evidence: In 1965, Lyndon B. Johnson received the first presidential briefing on climate change. At the time, geoengineering—the intentional manipulation of the climate—was presented as one of the only possible solutions. Proposals since then have ranged from the fanciful (dropping billions of white balls into the oceans to absorb sunlight) to the formidable (unfurling a giant sheet of reflective mesh between the Earth and the sun). Those ideas may sound "outlandish and upsetting," one scientific journal acknowledged—but they could give us an emergency brake to pull if we can't stop global warming. [...] As a result, no single governing body is overseeing geoengineering efforts on a global scale. What there are, instead, are laws and treaties that cover different areas but could provide some guidance for regulating geoengineering efforts. The Law of the Sea, for example, could prevent efforts to alter the oceans, such as by dropping in a billion white balls. A 1976 treaty prohibits the use of weather modification—conjuring up a snowstorm, for example—as a weapon. But no international agreement or enforcement mechanism directly addresses geoengineering.