An Inconvenient Truth, a climate change documentary by former US presidential candidate Al Gore, is opening across the UK.
It looks at scientific evidence on the causes and likely impacts of a warming world and at climate change politics.
Mr Gore says he wants to make ordinary people aware of the "terrifying" reality of climate change, and demand action from their political leaders.
More than two million people have seen it since its US release 16 weeks ago.
Its UK release comes in a week which has seen scientists release evidence that:
- old Arctic ice may be melting spectacularly fast
- humanity's greenhouse gas emissions are probably stoking the power of hurricanes
- observed temperature rise cannot be explained directly by changes in the Sun's output
An Inconvenient Truth is based on a lavishly-illustrated public lecture which Mr Gore has given in the US and elsewhere.
"I tried to the best of my ability [when I was vice-president] to act on climate change, and whatever failures that occurred were not for lack of effort," he told BBC News.
"There is incredible resistance and denial, which is why I decided to reach out directly to the public, making this presentation more than 1,000 times, plus the movie and the book, to a point where they'll demand that political leaders deal with it."
The film features Mr Gore speaking to a public audience, reminiscing about events in his personal life, and discussing his visits to China and other nations which are balancing concerns over climate impacts with the need to progress economically.
The film shows Patagonian glaciers have melted over 30 years
He discusses the death of his sister from lung cancer, comparing the stance of tobacco companies then with the stance of oil, coal and car companies today.
He cites cases of scientists who, he says, have been persecuted, even hounded from their jobs, because they have raised the "truth" about climate change - from which the movie gets its title.
In the US, An Inconvenient Truth has become the third highest grossing documentary of all time, returning more than $23m (£12m).
Environmental groups hope it will receive similar attention in Britain.
"It's a cliche to say a book or film will change your life, but this film is truly inspirational," said Ashok Sinha, director of Stop Climate Chaos, an umbrella organisation for campaigning groups.
"It's brilliantly clear both on the science and the gravity of where the policy of business as usual has got us today, and where it will lead if we don't start taking personal and political action now."