Report: China to increase use of cloud seeding

By ANITA CHANG

BEIJING

China plans to increase its use of cloud seeding to relieve drought in key areas and lessen its impact on agricultural production, an official newspaper reported Thursday.

China has used techniques such as cloud seeding for decades in an effort to produce rain, particularly in the arid north where much of the country's wheat is grown. The government also tries to chase away rain clouds to ensure blue skies for key events, such as the opening ceremony of the Beijing Olympics two years ago.

There is rising demand for weather modification to cushion the impact that drought and hailstorms pose to rural income and food supplies, the China Daily newspaper said, citing Zheng Guoguang, director of the China Meteorological Administration.

However, scientists elsewhere have raised questions as to whether the practice is actually beneficial. Zheng acknowledged the technique was imperfect, saying it was at a "research-and-use" stage.

Typically, authorities blast clouds with silver iodide, a chemical that is thought to help concentrate moisture in clouds and thereby produce rain or snow.

The biggest concern is the lack of conclusive evidence that cloud seeding actually increases precipitation, said Steven Siems, an associate professor at Australia's Monash University who studies the practice.

The challenge is "showing that you're increasing rainfall in a statistically significant amount in an area that is economically worthwhile," he said. "You can't just go out there and say we made it rain."

China appears undeterred and jumps at the chance when conditions are good.

"There must be a trend of precipitation. During the drought season, it's rare to get these kinds of conditions, but once we have those conditions, we proceed with the cloud seeding," Wang Guanghu, deputy director of China's Research Center for Weather Modification, told The Associated Press.

China has more than 20 percent of the world's population but less than 7 percent of its arable land, underscoring the need to maximize agricultural output. A drought in 2007, the worst in a decade, caused losses of 37.4 million tons of grain, out of an annual output of 500 million tons, China Daily said.

Last year, authorities ordered a record 840 flights in efforts to increase rain in 1.39 million square miles (3.6 million square kilometers) -- roughly one-third of Chinese territory. They also fired 116,000 rockets and 890,000 artillery shells.

Weather modification was expected to play a role in ensuring good weather during the World Expo in Shanghai this summer and the Asian Games in Guangzhou later in the year.