Bjørn Lomborg (45)

Self - Director, Copenhagen Consensus Center

Hashem Akbari

Self - Head of Heat Island Group, Berkeley Lab

Al Gore (62)

Self (archive footage)

James Hansen (69)

Self - Director, NASA Institute for Space Studies

Barack Obama (49)

Self (archive footage)

Barry Glassner

Self - Sociologist, USC and Author, 'The Culture of Fear'

Richard Lindzen (70)

Self - Professor of Atmospheric Science, MIT

Nathan Myhrvold

Self - Founder, Intellectual Ventures

Daniel Nocera

Self - Professor of Energy and Chemistry, MIT

Thomas Schelling

Self- Economist, Nobel Laureate

Jonathan Trent

Self - OMEGA Project Scientist, NASA Ames Research Center

Joe Barton (61)

Self (archive footage)

John Dingell (84)

Self (archive footage)