Review Reports - Weather Modification and Local Climate Management in the United States: A Review of Its Technological Evolution, Operations, Governance, and Local Implementation Challenges

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article examines the characteristics and challenges of climate change, which is innovative in its own way. At the same time, to make the article better, the following issues should be considered and corrected in the article:

1- Apparently, the authors have economic and commercial expertise. It is better to use a climatologist in the article in order to review the content in terms of climatology knowledge and at the same time make the necessary corrections.

2- The article has mostly emphasized cloud seeding as a method of climate modification or change, while there are currently numerous methods that need to be mentioned.

3- The evaluation of different methods of climate modification should be done from different perspectives such as infrastructural, social, environmental, etc. dimensions. This article only focuses on the economic aspect, which needs to be mentioned in other cases. However, the consequences of each of the different dimensions mentioned can also have economic consequences.

4- The advantages of the methods should be examined with and without the use of modification methods, and their comparison should be explained through special tables.

5- Currently, there are methods of weather modification through methods such as cloud ionization, and it is possible that these methods can be used to reduce precipitation in other countries as political tools alongside economic and military tools, which should be mentioned in the article.

Author Response

Response 1: Thank you for the suggestion. We agree that the current review paper focuses on the social, economic, and policy aspects of weather modification programs. As discussed in future research (the last paragraph of Section 8 – Concluding Remarks), a potential future research is to conduct an in-depth case study of a well-defined watershed or climatic/agricultural region. Such a case study will provide an opportunity for a close collaboration among climatologists, hydrologists, environmental scientists, and social scientists like economists. As for the climatology knowledge and terminologies used in this review, we strictly follow the convention in the literature to ensure they are widely understandable and acceptable.

2- The article has mostly emphasized cloud seeding as a method of climate modification or change, while there are currently numerous methods that need to be mentioned.

Response 2: Thank you for the comment. Yes, we agree that the review focuses on the cloud seeding method. The introduction section also mentions (clarifies) that cloud seeding is often used interchangeably with weather modification in the US context. We would like to note that cloud seeding is the dominant method in the US, likely due to state-level rules and regulations (now discussed in Section 5 – Program Governance). We also realize there are likely less regulated weather modification approaches practiced in other countries or regions, which is why we point out an in-depth comparison of international program experiences as a potential future research direction. It can certainly become a different paper with an international collaborative team.

When it is appropriate, the paper does introduce other weather modification technologies, such as using ultra-short laser pulses for weather control (Section 4 – Project Benefits, paragraph 2):

“In recent years, researchers have continued studying effective fog dissipation. For example, Rohwetter et al. and Wolf have focused on the use of ultra-short laser pulses for weather control, with applications to fog dissipation [40-41].”

Response 3: Thank you for the comment and suggestion. Admittedly, our manuscript is not a technical paper of weather modification technologies. The paper also does not focus on geoengineering, despite that there is an indirect connection between weather modification and geoengineering as mentioned in the introduction section. This review is designed to focus on the aspects related to costs, benefits, program governance, and local concerns, which cover beyond the economic aspect. However, following several very constructive reviewer suggestions (see responses below), we have substantiated Section 2 - Concepts, History, and Technological Evolution and Section 7 - Environmental and Health Concerns with more technical details to ensure the wholeness and clarity of the discussion, including more discussion of recent technical literatures.

4- The advantages of the methods should be examined with and without the use of modification methods, and their comparison should be explained through special tables.

Response 4: Thank you for the suggestion. The expanded Section 2 now compares different seeding methods. Table 1 compares manned aircraft-based and UAS-based methods. The following paragraph (the last paragraph of Section 2) discusses the ground-based cloud seeding method. Note that cloud seeding is the dominant method in the US, likely due to state-level rules and regulations (now discussed in Section 5 – Program Governance). We do realize there are likely less regulated weather modification methods practiced in other countries or regions, which is why we point out an in-depth comparison of international program experiences as a potential future research direction.

Response 5: Thank you for the suggestion. The revised manuscript incorporates this in the future research directions, to which the last paragraph of Section 8 – Concluding Remarks has been dedicated. Additionally, given that this review focuses on the US there is not enough space to conduct an in-depth comparison with international program experiences, which is why it is more suitable for it to be a separate study and paper for future research.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a comprehensive critical review of weather modification programs in the United States, covering technological evolution, cost–benefit analyses, governance structures, and implementation challenges. It offers a systematic perspective on weather modification as a local climate-management strategy and demonstrates a degree of originality and research value. Principal comments are as follows:

1.The authors should more strongly emphasize the study’s novel contributions and explicitly highlight how it differs from existing literature, underscoring its unique value in integrating multi-dimensional aspects of weather modification.

