제 31 호 Weather on Demand? The Promise and Risks of China’s Artificial Rain
Kicker: OPINION
Weather on Demand? The Promise and Risks of China’s Artificial Rain
By Sol-Mi Lim, Editor-in-chief
Image explaining the principle of artificial rainfall
As extreme heat and prolonged drought become increasingly common, governments are searching for new ways to respond to the effects of climate change. In China, artificial rain has emerged as one possible solution. Some regions, including Chongqing, have used cloud-seeding technology in an effort to increase rainfall, lower temperatures, and ease drought conditions. By attempting to influence natural weather conditions, artificial rain appears to offer a direct technological response to environmental problems that are becoming more difficult to manage through conventional measures alone.
However, the use of artificial rain has also raised questions about the risks of intentionally interfering with weather systems. After cloud-seeding operations in Chongqing, heavy rain and strong winds were reported, causing damage and leading to public debate over whether the unusual weather conditions were connected to the operation. At the same time, local meteorological authorities explained that the strong winds were caused by natural convective weather rather than artificial rain itself. This disagreement highlights a broader issue surrounding weather modification: even when a technology may help reduce heat and drought, its effects can be difficult to predict, and responsibility becomes unclear when unexpected damage occurs. As climate change increases interest in controlling natural conditions through technology, artificial rain raises an important question about how far humans should go in attempting to manage the weather.
Cloud Seeding Is Not a Weather Machine
The term “artificial rain” can give the impression that humans are able to create rain whenever and wherever they want. In reality, cloud seeding is far more limited. The technology cannot create clouds or bring water vapor into a dry region. Instead, it attempts to increase the amount of precipitation produced by clouds that already contain suitable moisture. Materials such as silver iodide are introduced into clouds through aircraft, rockets, or ground-based systems. These particles can encourage the formation of ice crystals or larger droplets, increasing the possibility that water will eventually fall as rain or snow.
This limitation is particularly important during droughts. Cloud seeding requires the right type of clouds, sufficient moisture, and appropriate atmospheric conditions. If suitable clouds do not exist, there is little that the technology can do. In Chongqing, local meteorological officials have repeatedly explained that artificial rainfall operations can only be conducted when appropriate cloud systems and rising air currents are present. In other words, humans may be able to influence an existing weather process, but they cannot simply turn rainfall on and off.
Scientific research also shows why expectations should remain realistic. The World Meteorological Organization states that there is evidence that some forms of cloud seeding can increase precipitation under specific meteorological conditions, but results can vary significantly depending on the type of cloud and the surrounding environment. A 2024 assessment by the U.S. Government Accountability Office similarly found that studies it reviewed estimated additional precipitation ranging from zero to 20 percent. The wide range shows both the potential of the technology and the difficulty of determining exactly how much rainfall would have occurred naturally.
This distinction matters because cloud seeding is sometimes discussed as if it could become a technological answer to drought itself. It cannot. At most, it may help make better use of favorable clouds when they appear. Treating it as a guaranteed solution risks exaggerating what current science can actually achieve.
What Really Happened in Chongqing?
The controversy in Chongqing demonstrates how difficult it can be to separate the effects of cloud seeding from natural weather. In late August and early September 2024, the city experienced prolonged extreme heat, with temperatures exceeding 40 degrees Celsius in many districts. Facing high temperatures and drought, authorities conducted artificial rainfall operations when suitable weather conditions finally developed. From the afternoon of Sept. 2 to the early hours of Sept. 3, artificial rainfall operations were conducted in 17 districts and counties. Authorities reported firing 158 artillery shells and 37 rockets and burning 24 seeding flares. Rainfall ranging from 0.1 to 31.4 millimeters was recorded in operational areas. After weeks of intense heat, even temporary rainfall provided some relief.
