The Earthshot brands itself the “most prestigious global environment prize in history.” The world-famous wildlife broadcaster and his royal sidekick appear to have played an active role in the prize’s inception, and media coverage has focused largely on them as the faces of the campaign.

But the pair are only the frontmen of a much larger movement which has been in development for several years. In addition to a panel of experts who will decide on the winners, the prize’s formation took advice from the World Wildlife Fund, Greenpeace and the Jack Ma Foundation.

With more and more global attention on the climate crisis, celebrity endorsement of environmental causes has become more common. But why do environmental causes recruit famous faces for their campaigns? And what difference can it make?

“We need celebrities to reach those people who we cannot reach ourselves,” says Sarah Marchildon from the United Nations Climate Change secretariat (UNFCCC) in Bonn, Germany. Marchildon is a 

proponent of the use of celebrities to raise awareness of environmental causes. In addition to promoting a selection of climate ambassadors who represent the UN on sustainability issues, Marchildon’s team has produced videos with well-known narrators from the entertainment world: among them, Morgan Freeman and Mark Ruffalo.

“We choose celebrities who have a lifestyle where they are already talking about these issues,” Marchildon explains. “Sometimes they reach out to us themselves, as David Attenborough did recently. And then they can promote the videos on their own social channels which reach more people than we do — for example, if they have 20 million followers and we have 750,000.”

Environmental groups focused on their own domestic markets are also taking this approach. One Germany-based organisation that uses celebrities in campaigns is the German Zero NGO. Set up in 2019, it advocates for a climate-neutral Germany by 2035. German Zero produced a video in March 2020 introducing the campaign with “66 celebrities” that supported the campaign, among them Deutschland 83 actor Jonas Nay and former professional footballer Andre Schurrle. They solicit support as well as financial contributions from viewers. “Count me in,” they say, pointing toward the camera. “You too?”

“We are incredibly grateful for the VIPs in our videos,” says German Zero spokeswoman Eva-Maria McCormack.

But quantifying the effectiveness of celebrity endorsement of campaigns is not a straightforward process. “In order to measure effectiveness, first of all you need to define what is meant by success,” says Alegria Olmedo, a researcher at the Zoology Department at the University of Oxford. Olmedo is the author of a study looking at a range of campaigns concerning pangolin consumption, fronted by local and Western celebrities, in Vietnam and China. But she says her biggest stumbling block was knowing how to measure a campaign’s success.

“You need a clear theory of change,” explains Olmedo. “Have the celebrities actually helped in achieving the campaign’s goals? And how do you quantify these goals? Maybe it is increased donations or higher engagement with a cause.”

A popular campaign in China in recent years saw famous chefs Zhao Danian and Shu Yi pledge to abstain from cooking endangered wildlife. While the pledge achieved widespread recognition, both Olmedo and Marchildon say it’s difficult to know whether it made any difference to people’s actions.

“In life we see a thousand messages every day, and it is very hard to pinpoint whether one campaign has actually made a difference in people’s behavior,” she explains.