2.Incorporating empirical case studies is recommended. Select representative weather modification projects and conduct in-depth field investigations and data analyses of their cost-effectiveness, governance performance, and environmental impacts to strengthen the paper’s scientific rigor and credibility.

3.The conclusion regarding the ecological toxicity of silver iodide remains at the qualitative level of “low concentration is safe.” Environmental thresholds (e.g., EPA acute/chronic aquatic criteria), actual monitoring data, and dose–response relationships are not provided.

4.The paper proposes principles such as “stakeholder participation” and “risk communication,” but it does not assess the real-world institutional capacity of any state or watershed.

5.Policy recommendations should be further refined by specifying implementation steps, responsible actors, oversight mechanisms, etc., to make them more actionable and instructive.

6.The limitations of the study are mentioned briefly at the end, and the discussion of future research directions is neither deep nor specific.

Author Response

Response 1: Thanks for the comment. The contribution of this review is to synthesize the existing literature and identify directions of new research, which is understandably different from a regular research paper with a focused study. Following the suggestion, the last paragraph of the introduction section and the first three paragraphs of Section 8 – Concluding Remarks have been re-written to highlight the contribution of this review.

Response 2: Thanks for the suggestion. The revised manuscript does include a few local weather modification programs as brief case studies embedded to support the discussion, such as the Santa Ana River Watershed Cloud Seeding Pilot Program in California. However, this paper is designed to be an overall review of weather modification programs and local climate management strategies in the US, not necessarily an in-depth case study itself. An in-depth case study could be a future research paper, for example, with a focus on the weather modification program operated in Eastern New Mexico as a homogeneous region. A new paragraph is added to Section 8 – Concluding Remarks to specifically discuss all future research directions inspired from the review.

Response 3: Thanks for the comment. This is a very good point. Please see our response to Reviewer #3 (comment #4), where discussions related acceptable threshold values and concentration level data from selected recent field assessments have been incorporated. As a result, Section 7 - Environmental and Health Concerns has been substantially expanded.

4.The paper proposes principles such as “stakeholder participation” and “risk communication,” but it does not assess the real-world institutional capacity of any state or watershed.

Response 4: Thank you for the comment. As mentioned above (response to comment #2), this is a review focusing on all states. Given that most of the western states in the US have some kind of weather modification programs and there are a lot of heterogeneities in geography and policy across different states, assessing institutional capacity would need to focus on a particular state or a region (e.g., the Southern High Plains region between NM and TX). It can be a future case study research with a survey or expert interview methodology, especially given the fact that most of the weather modification programs in the US are locally organized, not state-run programs. In this particular review, discussions related stakeholder participation and risk communication are important because they are essential components of program governance and local implementation.

5.Policy recommendations should be further refined by specifying implementation steps, responsible actors, oversight mechanisms, etc., to make them more actionable and instructive.

Response 5: Thank you for the suggestion. As mentioned above (response to comment #4), despite that many states provide financial support for weather modification programs, states usually do not run these programs. They are mostly locally organized and managed with state support. However, we agree that responsibility and program oversights are important aspects of program governance. The revised Section 5 – Program Governance has clarified on these aspects and pointed out challenges related to responsibility and program oversights. For example, in the last paragraph of Section 5, we discuss weather modification program oversight at three different levels: federal, state, and local. The importance of program oversight is now also highlighted in the article abstract.

6.The limitations of the study are mentioned briefly at the end, and the discussion of future research directions is neither deep nor specific.

Response 6: Thank you for the suggestion. Directions of future research have been discussed throughout the paper. The revised Section 8 - Concluding Remarks now highlights all the key future research directions in the last paragraph, including to

integrate ground-based approach and UAS-based approach in the future to improve seeding effectiveness and manage operation costs and environmental impacts;
compare US program experience and international program experiences;
develop in-depth case studies that focus on a particular region or watershed; and this is where interdisciplinary collaboration involving expertise in climatology, hydrology, environmental sciences, and system engineering can fructify;
provide more scientific evidence on the environmental impacts of could seeding materials, especially regarding silver ion accumulation and alternative seeding materials.

Reviewer 3 Report

Comments and Suggestions for Authors

This study provides an overview of weather modification and local climate management in the United States, summarizing its historical evolution and future challenges. The article features a clear structure and comprehensive data, offering valuable reference for managers and researchers in related fields. However, there is room for improvement in future development directions and critical analysis. Below are some revision suggestions:
1. The article focuses exclusively on the United States and emphasizes aerial seeding methods. It is recommended to supplement Section 2 on technological evolution with common methods used in other countries, such as China's frequent use of fixed-position cannons or rockets for dispersing catalysts.
2. In the section on challenges and issues, the author overlooks the significant reduction in high-moisture clouds caused by artificial precipitation operations, which may lead to droughts in other regions. This issue should be addressed.
3. The article relies heavily on textual descriptions with limited quantitative data analysis. It is recommended to incorporate additional metrics such as the cost per precipitation operation or the concentration of silver iodide in rainfall following such operations.
4. While the discussion on environmental risks of silver iodide is important, it remains insufficient. It is advised to include the threshold concentrations at which such substances may pose ecological risks or relevant studies on the severe consequences of contamination from these materials.

