As the movement to legalize marijuana gains traction, some environmental activists and celebrities are throwing in their support for legalization, while others have simply admitted to using pot at some point in their lives.

Many celebrities and politicians have publicly come forward as either current or reformed pot smokers. There are some, like Paul McCartney, who have reportedly left those days behind them. At the age of 69, McCartney told Rolling Stone that he smoked his share already. "Enough's enough," he said. On the other end of the spectrum are those still rolling, like famous director Oliver Stone. “It can be done legally, safely, healthy,” Stone insisted in a recent Associated Press interview.

Some environmentalists have voiced concerns over a report suggesting indoor marijuana growing may account for one percent of U.S. electricity consumption, with advocates arguing that by legalizing pot, the footprint could be reduced with more outdoor growing.

Take a look at the slideshow below of some environmentalists who have admitted to smoking pot, and share your thoughts on the marijuana debate in the comments below.

HuffPost Live will be taking a comprehensive look at America’s failed war on drugs Sept. 4 from 12-4 p.m. EDT and 6-10 p.m. EDT. Click here to check it out -- and join the conversation.

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  • Brad Pitt

    The <a href="" target="_hplink">"Make It Right" founder</a> and <a href="" target="_hplink">African wildlife supporter</a> has 'fessed up to other green activities in his past. In an interview with Parade magazine in 2009, Brad admitted that his early Hollywood days <a href="" target="_hplink">included some psychedelic downtime</a>. "I liked to smoke a bit of grass at the time, and I became very sheltered. Then I got bored. I was turning into a damn doughnut, really."

  • Morgan Freeman

    Morgan Freeman is a strong, but silent, environmental force. Not only did he narrate the <a href="" target="_hplink">Academy Award-winning documentary March of the Penguins</a>, but he also lent his voice to <a href="" target="_hplink">a PBS series about eco-consciousness</a>, supported the <a href="" target="_hplink">Mississippi Animal Rescue League</a>, advocates for <a href="" target="_hplink">natural disaster relief</a>, and sat on the <a href="" target="_hplink">Board of Directors for Earth Biofuel</a> (now defunct). How does he do it all without going crazy? "Never give up the ganja," <a href="" target="_hplink">Freeman advised in a 2003 interview</a> with The Guardian.

  • Cameron Diaz

    Known for <a href="" target="_hplink">playing against the stereotype of a demure blonde</a>, Cameron Diaz shocked again with her confession on the George Lopez show. The eco-driven star grew up in Long Beach with Snoop Dogg, and admitted she probably bought weed from him back in the day. "So you were green even in high school!" George Lopez exclaimed, giving a nod to <a href="" target="_hplink">Diaz's environmental activism</a>.

  • George Clooney

    <a href="" target="_hplink">George Clooney may be the arrested activist</a> we all know and love, but back in the day his illegal activities were less politically motivated. In an interview with The Daily Beast, Clooney admits that the skeletons in his closet haven't primed him <a href="" target="_hplink">for a political future</a>. "I f--ked too many chicks and did too many drugs, and that's the truth," he told the news site. He goes on to note that a smart campaigner would have to put it all out on the table and say "I did it all. I drank the bong water."

  • Natalie Portman

    As <a href="" target="_hplink">Hollywood's favorite vegan-turned-vegetarian</a> settles into family life, she has been forced to relinquish her youthful fun. "I smoked weed in college, but I haven't smoked in years," <a href="" target="_hplink">Portman told Entertainment Weekly in 2011</a>. "I'm too old. I wish I was that cool, but I'm like an old lady now." Her admission came a few weeks before the starlet's pregnancy announcement.

  • Mark Ruffalo

    Sometimes you can get high without even realizing it, as Mark Ruffalo learned the hard way. <a href="" target="_hplink">The famous anti-fracking activist and Huffington Post blogger</a> recounted a story on the Graham Norton Show about a prop gone wrong on opening night, when a stage hand <a href="" target="_hplink">swapped a fake joint for a real one</a>. "At the end of the play, I had the best review of my entire career!" Ruffalo fondly recounts in this clip.

