Originally published in The Hindu on June 14, 2007

AFTER WEEKS of watching the mercury soar, hardening the already cracked earth of their wilting orchards and farms, several farmers gather in the Fragrant Hills that line the western fringe of Beijing. Unlike their ancestors they do not assemble to perform a rain dance or to pray to the Buddha for rain.

Instead, they grab rocket launchers and 37mm anti-aircraft guns and begin shooting into the sky. What they launch are not bullets or missiles but pellets of chemicals. Their targets are wisps of passing cloud they aim to "seed" with silver iodide particles around which moisture can then collect and become heavy enough to fall.

The farmers are part of the biggest rainmaking force in the world: China's weather modification programme.

According to Wang Guanghe, the director of the Weather Modification Department under the Chinese Academy of Meteorological Sciences, all of China's more than 30 provinces and municipalities today boast a weather modification base, employing more than 32,000 people, 7,100 anti-aircraft guns, 4,991 special rocket launchers, and 30-odd aircraft.

"Ours is the largest artificial weather programme in the world in terms of equipment, size and budget," he says, revealing that the annual nationwide budget for weather-modification is between $60 million and $90 million.

Challenging projects

It is no coincidence that the world's biggest such project is in China. The country's leadership has never been chary of harnessing nature, taking on a slew of what were once thought impossible engineering challenges like the Three Gorges dam, the world's biggest hydroelectric project, and the Qinghai-Tibet railway, the world's longest highland railway.

For a largely agrarian country, the weather was thought to be far too important to be left to the caprice of god or nature. As a result, Chinese scientists began researching man-made rain as far back as 1958, using chemicals such as silver iodide or dry ice to facilitate condensation in moisture-laden clouds.

In the beginning, the idea was to ease drought and improve harvests for Chinese farmers but over the decades other functions have evolved such as firefighting, prevention of damaging hailstorms, and replenishment of river heads and reservoirs. Artificial rain has also been used by some provinces to combat desertification and sand storms. In 2004 Shanghai decided to induce rain simply to lower the temperature during a prolonged heat wave.

And now China's weather officials have been charged with another important task: ensuring clear skies for the Olympic Games in 2008.

Zhang Qiang, the top weather modification bureaucrat in Beijing, says her office has been conducting experiments in cloud-busting for the last two years, in preparation for August 8, 2008, the day the opening ceremony of the Games is scheduled.

She says that according to meteorological data from the past there is a 50 per cent chance of a drizzle on that day. To ensure clear skies, the Beijing Weather Modification Office is busy researching the effects of various chemical activators on different sizes of cloud formations at different altitudes. The aim is to catch pregnant clouds early on and induce rainfall ahead of the big day so that during the opening ceremony itself the sky is cloud-free.

Professor Wang adds that similar efforts in the past have already helped to create good weather for a number of international events held in China, including the 1999 World Expo in Yunnan and the 1993 East Asian Games in Shanghai.

Ms. Zhang, however, warns that her cloud-fighters will only be effective in the event of the threat of a drizzle. "A heavy downpour will be impossible to combat," she says.

Her caveat goes to the heart of the primary criticism levelled against weather modification efforts worldwide: doubt about their efficacy. Professor Wang admits that it remains notoriously difficult to establish how much real impact cloud-seeding has, since there is no fool-proof way to establish how much rain might have fallen without intervention.

The United States, which pioneered cloud-seeding techniques in the 1940s and 1950s, has long cooled in its enthusiasm for the science behind artificial rain. Israel and Russia, however, continue to have substantial weather modification programmes and Professor Wang says experiments conducted in these countries reveal cloud-seeding increases rainfall by 6 to 20 per cent.

Ms. Zhang adds that reservoirs in Beijing have shown an increase of 10 to 13 per cent directly attributable to the efforts of her rainmakers.

Despite some international scepticism, the Chinese authorities remain convinced of the merits of attempting to alter weather. Xinhua, the state news agency, recently reported that between 1999 and 2006, 250 billion tonnes of rain was artificially created, enough to fill the Yellow River several times over. Moreover, China's 11th Five Year Plan, which kicked off last year, calls for the creation of around 50 billion cubic meters of artificial rain annually.

While declining to provide specifics, Ms. Zhang says the budget for her office has seen sharp spikes in recent years and she expects it to continue to grow given northern China's extreme water shortages that are exacerbated by the impact of climate change. Indeed the annual per capita water supply for China is only 2,200 cubic meters, just 25 per cent of the global average according to the World Bank.

Artificial rain, however, is not controversy-free even within China. City dwellers have raised concerns about environmental pollution, though both Professor Wang and Ms. Zhang insist that silver iodide is used in such tiny quantities that it brings no negative health consequences.

Cloud-seeding shells and rockets have also sometimes gone astray, damaging homes and injuring inhabitants. Only last year a passer-by in the city of Chongqing was killed by part of a rain cannon that flew off during firing in May.

Professor Wang says that training programmes and the use of licences have sharply curbed accidents in recent years. Thus all the 135 farmers who comprise the on-call rainmaking force in Beijing go through intensive training lasting several weeks before they are let loose on the artillery. They are paid around $100 a month for their cannon and rocket launching duties, which they perform on average 40 times a year.

The person who gives the shooters the green signal to launch their cloud attacks is none other than Ms. Zhang, China's modern-day equivalent of Zeus and Indra. The businesslike bureaucrat is, however, modest when it comes to describing her role, "We try our best but there are no guarantees of success." Could the rain gods have claimed different?