(CBS) Self-avowed “P.R. agent for the planet” Al Gore says those who still doubt that global warming is caused by man - among them, Vice President Dick Cheney - are acting like the fringe groups who think the 1969 moon landing never really happened, or who once believed the world is flat. The former vice president and former presidential candidate talks to 60 Minutes correspondent Lesley Stahl in an interview to be broadcast this Sunday, March 30, at 7 p.m. ET/PT. Confronted by Stahl with the fact some prominent people, including the nations vice president, are not convinced that global...