These environmental warriors are on the front lines of the fight to stop climate change, working with organizations worldwide that seek to protect the ocean, provide clean water, reduce dependence on fossil fuels, stop fracking and much more. They don’t hesitate to get arrested, stand up before the United Nations, or sail the Sargasso Sea in their quest to bring the urgent message to the public. They’re some — though by no means all — of the high-profile names in Hollywood and beyond that are increasingly making climate a priority for their activism. Find out more about how you can get involved by clicking on the organizations’ names.

James Cameron and Suzy Amis Cameron
Carbon reduction avatars

This power couple has been championing environmentalist causes for decades. Suzy Amis Cameron has led a charge toward plant-based eating in efforts to reduce the dramatic carbon footprint that meat protein creates. James Cameron, the filmmaker behind classics such as “Titanic,” has woven climate-conscious themes into franchises like “Avatar.” He tells Variety the forthcoming three sequels will do the same. (Read more here.)

David Attenborough
Veteran U.K. spokesman
Experts now talk about the “Attenborough effect” when describing changes in consumer behavior wrought by British broadcaster and naturalist David Attenborough. He may be 93, but he has been campaigning tirelessly to change minds on climate change. In the past year, he has spoken on the subject at the U.N.-sponsored climate talks in Poland, the World Economic Forum in Switzerland, the World Bank/IMF Spring Meetings in Washington, D.C., and the Student Conference on Conservation Science in Cambridge, U.K., among other events. But he continues to make his greatest impact through his TV series, which have recently included Netflix’s “Our Planet” and the BBC’s “Climate Change — The Facts.”

Matt Damon
Clean water crusader

The “Ford v Ferrari” star has long been a crusader for clean water and infrastructure in the developing world. In 2006, Damon launched an NGO called the H20 Africa Foundation, which three years later would combine with Gary White’s WaterPartners to form Water.org. Ten years on, the entity remains a relevant and successful force in educating and improving underserved communities around the globe.

Dave Matthews Band
Sustainable touring pioneer

The Dave Matthews Band has played numerous environmental benefits, including the NRDC’s Music Saves Mountains and a benefit for Standing Rock. Since 2005, the band has partnered with the nonprofit organization Reverb on the BamaGreen Project, an ambitious program to lessen the group’s environmental footprint. The project includes using biodiesel for buses, sourcing local farms for catering, recycling and composting backstage waste and funding solar and wind energy projects. Matthews, a U.N. Environment Programme goodwill ambassador, owns the wine label Dreaming Tree, which supports The Wilderness Society and Living Lands & Waters. (Read more here.)

Laurie David
Documentarian with impact

The writer and producer, a long-standing environmental advocate, is best known for producing “An Inconvenient Truth,” the 2006 Oscar-winning documentary about Al Gore’s campaign to raise awareness about global warming. She has also produced films on genetically modified foods (“GMO OMG”), animal poaching and conservation (“The Last Animals”), and sustainable agriculture (“The Biggest Little Farm”), in addition to “An Inconvenient Sequel: Truth to Power,” the 2017 film that followed up on Gore’s climate change awareness efforts. David co-wrote “The Down-to-Earth Guide to Global Warming.”

Leonardo DiCaprio
Philanthropist with content

The Oscar-winning actor is arguably the most visible Hollywood figure at the front lines of the climate crisis. DiCaprio walks his walk through sizable donations, calls to action in documentary films and regular public remarks about natural disasters, extinction and other symptoms of climate change. In August, he donated $5 million to combat devastating wildfires in the Amazon rainforest through the organization Earth Alliance, which he co-chairs with philanthropist Laurene Powell Jobs. Notable contributions on film include this summer’s HBO doc “Ice on Fire” and the Toronto-premiering “And We Go Green,” about professional drivers on the international Formula E circuit.

Marshall Herskovitz
Fossil fuels fighter

The “Thirtysomething” and “Nashville” producer has been a climate activist for 20 years. In 2005, testifying before Congress, Herskovitz called for an immediate World War II-style national mobilization, only to discover that mainstream environmental organizations had adopted far less aggressive positions. He spent several years building a large-scale communications campaign for climate solutions and in 2007 co-founded 1Sky, an activist organization that later merged with 350.org. For the past two years he has been an adviser to The Climate Mobilization, which advocates the policies Herskovitz urged on Congress 14 years ago.

