies? Recommendation? How to tackle the issue via this element. You have listed the recommendation in the conclusion section perhaps any viable connection could be added to the discussion? 

4. The data might not be quite extensive as it was only referring to the dietary element. Does the CO2 emission dataset of the varied eating groups represent a complete loop from farm to fork cycle (Table A1)? The emission might not be the overall combos which could include the food waste emission generated from the same studied consumer group. 

Author Response

Response Reviewer #3

We are very pleased to have the opportunity to resubmit the manuscript “How compatible are western European dietary patterns to climate targets? – Accounting for uncertainty of life cycle assessments by applying a probabilistic approach” after major revisions. We are grateful to the three reviewers for their feedback and suggestions.

The revised manuscript contains several revisions following the suggestions of the reviewers. We feel that the manuscript has improved after these changes. Our detailed responses to your statements are bulleted and italicized below for each of the individual points raised.

In addition to the comments to your remarks below, you also find the response letter to all reviewers attached.

Reviewer #3

1. Good representative of survey studies on food security issues.

• Thank you very much for your feedback. We very much appreciate it.

2. I have no issue with endorsing this article to be published as it would be a good indication of the current food security issues with regard to climate change.

• Thank you very much for recommending our article for publication.

 

3. Is there any possibility of having any 4.0IR element in the studies? Recommendation? How to tackle the issue via this element. You have listed the recommendation in the conclusion section perhaps any viable connection could be added to the discussion?

• We have added a section in the discussion (ll. 500-515) that addresses the industrial mitigation options and opportunities in more detail. Reducing food waste and adapting agronomical practices are expected to have a large impact on food-related greenhouse gas emissions [5]. Measures to reduce emissions in industry, like receiving energy from renewable sources and improved efficiency in electricity and (fossil) fuel consumption mainly reduce carbon dioxide emissions. In agricultural production, however, the majority of emissions arise from other gases than carbon dioxide [6]. Therefore, greenhouse gas emission abatement in industry is expected to only have minor effects on the dietary pattern carbon footprints examined in our study.
• We have touched on specific technological options in this newly added section, but discussing all possible measures in detail goes beyond the scope of our study since we have not generated our own data to discuss further on this matter. The focus of our work centers on mitigation options derived from consumption patterns. Therefore, those are covered in more detail in the conclusion.

 

4. The data might not be quite extensive as it was only referring to the dietary element. Does the CO2 emission dataset of the varied eating groups represent a complete loop from farm to fork cycle (Table A1)? The emission might not be the overall combos which could include the food waste emission generated from the same studied consumer group.

• We have edited the description of Table A1 (ll. 649-651) to clarify the life cycle stages for which the emissions were calculated for (cradle-to-farmgate). We acknowledge that our data does not cover emissions after the farmgate (e.g., transport, retail, cooking). Data availability for food product LCAs beyond the farmgate is very limited, as pointed out in our method chapter. We also chose cradle-to-farmgate data as it was crucial for our analysis. It ensured that the dietary pattern emissions and the 1.5- and 2-degree emission budgets available for the food system cover the same scope. If we had accounted for post-farmgate emissions in the dietary pattern carbon footprints, a meaningful benchmarking had not been possible due to divergent system boundaries.
• We acknowledge that it is crucial to consider greenhouse gas emissions generated from food waste. Post-supply food waste emissions are included in our study since we used food balance sheets of the “Food and Agriculture Organization of the United Nations” as a basis for the dietary patterns’ food category quantities. The food balance sheets provide the food supply to a region (and not only data on the food consumed). We have added a footnote in the method section to further elaborate on the details of food balance sheets in order to clarify the matter (ll. 192-194). Only consumption amounts for plant-based beverages derived from a survey due to lack of data (see Table 2 for the discussion of this limitation).
• Also, we have revised and further illustrated the section explaining our approach to determine the dietary patterns’ food category quantities based on the food balance sheets (ll. 654, 668-674).

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been sufficiently improved and can be published.

 

Author Response

Thank you very much for recommending our article for publication.