Greenhouse gas emissions are at unprecedented levels and still rising. As climate deniers and their allies in industry and government thwart conservationists' efforts, some scientists are working to develop a back-up plan: use technology to "geoengineer" the Earth's atmosphere and reduce the effects of climate change. Shane Smith and Ben Anderson find out how this technology would work and how effective this radical, and potentially dangerous, plan could be.
Stars: Ben Anderson, Shane Smith