Can celebrities influence environmental issues? Experts weigh in.

ABC News is taking a look at solutions for issues related to climate change and the environment with the series, "The Power of Us: People, The Climate, and Our Future."

Your eyes do not deceive you -- notable public figures are teaming up with sustainable brands and environmental movements more than ever before.

The sustainability movement is increasingly getting a boost from famous faces as celebrities lend their voices to causes close to their hearts and environmental issues that they are most concerned about, experts told ABC News.

The idea of celebrity endorsements is a well-known phenomenon, but the growing trend of famous people promoting environmental causes is emerging at the same time that the climate crisis is inching further into the public awareness, which amplifies the importance of getting messages promoting environmental action to the masses, Christy Denckla, an assistant professor of social and behavioral sciences at Harvard University, told ABC News.

Celebrities, with their wide reach and significant following, could potentially have the capacity to "really mobilize tremendous action" at a scale to effectively address change, Denckla said.

They also could provide a focal point for a complex topic such as environmentalism, where public messaging can range anywhere from cautioning against overconsumption, to biodiversity conservation to the ranking of the most dangerous greenhouse gases and where the emissions come from, Thomai Serdari, professor of marketing at the New York University Stern School of Business and director of the Fashion & Luxury MBA, told ABC News.

"I think the consumer has had difficulty understanding where the truth is and who to believe," Serdari said.

InStyle Fashion Director Kevin Huynh has noticed a "dramatic shift" towards brands and celebrities championing environmental initiatives, as transparency becomes an important factor for consumers.

"With such a wide breadth of information available at their fingertips, they no longer want to buy into anything that doesn't align with their personal beliefs," Huynh said.

The more household names that get involved in environmental causes, the better, Serdari said, adding that authenticity, passion and leading by example are integral in getting the message across as well. Celebrities need to be consistent and "constantly" talk about their projects and demonstrate how the causes they're fighting for impact people's lives. People who are passionate have an easier time explaining the issues more clearly and can ignite passion in others, she said.

"People are skeptical," Serdari said. "Those who don't understand what sustainability is, they're skeptical."

Many notable figures are natural-born storytellers and are able to bring their passions and personal lived experiences to the forefront of the causes they promote, Carolina García Jayaram, CEO of the Elevate Prize Foundation, which honors celebrities who use their platform for good, told ABC News.

There is no question that celebrity endorsements can elicit more community action on an issue, but the next critical question becomes whether those actions are actually effective, Denckla said.

The rate of efficacy from these endorsements is currently unclear, particularly when it comes to impacting major policies and industry practices, according to some experts.

In past decades, A-list names like Jane Fonda, Daryl Hannah and Leonardo DiCaprio were among the celebrities best known for environmental work. But the list is ever-growing.

ABC News spoke to several celebrities on why they decided to endorse environmentally friendly brands and causes:

Taye Diggs saw how easy it is to make sustainable changes

Actor Taye Digg admits he was "very late" to the sustainability movement, but it was a logical move once he realized how making small changes at home could lead to exponential mitigation impacts down the road, he told ABC News. The complexity of environmentalism as a whole can be daunting, but narrowing down how he could contribute to the climate fight by making simple swaps made participating in climate action more feasible and solutions-based.

"The type of person I am -- I have to focus on the micro, instead of the macro," he said.

Diggs, known for his roles in "Stella Got Her Groove Back," "Rent" and "Private Practice," has partnered with Tru Earth, an eco-friendly, hypoallergenic laundry strips that eliminate the consumption of plastic.

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Can celebrities help move the needle on climate change? 

Actors become activists as they lend their public platforms to fight for climate action.

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That partnership came with an education from the brand on incremental steps people can take at home.

"There are small things you can do that could have a major effect on the environment, and that's why I've lent my name and decided to come on board," Diggs said.

Diggs emphasized that those who use their platforms to speak on an issue need to come from a "real place" and stand "behind something that makes sense to them." For him, a love of the outdoors -- whether it be playing basketball with his son or enjoying a vacation in the Bahamas -- is enough of an impetus to preserve the planet for himself and future generations.

"It helps me feel good about doing what I can to help the planet as opposed to just completely ignoring everything because it's so mammoth [of] an issue," he said.

Matt Damon's travels sparked a passion for water access

Actor Matt Damon cofounded international nonprofit Water.org in 2009 after decades of witnessing the enormity of the water crisis around the world, he told ABC News via email. He first learned about water access inequalities in the 1980s during a trip to Guatemala with his mother and then again years later when he spent time with families in a village in Zambia. There, he accompanied a young girl on a trip to collect water after her school day had ended.

The girl's story had a profound effect on Damon.

"Had there not been a water source implemented in her community, she might not be able to attend school, and have dreams of one day moving to the big city and becoming a nurse," he said. "Her primary focus would be on where she sourced water for her family each day. It was shocking to me – both the awareness that living without access to safe water and sanitation came at the expense of lives and opportunities, and that no one was talking about it."

