Clouds and Conspiracies: Concerns Over Push to Make Rain

Can countries control the clouds? And should they?

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As climate change drives floods and drought, rainmaking is in fashion across the world, despite mixed evidence that it works and concerns it can stoke cross-border tensions.

While attempting to control the weather might sound like science fiction, countries have been seeding clouds for decades to try to make rain or snow fall in specific regions.

Invented in the 1940s, seeding involves a variety of techniques including adding particles to clouds via aircraft.

It is used today across the world in an attempt to alleviate drought, fight forest fires and even to disperse fog at airports.

In 2008, China used it to try to stop rain from falling on Beijing's Olympic stadium.

But experts say that there is insufficient oversight of the practice, as countries show an increasing interest in this and other geoengineering techniques as the planet warms.

The American Meteorological Society has said that "unintended consequences" of cloud seeding have not been clearly shown - or ruled out - and raised concerns that unanticipated effects from weather modification could cross political boundaries.

But experts say the main risk might be more a matter of perception.