David Keith is a professor of geophysical sciences and founding faculty director of the Climate Systems Engineering initiative at University of Chicago. Known for his work on the science, technology and public policy of solar geoengineering, he previously led development of the Solar Geoengineering Research Program at Harvard, where he was a professor of applied physics and public policy. Keith has also taught at University of Calgary and Carnegie Mellon. He founded Carbon Engineering, a Canadian company developing technology to capture CO2 from ambient air, and has taught an online energy course reaching 150,000 students worldwide. Author of “A Case for Climate Engineering” and over 200 academic publications, Keith won MIT’s prize for excellence in experimental physics and was one of TIME’s Heroes of the Environment, among other accolades.