Davis Guggenheim's 2006 Al Gore slideshow on climate change. Won Best Documentary Oscar; arguably the most-influential climate-message film ever made.
From Wikipedia
An Inconvenient Truth is a 2006 American documentary film directed by Davis Guggenheim about former vice president of the United States Al Gore's campaign to educate people about global warming. The film features a slide show that, by Gore's own estimate, he has presented over 1,000 times to audiences worldwide.