China's rainmakers

Published: Thursday 15 June 2006

Chinese weather specialists resorted to artificial rainmaking in the first week of May to save Beijing from choking in a dust storm that painted the city yellow for almost two weeks.

Technicians working with the Beijing Weather Modification Office fired seven rocket shells with 163 cigarette-size sticks of silver iodide from six districts and counties on May 5, Chinese news agency Xinhua reported. The injected chemical silver iodide resulted in nearly 10-mm of rainfall, which helped wash down the dust, improving the city's air quality and also increasing soil moisture.

While scientists debate if cloud seeding actually works, China has been experimenting with this artificial rainmaking technique for decades, particularly in drought-prone areas. The us National Academy of Sciences, however, described the science behind cloud seeding as "too weak" in 2003.

Every year, China witnesses moderate to severe sandstorms. This year's storm, considered the fiercest in the past five years, commenced on April 18. Weather experts estimated that every day as much as 300,000 tonnes of sand blew into the city -- that's about 20 kg per resident on an average.

The abnormal weather led to several health problems, especially respiratory ailments. When hospitals reported a sudden jump in cases of breathing problems, the authorities issued a health warning to keep children indoors.

With Beijing getting ready to hold the 2008 Olympics, experts have urged the authorities to build a shelterbelt forest around Beijing and plant more trees to curb desertification in Inner Mongolia. To date, China has invested us $6.97 billion in projects, including tree planting, designed to prevent sandstorms in Beijing and in neighbouring Tianjin province.

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