An expert in energy and environmental technology, David Keith studies our climate and the many ideas we’ve come up with to fix it. A wildly original thinker, he challenges us to look at climate solutions that may seem daring, sometimes even shocking. Currently a professor at Harvard University, David was listed as one of Time magazine’s “Heroes of the Environment” in 2009, and advises on a number of high-profile advisory panels around the world. His new book, A Case for Climate Engineering, has recently debuted, and David had the chance to sit down with Stephen Colbert to talk about his solution to global warming (watch above).