With rising sea levels threatening to swallow coastal cities and bizarre weather patterns disrupting the global food supply, geoengineering -- or deliberate, large-scale intervention to reverse the effects of global warming -- looks like a much-needed lifeboat for humanity. But tinkering with the climate also comes with risks -- and a glance at the dubious history of climate hacking isn't all that reassuring. From the early cloud-seeding experiments of the Cold War to America's rainmaking exploits in Vietnam to China's weather manipulation efforts at the Beijing Olympics, our efforts to master Mother Earth have left much to be desired. And today's geoengineering schemes promise much steeper downsides. Herewith, then, are seven far-out geoengineering ideas that could save the planet -- or destroy it trying.
Plans for reducing the amount of sunlight that reaches the planet -- a technique known as solar radiation management (SRM) -- range from injecting reflective aerosols into the atmosphere to whitening the tops of buildings in order to bounce solar radiation back into space. But perhaps the most ambitious SRM proposal, presented by physicist and former Pentagon weapons designer Lowell Wood at a roundtable convened by the White House in 2001, is to launch a giant mirror into orbit between the sun and the Earth. The mirror (or a few smaller ones), would be composed of tiny aluminum threads and span roughly 600,000 square miles -- enough to deflect approximately 1 percent of incoming solar radiation. "If they had broadcast that meeting live to people in Europe, there would have been riots," recalled one participant in the roundtable where Wood presented his idea. "Here were the bomb guys from Livermore talking about stuff that strikes most greens as being completely wrong and off-the-wall."