Ready, aim, fire and rain

By Pallavi Aiyar

BEIJING - After weeks of watching the mercury soar, hardening the already cracked earth of their wilting orchards and farms, a group of farmers on the outskirts of Beijing gather in the Fragrant Hills that line the western fringe of China's capital city. Unlike their ancestors, they do not assemble to perform a rain dance or gather in a temple to pray to the Lord Buddha to bring the rain.

Instead, they grab rocket launchers and a 37-millimeter anti-aircraft gun and begin shooting into the sky. What they launch are not bullets or missiles but chemical pellets. Their targets are not

enemy aggressors but wisps of passing cloud that 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 rain-making force in the world: China's Weather Modification Program.

According to Wang Guanghe, director of the Weather Modification Department under the Chinese Academy of Meteorological Sciences, each of China's more than 30 provinces and province-level 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 across the country.

"Ours is the largest artificial weather program in the world in terms of equipment, size and budget," Wang said, adding that the annual nationwide budget for weather modification is between US$60 million and $90 million.

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

For a largely agrarian country like China, the weather was thought of as far too important to be left to the whim of gods 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 hailstorms, and replenishment of river heads and reservoirs. Artificial rain has also been used by some provinces to combat drought and sandstorms. In 2004, Shanghai decided to induce rain simply to lower the temperature during a prolonged heat wave to bring relief to an increasingly hot and sweaty urban populace.

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

Zhang Qiang, the top weather-modification bureaucrat in Beijing, said her office has been conducting experiments in cloud-busting for the past two years in preparation for the Games' opening ceremony on August 8, 2008.

She said that according to past meteorological data, there is a 50% chance of drizzle on that day. To ensure blue 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 and induce rainfall ahead of the big day so that during the opening ceremony the sky is cloud-free.

Wang said 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 Horti-Expo in Yunnan and the 1993 East Asian Games in Shanghai.

However, Zhang warned 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."

Her caveat goes to the heart of the primary criticism leveled against weather-modification efforts worldwide: doubts about their effectiveness. Wang himself admits that it remains notoriously difficult to establish how much real impact cloud-seeding has, since there is no foolproof 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. However, Israel and Russia continue to have substantial weather-modification programs and Wang said experiments conducted in these countries reveal that cloud-seeding can increase rainfall by between 6% and 20%.

Zhang said reservoirs in Beijing have shown an increase of 10-13%, one directly attributable to the efforts of her rainmakers.

Despite some international skepticism, the Chinese authorities remain convinced of the merits of attempting to alter weather. China's state news agency Xinhua 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 about 50 billion cubic meters of artificial rain annually.

While declining to provide specifics, Zhang said her office's budget has seen sharp spikes in recent years and she expects it to continue to grow given northern China's extreme water shortages, which 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% 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 Wang and 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 municipality of Chongqing was killed by part of a rain cannon that flew off during firing in May.

Wang says training programs and licenses have sharply curbed accidents in recent years, and 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. The farmers are paid about US$100 a month for their cannon and rocket-launching duties, which they perform about 40 times a year.

The person who gives the shooters the green signal to launch their cloud attacks is none other than Zhang, China's modern-day equivalent of Zeus, Indra, or the Chinese rain god Xuantian Shangdi. However, the businesslike bureaucrat is modest when it comes to describing her role: "We try our best, but there are no guarantees of success."