As climate change churns up extreme weather, would-be geoengineers are proposing revolutionary new technologies to minimize the effects of global warming: Reflect sunlight into space with orbiting mirrors! Absorb atmospheric carbon dioxide with artificial trees! Bulk up sea ice by cooling it with giant pumps! Even proponents acknowledge that such extravagant measures would be risky, assuming they could be implemented. But tinkering with the planet’s thermostat isn’t an entirely new idea, as you can see from these past schemes—all ingenious, some downright explosive.
Soldiers had long observed that rain seemed to follow battles, and common wisdom attributed this apparent link to the smoke and noise caused by munitions. In August 1891, Robert Dyrenforth, a Washington patent lawyer and retired Union Army major, took this idea to its logical conclusion in the first government-funded effort to control the weather. Supplied with $7,000 from the U.S. Senate and armed with mortars, electrical kites and hydrogen balloons, Dyrenforth traveled to West Texas, where he attempted to create a downpour by setting off a series of loud explosions in the lower atmosphere. He took credit for the precipitation that fell several hours after each volley, but it may be that what Dyrenforth got right was just timing: The rainy season was due to start anyway.
For more than a century, farmers around the world have fired hail cannons at the sky to stave off icy precipitation that could destroy delicate crops. (The trend began in the 1890s, when one Austrian winegrower raised a small army to wage “war on the clouds.”) The tall conical devices are believed to disrupt the formation of hail by blasting shock waves every few seconds during a storm. While proof of their efficacy is anecdotal at best, hail cannons are still in use at vineyards from California to New Zealand.
In 1946, Vincent Schaefer, a General Electric chemist, discovered that dry ice—super-cooled solid carbon dioxide—could be used to create an artificial cloud full of tiny ice crystals. Further experimentation led to “seeding” clouds with dry ice, silver iodide or other chemicals dropped from an airplane to catalyze precipitation. Though cloud-seeding has not fulfilled all its promises, it is used to generate powder for ski areas and rainfall in the United Arab Emirates, where up to 15 percent of annual precipitation is man-made.
In the Shade
In 1989, James Early, a California engineer, proposed going to the Moon to assemble a glass parasol more than 1,200 miles across that would be launched into space to deflect solar radiation. Other experts have made similar suggestions, including an enormous orbiting mirror or a cloud of millions of umbrella-like spacecraft floating between the Earth and the Sun.
James Espy, a 19th-century schoolteacher known as “the Storm King,” made contributions to the study of cyclones. But he never secured permission to test his most audacious idea: setting massive forest fires to regulate the continent’s weather. The heat from weekly blazes in the Rocky and Appalachian mountains, he argued in 1845, would ensure that “it will rain enough and not too much... and the health and happiness of the citizens will be much promoted.”
“Operation Popeye” was a classified U.S. program that deployed cloud-seeding during the Vietnam War. The aim was to hinder North Vietnamese troops and suppress anti-aircraft fire. Whether the program worked remains in question. But after it became public, in 1972, it prompted a congressional investigation and, eventually, a United Nations treaty forbidding military action intended to cause “earthquakes, tsunamis [or] changes in weather patterns.”