The west and southwest U.S. are about to face "unprecedented drought conditions," according to a new study published in the journal Science Advances. The authors say the decades-long droughts known as “mega droughts” are probably on the way by mid-century. Pronouncements like these are making geoengineering sound more palatable. Once written off as wacky science fiction, geoengineering is now being taken seriously. This week, a panel at the National Academy of Sciences recommended proceeding with research on technologies that could suck carbon dioxide out of the air and reflect back sunlight. We hear from two scientists about the possible risks and rewards of this technology.