The flood that hit Spain, causing almost 220 victims and 2000 missing, has put the spotlight back on climate change and its increasingly extreme effects. However, among the legitimate concerns, they have also crept in conspiracy theories who try to attribute the storm to activities of “cloud seeding“ (cloud seeding) conducted in Morocco last August.
To clarify, we asked Antonello Pasiniclimate physicist and leading researcher at the Cnr, who explained to us why these theories have no scientific basis. “Cloud seeding is an experimental technique for making rain, used for decades, but which has never led to certain results“, says Pasini. “For sure, the technique used in Morocco in August cannot cause what happened in Spain. It is a technique that can increase rainfall by 10, 15 or at most 20%, but not cause such a significant flood, especially at a long distance from where the cloud seeding was possibly done.”
But what exactly is cloud seeding?
This is a cloud modification technique that aims to increase precipitation. In practice, they shoot into the clouds, via planes or cannons, silver iodide particles which favor the condensation of water vapor and the formation of raindrops.
This technique is used especially in countries with arid climates, such as the United Arab Emirates, to try to mitigate the effects of drought. But as Pasini points out, “it rains a little more in the area where it is experienced and downstream from that area, if anything, it rains less. So there are possibly cross-border problems due to this fact, as happens in the Middle East where the country that uses this technique benefits from it while neighboring countries find themselves forced to experience drought“.
Why couldn’t cloud seeding in Morocco have caused the flood in Spain?
There are several reasons why this hypothesis is unfounded. First of all, as Pasini explains, cloud seeding has a local and time-limited effect. “You can’t do it in Morocco and have effects in another country,” says the physicist. “Furthermore, the effects of this technique are limited to a few tens of minutes after the operations, at most a few hours: it is therefore to be excluded that operations carried out days or weeks before could have had even a minimal influence on what happened in Spain“.
Second, the effectiveness of cloud seeding is very limited, even where it works best. “It can increase rainfall by about 10%,” explains Pasini. “We don’t know in detail the results of the experiments carried out in Morocco, but even assuming a 10% increase in rainfall, the Valencia event would still have been catastrophic, given the amount of rain that fell”.
Finally, it’s important to remember that with cloud seeding you can’t make it rain on command. “At most we can increase the rainfall that would already have occurred due to natural causes,” specifies Pasini.
The real cause of the flood: the climate crisis
The floods that hit Spain were caused by a combination of meteorological factors, including a “cold drop” that produced violent, self-healing storms. But the background intensifier is the climate changewhich is increasing the frequency and intensity of these extreme events.
As pointed out by the World Meteorological Organization“precipitation was approximately 12% more abundant and twice as likely as the climate in pre-industrial times.”
It is therefore vital to urgently address the climate crisis by reducing greenhouse gas emissions and investing in adaptation measures to protect communities from the increasingly devastating impacts of climate change. Spreading conspiracy theories is not only useless, but it diverts attention from the real problem and, above all, delays the actions necessary to address it.
