Al Gore’s An Inconvenient Truth is cinematic brussel sprouts – a brand of good-for-you documentary that’s far from alluring but undeniably intellectually nutritious. Largely a filmed version of Gore’s oft-given speech on global warming, Davis Guggenheim’s movie deftly alternates its visual attention between the surprisingly charismatic former V.P. and his easily digested, graphics-heavy PowerPoint presentation, keeping things just lively enough to prevent the proceedings from devolving into a tedious schoolroom lecture. But it’s the facts themselves that really prop up this latest act of big-screen activism, with Gore clearly and compellingly laying out the alarming evidence regarding the Earth’s escalating temperatures and CO2 levels (and the environmental disasters such developments will continue to cause). Despite the credible scientific – and, it should be noted, non-partisan – contentions about planetary climate changes put forth by An Inconvenient Truth, Guggenheim can’t resist trying to use the film as a p.r. defibrillator for Gore’s political career, the regular interludes about its headliner’s personal tragedies (involving his young son’s almost-fatal accident and the lung cancer death of his sister) seemingly aimed less at explicating his motives for wanting to better the world than at reshaping his image for a potential 2008 presidential run. Such distracting machinations, however, can’t obscure the urgency of the problem Guggenheim’s doc distressingly lays out, nor the comprehensiveness and persuasiveness of its lucid arguments.