A project to restore tropical forests and a global ocean treaty initiative are among the winners of this year's Earthshot Prize.
The winners, named at an awards ceremony in Brazil on Wednesday, will each be given £1m to scale up their projects to repair the climate.
The Prince of Wales, who founded the global environmental award in 2020, said the winners were an inspiration and proof that progress is possible.
Brazilian football legend Cafu, Olympian Rebeca Andrade and former Formula 1 driver Sebastian Vettel were among the presenters, while pop stars Kylie Minogue and Shawn Mendes performed at the ceremony in Rio de Janeiro's Museum of Tomorrow.
UK Prime Minister Sir Keir Starmer, Energy Secretary Ed Miliband and London Mayor Sir Sadiq Khan were also in attendance.
Prince William, who is the president of the prize, told those gathered at the ceremony that he had founded the award with the aim of making this the decade in which we transformed our world for the better.
There are five Earthshots, or goals, for which an award is given: Protect and Restore Nature; Clean Our Air; Revive Our Oceans; Build a Waste-Free World; and Fix Our Climate.
The future king has committed himself to the prize for 10 years, with Rio marking a halfway point for the venture.
This year, nearly 2,500 nominees were submitted from 72 countries. Of these, 15 finalists were selected, from which the five winners were chosen.
Chief executive of re.green, Thiago Picolo, said that winning the Protect & Restore Nature prize puts the organisation on the right path.
Referring to the winners as innovators, Prince William called the Earthshot Prize a mission driven by the kind of extraordinary optimism we have felt here tonight.
Earlier in the day, Prince William met the 15 finalists during a visit to the Christ the Redeemer statue, where he posed for a photograph on the same spot his late mother, Diana, Princess of Wales, did 34 years ago.
