Newt Gingrich
Speaker of the U.S. House of Representatives from 1995 to 1999, Gingrich oversaw the "Republican Revolution" of the mid-1990s. Here he discusses the Kyoto Protocol and other global warming initiatives that came before Congress during his tenure and why he thinks there has been "gridlock" on the issue.

Sen. Chuck Hagel
In 1997, Hagel (R-Neb.) and Sen. Robert Byrd (D-W.Va.) sponsored a resolution opposing certain provisions of the Kyoto treaty. Here, Hagel discusses that resolution, why he still thinks Kyoto was a bad idea and why he is now convinced that global warming is a serious concern.

James Hansen, Ph.D.
The head of NASA's Goddard Institute for Space Studies, Hansen was one of the first scientists to speak out about the dangers of global warming, testifying at a Senate hearing in 1988. Nearly two decades later he was back in the spotlight when NASA press officials attempted to curb his public comments on the subject. Here, Hansen discusses those incidents and the science of global warming that developed between them.

Frank Luntz
An influential Republican pollster in the 1990s, Luntz contributed to 1994's "Contract With America" and authored a memo that laid the groundwork for efforts by skeptics to discredit the scientific evidence for global warming. Here, Luntz contrasts the longevity of his memo with the failings of "hysterical" global warming advocates and explains why he thinks the issue will not play into the 2008 elections.

Rick Piltz
Piltz is the director of the Climate Science Watch at the non-profit Government Accountability Project. Here he discusses his 2005 resignation from the U.S. Climate Change Science Program over tampering with scientific reports by representatives of the Bush administration.

William K. Reilly
Reilly served as administrator of the Environmental Protection Agency under President George H.W. Bush. More recently, as a consultant for the private equity firm Texas Pacific Group, he helped broker the leveraged buyout of the Texas energy company TXU. Here he discusses that deal and his work with the first President Bush on climate change.

Frederick Seitz, Ph.D.
A physicist by training, Seitz is a past president of the National Academy of Sciences and of Rockefeller University. He is chairman emeritus of the board of the George C. Marshall Institute, a think tank that has long been skeptical of global warming. Here, Seitz discusses his continued dismissal of climate change as a serious threat and his financial ties to the tobacco and energy industries.

Christine Todd Whitman
While serving as EPA administrator from 2001 to 2003, Whitman told the 2001 G8 summit that Bush would uphold his campaign promise for a nationwide cap on carbon emissions. She found her credibility affected when the White House reversed course shortly thereafter. Here, Whitman tells that story, comments on allegations that the government suppressed data on global warming and gives her thoughts on the future of energy production.

Timothy Wirth
Former Senator (D-Co) and Clinton official Timothy Wirth is now president of the United Nations Foundation. Wirth organized the 1988 Senate hearing at which James Hansen addressed global warming, and he led the U.S. negotiating team at the Kyoto Summit. In this interview, Wirth describes the debate surrounding global warming within the Bush I and the Clinton administrations and why neither took action.