This study investigated that the historical levels of atmospheric ammonia (NH₃) pollution in south-eastern Europe. The results showed that The NH⁴⁺ ice core record indicates a 3.5-fold increase of annual concentrations from 34 ± 7 ng g^-1(~1750-1830) to 117 ± 23 ng g^-1 over the recent decades (1980-2009). And this pre-1750 natural level mainly related to natural soil emissions represents ~20% of the 1980-2009 NH⁴⁺ level, a level mainly related to current agricultural emissions that almost completely outweigh biogenic emissions from natural soils. I recommend the manuscript be revised before being accepted for publication.

1. Line 50, the authors mention:"up to now only two studies have compared ammonium trends extracted from Alpine ice cores to atmospheric chemistry-transport models (Engardt et al., 2017; Fagerli et al., 2007)", but what are the key findings in these previous studies? A brief introduction to previous studies can better highlight the research content.
2. Line 70, "a difference by ~25 years is observed at the end of the record". Does this difference have an impact on the comparison of results from analyzing observations and simulations?
3. Lines 73-74, "removing ∼3 mm with a pre-cleaned electric plane tool under a clean air bench.", What is the scientific basis for it, please add.
4. Line 259, "countries for which FLEXPART simulations indicate a significant contribution to the NH⁴⁺ deposition in ELB ice include Russia and several Middle East countries (Turkey, Iran, Egypt, Fig.4b)". How this "significant contribution" is judged, the graph shows that the rest of the countries are relatively high compared to Iran or Egypt.
5. Fig.6b and Fig.6d have a low correlation for the scatter fit (0.26 and 0.37), can the authors try a segmented fit, which is negatively correlated up to the first half of the x-axis as can be seen in the figure.
6. Lines 374-376, "increased modestly between 1900 and 1950". That's too vague a descriptionare. It would have been clearer if a comparison in terms of data had been given. This makes the paper more rigorous and academic. Note other similar descriptions in the manuscript.
7. Lines 400-415, "In winter, SO4^2-red observed deposition fluxes in ice deposited … would permit to better evaluate this effect". The authors explain a lot about this phenomenon, but there doesn't seem to be a clear explanation, the authors should summarize and analyze to get a clear point of explanation.
8. The manuscript is too long and not clear enough. The authors should adjust it so that the structure of the manuscript is expressed more clearly and concisely.
9. Line 23, "0.5°x0.5°" should to be multiplication sign "×", not the letter "x". Note the change!
10. Now that there are too many graphs in the manuscript, please organize some of them and place them in the supplementary Material.

The manuscript presents a thorough analysis of ammonia (NH3) emissions over several centuries using an ice core record from Mount Elbrus. It focuses on both natural and anthropogenic sources of ammonia in the atmosphere and emphasizes the critical sources from agriculture. The study is significant as it provides insights into historical emission trends and their environmental impacts, contributing valuable data to atmospheric and environmental science, especially in the context of increasing agricultural practices and climate change. The proposed methodology and results in this paper are commendable and will undoubtedly serve as a reference point for future research in the field. Here are my specific suggestions.

1. The introduction is generally clear, it might benefit from a brief overview of the significance of ammonia emissions in the context of atmospheric science and environmental policy to set a stronger foundation for the research.

1. The methodology for the comparison process in this paper, including statistical methods or software tools employed, and any adjustments made for the comparison should be clearly outlined. Ensuring that the ice core data, model input files, and emission inventories are publicly available would greatly enhance reproducibility. Providing access to these datasets through repositories or as supplementary materials is important. This can ensure that other researchers can replicate the findings reliably.

1. Although the methods are described in detail, some sections could use additional clarity, particularly for readers less familiar with specific techniques. It is recommended to supplement the text with more detailed explanations of these methodologies and any assumptions made during the analysis. Consider adding diagrams or flowcharts to visually represent the process.

1. It is suggested to expand certain sections of the discussion to provide a more in-depth analysis of the implications of the findings, particularly expanding the discussion to cover the broader implications of the findings, potential limitations, and areas for future research would be beneficial.

The authors investigate historical atmospheric ammonia (NH3) pollution using a 182 m long ice core from Mount Elbrus. The ice core data reveal a 3.5-fold increase in ammonium (NH4+) concentrations from approximately 1750 to 2009, with a significant rise post-1950 due to industrial and agricultural activities. The study utilizes FLEXPART atmospheric transport modeling to compare the ice core trends with past anthropogenic NH3 emissions, highlighting the substantial impact of human activities on atmospheric NH3 levels. The research also differentiates between natural and anthropogenic contributions to NH4+ concentrations, providing a baseline for pre-industrial natural emissions and underscoring the predominance of agricultural emissions in recent decades. The authors are leaders in this type of work; the data and methodology are all sound; and the topic and scope will be of interest to ACP readers. Overall, this article makes a significant contribution to the understanding of historical ammonia emissions in south-eastern Europe. Its robust dataset, interdisciplinary approach, and detailed methodology are commendable. I believe the paper is publishable mostly as is, but I encourage the authors to consider these points when revising:

• Model Assumptions and Limitations: The study relies heavily on the FLEXPART model, which, while robust, has limitations. The assumption that atmospheric transport has not changed significantly over the ice core record period might oversimplify complex atmospheric dynamics. Some type of sensitivity analyses to explore the impact of varying transport conditions would be helpful.
• Winter Data Uncertainties: The ice core data for winter months are less reliable due to fewer samples and potential wind erosion. This limitation weakens the study’s conclusions about seasonal variations in NH3 emissions. Additional measures or methods to improve winter data accuracy would strengthen the overall findings.
• Spatial Resolution of Emission Sources: The study identifies significant contributors to NH4+ deposition, but the spatial resolution of these sources could be improved. A finer resolution might reveal more localized sources and patterns of emissions, offering better-targeted mitigation strategies.
• Consideration of Other Pollutants: While the focus on NH3 is clear, the interplay between NH3 and other atmospheric pollutants (e.g., SO2, NO2) is mentioned but not deeply explored. A more detailed examination of how these pollutants interact and affect NH3 deposition could provide a fuller picture of atmospheric chemistry dynamics.
• Climate Change Implications: The study briefly touches on the potential impact of climate change on NH3 emissions but does not delve deeply into future projections. Integrating climate models to predict future NH3 emissions under different climate scenarios would add valuable forward-looking insights.