Hollywood's newest It Girl: Our Planet

She may be over four billion years old, but right now Mother Earth is more popular in Hollywood than Lindsay Lohan, Jessica Simpson and Nicole Richie combined. With everyone from silver-screen legend Robert Redford to tabloid target Scarlett Johansson hopping into eco-friendly Priuses, supporting environmental causes has never been trendier.

The 2007 Academy Awards highlighted the overwhelming popularity of environmental activism in Hollywood. The week prior to the awards ceremony, Global Green USA, an organization devoted to curtailing climate change by promoting green and eco-conscious living, held a pre-Oscar party at the trendy club Avalon. Oscar nominees Penelope Cruz and Leonardo DiCaprio co-hosted the event. Kirsten Dunst, Orlando Bloom and Ryan Gosling walked the appropriately green carpet. When Oscar Sunday came, paparazzi captured many attendees stepping out of hybrid cars instead of stretch limousines.

The Oscars ceremony itself included a Best Documentary win for "An Inconvenient Truth," the film that features former Vice President Al Gore warning viewers about the consequences of global warming. Gore's increased focus on environmental issues following his loss in the 2000 presidential race has caused a fundamental shift in his public image from stuffy politician to Hollywood celebrity. He appeared on the cover of Entertainment Weekly this summer and seemed comfortable and chummy with DiCaprio as they exchanged banter onstage at the Oscars. Many expect Gore to use his environmental efforts as a launching pad for a 2008 presidential bid.

Celebrity activism began with only a handful of devoted stars. Audrey Hepburn and Elizabeth Taylor were two of the first famous entertainers to devote their time and valuable media attention to the plight of third-world children and AIDS, respectively. Redford might be the first celebrity environmentalist, having purchased in 1969 the land that would eventually become Sundance, a retreat dedicated to both environmental conservation and original artistic vision.

Today, celebrity environmentalism is a widespread phenomenon. While many celebrities simply publicize living in an eco-friendly way — using recycled products, driving hybrids and trying to cut back on their "carbon footprints" — a number also attach themselves to specific groups. For nonprofit organizations struggling for media attention and private funding, a celebrity endorsement or special appearance can be a huge coup.

"Celebrities serve marketing and publicity purposes," said Sarah Wood, a senior at the University of Virginia who will be working next year for an environmental nonprofit group. Wood is the development coordinator for MIT's Earth System Initiative and managing director of the Chesonis Family Foundation. "It is great that we can invite Al Gore or Maroon 5 to an event at MIT and have a clip of the conference on the news. If more people learn [about our work], that's exciting," she said. Wood had her first exposure to the world of celebrity environmentalism at the Environmental Media Awards last fall. The Environmental Media Association aims to educate the entertainment industry about environmental issues. After meeting Daryl Hannah, the Red Hot Chili Peppers, Kristen Davis and others at the event, Wood recognizes the good a celebrity can do for her cause.

"The attention the film ['An Inconvenient Truth'] has garnered over the past months has spurred us to craft a conference at MIT featuring Al Gore in the next year," she said. "He's going to come to give his presentation alongside MIT scientists and celebrities from EMA."

Princeton students agree that the Hollywood trend can be a positive for reaching out to the average American.

"On a national scale, I do think the celebrity factor has helped more than hurt [environmental causes]," former president of Princeton Environmental Action Tom Brennan '07 said. "Actors definitely raise awareness, and for smaller issues, any press is good press."

Wood had a slightly different view. "Publicity seekers may not be appropriate for certain science-based events," she said. "Being green is most definitely a fad in Hollywood right now, and Nicole Richie and Wilder Valderrama are not as active as Leonardo DiCaprio and Daryl Hannah."

Still, Wood agrees with Brennan that any action is better than none.

"I would never criticize celebrities for jumping on the bandwagon," she said. "No matter how empty it seems, if Nicole Richie wears a dress made of recycled material and someone writes about it, it is a help."

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The increased popularity of green living in Hollywood is also a good barometer for mainstream America's shifting view of environmental issues.

"Being eco-conscious in increasingly more common because climate change is less of a fringe issue and more an accepted fact of life," Brennan said.

In the eyes of some Princeton students, however, celebrities who aren't completely devoted to a cause can distract from or even delegitimize the issues at hand.

"The fleeting trendiness of it doesn't last," co-president of Greening Princeton Kelsey Stallings '09 said. "It's only beneficial when the information sticks after the trend passes."

Brennan recognizes that people who are disinclined to believe scientific evidence supporting the existence of climate change probably won't trust celebrities either.

"A large segment of the population is definitely turned off by Hollywood campaigners," he said. "There's a lot about that culture not to like, and that can often overshadow legitimately good things coming from there."

Johnny Love '09 reacts negatively to celebrities' outspoken environmental stances. "I believe that celebrities have a negative effect on the nation when it comes to the environment," he said. "When [they] give talks and espouse views, it puts pressure on politicians to enact policy measures that might not make sense with what the truth is scientifically."

Overall, Princeton students appear to believe that scientific facts, and not celebrity endorsement, have a greater impact on the Princeton student body.

"[Celebrities] are actors, singers, models," Love said. "What Leonardo DiCaprio says has no greater effect on me than what a random stranger says. They are not scientists or experts."

Brennan connects this distrust of celebrities with Princeton students' academic, logic-based mindsets. "I think Princeton is probably less celebrity-obsessed and more celebrity-skeptical than the general population," he said. "I think this is an unequivocally good thing."