Taking to Twitter, the former U.S President posted a message of support for the royals' new initiative, The Earthshot Prize.
The 59-year-old retweeted a video announcing the campaign, as he wrote: "It’s going to take a lot of big-thinking and innovation to save the one planet we’ve got—and that’s why @KensingtonRoyal’s leadership on climate change can make a real difference."
The ambitious new prize will see £50 million paid out over the next ten years to projects which tackle some of the world's biggest environmental challenges.
WATCH: Prince William expresses hope for future
Prince William discussed the Earthshot Prize alongside Sir David Attenborough in an interview for BBC Radio 4's Today programme.
William said: "I felt very much that there's a lot of people wanting to do many good things for the environment and what they need is a bit of a catalyst, a bit of hope, a bit of positivity that we can actually fix what's being presented.
"And I think that urgency with optimism really creates action.
Prince William announced his new project alongside Sir David Attenborough
"And so the Earthshot Prize is really about harnessing that optimism and that urgency to find solutions to some of the world’s greatest environmental problems."
The Prince went on: "We believe that this decade is one of the most crucial decades for the environment and by 2030 we really hope to have made huge strides in fixing some of the biggest problems the Earth faces."
Barack Obama shared his support for the prize on Twitter
A global prize council of major names from the worlds of sport, the environment, entertainment, business and philanthropy will pick the projects to focus on, with five £1million winners each year between now and 2030.
Nominations for the prize open on 1 November with an annual global awards ceremony to be held in a different city each year.
The first Earthshot Prizes will be presented in London in autumn 2021 and the BBC will screen a five-part series ahead of the awards ceremony.
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