Yet the rain was accompanied by another dramatic phenomenon. Seventy weather stations across 20 districts and counties recorded strong gusts reaching at least level eight on the Chinese wind scale. Videos of trees bending, objects being blown through streets, and even laundry flying from high-rise buildings quickly spread online. International media later described the incident as an “underwear storm,” while some residents questioned whether the attempt to create rain had unintentionally produced dangerous winds. The timing made the suspicion understandable. Cloud-seeding operations took place, rain followed, and strong winds appeared at roughly the same time. However, sequence alone does not prove causation. Chongqing meteorological officials rejected the claim that cloud seeding created the strong winds. They explained that the gusts were generated by natural thermal convection, the same atmospheric conditions that had created the clouds necessary for the rainfall operations in the first place. The World Meteorological Organization provides an important scientific perspective on this issue. According to the organization, the energy contained in weather systems is far too great for current cloud-seeding techniques to create major storm systems, control wind patterns, or eliminate severe weather. Cloud seeding can influence certain processes within an existing cloud, but this is very different from producing an entire storm.
Therefore, describing the Chongqing winds as a “cloud-seeding disaster” would go beyond the available evidence. At the same time, simply dismissing public concerns would also be a mistake. When governments deliberately intervene in weather systems, people naturally want to know what changed because of human action and what would have happened naturally. The fact that this distinction is scientifically difficult to establish is itself one of the most important limitations of weather modification.
Innovation Requires Responsibility
The Chongqing incident matters beyond one unusual day of weather because China has placed weather modification within a much larger national strategy. In 2020, the Chinese State Council announced plans to develop its weather-modification system and aimed for artificial rain and snow operations to cover more than 5.5 million square kilometers by 2025. The technology has been promoted for drought relief, agricultural protection, ecological restoration, forest-fire response, and other forms of disaster prevention. There are reasonable arguments for such investment. Climate change is increasing pressure on water resources, agriculture, and communities exposed to extreme heat. If cloud seeding can provide even modest additional rainfall during the right conditions, it could become one useful tool among many. Rejecting the technology simply because humans are “interfering with nature” would overlook its potential benefits.
However, the larger the scale of weather modification becomes, the greater the need for scientific transparency. A government should not only report that cloud seeding was conducted and rain followed. It should also explain the atmospheric conditions before the operation, how much precipitation was expected naturally, what materials were released, and how researchers evaluated the operation afterward. Without this information, successful rainfall may easily be credited to technology while unexpected weather is attributed entirely to nature. Environmental questions must also remain part of the discussion. Silver iodide is one of the most commonly used substances in cloud seeding. Current studies reviewed by the WMO and the U.S. GAO have generally not found significant health or environmental harm at the concentrations used in existing operations. However, both organizations note that questions remain about significantly expanded use and potential unintended effects. Evidence that small-scale use appears safe should therefore not become an excuse to stop monitoring what happens when operations become larger and more frequent.
There is also a question of responsibility. Weather does not follow administrative borders. If an intervention intended to benefit one area is suspected of affecting another, governments need credible scientific systems capable of evaluating such claims. Even when an alleged connection is ultimately rejected, transparent data and independent research are necessary to maintain public trust. Technology becomes most dangerous not when it is imperfect, but when confidence in it grows faster than the evidence supporting it.
Artificial rain should neither be celebrated as a technological victory over climate change nor rejected as an unnatural experiment. It is better understood as a limited tool that may increase precipitation when nature has already provided favorable conditions. Chongqing demonstrates both sides of that reality. Cloud seeding was followed by rainfall that temporarily eased extreme heat, but the strong winds occurring at the same time also generated fear and confusion over how much influence humans actually had on the weather. The lesson should not be that cloud seeding must stop. Instead, it should be that weather modification requires more caution precisely because its effects are difficult to separate from natural atmospheric processes. Governments using the technology should provide transparent operational data, continue independent scientific evaluation, monitor environmental effects, and establish clear standards for investigating unexpected events.
Most importantly, cloud seeding must not become a substitute for addressing the causes and broader consequences of climate change. A rocket carrying silver iodide may help extract a little more rain from the right cloud, but it cannot create water in a cloudless sky, reverse rising global temperatures, or eliminate drought on its own. The more climate change pushes societies toward technological intervention, the more important it becomes to recognize the difference between influencing nature and controlling it.
Sources:
https://wmo.int/content/wmo-statement-weather-modification
https://www.gao.gov/products/gao-25-107328
https://www.kma.go.kr/down/t_policy/t_policy_202412.pdf
