Matthew Lewis/Getty Images
Al Gore addressing the major climate change challenges that threaten economic sustainability, at the Octagon Centre on February 7, 2007 in Sheffield, England.
Former Vice President Al Gore has been on the forefront of warning against global warming for many years. His critically acclaimed documentary on the subject, An Inconvenient Truth, is up for Academy Awards for Best Documentary Feature and Music Written for a Motion Picture. This interview originally aired on May 30, 2006.