Queen Elizabeth II's grandson Prince William will bestow his inaugural "Earthshot" environmental prize at a gala ceremony on Sunday, after a buildup marked by royal displeasure at world leaders' inaction on climate change.
At the televised event - featuring the renowned naturalist David Attenborough and performances by Coldplay, Ed Sheeran and others - five international winners will each receive A$1.85 million (1 million pounds).
William hopes the event will help propel the fight against climate change leading up to the COP26 summit in Scotland, calling those on the shortlist "innovators, leaders and visionaries".
"We can't have more clever speak, clever words but not enough action (at COP26) and that's why the Earthshot Prize is so important, because we're trying to create action," he told the BBC.
"I'm hoping the prize will galvanise a lot of people in positions of responsibility to go further, bigger and actually start to deliver."
Those nominated include an Indian teenager who has designed a solar-powered ironing cart, and Costa Rica, which is pioneering a project to pay people to restore natural ecosystems.
A food waste hub in Milan, Italy, a coral replacement scheme in the Bahamas, and a clean-air app from China are also on the shortlist.
Each of the finalists - chosen by experts from more than 750 nominations - will be given help from companies to develop their projects.
William also used his BBC interview , for neglecting problems closer to Earth, while his father and grandmother have also weighed in this week on climate change.
Opening the Welsh legislature in Cardiff on Thursday, the 95-year-old monarch was overheard upbraiding world leaders who "talk" but "don't do" enough about the planetary crisis.
The queen complained that not enough leaders had confirmed their attendance at COP26, with Chinese President Xi Jinping and Indian Prime Minister Narendra Modi among the key players in doubt.
Royal double standards?
William's father, long-time environmentalist Prince Charles, meanwhile told the BBC that he worried the leaders coming would "just talk", rather than implement "action on the ground".
Charles, whose Highgrove estate in western England has an entirely organic garden and farm, also outlined some of his own actions to reduce his carbon footprint, including cutting down on meat and fish.
In 2008, his office revealed he had converted a vintage Aston Martin car to run on biofuel made from surplus English white wine and whey from cheese manufacturing.
However, campaigners alleged climate hypocrisy from the royal family, which is Britain's biggest landowner, including large tracts of Scotland given over to hunting and farming.
Last weekend, TV presenter and environmentalist Chris Packham led a children's march to Buckingham Palace in London to deliver a petition with more than 100,000 signatures asking the queen to rewild royal lands.
"If they were to do so it would be a very powerful message that would resonate with people all over the world," he said.
The Earthshot Prize, launched in October last year, was inspired by US president John F. Kennedy's "Moonshot" project in the 1960s to put a man on the moon.
It covers five areas: how to protect and restore nature; clean our air; revive our oceans; build a waste-free world; and fix our climate.
The shortlisted candidates are:
Protect and restore nature:
Pole Pole Foundation (Democratic Republic of Congo)
Costa Rica
Restor (Switzerland)
Clean air:
The Blue Map App (China)
Takachar (India)
Vinisha Umashankar (India)
Revive oceans:
Coral Vita (Bahamas)
Pristine Seas (USA)
Living Seawalls (Australia)
Build a waste-free world:
City of Milan food waste hubs (Italy)
Sanergy (Kenya)
Wota Box (Japan)
Fix our climate:
AEM Electrolyser (Thailand/Germany/Italy)
Reeddi Capsules (Nigeria)
Solbazaar (Bangladesh)
