Geo-engineering, using slight tweaks to the environment to produce significant effects, is being considered as a counter to climate change. For example, small amounts of finely powdered salt might be sprayed into the upper atmosphere to reflect solar radiation. It will come as no surprise to FT readers that back in the dark days of the Cold War, Pentagon scientists explored the military potential of such techniques with unexpected results.
During the Vietnam War, outside assistance was an enormous factor. American military planners believed that if they could stop supplies from other countries reaching the Viet Cong,
