Us­ing tech to con­trol the weather

Do anti-hail can­nons and cloud seed­ing re­ally work?

Vocable (All English) - - Édito | Sommaire - OLIVIA SOLON

It is well known, a big hail­storm can dam­age an oth­er­wise com­pletely vi­able har­vest. Un­ex­pected weather con­di­tions are not new, nor are the ef­forts to con­trol it. The first anti-hail can­nons ap­peared in the 19th cen­tury, and since then sys­tems to con­trol the weather have mul­ti­plied and be­come more com­plex. What ev­i­dence is there that they ac­tu­ally work?

Farm­ersin Mex­ico have ac­cused Volk­swa­gen of ru­in­ing their crops by in­stalling “hail can­nons”, which fire shock­waves into the at­mos­phere in an ef­fort to pre­vent hail storms from dam­ag­ing the cars rolling off the pro­duc­tion line. The de­vices are be­ing blamed for caus­ing a drought dur­ing months when farm­ers near the Ger­man car­maker’s plant in Pue­bla ex­pected plenty of rain. 2. While some may be con­vinced of the hail can­non’s power, sci­en­tific re­search has cast doubt on these ob­ser­va­tions. But ef­fec­tive or not, the tech­nol­ogy rep­re­sents hu­man­ity’s lat­est at­tempt to con­trol the weather – rain danc­ing 2.0 – and has raised con­cerns about the lack of reg­u­la­tion and the as­sump­tion that there is a quick fix for com­plex me­te­o­ro­log­i­cal phe­nom­ena. Both hail can­nons and hail rock­ets emit loud noises in the sky, and man­u­fac­tur­ers claim this dis­rupts the for­ma­tion of hail so that it falls in­stead as rain or slush.

HAIL CAN­NONS

3. In 2005, Nis­san in­stalled 20ft hail can­nons at its plant in Mis­sis­sippi af­ter a hail­storm, much to its neigh­bours’ an­noy­ance. When ac­ti­vated, the sys­tem fired off gun­shot sounds

into the sky ev­ery six sec­onds. “It was like hav­ing a boom­box in my drive­way,” said one neigh­bour at the time. Farm­ers have also used hail can­nons to try to pre­vent their crops from be­ing crushed.

4. How­ever, a re­view by the Dutch me­te­o­rol­o­gist Jon Wieringa con­cluded that these tech­nolo­gies were “a waste of money and ef­fort” – a sen­ti­ment echoed by the World Me­te­o­ro­log­i­cal Or­ga­ni­za­tion. “The only ben­e­fi­cial ef­fect of fir­ing ex­plo­sive rock­ets and grenades at hail clouds may be the emo­tional sat­is­fac­tion of the gun­ners, who have fired at the en­emy,” he wrote.

CLOUD SEED­ING

5. Cloud seed­ing has been shown to be more ef­fec­tive at con­trol­ling pre­cip­i­ta­tion. It in­volves shoot­ing chem­i­cals into clouds – of­ten from a small air­craft – to cause rain­fall or snow. It’s done in more than 50 coun­tries world­wide for var­i­ous rea­sons in­clud­ing dis­pers­ing fog at air­ports, re­duc­ing prop­erty dam­age from gi­ant hail­stones in Canada and to in­crease snow­fall in Colorado and sum­mer rain­fall in Texas.

6. “You have to be very care­ful about what types of clouds and what you are try­ing to do,” said Wil­liam Cot­ton, a pro­fes­sor of at­mo­spheric sci­ence at Colorado State Univer­sity. Seed­ing win­ter­time moun­tain clouds can, he said, in­crease pre­cip­i­ta­tion by 6-8%. “That’s enough for a lot of wa­ter users to be happy and will­ing to pay for it,” Cot­ton said. The ev­i­dence to sup­port sum­mer­time cloud seed­ing seems to be much more shaky, with the Na­tional Re­search Coun­cil con­clud­ing in 2003 that “there is still no con­vinc­ing sci­en­tific proof of the ef­fi­cacy of in­ten­tional weather mod­i­fi­ca­tion ef­forts”.

7. Crit­ics are con­cerned that ma­nip­u­lat­ing the weather is only treat­ing the symp­toms of drought rather than tack­ling the un­der­ly­ing causes. “Even if it’s lo­cal, it’s wor­ry­ing that in the face of cli­mate change these kinds of al­ter­na­tives come up,” said Sil­via Ribeiro, the Latin Amer­ica di­rec­tor of ETC Group, which ex­am­ines the so­cio-eco­nomic and eco­log­i­cal im­pact of new tech­nolo­gies. “We con­trol the symp­toms in­stead of mod­i­fy­ing what is pro­duc­ing the ef­fect.”

A WHOLE NEW SCALE

8. That hasn’t stopped states and busi­nesses from con­tin­u­ing to seed clouds, in some cases on a dizzy­ing scale. The Chi­nese gov­ern­ment is de­vel­op­ing the world’s most am­bi­tious cloud seed­ing project to boost rain­fall across the Ti­betan plateau, an area span­ning 620,000 sq miles – three times the size of Spain.

9. The state-owned China Aero­space Sci­ence and Tech­nol­ogy Cor­po­ra­tion has de­signed and con­structed cham­bers that use mil­i­tary rocket en­gine tech­nol­ogy that burn fuel to pro­duce the cloud-seed­ing agent sil­ver io­dide. When the cham­bers are in­stalled on moun­tain ridges, the par­ti­cles travel up into the clouds and trig­ger rain­fall in one of the dri­est places on Earth.

10. Be­cause of the large area cov­ered, some are con­cerned that the Ti­bet project teeters from weather mod­i­fi­ca­tion into geo­engi­neer­ing ter­ri­tory. “Weather mod­i­fi­ca­tion tends to be quite lo­cal. You do it, it hap­pens. You stop and it’s gone. Geo­engi­neer­ing, or mod­i­fi­ca­tion of the cli­mate, means you do some­thing in a way that it stays like that,” ex­plained Janos Pasz­tor, the ex­ec­u­tive di­rec­tor of the Carnegie Cli­mate Geo­engi­neer­ing Gov­er­nance Ini­tia­tive, which seeks to cre­ate ef­fec­tive gov­er­nance for cli­mate en­gi­neer­ing tech­nolo­gies. “If [weather mod­i­fi­ca­tion in Ti­bet] were done long enough, it will have an im­pact on the cli­mate, not just the weather,” he said.

11. Med­dling with the cli­mate in this way is highly con­tro­ver­sial and raises all sorts of eth­i­cal and lo­gis­ti­cal ques­tions. “We have one at­mos­phere so we must get it right,” said Pasz­tor.

“We con­trol the symp­toms in­stead of mod­i­fy­ing what is pro­duc­ing the ef­fect.”

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