Suffocating temperatures, lack of rain… A heat wave of unprecedented magnitude is causing drought in China over half of its vast territory, from the snow-capped mountains of Tibet to the beaches in the east of the country. On the podium of the hottest Chinese cities in recent days, the municipality-province of Chongqing (southwest), where 31 million people live, continued to suffer this Thursday, August 25. While the thermometer reads 41.9°C, many residents are looking for a bit of freshness in shopping centers or the metro. Since the beginning of its meteorological records in 1961, China had never known such a hot summer, a historic heat wave both in its duration and in its magnitude.
Many rivers have dried up, like the largest river in the country, the Yangtze. Main reservoir of drinking water in the country, this river is dry in many places, displaying a cracked ground. In lack of water for its crops, China is trying to artificially cause rain by launching projectiles loaded with silver iodide into the sky, according to images from state television CCTV. A method called “cloud seeding”.
On August 18, central China’s Hubei Province was the latest to announce that it would be “cloud seeding”, using silver iodide rods to induce rainfall, CNN reports. These cylindrical projectiles, which are usually the size of a cigarette, are fired into existing clouds to help form ice crystals. The crystals then help the cloud to produce more rain, which makes its moisture content heavier and thus helps to facilitate precipitation.
This technique is not new: “cloud seeding” has been practiced since the 1940s. It began in the United States in 1947 under the impetus of the army and Americans believed until the 1980s that They could solve their meteorological problems thanks to this technology, as France 24 reminds us. The United Arab Emirates, one of the driest countries in the world, is used to using this method to cause false rains. This country launched in 2010 a program endowed with a budget of 11 million dollars to conduct “cloud seeding” experiments. The stated goal was to increase annual precipitation by more than 15%.
But it is China that has the largest program in the world in this area. As France 24 points out, Mao Zedong, the father of communist China, laid the foundations at the end of the 1950s. conducted in 1958 in the province of Jilin, in the north of the country, which had just experienced its worst period of drought in sixty years.
China officially launched a “weather modification” program in 2002 and the country has since carried out “more than 560,000 weather manipulations by launching rockets and projectiles, bringing down 489.7 billion tons of rain, or the equivalent in water of three times the content of the Three Gorges dam”, announced Zheng Guoguang, the director of the Chinese Meteorological Authority, in 2012. In addition, more than 50,000 Chinese work in this national effort.
Beijing said it used cloud “altering technologies” during the 2008 Olympics to ensure the opening ceremony took place under perfectly blue skies. The technique can also be used to cause snowfall or to soften hail. However, the results of the operations practiced along the Yangtze River remain mixed for the moment. The reason: the too thin cloud cover over the river in recent days.
It must be said that the technique does not work well. When it comes to triggering a downpour, “it only increases precipitation by 5 or 10%,” says MarianneFrançois Bouttier, researcher at Météo-France, head of the precipitation research team. And this in the most favorable situations, because “cloud seeding” consists only of bringing down the water that the clouds already contain. In addition, this technique could have negative effects on the climate. “We don’t really know how to quantify the beneficial and harmful effects. And there may be chain reactions that we did not foresee”, warns Marianne Nicolas Maury, postdoctoral fellow at the Dynamic Meteorology Laboratory, at Paris.
The drying up of the rivers, which feed the hydraulic dams, also forces the authorities to locally ration electricity, at a time when the inhabitants are running the air conditioners at full speed to cool off. The lack of water is problematic, particularly in Sichuan, which has nearly 84 million inhabitants and is 80% dependent on dams for its electricity.
These weather conditions represent a challenge for agriculture, in a country already in normal times with a shortage of arable land. Drought is particularly problematic for rice and soybean crops, which are very water-intensive. The Chinese authorities now fear for the food security of the Asian giant, a subject taken very seriously in China because the country has in its history been hit by several episodes of famine. China provides more than 95% of its rice, wheat and corn needs.
Poor harvests are likely to increase imports from the most populous country in the world, at a time when the supply of cereals is already undermined by the war in Ukraine. The drought could cause the loss of 20% of the crops, estimates Faith Chan, associate professor of geographical sciences at the University of Nottingham Ningbo (China) interviewed by AFP. “But that will depend on the evolution of the heat wave which could last another one or two weeks”, according to him. In this context, the government decided on Wednesday to release a special envelope of 10 billion yuan (nearly 1.5 billion euros) to support farmers in the face of drought, CCTV said.
