Bloomberg OpinionVerified account

Over the next 24 hours, the county received more than two inches of rain that, according to local officials: Alleviated the drought Lowered the risk of forest fires Improved air quality https://trib.al/Mpl5FZl pic.twitter.com/tKUp0jgeWI

For decades, China has been home to one of the world's most advanced weather-modification programs. Its goals have been modest: More rain in arid places Less field-destroying hail Sunny days for big national events https://trib.al/Mpl5FZl pic.twitter.com/zu4y4EaTsn

But that modesty is starting to give way. Earlier this month, China announced plans to expand its rainmaking capabilities to cover nearly 60% of the country by 2025 https://trib.al/Mpl5FZl pic.twitter.com/9q3Il0Za3c

Details are sketchy, but fears are rising about the potential military uses of these capabilities, and their effects on an already changing climate. For China, and the world, these concerns need to be addressed soon https://trib.al/Mpl5FZl pic.twitter.com/Xin0a8DlZW

Humans have dreamed of controlling the weather for millennia. But it wasn’t until 1946 that scientists at General Electric discovered that dry ice can create precipitation when it interacts with clouds under certain conditions https://trib.al/Mpl5FZl pic.twitter.com/4zCCLzxJp5

By 1953, roughly 10% of the land area of the U.S. had been targeted for cloud seeding. 12 years later, the government was spending millions of dollars on weather-modification research each year, and 15 other companies started cloud-seeding operations https://trib.al/Mpl5FZl pic.twitter.com/EXn1FSXIq4

It wasn’t just about rainfall, however. During the Vietnam War, the U.S. military weaponized cloud seeding to inhibit enemy troop movements and reduce the effectiveness of anti-aircraft attacks, among other things https://trib.al/Mpl5FZl pic.twitter.com/E2BTRaJA8c

Weather modification began to alarm officials so they began seeking an international agreement to end “environmental warfare.” In 1978, the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification went into force https://trib.al/Mpl5FZl pic.twitter.com/5MSrNpKGSx

Although China ratified the treaty in 2005, its interest in controlling the weather and the environment didn’t wane. Meteorological calamities such as hail and flooding account for more than 70% of China’s annual disaster-related damage https://trib.al/Mpl5FZl pic.twitter.com/YhSypVWa2L

Weather modification is relatively inexpensive. In the 1980s, the government began making substantial investments in cloud physics. But definitive scientific proof for the effectiveness of cloud seeding emerged only in 2018 (and in Idaho, not China) https://trib.al/Mpl5FZl pic.twitter.com/lXvjMNZnhA

China claimed a great success in 2008, when Beijing launched 110 allegedly rain-suppressing rockets to ensure that the Olympic opening ceremonies were dry. They were, although scientists have questioned whether the rockets had much to do with it https://trib.al/Mpl5FZl pic.twitter.com/1g5zF3qDgJ

By 2015, there were rainmaking and hail-suppression programs in 30 Chinese provinces, employing some 35,000 people. In 2017, China showered $175 million on a system designed to bring more precipitation (among the items purchased: 897 rocket launchers) https://trib.al/Mpl5FZl pic.twitter.com/duHCsFaQg9

In 2018, Chinese aerospace and defense companies were reportedly building thousands of fuel-burning chambers intended to produce vast amounts of precipitation along the Alaska-sized Tibetan plateau https://trib.al/Mpl5FZl pic.twitter.com/wav6Ovq7vD

Even modest success at weather modification might worry rivals and neighbors. Other Asian countries are increasingly concerned that China’s program could negatively affect the monsoons and regular rains that have fed their people for millennia https://trib.al/Mpl5FZl pic.twitter.com/l5cKY1nAcL