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Many people are suffering from extremely high temperatures this summer. According to evaluations by the EU climate change service Copernicus and the World Meteorological Organization, July was the hottest month since weather records began. Forests are burning all over the world, most recently in Greece, Canada and Hawaii.
Alvaro Soto, WMO climate expert:
"This is indeed the new normal and does not come as a surprise. For example, the frequency and intensity of many extremes, such as heat waves and heavy sweating, have increased in recent decades, and it is very likely that human-induced climate change is the main cause of these changes."
Forest fires are facilitated by drought – by 2050, more than three-quarters of the world's population could be affected by droughts – a real problem for people and farmers. Rain would help. But what do you do when it's not raining?
Research has been going on for a long time, and silver iodide was experimented with in the USA as early as the 1960s. "Cloud seeding" is the name given to a process in which the yellowish salt is scattered into the clouds. As a result, the droplets or ice in a cloud become heavier and larger. At some point they become too heavy, the cloud rains down.
Today, the procedure is used in many states. In the United Arab Emirates, for example, it is intended to replace energy-intensive and expensive seawater treatment, at least in part.
Abdulla Al Hammadi, Head of the Department of Rain Enhancement at the National Meteorological Centre of the United Arab Emirates:
"According to our calculations, the cost of cloud seeding is much lower than that of desalination. However, cloud seeding requires rain clouds, and that's a problem, because they don't always exist."
Mexico is also relying on the technology to counteract the desertification of already arid regions. A start-up is currently advancing the application in collaboration with the Mexican Ministry of Agriculture and the military.
Alejandro Trueba, founder of "Startup Renaissance":
"When we release the silver iodide molecules into the clouds, the water particles are tiny, with a micrometric diameter, the size of a water molecule in the clouds is between eight and ten micrometers, but when they are attracted to the silver iodide, they grow up to 150-200 micrometers. This compound forms droplets, and the drops become rain."
Whether the process actually brings more rain, however, is controversial. The governor of the Mexican state of Nuevo León is enthusiastic in a video during a flight. Cell phone videos of the start-up are said to show rain after stimulation flights. But the effect can hardly be scientifically confirmed.
Jessica Martinez, meteorologist at Startup Renaissance:
"Evaluating the results is the hardest part. We know it's raining, but it's not easy to prove it, because the atmosphere is a dynamic system, i.e. in constant motion."
The flights will take place in selected areas. There, the amount of precipitation is measured to prove the success of the rain stimulation.
Jessica Martinez, meteorologist at »Startup Renaissance«:
»We have installed a network of rain gauges with which we measure precipitation. This is the polygon above the Sonoran Desert. Every point you see is a rain gauge to measure the annual rainfall."
After sowing the clouds, the data is compared with the predicted amount of precipitation for the region, according to research in the journal Nature. After 104 rain stimulation flights since 2020, the amount of precipitation in these areas is said to have increased by an average of 45.1 percent.
But the weather forecasts are inaccurate, and the clouds could have produced rain without the chemicals, says Fernando García, a cloud physicist at the National Autonomous University of Mexico.
Even if the rain stimulation succeeds, it alone is not enough to combat the water shortage in Mexico. There is a lack of an overall strategy to solve the crisis. Nevertheless, the Mexican government wants to expand the project – and other countries are also sticking to it.