  • Michael Bloomberg

    <a href="" target="_hplink">A notoriously "green" politician, New York Mayor Michael Bloomberg</a> can connect with his younger, liberal citizens on many levels. That includes his past indulging in reefer. The mayor stirred up controversy in 2002 when he responded ''You bet I did. And I enjoyed it,'' <a href="" target="_hplink">when asked if he ever smoked marijuana</a>. Bloomberg said he regretted making the comment, even though it "was truth."

  • Sir Paul McCartney

    Paul McCartney, ex-Beatle, Arctic activist and <a href="" target="_hplink">HuffPost blogger</a>, is not shy about <a href="" target="_hplink">his pot-filled past</a>. However, he was finally ready to give it up <a href="" target="_hplink">at the ripe age of 69</a>. "I smoked my share," McCartney told Rolling Stone. "Enough's enough."

  • Barbra Streisand

    As an avid <a href="" target="_hplink">climate change initiative supporter and conservationist</a> (according to Politico), Barbra Streisand knows the importance of the environment. But she also knows how important it is to be comfortable in your personal environment. In an interview with Rolling Stone, <a href="" target="_hplink">Streisand remembers how she used to loosen up on stage</a> in Vegas: <blockquote>"Anyway, since I get nervous in places like Vegas, it occurred to me to do this funny little routine--actually telling the audience about my hangup. The point was, you shouldn't rely on emotional crutches. It was almost a sermon--no crutches, people; crutches are a no-no. Then at the end, I'd take out a joint and light it. First, just faking it. Then I started lighting live joints, passing them around to the band--you know. It was great--it relieved all my tensions. And I ended up with the greatest supply of grass ever. Other acts up and down the Strip heard about what I was doing --Little Anthony and the Imperials, people like that--and started sending me the best dope in the world. I never ran out. Hm ... I wonder if I should tell that story."</blockquote>

  • Al Gore

    The former vice president of the United States, known for his <a href="" target="_hplink">dedication to global warming education</a>, has not shied away from his less-than-legal past. According to OnTheIssues, <a href="" target="_hplink">Gore allegedly admitted to using marijuana</a> after coming back from Vietnam. "When I was young, I did things young people do," he justified to the Washington Post in 2000.

  • Michael Pollan

    <a href="" target="_hplink">Renowned environmentalist and author Michael Pollan</a> may not have the "stoner look", but he readily admits that he used to grow his own pot. In his book "The Botany Of Desire" <a href="" target="_hplink">he makes mention of his marijuana-growing past</a>, and even discusses it in The New York Times Magazine. "A bit of historical perspective, by way of a confession," he begins. "Not only did your correspondent once inhale but, like a great many other gardeners (and nongardeners) of my generation, I also once grew."

  • Woody Harrelson

    <a href="" target="_hplink">Woody Harrelson, a vegan and anti-oil activist</a>, has been a vocal advocate of the pro-marijuana movement. Besides for narrating <a href="" target="_hplink">the documentary Grass</a>, Harrelson sits on the <a href="" target="_hplink">advisory board for NORML</a>. And while supporting marijuana legalization is not the same thing as smoking it, <a href="" target="_hplink">Harrelson was arrested for possession of hemp seeds</a> and later acquitted of all charges, according to Reuters. Also, check out <a href="" target="_hplink">these pictures of him hanging out with a suspiciously green baggie</a>.

  • Eddie Vedder

    Eddie Vedder, lead singer of Pearl Jam, has taken great strides with the rest of the band in being <a href="" target="_hplink">as environmentally friendly as possible</a>. He also isn't shy about his psychedelic past. When discussing his musical influences with SPIN magazine, <a href="" target="_hplink">Vedder admitted that he may not have the clearest memories</a> of his early musical influences. "Those were the years when I was smoking pot, so there might be a few things lost to memory," he told the magazine.

  • Oliver Stone

    Oliver Stone is an international marijuana smoker. According to the AP, <a href="" target="_hplink">he has smoked weed from all over the world</a>, yet prefers the home grown stuff and isn't afraid to admit it. "There's good weed everywhere in the world, but my God, these Americans are brilliant," Stone said. The famous director is also an avid animal lover, <a href="" target="_hplink">narrating a PETA expose called "End The War On Animals."</a>