WASHINGTON - MARCH 21:  Former U.S. Vice President Al Gore testifies during a hearing before the Senate Environment and Public Works Committee March 21, 2007 on Capitol Hill in Washington, DC. Gore was on the Hill to testify for the House and Senate on global warming and environmental protection issues. Getty Images logo Getty Images 62 months ago

WASHINGTON - MARCH 21: Former U.S. Vice President Al Gore testifies during a hearing before the Senate Environment and Public Works Committee March 21, 2007 on Capitol Hill in Washington, DC. Gore was on the Hill to testify for the House and Senate on global warming and environmental protection issues.