If Al Gore’s new movie weren’t titled “An Inconvenient Truth,” I wouldn’t have quite so many problems with it.

He should have gone with something closer to “Revenge of the Nerd.” That’s the heartwarming angle to global warming. A college student is mesmerized by his professor’s bold measurements of carbon dioxide in the atmosphere. Our hero carries this passion into Congress, where no one listens to him, and then works up a slide show that he inflicts on audiences around the world, to no discernible effect.

But then his slide show becomes a horror movie — and it turns into a cult hit. The nerd becomes the toast of Hollywood, Sundance and Cannes. He is cheered at premieres across America. Audiences sit enraptured through a film starring graphs of CO2 concentrations and close-ups of ice cores.

The documentary doesn’t open in theaters until tomorrow, but it’s already a cinch for an Oscar, and deservedly so. Getting anyone to voluntarily endure 100 minutes of Al Gore and his slides is a historic cinematic achievement.

Gore isn’t exactly likable in the film — he still has that wooden preachiness and is especially hard to watch when he tries to be funny. Yet you end up admiring him for his nerdly persistence. He turned out to be right about something important: global warming is a problem worth worrying about.

But the story he tells in the movie is hardly “an inconvenient truth.” It’s not really true, and it’s certainly not inconvenient for him or his audience.

In his morality tale, global warming has been an obvious crisis-in-the-making for decades, and there are obvious solutions that could have been adopted without damaging consequences. But supposedly America, almost alone among industrialized nations, has refused to do anything because the public has been bamboozled by evil oil companies and Republicans — especially one villain who, we’re reminded, got fewer popular votes than Gore did in 2000.

As therapeutic as this history may be for Gore, it has certain problems. Scientists recognized the greenhouse effect long ago, but the question was how much difference it would make. And until fairly recently, when evidence of global warming accumulated, many non-evil economists doubted that the risks justified the costs of the proposed remedies.

Gore calls such cost-benefit analysis a “false choice,” as if the remedies really weren’t expensive, and he castigates the U.S. for refusing to sign the Kyoto Protocol. But most nations that did sign aren’t meeting their goals because cutting emissions turned out to be so difficult. Global warming is a genuine long-term risk, but it’s not easy persuading voters anywhere to make short-term sacrifices.

Gore’s cinematic strategy for rousing them is to present doomsday scenarios and ignore the evidence that civilization may just survive after all. You could argue that the ends justify the means — that only by terrifying the public can you rouse politicians into doing the right thing.

But even as propaganda, the film is ultimately unsatisfying. Gore doesn’t mind frightening his audience with improbable future catastrophes, but he avoids any call to action that would cause immediate discomfort, either to filmgoers or to voters in the 2008 primaries.

He doesn’t propose the quickest and most efficient way to reduce greenhouse emissions: a carbon tax on gasoline and other fossil fuels. The movie gives him a forum for talking sensibly about a topic that’s taboo on Capitol Hill, but he instead sticks to long-range proposals that sound more palatable, like redesigning cities to encourage mass transit or building more efficient cars and appliances.

Gore shows the obligatory pictures of windmills and other alternative sources of energy. But he ignores nuclear power plants, which don’t spew carbon dioxide and currently produce far more electricity than all ecologically fashionable sources combined.

A few environmentalists, like Patrick Moore, a founder of Greenpeace, have recognized that their movement is making a mistake in continuing to demonize nuclear power. Balanced against the risks of global warming, nukes suddenly look good — or at least deserve to be considered rationally. Gore had a rare chance to reshape the debate, because a documentary about global warming attracts just the sort of person who marches in anti-nuke demonstrations.

Gore could have dared, once he enticed the faithful into the theater, to challenge them with an inconvenient truth or two. But that would have been a different movie.