A movie based on a PowerPoint presentation by a former presidential candidate may not sound exciting, but once An Inconvenient Truth hits its stride viewers may be surprised how compelling the subject matter proves to be.

While many high-ranking political figures continue to argue about global warming, Al Gore has plunged headlong into a serious wake-up call for the planet with a series of lectures about the problem. It's on one of these lectures that this movie from director Davis Guggenheim is based. Guggenheim breaks up Gore's delivery by illustrating his points with film footage, much of which features the former Democratic nominee exploring the globe as he examines the effects of global warming. Gore's speech is neatly divided between calm recitations of the facts about the issue and several stories of a personal nature. His skills as an orator are considerable, and it's hard not to be alarmed by most of what he has to say. Indeed, as Gore relates tales of melting polar icecaps, rising global temperatures, and the reluctance of political leaders to do something about the problem, the film takes on an air of hopelessness and doom, especially as no easy solutions are offered. Gore's advice is for individuals to take steps to reduce their own inadvertent poisoning of the atmosphere, and to persuade others to do likewise.

It's a powerful message, and one that is likely to remain in non-cynical minds long after the film comes to a conclusion.