Seeding Clouds in China

China uses silver iodide to seed clouds not only to break long dry spells, but also to trigger rains so that the skies are clear during important events such as the Olympic Games and the People's Republic's 60th birthday. Beijing is reported to have spent some 500 million US dollars on cloud seeding in the past five years.

But China is by far not the only country taking advantage of cloud seeding. Others include the United States, the United Arab Emirates, Russia and Venezuela. Whilst Germany uses silver iodide to reduce the size of hail. Silver iodide is either sprinkled, shot or evaporated into thunder clouds, where it binds with particles and moisture, causing precipitation.

Andreas Friedrich from Germany’s meteorological centre says that although cloud seeding technology has been around since the 1950s, not all meteorologists agree that it is effective.

“The energy in the atmosphere is very powerful. The local effects that can be caused by using aeroplanes or rockets are very small in my opinion. The difference silver iodide makes is so small, it is like drops of water in the sea. But nature is so immense that the kind of changes caused by this technology are temporary if anything at all.”

Cloud seeding gone wrong

China, however, received criticism from within its borders at the beginning of November for inducing early snow. The weather ministry’s plans to interrupt a long dry spell in the north by shooting over 100 rockets containing silver iodide into the clouds did not take into consideration a cold front coming from the south.

It did not rain. Instead, around 16 million tons of snow buried Beijing, causing chaos and aggravating the city’s inhabitants, whose heating had not yet been activated.

Last week at the UN Climate Summit, China criticised the climate fund for developing countries, stating the allocated 10 billion US dollars is not enough.

Does it make sense?

But environmentalists have their doubts. “The technology itself is quite safe but the problem really is whether this is a wise investment, whether this is the right solution to the environmental problems in China because we all know that China is faced with very big environmental challenges nowadays,” says Yang Ailun from Greenpeace China.

“However, a lot of these challenges really need a long-term solution, they need very strict environmental regulations and also very good implementation. Given how urgent the environmental problem is, should China really rely on these short-term and expensive measures or actually try to invest in longer-term solutions that can actually solve the problem?” Yang Ailun asks.

There are environmental concerns as well. According to the Toxic Metals Research Program at Dartmouth College in the US, high concentrations of silver in the air and water could lead to permanent damage to human health and could especially be hazardous to aquatic life.

But groups that support cloud seeding, among them the US National Weather Modification Association, claim that the amounts of silver used are far too small to cause damage.

Author: Sarah Berning
Editor: Thomas Bärthlein