Dir: Davis Guggenheim. US. 2006.98mins

"I'm Al Gore. I used to be the next president of theUnited States... I don't find that particularly funny," former vice-presidentAl Gore declares early on in Davis Guggenheim's fascinating documentary,bounding on stage before one of his multi-media lectures about global warming.

Gore is a contradictoryfigure, aloof and folksy, reserved and passionate, sanctimonious and self-mocking.Quoting Mark Twain, cracking deadpan jokes, citing endless graphs andstatistics, the portly former presidential candidate earnestly alerts hisaudiences to the fact that the planet is on the verge of catastrophe.

In normal circumstances, An Inconvenient Truth would be acuriosity item at best: a project with obvious currency in schools anduniversities and at political meetings - but with only the most limitedpotential to crossover into mainstream theatrical distribution.

However, there are somepowerful groups determined to ensure Gore's gloomy warnings are heeded. Thedocumentary was co-produced by Lawrence Bender (best known for his work withQuentin Tarantino) and backed by Jeff Skoll'sParticipant Productions (the crusading outfit behind Good Night, And Good Luck and Syriana amongothers).

Since its premiere atSundance in late January, An InconvenientTruth has generated intense media interest. It will be screening inofficial selection at Cannes just prior to its (limited) US release later thismonth through Paramount Classics. A book is being published to accompany thefilm and there is already a strong internet campaign behind it. In territorieslike the UK, UIP distribute in the early autumn.

Gore himself seems ready tomarket the movie tirelessly, if only because he so fervently wants to wake upthe world to the fact that "humanity is sitting on a time bomb."

Documentaries andpolitically committed dramas have done well at the box-office in recent yeas,but An Inconvenient Truth (as its owntitle hints) will remain a hard sell. Footage included in the film show justhow ostrich-headed politicians remain in the face of overwhelming evidenceabout the perils of global warming. Unless their jobs or those of theirconstituents are at immediate risk, few care. Moreover, what Gore has to tellhis audience is downbeat and unsettling in the extreme, even if he does suggestit's not too late to avert disaster.

Nonetheless, Gore presentshis information clearly and sometimes wittily. He certainly seems far morerelaxed here than in the 2000 presidential campaign, when his stiff,stand-offish demeanour is thought to have cost him crucial votes. It helps,too, that the film is so slickly shot and edited.

Director Guggenheim has anextraordinarily varied CV, encompassing everything from teen thrillers like Gossip and TV shows like 24 and Deadwood to documentaries about the LA school system. His functionhere is to provide the best possible platform for Gore. This he doeseffectively enough.

Nonetheless, on one level,the documentary can't help but seem a missed opportunity. What's frustrating isthat Guggenheim isn't able to probe more deeply into Gore's story or to examinejust how deeply he was affected by having the 2000 election snatched away fromhim.

Alongside the lecturematerial there are fleeting insights into Gore's private life. We hear himreminiscing about his childhood; we see him at the turning where he wrecked hiscar as a teenager; we watch him poring over spreadsheets on an Apple Mac. Thereis a surprising amount of footage of him walking through airway departurelounges. He talks movingly about how his priorities changed when his six-year-oldson almost died. We visit the farm on which he used to spend four months ofeach year as a kid (For the other eight, he was holed up in a small apartmentin a hotel in Washington DC where his father was a senator.)

This material is tantalisingbut unsatisfying. One can't help but wish that Guggenheim was able to gofurther in providing a full biographical portrait of one of the unluckiestfigures in recent US politics. That, though, was not the purpose of the film.The real intention was to bring Gore's travelling slide show on the environment(a presentation he has given more than 1,000 times) to the biggest audiencepossible.

Gore wants us to know that thesnow is disappearing on Kilimanjaro and that the ice caps are melting and thatthe world is currently prey to some of the most extreme weather in human history.

If he has to reveal a littlebit about himself to make us listen to his arguments about climate change,he'll do so, but he makes it very clear that he wants the science foregrounded. If he is a showman, he is a very reluctantone. The surprise is just how accessible the film remains in spite of hisreticence and the bleak message he has to share.

Production company
Participant Productions

US distribution
Paramount Classics

International distribution
UIP

Executive producers
Jeff Skoll
Davis Guggenheim

Producers
Laurie David
Lawrence Bender
Scott Z Burns

Cinematography
Bob Richman
Davis Guggenheim

Editors
Jay Cassidy
Dan Swietlik

Music
Michael Brook