Shooting Clouds

In an article titled, “The Rainmakers”, in the current issue of Orion magazine, Kathryn Flagg provides some interesting field reportage on China’s conflicted urban relationship with water resources and its ambitious cloud seeding efforts:

“It turns out that firing rockets into the sky in the hopes of making rain doesn’t feel foolish at all….Its hard to track down firm numbers, but scientists within the China Meteorological Administration (CMA) estimate that China employs more than thirty thousand people in its weather modification program.  Most of these are peasants or farmers trained to deploy weapons at the command of regional meteorologists.”

All but two of China’s provinces regularly practice cloud seeding, and during the drought this past summer, China shot so much silver iodide into its atmosphere that it nearly ran out of the specially-designed artillery shells used to transport the chemical into the clouds.  China far exceeds any other nation in terms of its quantitative efforts in weather making.  But as Flagg points out, the efficacy of designed storms are vague at best:

“Seventy years into an international experiment in weather modification, scientists still haven’t arrived at any consensus on whether or not the process works.  We know that silver iodide mimics the crystalline structure of ice, and that when it’s injected into clouds – either by aircraft flying overhead, or on the ground generators that send up plumes of vapor, or, in the case of China, by decades old artillery – the chemical forms small ice nuclei in the clouds, and additional moisture gloms onto the crystals.  Once the crystals are large enough or heavy enough, they fall from the cloud.  Yet weather patterns are so variable that’s it hard for scientists to know when to attribute precipitation to cloud seeding.”

Similar to Japan’s entropic attachment to the manufacturing of tetrapods, one wonders to what extent the weather economy engendered by cloud seeding actually becomes its own ulterior motivation for its Sisyphean efforts.  As the guardian reported earlier this year, just the artillery shells alone cost about 1,000 yuan each.

Some Chinese reports claim that cloud seeding can locally increase precipitation by 10-20%.   The U.S. National Center for Atmospheric Research (whom China calls upon for technical support and weather mapping technology) may question that claim.   But even though the percentage of effect is likely lower, the sheer economy of scale with which China is experimenting with rainmaking removes the practice from the micro to the mesoscale of geoengineering, like a contemporary replay of “the rain follows the plow”.  Is there a cumulative as production continues to increase?   Is China lessening, ever so slightly, the amount of rainfall that might otherwise arrive on the other side of the Pacific?

Speculating on the flipside, if the practice of cloud seeding becomes more effective in the future through all the research and practice going into it,  it could potentially create vexing questions related to water claims.  Water rights are largely based on terrestrial delineation and the order in which they were appropriated.  If appropriation for “beneficial uses” includes the sky, meteorological mapping might then become implicated with water adjudication at an international level.  The U.N. would have a new set of challenges to sort through and lawyers might end up delineating water claims as tentative inscriptions in elaborate water cycle diagrams, thereby catching an inadvertent view into how interconnected it all is.

Seeded cloud image from here and here.

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