Celebrity environmentalists

Actor Robert Redford has criticized President Barack Obama for what Redford sees as a lack of follow-through on environmental issues. Redford is a trustee of the Natural Resources Defense Council.

The Dave Matthews Band's Bama Green Project aims to make amends for the carbon dioxide emissions released by its tour buses and fans' automobiles. (June 20, 2012)

Australian actress Cate Blanchett, whose Sydney mansion is powered by solar energy, has appeared in TV commercials advocating for environmental issues. (July 25, 2012)

Time magazine named Richard Branson of Virgin records a "hero of the environment" in 2007. (Feb. 11, 2012)

Pearl Jam frontman Eddie Vedder is a surfer and has been active with The Surfrider Foundation, a conservation group. He also has an Earth First! tattoo on his right calf. (Oct. 24, 2010)

Late folk singer Pete Seeger was a longtime advocate for the environment. He co-founded Hudson River Sloop Clearwater in 1966. (Sept. 15, 2012)

Yoko Ono helped start the Artists Against Fracking advocacy group, which has targeted politicians like Gov. Andrew M. Cuomo. (April 2, 2013)

Actor Ted Danson has spent much time advocating for conservation of Earth's oceans. In 2011, he published a book, "Oceana: Our Endangered Oceans And What We Can Do To Save Them." (Sept. 21, 2010)

Palisades native Hayden Panettiere, an actress, has been a defender of dolphins and whales, confronting Japanese fishermen in 2007 along with The Whaleman Foundation.

Actress Alicia Silverstone is a supporter of PETA and published a vegan cookbook called "The Kind Diet." (Sept. 27, 2012)

Former Vice President Al Gore is widely known for spreading awareness about climate change, as documented by the film "An Inconvenient Truth."

Actor Mark Ruffalo organized screenings of "Gasland," an anti-fracking film, in Pennsylvania and has appeared on news programs to speak about the envronment. (Oct. 2, 2010)

Actress Cameron Diaz was named a 2009 "Hero of the Environment" by Time magazine for her environmental activism.

Actor Harrison Ford publicly urged the United States to ratify an international conservation treaty in 2010.

Famous anthropologist Jane Goodall was the president of the Scottish organization Advocates for Animals until 2008. She is also a vegetarian for environmental reasons.

Actor Josh Hartnett has supported Global Cool, a climate change charity in the United Kingdom that works to reduce carbon footprints.

The Canadian rock band Barenaked Ladies teamed with eco-friendly organization Reverb to use wind power to fuel a cruise ship that the band toured on.

Country music star Willie Nelson was given the Environmental Outstanding Achievement award by the federal Environmental Protection Agency for opening a biodiesel retail outlet in San Diego. (Nov. 1, 2012)

The rap group Beastie Boys worked with the eco-friendly organization Reverb in 2007. (1989)

Actor Orlando Bloom has also worked with Global Cool. (April 25, 2011)

Rocker Alanis Morissette has donated lots of time and money to charities but tries to focus especially on environmental causes.

Actor Edward Norton, whose father was an environmental lawyer, urged his fans to join the Be Green 2013 movement in January. (July 30, 2012)

Actor Brad Pitt traveled to New Orleans after Hurricane Katrina to promote a plan to rebuild the city in an environmentally friendly way.

A species of Colombian tree frog, Dendropsophus stingi, was named after Sting, the former bassist of The Police, for his efforts to save rain forests. (April 7, 2013)

Musician Neil Young's "Fork in the Road" album stood up to the U.S. car industry's environmental record.

California rockers Red Hot Chili Peppers dedicated their Big Day Out shows in early 2013 to Sea Shepherd, a conservation group on whose board of directors singer Anthony Keidis (right) sits.

Skateboard legend Tony Hawk released a video with Ziggy Marley to raise awareness about the environmental impact of cigarette butts in 2011.

Musician Ziggy Marley released a video with Tony Hawk to raise awareness about the environmental impact of cigarette butts in 2011.

Actor Tom Hanks drove around Los Angeles in a small electric car called an eBox to raise awareness about the environment. He has advocated for electric cars for years.

U2 frontman Bono and his band have championed the environment throughout their careers.

Actor Sean Penn traveled the country in a fleet of biodiesel buses in 2008 to try to empower young people and advocate for environmental and other issues. (AP / Oct. 5)

Actress Alyssa Milano appeared in an advertisement for PETA in a dress made solely out of vegetables. (May 15, 2012)

Actor Owen Wilson submitted a personal essay to The Green Book, which is about eco-friendly living, in 2007. (AP / May 19)

New York City Mayor Michael Bloomberg wants to be known as "The Green Mayor" and has stated he thinks climate change may have been a reason for Hurricane Sandy. (Jan. 18, 2013)

Arnold Schwarzenegger wrote an opinion piece in April for the Los Angeles Times advocating for environmental change in California, where he was once governor. (April 6, 2013. Photo by Errol Anderson.)

Model Gisele Bundchen served as an ambassador for World Environment Day in 2012. (June 30, 2003)

The website for NBA star Steve Nash's charity gives people tips on how to live greener lives.

"Entourage" star Adrian Grenier co-founded an eco-friendly website called Shift.com and supported President Barack Obama because of environmental issues. (Aug. 21 2012. Photo by Andrew H. Walker/Getty Images)

Billionaire Bill Gates has used his clout (and his money) to support the efforts of climate change scientists and other environmental initiatives. (AP / Sept. 27)

The band Maroon 5 has promoted recycling at its concerts and have headlined the Greenbuild International Conference and Expo.

Musician John Mayer played at Live Earth, a music festival raising awareness about global warming. (Dec. 10, 2009)

The band Radiohead has been one of the most prominent and aggressive acts to use eco-friendly touring. (April 14, 2012)

Jake Gyllenhaal said he wanted to act in "The Day After Tomorrow" because of the film's environmental themes. (AP / Sept. 21)