Environmental scientist David Keith works at the intersection of climate science, way-new energy, and public power. His research has taken him into some far-out realms of geoengineering -- dramatic, cheap, sometimes shocking solutions to a warming atmosphere, such as blowing a Mt. Pinatubo-size cloud of sulfur into the sky to bring the global temperature down.

His other areas of study include the capture and storage of CO2 , the economics and climatic impacts of large-scale wind power , and the use of hydrogen as a transportation fuel. Another interest: How we make decisions when we don't have reliable scholarly data.

He teaches at the University of Calgary, and was named Environmental Scientist of the Year by Canadian Geographic in 2006.