When Al Gore ran for US president, in that infamous election of 2000, he was constantly ridiculed for his wooden public performances. Along comes a film starring the Gore man, giving a slide show, and surprisingly, it is receiving warm praise from mainstream critics in the US and floating on a draught of greenhouse gases up the box office charts.

Global warming is a subject close to Gore's heart. The film shows how since he was robbed of the presidency, he has reinvented himself as the respectable face of eco-warriordom. Davis Guggenheim's documentary follows Al Gore as he goes on tour with his high-tech lecture in which he tells audiences that immediate action is needed to reduce greenhouse gas emissions and to tackle what he calls solveable problems, before it is too late.

"If you look at the 10 hottest years ever measured, they've all occurred in the last 14 years," says Gore, using a slick, computer-generated map to highlight the impact of rising sea levels.

The documentary should set straight any climate-change doubters who are still out there: it is real, it is happening right now, and the consequences could be catastrophic for the future of civilisation if we don't act immediately.

The big question most climate scientists don't seem to agree on is exactly how global warming is going to impact the planet. Weather and climate are chaotic systems making it difficult to make accurate predictions, but one of the doomsday scenarios (there are several), posited here, is that temperatures could keep rising until Greenland starts melting at such a rate that our coastal cities start disappearing under water. Gore suggests that we may have 10 years to change our ways before we are past the point of no return. That could be a hopeful message or not, depending on what climate change model you subscribe to.

The film offers many personal insights into the man most of us never really knew, including how the near-fatal accident of his young son in 1989 inspired him to take a leading role in highlighting climate change. He seems more at ease with people here, and leavens the heaviness of his subject with occasional humour. The presentation, with its slick, state-of-the-art graphics and computer-imagery, is polished and accessible, with unsettling evidence, such as before and after images of the disappearing snows of Mount Kilimanjaro in Tanzania and proliferating hurricanes, including Katrina, to illustrate the dangers to life on Earth. Watch the trailer and find screenings worldwide on the movie's web site at www.climatecrisis.net.