The documentary “Hot Politics” on “Frontline” (8 p.m., PBS, check local listings) looks at the decades-long debate over global warming and asks why it has taken so long for the federal government to react to the crisis.

The makers of this documentary contend the scientific debate is essentially over. As this “Frontline” makes clear, so-called global-warming skeptics have followed a playbook of propaganda, confusion and deception that was written by big-tobacco companies when they were trying to disprove a well-established link between smoking and cancer. Correspondents talk to global-warming “skeptics” here who admit to being bought and paid for by firms representing energy interests.

“Hot Politics” looks back at the Bill Clinton years as a time of lofty rhetoric, political ineptitude and botched opportunities to limit greenhouse-gas emissions. Clinton signed a Kyoto Treaty capping greenhouse gases but made no efforts to get it ratified by a Senate that had previously passed a nonbinding resolution condemning Kyoto by a bipartisan romp of 95-0.

In 2000, candidate George Bush surprised many by proposing a mandatory “carbon cap.” But once in office, Bush changed his position so abruptly that he shocked and embarrassed his Environmental Protection Agency director Christine Todd Whitman. Bush then stunned the international community by simply walking away from the Kyoto negotiations. Whitman, a loyal Republican of long-standing, discusses the policy shift with breathtaking candor. “The way it happened was the equivalent to flipping the bird, frankly, to the rest of the world … on an issue about which they felt so deeply.”

Just as earlier “Frontline” documentaries featured CIA agents who had questioned the cooked intelligence that lead to the invasion of Iraq, “Hot Politics” presents a parade of government scientists and experts who were subject to censorship and harassment for defying the Bush administration’s “see no evil” policy on global warming. “In my 30-some years in government,” says NASA scientist James Hansen, “I’ve never seen constraints on the ability of scientists to communicate with the public as strong as they are now.”

Many condemn contemporary TV journalism for its emphasis on trivia, scandal and fluff. But when the history of our time is written, these “Frontline” pieces on the behavior of the Bush administration will offer an invaluable resource. For those who can’t wait for history’s judgment, they are beginning to look like a legal brief.

¢ Now 100 percent Sanjaya-free, “American Idol” (7 p.m., Fox), spends two nights raising funds for charities in Africa and closer to home. The six contestants perform songs of inspiration, and one faces elimination on Wednesday.

Tonight’s other highlights

¢ Rory and Paris mull postgraduate plans on “Gilmore Girls” (7 p.m., CW).

¢ “Nova” (7 p.m., PBS, check local listings) looks at the promise of solar energy.

¢ “Biography” (7 p.m., Biography) profiles Meredith Vieira.

¢ A con artist’s condition remains a mystery on “House” (8 p.m., Fox).