Alan Horn
NRDC chairman

Cindy Horn
Climate Reality Project

The leader of Disney’s industry-dominant film division is also an established environmentalist. Horn and his wife, Cindy Horn, co-founded the Environmental Media Assn. with Lyn and Norman Lear in 1989 to help bring environmental messages and concerns to the attention of artists in music, film and television. In 2018, Horn was appointed chairman of the Natural Resources Defense Council, one of the world’s most active environmental advocacy organizations. He’d been vice chairman of the organization since 1995 and a trustee since 1991. Horn sees the considerable commitment to serving as a leader of NRDC as his effort to “leave our children a livable world.” Cindy Horn is also on the board of Al Gore’s Climate Reality Project.

Norman Lear
Lyn Lear
Climate and political activists

The iconic TV producer, who helped create classic sitcoms like “All in the Family” and “The Jeffersons,” is also known for his political and social activism via organizations such as his People for the American Way advocacy group. Lear, his wife, Lyn, as well as Cindy and Alan Horn, founded the Environmental Media Assn. In addition to building awareness of environmental issues via programming and public service announcements, the group hosts the EMA Awards and presents the Green Seal award, recognizing environmentally responsible production efforts. The Lear Family Foundation, created in 1997, supports causes that include Global Green, Heal the Bay, the Natural Resources Defense Council and the Rainforest Alliance.

Julia Louis-Dreyfus
Oceans and parks activist

The “Seinfeld” and “Veep” star works with the Waterkeeper Alliance, a nonprofit focused on protecting clean water sources worldwide, and The Trust for Public Land, a group that aims to create parks and push for legislation to fund conservation. Ahead of the 2016 election, Louis-Dreyfus created a short video for the group NextGen Climate in which she endorsed Hillary Clinton for her position on climate change and clean energy. Proactive in environmental issues — her Montecito, Calif., home is optimized for energy efficiency — Louis-Dreyfus sits on the board of Heal the Bay and is an honorary board member of Heal the Ocean, in addition to occupying a seat on the leadership council for the Natural Resources Defense Council.

Ed Begley Jr.
He walks the walk

Veteran actor Ed Begley Jr., who was galvanized by the very first Earth Day in 1970, has been the poster child for the environmental movement for several decades. But threats to the planet are growing more dire, so he says Hollywood needs to “up the ante” with its messaging about the crisis. “The predictions are ahead of schedule; there’s more ice melting,” he says.

“The media is quite important,” Begley Jr. continues. “There’s no time to go door to door.”

He points out that doing the right thing for the climate needn’t be painful or expensive: “We have the toughest green laws in California, and our economy is thriving.” The actor urges corporations to double their efforts on green programs and have their leadership get the word out about what they’re doing.

Begley Jr. and his wife appeared in the video series “On Begley Street,” which detailed their efforts to save water and energy at home, and he says there are plenty of ways to make a difference. Families can invest in renewable energy, eat less meat, buy a rain barrel, use an energy-efficient thermostat and aim to have a LEED Platinum home, which results in low energy bills.

“The cost of doing nothing is quite severe — flooding and wildfires. That’s the most expensive choice ever.”

Don Cheadle
Clean energy warrior

On screen, he was the War Machine, but in real life, the Oscar-nommed actor is an Avenger for climate justice. Along with the Hulk, aka Mark Ruffalo, Cheadle works with the Solutions Project, an organization devoted to female leadership and leaders of color working for clean energy in their communities. The U.N. Environment Programme goodwill ambassador says his interest in protecting the environment is “to preserve the only home we all have and to protect the biodiversity that ultimately will protect us all as well.” Cheadle points to youth movements like the Zero Hour kids as especially important voices surrounding the climate crisis.

Content is also key. “One could argue that the entire plot of ‘Infinity War’ was playing with those exact themes,” he says, “and the subject matter is smuggled into TV and movie narratives more and more. It can’t not be.”

Being entertaining doesn’t have to mean purely escapist fare, he says. “It can also mean engaging.” Cheadle calls for the entertainment industry to get in involved in both political and grassroots campaigns to keep pushing for solutions. “I’ve only noticed an uptick in activity,” he says. “We’re in this s— for the long haul. We have to be.”

