Financial Times FT.com

China asks rainmakers for blue skies Olympics

By Mure Dickie in Beijing

Published: June 16 2006 19:43 | Last updated: June 18 2006 05:49

When a sandstorm dumped an estimated 300,000 tonnes of dust on Beijing in April, the local arm of the world’s largest rainmaking operation swung into action.

Workers sent by municipal meteorologists scaled hills around the capital and burned silver iodide from their peaks in an effort to clean the air by coaxing rain from the grit-filled skies.

But coping with sandstorms is far from the only role played by China’s 37,000 full and part-time rainmakers, says Wang Guanghe, the director of the Chinese Academy of Meteorological Sciences’ institute of weather modification.

Experts on artificial precipitation across China use about 30 aircraft, 4,000 rocket launchers and more than 7,000 artillery pieces to ease droughts, cool overheated cities, prevent damaging hailstorms, put out forest fires and replenish riverheads. And with the Beijing 2008 Olympics fast approaching, the weather changers have a new responsibility: ensuring a rain-free games.

“The Beijing city government is very concerned about the weather for the Olympics ,” says Prof Wang in an interview immediately followed by an apparently serendipitous June shower. “There is a plan to undertake rain prevention work, particularly if there is [threatening] weather for the opening and closing ceremonies.”

Officials are convinced of the merits of weather modification in a nation troubled by chronic water shortages in its arid north. The state Xinhua news agency this month reported that rainmaking aircraft alone had in the past five years “undertaken enough missions to fill four Yellow Rivers”.

The National Meteorological Bureau’s latest five-year plan includes an expansion of the weather-modification system intended to “achieve an annual increase in rain of around 50bn cubic metres”.

What is less obvious, however, is whether the efforts, expense and occasional accidents involved are justified. The technology behind most rainmaking is well-established: aircraft, rockets, artillery shells or hill-top burners are used to “seed” clouds with silver iodide particles around which moisture can collect and become heavy enough to fall.

Advocates say they can induce rain from clouds that might otherwise either dissipate or grow to a scale that might threaten a sporting event. But cloud-seeding has in the past been likened by sceptics to more primitive approaches to weather modification, such as rain dances.

Prof Wang accepts that it remains notoriously difficult to establish how much impact cloud-seeding has, since there is no way to be sure how much rain might have fallen without intervention. However, he says research in south-eastern Fujian province suggested cloud-seeding resulted in 23 per cent extra rain.

But even ardent proponents acknowledge that it can never be a panacea for problems such as drought in northern China. Officials should also not rely too much on technology to prevent any presumptuous precipitation from dampening Olympic spirits in 2008.

Heavy rain is relatively unusual for Beijing in August, and the bigger challenges are likely to be the summer heat and polluted air. But Prof Wang says he “would not dare” to promise a dry games, noting that Beijing’s weather-changers may be able to dispel light showers but would struggle if a downpour threatened at the wrong time.