But with geoengineering, “You can’t build a scale model of the atmosphere or tent off part of the atmosphere. As such you are stuck going directly from a model to full scale planetary-wide implementation.” In short, you could not conduct meaningful tests of these technologies without enlisting billions of people as guinea pigs—for years. Which is why science historian James Fleming calls geoengineering schemes “untested and untestable, and dangerous beyond belief.”