Adam McKay
Mobilizer for change

Despite his start making lowbrow comedies with Will Ferrell, McKay has transformed into a geopolitical force through his storytelling and firebrand calls for public action. McKay is a member of the advisory board of The Climate Mobilization, whose mission statement is as dramatic as any of McKay’s script loglines: The group hopes to inspire “a WWII-scale mobilization to reverse global warming and the mass extinction of species in order to protect humanity and the natural world from climate catastrophe.” McKay signaled earlier this year that his next feature film will tackle the ethics of the fossil fuel industry and humanity’s apathy for the climate crisis.

Bill Nye
Viral messenger

Bill Nye has become a key face of science-related programming on TV. After 20 years as an engineer in Seattle, he broke into TV as “Bill Nye the Science Guy” and more recently is hosting “Bill Nye Saves the World” on Netflix. In May he launched the podcast “Science Rules! With Bill Nye,” a weekly magazine-style serving of science-related stories and informational segments, and went viral for his appearance on “Last Week Tonight With John Oliver” when he lit a globe with a blowtorch. “What I’m saying is, the planet’s on f—ing fire,” he said on the show.

Gwyneth Paltrow
Sustainable celebrity

Gwyneth Paltrow is aware that one of the key components of an optimal lifestyle is, um, a habitable planet. The Academy Award winner has been celebrated by the Environmental Media Assn. and the Environmental Working Group for carbon-neutral living as well as using her celebrity to spread a message of sustainability. She has dramatically stepped up her game as an entrepreneur, leading a crusade against toxins in beauty and household products via her company Goop. “We use Goop to connect the dots for readers between environmental health and what is happening in our households and bodies, and to bring a heightened consciousness to all of our consumption patterns,” Paltrow says.

Pearl Jam
Shredders saving Earth

Since 2003, Pearl Jam has promoted green touring by taking into consideration the carbon footprint resulting from its tours and donating a portion of ticket sales to environmental causes. Frontman Eddie Vedder, who has been known to write love songs to the ocean, is curating the Ohana Music Festival in Dana Point, Calif., Sept. 27-29, earmarking a portion of proceeds to benefit local beaches. Guitarist Stone Gossard has long advocated for reducing carbon footprints and invested in reforestation efforts throughout the world. The band’s efforts have included partnering with Conservation Intl. on the Oceans Campaign, supporting the work of the Gulf Restoration Network in wetlands and collaborating with EarthCorps.

Robert Redford
Steward of the land

The elder statesman of Hollywood multi-hyphenates is also one of its pioneering environmental activists. Since the early 1970s, Redford has used his celebrity to advocate for conservation and green causes. He’s pledged more than 5,000 acres of his land holdings in Sundance, Utah, to be protected from development and has made numerous appearances before Congress and the United Nations on environmental issues. In 1975, Redford took his case against the construction of a coal-fired power plant in southern Utah to “60 Minutes,” demonstrating the power of Hollywood stars to bring attention to environmental concerns. The Oscar winner has been a trustee of the Natural Resources Defense Council since 1972.

Kevin Reilly
Networker for action

The veteran TV programming executive has been active on environmental issues since becoming engaged during his years at Cornell University in the 1980s. Reilly, who is chief content officer of HBO Max and president of TNT, TBS and TruTV, is chairman of the California board of The Nature Conservancy and a former board member of the Environmental Media Assn. He’s pushed for green improvements on TV sets and in network suites during his long run as a top executive at NBC, FX, Fox and Brillstein-Grey Entertainment.

Mark Ruffalo
Fracking opponent

This longtime indie treasure and Marvel star isn’t just green on screen as the Hulk — he’s a passionate environmentalist whose focus in recent years has turned to the fight against fracking. In 2016, he executive produced and narrated the documentary “Dear President Obama,” criticizing the leader for expanding the controversial practice of applying pressure to rock formations to speed up the release of natural gas and petroleum. He also appeared in the 2017 doc “In This Climate” to push the issue. At the end of the year, he’ll take the cause to the screen in “Dark Waters,” a new drama from Todd Haynes. Ruffalo will play a lawyer who brings an international scandal to light by suing the DuPont chemical company for poisoning the Ohio River for decades.

