File photo of former U.S. Vice President Al Gore and his wife Tipper leaving after holding a news conference in Palo Alto.

 
File photo of former U.S. Vice President Al Gore and his wife Tipper leaving after holding a news conference in Palo Alto.
Former U.S. Vice President Al Gore (L) and his wife Tipper leave after holding a news conference in Palo Alto, California after winning the Nobel Peace Prize in this October 12, 2007 file photo. REUTERS/Kimberly White/Files