There are many ways to describe Leonardo DiCaprio: heartthrob, Hollywood megastar, serious actor, eligible bachelor. Now you can add one more: environmental activist.

The three-time Academy Award nominee has written, produced and narrated The 11th Hour, a feature-length documentary that sounds a serious alarm about the consequences of humanity’s harm to the global environment and cries for action to reverse the damage.

The 32-year-old actor became interested in environmental issues following a conversation ten years ago with then-vice president Al Gore, an early advocate of the existence of global warming and finding ways to alleviate its effects. Gore’s recent An Inconvenient Truth, another feature-length documentary decrying man’s impact on nature, not only won him an Oscar but also did well at the box office.

DiCaprio appeared alongside Gore at the Academy Awards last February, signaling that he’s following the former veep’s lead in getting the word out about the causes they both believe in. Although it remains to be seen whether The 11th Hour, which debuted in New York and Los Angeles on Aug. 17, will achieve the same popularity as Gore’s film, it carries, if anything, a stronger message.

The film serves up evidence that there’s not much time left to take action to reverse environmental damage—hence its title. “Not only is it the 11th hour,” says one of the doc’s many interviewees, “it’s 11:59 and 59 seconds.”

DiCaprio’s environmental credentials are firmly established. He sits on the boards of the Natural Resources Defense Council and Global Green USA. He also collaborated on two earlier environmental shorts—Global Warning and Water Planet—with Nadia Conners and Leila Conners Petersen, the two sisters who directed The 11th Hour.

The film has a complicated structure. Its elements include stock footage of environmental damage, shots of DiCaprio against various natural and man-made backdrops, computer-animated sequences of potential technical solutions for pollution caused by buildings and vehicles, and—interspersed throughout the film—bits of interviews with 54 environmental experts and quasi-celebrity commentators, including Mikhail Gorbachev and Stephen Hawking.

Weaving these elements together was a challenge, says Brian Gerber, one of the film’s producers and part of Tree Media Group. The nine-year-old Tree Media Group, which served as the film’s production company, was set up by Leila Conners Petersen and Nadia Conners with the mission of using the media to foster social goals. In addition to helping conceive the project, Gerber oversaw much of its physical production, including hiring the crew and coordinating logistics.

One of the hardest tasks, according to Gerber, was establishing a unified look—or at least one that made sense—while weaving together incredibly disparate elements. “The whole movie is a mix of media. It’s a mix of stuff we shot and different stock footage we used.”

Gerber hired three cinematographers for The 11th Hour: Peter Youngblood Hills shot original 16mm footage; Andrew Rowlands filmed additional original material on 35mm; and Brian Knappenberger served as DP for the 50-plus interviews, which were shot on video in multiple locations in the U.S. using Panasonic DVCPRO50 equipment. The sole exception was the interview with Stephen Hawking, which was shot in HD in the U.K.

Needless to say, gathering all that material was no easy task. “We shot in fits and spurts,” says Gerber. “We would try to do three interviews a day.” Each one could last two hours or longer, yet time limitations permitted using only a few seconds from each in the film.

While Knappenberger was wielding the Panasonic cameras, Rowlands was fielding 35mm gear from Panavision outfitted with reels of Fuji film stock. Rowlands gathered shots of DiCaprio speaking to the camera, commenting on the ills of the environment and his hopes for its healing.

Rowlands had worked with DiCaprio on earlier projects, having served as camera operator on three Martin Scorsese-directed, DiCaprio-starring movies: Gangs of New York, The Aviator and The Departed. After the latter film wrapped, Rowlands told the actor, “If you ever need a hand, give me a call.”

DiCaprio—or his people—called. In discussing film formats, “Leo and I talked about those big, majestic outdoor locations where we would be shooting, like the Sierras,” Rowlands recalls. “We wanted a big, widescreen aspect ratio for those. Plus, it was Leo, and we wanted to make him look really good while delivering his message.”

So the production team decided to use 35mm, and then “Panavision came through with a Platinum package,” says the DP, who made use of Panavision’s Primo lenses, a Libra camera head and crane technology from Panavision’s Remote Systems division.