Jaden Smith
Plant-based multitasker

Actor, rapper, budding iconoclast and print model Jaden Smith — son of Will and Jada Pinkett Smith — is not so obsessed with brand building and artistry that he can’t take time to hug the planet. The 21-year-old is the recipient of an honor from the Environmental Media Assn. for his work with Just Water, which ethically sources non-plastic containers. Smith got a lot of love in Los Angeles this summer for launching a free vegan food truck (named, naturally, I Love You) to serve the homeless population lining Skid Row. This fall, he’ll participate in the Al Gore-sponsored global education event 24 Hours of Reality.

Emma Thompson
Rebel for ecological justice

The Oscar-winning actress recently played an environmentalist locking horns with the authorities in a short film that featured real-life footage from Extinction Rebellion’s wave of headline-grabbing London protests. The film and TV star also vocally joined the activist group’s U.K. demonstrations, notably from its signature pink boat. “The climate change argument is now a race between consciousness and cataclysm,” Thompson said in a video message posted on Extinction Rebellion’s Facebook page. “It is time to stand up and save our home.” She has also joined Barack Obama in backing Earth Hour, a World Wildlife Fund campaign that advocates for urgent action on environmental issues.

Greta Thunberg
Powerful young voice

At 16 years old, Greta Thunberg carries a lot on her shoulders. In August 2018, the Swede protested in front of the Swedish Parliament for swift action on climate change. The school strike for climate, thus named because Thunberg skipped school that day, began a global youth movement — some 1.6 million in more than 100 countries have participated — that has picked up momentum since.

Thunberg’s efforts on behalf of the world climate crisis, a leading cause of kids her age, have taken her to the World Economic Forum, the European Parliament in Strasbourg, the National Assembly in Paris and the United Nations, where she spoke to the assembled of the “burden you leave to us children … because we are facing an existential threat and there is no time to continue down this road of madness.” On Aug. 30, she organized a protest outside the U.N. in New York City — it drew more than 1,000 young activists — ahead of the Global Climate Strike on Sept. 20-27 and the speech she will give at the U.N. Climate Action Summit this month.

Putting action to words, Thunberg arrived in New York following a two-week transatlantic journey on an emission-free 60-foot racing boat. Once ashore, she was met by scores of believers cheering on her efforts. As Thunberg has said: “You are never too small to make a difference, and if a few children can get headlines all over the world just by not going to school, then imagine what we could all do together if we really wanted to.”

Pharrell Williams
Using music for the message

“Climate change is one of the most defining issues of our time that threatens our very existence on Earth,” Pharrell Williams told the assembly at the COP 21 conference in 2015 in Paris. Though his 24-hour Live Earth concert with Al Gore of that year was suspended due to the terrorist attacks in Paris, he participated in a social media campaign to celebrate the U.N.’s World Water Day in 2016 and made a cameo in Gore’s 2017 “An Inconvenient Sequel: Truth to Power.” His 2017 single “100 Years,” pressed on clay vinyl, will be released in 2117. Williams is the creative director of Bionic Yarn, which creates textiles out of recycled plastic, and collaborated with G-Star Raw to produce clothing made from recycled ocean plastic.

Shailene Woodley
Grassroots connector
The “Divergent” and “Big Little Lies” actress recently teamed up with Greenpeace, venturing out into the Sargasso Sea to examine plastic pollution in the ocean and advocating for the U.N. to create a treaty to protect at least 30% of the world’s oceans by 2030.

“It came from a desire to understand more holistically what’s going on with our planet,” Woodley says of her Greenpeace expedition. “I feel like you can’t talk about environmentalism or racism or sexism or any type of disparity or injustice without addressing the whole picture, and the oceans are a major part of environmentalism that I didn’t know about.”

She has also worked on a video for Conservation Intl. advocating against deforestation, an activity that accelerates climate change. In 2016, Woodley — who was arrested while protesting the Dakota Access Pipeline — was honored by the Environmental Media Assn. with the Female EMA Futures Award for her activism related to climate change, the pipeline and other issues.

“A huge way we in the entertainment industry can be impactful in this world is not using our voices to tell people what to do, but using our platforms to connect people on the ground, in the grassroots movements, with our audiences,” she says.

Leo Barraclough, Stewart Clarke, Matt Donnelly, James Patrick Herman, Cynthia Littleton, Elaine Low, Pat Saperstein and Will Thorne contributed to this report.