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Weather modification, Mexican edition

10 May 2023 | OP ED Watch

No, contrails are not mind control. And no, the world’s governments are not secretly changing the weather in some vast Davos-centred cabal. If they were, do you seriously think it would change in the way they planned? Is that your experience with things your own governments are allowed to be doing like, say, fixing potholes, controlling inflation or protecting national security? Still, we do have to mention that the Mexican government is carrying out experiments to try to relieve its “second-worst drought in a decade”, presumably therefore proof positive of climate heating, by seeding clouds in Tamaulipas and Baja California with silver iodide. The only hitch is, it’s quackery. Nature says “scientists warn that there is scant evidence that cloud seeding works”. And while “scientists say” normally raises our hackles, we believe it before we believe “the Mexican government says”, which it does that “it has had successes”.

As so often with news stories, it gets worse. And not only because the Mexican government has been messing with this stuff since the 1940s, given that it’s not climate change that has made the place dry, and it’s still dry. The big problem is that:

“Mostly, there is ‘theoretical evidence’ that cloud seeding can increase precipitation, says Fernando García, a cloud physicist at the National Autonomous University of Mexico (UNAM) in Mexico City. Some rigorous experiments have resulted in a modest increase in precipitation. But there is no evidence that it will work every time, García says. ‘I can modify [a cloud]. What I don’t know is whether I’m going to increase rainfall or even suppress it, because that can happen too.’”

Why does he not know? It’s very simple and very powerful. It’s that we don’t understand the physics of clouds. Climate models gloss over it on the principle that if you can’t model it, it must not matter. (Aka the drunk looking for his key under the street lamp though he dropped it by his door, because the light is better out on the sidewalk.) But while we know that water vapour is the most important greenhouse gas, and that an important reason why is that it forms clouds, of various sorts, which then do complicated stuff, we don’t know what impact clouds have on climate except it’s hugely important in the real world, whatever is going on inside the computers.

When in doubt, of course, you retreat into the computers. As the Nature story explains, you could use statistical analysis of actual seeding to figure out if it’s effective. But that would be a lot of work over a lot of time. So guess what:

“The other way is with simulations. Computer models can now predict how clouds behave with and without seeding. Researchers compare the outputs of those models with measurements of how much water clouds hold before and after being seeded with silver iodide...”

Yeah. They can predict it, with as many decimals as you want. But those predictions are a reflection of your assumptions not of reality.

In reality we don’t even understand clouds well enough to know whether seeding them with silver iodide is worthy of Buck Rogers or a carnival barker. Although as another cloud physicist quoted in the story points out, you can only get out of a cloud as much water as it contains and when it’s parched and dry, it’s probably because there aren’t a lot of rain clouds. That much we do know.

We also know if you talk a government into believing you can make it rain, with an aeroplane or a dance or a prayer or what have you, it will give you, say, 15 million pesos. Muchas gracias.

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