Experts say uncertain rainfall yields and technological costs could hinder the large-scale expansion of weather modification programs

Will it be clear skies or gray skies today? If a new program announced last November comes into place, the question may be more of a choice on the part of the government.

Already in place in thousands of counties across China are airplanes equipped with rocket-launchers and stockpiles of chemicals dedicated to inducing rainfall. Cloud-seeding programs have been in use in China for decades, but in May, the head of the China Meteorological Administration (CMA) provided details on the new weather modification program, adding that the country would seek to increase precipitation by 3 to 5 percent in the next five years through cloud-seeding.

In March, Zheng said the potential of average artificial rainfall could reach up to 280 billion tons per year, which is equal to seven times of the storage capacity of the Three Gorges Dam.

Guo Xueliang, director of the artificial weather intervention center under the CMA, said total atmospheric water in China is typically 30 trillion tons per year while annual rainfall is about 6 trillion tons. “At least one more percent of cloud water could be transferred to rainfall every year, roughly 280 billion tons.”

According to Xinhua News, the Ministry of Finance has allocated 160 million yuan so far this year to subsidize local government weather modification projects.

Thunder from Below

China started its cloud-seeding program in 1958 based on rain formation theory by the Swedish scientist Tor Bergeron. That summer, Jilin Province received its first artificial rainfall from a government cloud-seeding project.

Across the country, 2,235 counties have already conducted cloud-seeding projects among 2,900 counties in total. In the past decade alone, roughly 490 billion tons of water were released as a result of cloud-seeding projects.

Globally, around 30 countries have developed cloud-seeding programs, but few remain in use given high costs and fears that such activities could pose a risk to the environment. China’s cloud-seeding projects already outnumber the others worldwide.

Chinese officials say artificial rainfall projects are a direct response to the country’s current climate conditions. “China ranks first in terms of precipitation projects because our country has a desperate water shortage,” said Wang Guanghe, the deputy director of the artificial weather intervention center under the CMA. “Other countries like the United States and France have more water resources, so accordingly, the scale of their artificial rainfall projects are not as large as ours.”

Rainy Day Funds

Since the creation of the artificial weather intervention system under the CMA in 2007, the uncoordinated use of cloud-seeding technology and public funds dedicated to the program has stirred heated debate.

“In theory, the whole amount of cloud water resources is constant. If one place conducts a precipitation project, cloud-seeding projects in other places will be affected,” said Chen Guangting, a researcher at the Chinese Academy of Sciences.

Environmentalists argue that with the greater use of cloud-seeding projects in southeast coastal areas, western inland areas will become even more arid.

Artificial rainfall probably affects the total distribution of rainfall, “but the effect is insignificant,” Zheng said at a conference in June.

Under such circumstances, Guo said local governments may not have a large impact if rainmaking programs are stopped on an individual basis. But if provinces coordinate cloud-seeding programs, a larger amount of rainfall may be brought about.

Since May, some provinces have proposed regional programs modeled after one already in place in northeastern China.

Whims of the Gods

Despite the bright optimism on cloud-seeding programs from official statements, some scientists remain highly skeptical of the actual rainfall yield such activities directly produce. A meteorologist who refused to be named said: “The present technology is incapable of ensuring how much artificial rainfall will be produced. In addition to this, it could be a huge waste of resources if rainfall can’t be consistently maintained.”

In a similar appraisal on the reliability of cloud-seeding technologies, Professor Mao Jietai at Peking University’s Department of Atmospheric Science said: “Human beings need to acknowledge their reliance on nature.”

A source that has worked in China’s meteorology programs since the 1980s said the country’s cloud-seeding programs have met two major obstacles: the expansion of programs to include large-scale rainfall and, high costs. Research on the effects of cloud-seeding on overall weather patterns has been limited.

While many countries are still conducting research on cloud-seeding technology, they have yet to match the scale of China’s programs, said Lu Chen, a senior engineer at the Beijing Meteorological Bureau.

“Studies on artificial rainfall are very important, but the use of cloud-seeding technology on a large-scale remains open to question,” said Lu.

By staff reporter Liu Hongqiao