Author Response

The article focuses exclusively on the United States and emphasizes aerial seeding methods. It is recommended to supplement Section 2 on technological evolution with common methods used in other countries, such as China's frequent use of fixed-position cannons or rockets for dispersing catalysts.

Response 1: Thanks for the suggestion. Another paragraph has been added toward the end of Section 2 - Concepts, History, and Technological Evolution to summarize new developments in ground-based cloud seeding technologies. The discussion is also complemented by briefly discussing a highly relevant case study in the US - Cloud Seeding Pilot Program in the Santa Ana River Watershed in California.

“Despite the fact that ground-based cloud seeding method is not popular among key applications (e.g., agriculture and hail suppression) in the US, it is commonly used for snowpack enhancement in wintertime and it has also experienced some technological advancements. In particular, remote sensing and data analytics have been deployed to improve operational monitoring and seeding precision (e.g., see [21]). Because of the growing role of data analytics in weather modification operations across technology, it is highly possible to integrate ground-based approach and UAS-based approach in the future to improve seeding effectiveness and manage operation costs and environmental impacts. In practice, advanced ground-based cloud seeding methods have been developed in the US West. The Santa Ana River Watershed Cloud Seeding Pilot Program in California is a recent example of this (https://sawpa.gov/santa-ana-river-watershed-cloud-seeding/, accessed January 10, 2026). With a project goal to increase snowpack and water supply for the entire watershed, it combines remotely controlled seeding equipment with manually operated generators to improve seeding effectiveness and optimize operation costs.”

In the section on challenges and issues, the author overlooks the significant reduction in high-moisture clouds caused by artificial precipitation operations, which may lead to droughts in other regions. This issue should be addressed.

Response 2: Thanks for raising this critical point. A new set of literature discussion has been added to Section 6 – Local Implementation (the new paragraph toward the end).

“Another precipitation outcome-related local implementation challenge is the public perception of downwind effects. The early literature suggested that cloud seeding operations can be associated with a significant loss of rain (e.g., 40-45%) in the downwind direction ranging from 100 km to 290 km [65-66]. However, more recent studies showed that the extra-area (downwind) effects are mixed. For instance, both field assessments and simulation modeling suggest that the downwind areas are more likely to receive augmented precipitation, which contradicts the conventional idea of cloud seeding causing potential droughts in neighboring regions (e.g., see [67-68]). Both the previous and new research reinforces the need for regional collaboration (e.g., basin-wide) in weather modification programs and operations. It allows for effective internalization of cost and benefit-related externalities, enabling equitable mechanisms for sharing program costs and benefits.”

The downwind effect issue is also addressed to some extent in Section 5 – Program Governance, paragraph 3.

The article relies heavily on textual descriptions with limited quantitative data analysis. It is recommended to incorporate additional metrics such as the cost per precipitation operation or the concentration of silver iodide in rainfall following such operations.

Response 3: Thanks for the suggestion. Given that this is a review paper it is not designed to conduct a focused quantitative data analysis. However, the revision does incorporate new information on metrics and estimates as suggested in this comment and the next comment (on safe threshold limit values of silver ions). For example, the follow discussion is added to the second paragraph of Section 3 – Operation Costs:

“Additionally, recent assessments of cloud seeding projects in the US suggest that regional cloud seeding programs are cost-effective, with estimated benefit-cost ratios of at least 5:1 (e.g., see [25-26]).”

While the discussion on environmental risks of silver iodide is important, it remains insufficient. It is advised to include the threshold concentrations at which such substances may pose ecological risks or relevant studies on the severe consequences of contamination from these materials.

Response 4: Thanks for the suggestion. The threshold concentration for environmental risks has been incorporated into the first paragraph of Section 7 on environmental and health concerns. We also pointed out the spatial heterogeneity of such threshold values across different environments. For example,

“In terms of a safe level of concentration of silver ion in the water, the classic literature suggests a maximum concentration of 50 μg/L of silver in drinking water in the US [71]. Recent studies suggest a more conservative toxicity threshold of around 1 μg/L [73]. Rainfall silver ion concentrations after cloud seeding operations are significantly lower than these limits. Additionally, there expect to be spatial heterogeneities in setting such threshold limit values (TLV) because of variations in the environmental conditions. For instance, certain plants (e.g., higher plants and fungi) may be more vulnerable to silver accumulation [73].”

