“It is well within the capabilities of current technology to create a stratospheric haze via any of a number of methods, including additives to jet fuel or artillery shells that disperse the gas hydrogen sulfide (H2S, which smells like rotten eggs) at high altitude. This would not be a onetime exercise: the haze would have to be refreshed constantly, as the particles settle out over a year or two. The amount of sulfur that would have to be added to the stratosphere each year would be only about one-tenth of that humans currently emit at much lower altitudes, so direct health impacts would be minimal. And projected costs are low enough that a small nation or even a single wealthy individual could carry out the entire project themselves.”