One in four people on Earth, or about 2.2 billion people, lack access to safe drinking water, according to the United Nations. As climate change exacerbates issues like rising sea levels and more frequent and extreme occurrences of flooding and drought -- events that affect water systems -- those living in poverty are feeling the impacts more acutely, Damon said.

Damon's passion was driven by a shared belief with Water.org CEO Gary White that community-led solutions would honor the agency of those people, he said.

"The pervasiveness of the water crisis is unconscionable, and it does not have to be this way," Damon said.

Damon, known for roles like "Good Will Hunting," "The Bourne Identity" series and "Oppenheimer," believes that everyone has the opportunity to leave the world a little better than they found it. He has received public recognition for his desire to elevate awareness of social impact issues, most recently in January when he was awarded the Elevate Prize Catalyst Award. It recognizes prominent individuals who use their influence to inspire social action and provides $250,000 in unrestricted funding to advance their mission and scale their work.

Water.org has provided more than 63 million people with safe water and sanitation to date, Damon said.

"I have been fortunate enough with my platform to amplify the ubiquity of the water crisis, but I am only one piece of a very dedicated network of people at Water.org and beyond who have committed their lives and careers to making universal access to safe water and sanitation a reality," he said.

Nikki Reed's family inspired her to work for a healthier planet

Actress Nikki Reed said she was pregnant during the making of "Common Ground," a documentary that showcases white, Black and Indigenous farmers who are using regenerative models of agriculture that could help to balance the climate, make food more healthful and stabilize America's economy, she told ABC News.

It was Reed's two children -- and the reprioritization of family during the slowdown of the COVID-19 pandemic -- that helped her envision a future where generations of kids could understand how to "take care of the earth," she said.

Reed said that while it can be "daunting" and "overwhelming" to talk about the climate crisis as a whole, the filmmakers wanted to highlight how every person on the planet is affected by the health of soil. Making the connection between consumers and the making and production of their food was a critical component of the film, Reed said.

"I think humanity is becoming more disconnected from the things that are right in front of us, including what's on our plate, right?" she said. "And so part of seeing the faces and the stories and the lives and the love and the loss, and also the triumph is, I think, a really important component of this film."

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Can celebrities help move the needle on climate change? 

Actors become activists as they lend their public platforms to fight for climate action.

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Reed's husband, fellow actor Ian Somerhalder, also a producer on the documentary, said that it is "critical to adopt more regenerative farming practices that return to working with nature, not against it."

Other notable names in the film include Jason Momoa, Donald Glover, Laura Dern, Rosario Dawson and Woody Harrelson -- each of whom is a parent themselves, the film's director Rebecca Harrell Tickell told ABC News.

"That's really what I think this film invokes is that inspiration to take action, especially if you are parents," Tickell said.

Somerhalder lent his voice to another environmental documentary that premiered in September, "Tail of Two Farms," to encourage more people to research and get involved in the healthy soil movement, he said in a statement.

Reed, known for her roles in "Thirteen" and the "Twilight" series, believes in devoting her platform to what she believes to be her moral responsibility -- in this case promoting sustainable solutions to ease the environmental crisis, she said.

"It is more urgent now than ever," Reed said. "Yes, because of the climate crisis, but also because of how connected we all are to the degradation of of our soil."

"Common Ground" will be screened at more than 100 AMC theaters to commemorate Earth Day on Monday.

Lance Bass' allergies made clean air quality a top concern

Musician Lance Bass has experienced severe symptoms from seasonal allergies for as long as he can remember, he told ABC News via email. While living an outdoor lifestyle in Los Angeles, a mere whiff of the oak tree in his backyard or of bluegrass during a hike can trigger his allergies, he said.

When Bass became a father, clean air quality became more important to him than ever, especially for family hikes and trips to the park.

"I want my kids to be able to breathe clean air!" he said. "You never even realize how many factors affect the air we breathe, especially air pollution."

Bass said he noticed his allergies getting worse in recent years, a phenomenon scientists say could be connected to climate change. Bass said his symptoms are more severe and last for much longer than the typical allergy season.

Bass has now partnered with Allegra Airways, the real time navigation tool that helps users/commuters find routes with less pollen and air pollution

The app, which uses real-time data, has been a "game changer" for Bass' family, he said.

Bass, a member of boy band *NSYNC, has always tried to use his platform for social change and awareness, he said, adding that he hopes his endorsement helps to accelerate progress on the climate fight.

"I am so lucky to have an amazing group of fans and be in a unique position where I can educate, motivate, and inspire people to better the world," he said. "I have always been super passionate about the environment and educating others on the harmful effects of climate change."

In his daily life, Bass tries to reduce his own environmental footprint by producing the least amount of waste possible. Examples include carrying a reusable water bottle, walking instead of driving and reducing single-use plastics.

"I want to set an example for my kids by making environmentally friendly choices that they grow up implementing," he said.

Bass also serves on the board of the Environmental Media Association, an organization that provides a unified voice for our planet through entertainment, storytelling and education.

"I like to think that I can be a voice advocating for sustainable lifestyles to help our planet," he said. "I want to leave this place in a better place for my kids!"