Dan Chiras, visiting professor of environmental science and director of The Evergreen Institute in Missouri, discusses America at a crossroads in its history. The world is changing rapidly. How we react to these changes, among them global climate change and shortages of key energy resources, will determine whether we prosper or flounder. Unfortunately, extremely powerful forces now prevent us from enacting the measures required to build a truly sustainable future based on a renewable energy economy. Part of Notable Lectures & Performances series, Colorado College. Recorded April 27, 2011.