Mindful that the 35mm footage would have to be mixed with the video footage of the interviews, Rowlands overexposed his film a bit. “I did that so we could get more contrast out of it, so it would match the video stuff, because the video can be contrasty. If we had been more flat, [the 35mm footage] would have stood out a lot more.”

Rowlands shot with sound. “A lot of the locations, like Simi Valley, were good for that,” he says. “Occasionally the odd plane would fly overhead, but the sound was fine, even in downtown L.A. And we could take stuff away in the final mix.”

Other original footage was shot by Hills on 16mm using Kodak stock. “We were big fans of his work as an artist,” says Gerber. “He does beautiful work on 16, so we turned Peter loose with some guidance and direction to go out and capture some evocative stuff. We thought it would be a good mix with the other material.”

Taking Stock

Then there was all the stock footage that was used—literally from hundreds of sources, on dozens of formats, of varying quality. “Oh, man! Dealing with it was a monstrous job,” says Gerber. “Our team here, especially Stephan McGuire, who was associate producer, did a hero’s job leading that charge, bringing it all in and getting it licensed.”

The footage, which supports DiCaprio’s narration as well as the arguments made in the multiple interviews, consists of shocking scenes and natural disasters. We see images of tsunami devastation, Hurricane Katrina misery, deforestation, Arctic melting, animals being slaughtered, belching chimneys and gridlocked traffic.

“We got the footage mostly on tapes,” says Gerber. “We would do selects from the tapes and cut it together. Then we would order the masters, which normally came in on Beta or DigiBeta but in some instances on film.”

Tree Media worked with more than 300 different footage providers, including BBC Motion Gallery and National Geographic. In addition, the production used footage from various organizations and nonprofits such as Greenpeace. There are about 2,000 stock footage shots in the movie.

“BBC Motion Gallery met with us several times over the course of the project, provided research for everything we needed and even came to screenings to offer their opinion on how we were using the shots. They walked us through the approval process of licensing news archival clips of well-known anchors,” says Conners Petersen. “This was our first foray into licensing pre-existing footage, and BBC Motion Gallery was incredibly accommodating. That, coupled with their very practical and user-friendly ‘search widget’ for the Mac, made it much easier to find the exact shots we were looking for.”

In addition to illustrating the film’s arguments, Gerber sees the stock material making an additional point. “Part of the idea of using all that different stock was in line with the idea of the movie, which is recycling. Rather than us flying to the Arctic or Greenland or Africa and spending all the resources and burning carbon going to those places, a lot of the material [we wanted] already exists, so there was an environmental reason for using that footage as well.”

Stock footage aside, The 11th Hour’s final form flowed from the gathered interviews. “We transcribed every interview,” says Gerber. “Then, before the editors came on board, Leila, Nadia and the rest of the creative team here went through the transcripts and identified which parts we wanted to use. Basically, we crafted a script from the transcripts, then we gave the footage to the editors. They watched everything, but they also had our transcript notes, which were timecoded, so they could say, ‘Okay, this is the part they liked.’”

The 11th Hour was edited on Avid systems at Tree Media’s own facility in Santa Monica, set up specifically for that task. The overall editor was Pietro Scalia. Luis Alvarez y Alvarez served as the primary day-to-day editor. Dealing with a large amount of material, the creative editorial process took about a year and a half. Finishing took place at the Motion Picture Imaging division of Warner Bros. (Warner Independent is the film’s domestic distributor.)

If The 11th Hour achieves critical and financial success, it would be a bonus for the producers. At the same time, they feel they can contribute to their cause just by making available all the information they gathered while creating the film. Because there is so much of it, the lion’s share of that information is not on the print that is being released.

Tree Media is archiving all the interviews, which total over 100 hours. It could all be made available online some day, according to Gerber, and there are already plans to release some of it on DVD.

Tree Media has launched the Web site www.11thhouraction.com to spur commitment to the causes espoused by the film. “We’re running a social-action campaign,” says Gerber. “We want to get people to take action after they’ve seen the movie.”