The Chinese government is considering setting up what would be the world’s largest cloud seeding operation, in Tibet. A state-owned defence company has built 500 burners on Himalayan ridges in the path of the monsoon. They are testing a system that involves lofting particles of silver oxide from the machines into the atmosphere. When the water-laden air of the monsoon hits the particles, ice crystals are supposed to form and later fall as rain or snow. The plan is to build tens of thousands of these burners and increase rainfall by up to 10 billion cubic metres a year in an area that feeds the Yangzi and Yellow rivers as well as others that China’s neighbours rely on.
However, the largest study of iodine cloud seeding so far, the Wyoming Weather Modification Pilot Programme, found in 2016 that, although the technique can increase precipitation if the wind and other conditions are just right, it cannot do so over a long period or on a large scale. Changing the weather in the fragile environment of Tibet could also be fraught with unexpected consequences.
Perhaps the government should think again before authorising a project which could be a huge, risky way of avoiding conservation and pollution controls, says an Economist journalist.