Reviewer 4 Report

Comments and Suggestions for Authors

The article proposed for review is an overview, without claims of scientific significance. This review article presents concisely and briefly various aspects related to Weather modification and local climate management in the United States over the past century. Attention is paid to both the technological side of the weather modification methods used in the USA, as well as to various aspects such as economic costs and benefits, problems with regulations and restrictions of this research, and the impact on nature and humans. For me, it is very interesting and informative, but I think more research could have been included in the field of weather modification, especially considering that the US is a pioneer in this field and their experience dates back nearly a century.

It is striking that publications from the last 10-15 years are mainly cited, while those from previous decades are poorly represented. I am aware of the requirement to mainly cite new research, but this is a review concerning weather modification activities in the United States over a very long period. I consider it appropriate to draw attention to research on this topic in the United States, published from the 1970s to the beginning of the present century. They could enrich this review, because the research of authors such as S. A. Changnon - father and son, etc. are well known around the world among scientists interested in the issue of weather modification.

The last section, entitled „Environmental and Health Concerns“, is too short and contains few examples of the benefits and harms of weather modification. Is this due to the lack of research on the subject or is it simply not well researched? With so many new restrictions and suspensions of scientific programs related to weather modification in the US, I rather expect there to be more publications on this topic and if there are, I recommend that they be briefly described in order to complete the review.

I have no significant remarks on the text and I would recommend that it be published in Climate even in this form.

Author Response

Response 1: Thank you for the overall suggestion. The revision has improved in two aspects to address your concerns: (1) newer studies from the past two decades have been incorporated into the discussion; (2) more US-based field assessments and studies have been included to accompany the discussion of policy and regulatory issues faced by weather modification programs and practitioners in the US. As for the US technology leadership in this area, the enhanced Section 2 - Concepts, History, and Technological Evolution does highlight it.

Response 2: Thank you for the comment. We humbly accept the suggestion. More studies throughout the past half century have been cited in the review. The total number of unique references has gone from 65 to 82. For example, for the Environmental and Health Concerns section discussed in the next comment, seven new studies from post 2000 have been organically incorporated in the discussion:

Azeez, H. M., Ibraheem, N. T., & Hussain, H. H. (2024). Alternate Chemical Compounds as a Condensation Nucleus in Cloud Seeding. Nature Environment and Pollution Technology, 23(3), 1795-1799.

Caro, D., Wobrock, W., & Flossmann, A. I. (2002). A numerical study on the impact of hygroscopic seeding on the development of cloud particle spectra. Journal of Applied Meteorology, 41(3), 333-350.

Fisher, J. M., (2017). Trace Chemical Evaluation of Cloud Seeding in the Payette Basin. Boise State University Theses and Dissertations, 1294.

Jung, E., & Hyun, K. (2026). Impact of Artificial Precipitation on Stream Water Quality During Snowmelt Season. KSCE Journal of Civil Engineering, 100532.

Koo, H. J., Chang, K. H., Chae, S., Cha, J. W., Hwang, H., Kim, M. H., ... & Rosenfeld, D. (2025). A Suggestion of Verification Method for Cloud Seeding Experimental Results via Analyses of Chemical Components of Precipitation. Journal of Applied Meteorology and Climatology, 64(5), 497-512.

Rosenfeld, D., Axisa, D., Woodley, W. L., & Lahav, R. (2010). A quest for effective hygroscopic cloud seeding. Journal of Applied Meteorology and Climatology, 49(7), 1548-1562.

Williams, B. D., & Denhom, J. A. (2009). An assessment of the environmental toxicity of silver iodide-with reference to a cloud seeding trial in the snowy mountains of Australia. The Journal of Weather Modification, 41(1), 75-96.

Specific to Changnon, two classic studies have been referenced:

Changnon, S. A., & Lambright, W. H. (1987). The rise and fall of federal weather modification policy. The Journal of Weather Modification, 19(1), 1-12.

Huff, F. A., & Changnon Jr, S. A. (1972). Evaluation of potential effects of weather modification on agriculture in Illinois. Journal of Applied Meteorology and Climatology, 11(2), 376-384.

Response 3: Thanks for the comment and suggestions. We have done an additional round of literature review related environmental and health concerns to enhance the section. A new paragraph (paragraph 2) is added to the section to focus on representative studies done in and outside the US in the past 20 years, including field assessments of impacts and developing alternative solutions for managing the impacts. The revised section also points out that with all the new policy developments related to weather modification in the US, the research communities still need to catch up with understanding the implications of these changes.

I have no significant remarks on the text and I would recommend that it be published in Climate even in this form.

Response 4: Thanks. The manuscript text has been significantly improved after incorporating all the comments and suggestions from all four sets of reviews, including yours.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

In my opinion, all necessary revisions have been made and the required explanations have been provided, and the article is acceptable from my point of view.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been improved, and therefore the manuscript is acceptable.