Prime Minister Jacinda Ardern has delivered a speech on behalf of Prince William at a star-studded New York event attended by Hollywood's Matt Damon and billionaire Michael Bloomberg.
The climate-focused Earthshot Prize Innovation summit took place at the Plaza Hotel in the early hours of Thursday (NZT) on the sidelines of the United Nations general assembly.
Ardern was introduced by Bloomberg, a former New York mayor and philanthropist, as a "global leader on climate change".
The prime minister told guests she was "humbled" to have been asked to speak on behalf of Prince William - who withdrew from the event following his grandmother's death.
"I am an exceptionally poor substitute, but I also know we all understand the need for His Royal Highness to be with his family at this time," Ardern said.
The Earthshot Prize was founded by Prince William in 2020, designed to incentivise efforts to find solutions to repair and protect the planet.
Ardern described it as "the Nobel Prize for innovation in environmentalism". She said the world was at a crossroads when it came to the climate change crisis.
"It won't just take our global collective will to create the scale of change required to turn around our environmental trajectory - it will also take innovation," she said.
"The speed we need to move, demands it."
Ardern said governments had a responsibility to create incentives and space for innovators to flourish.
"We can all, and should, marvel at the ideas we see here today, but let us also remember that we have a role to play in helping pave the way for them.
"As guardians, our children expect nothing less."
In a pre-recorded video, Prince William thanked the prime minister for her "generous words" - using just her first name - and told guests there was a need for urgency.
"I know that the world is an uncertain place right now… from conflict, to energy crisis, and food shortages.
"While addressing these in the short-term, we must also remain resolutely focused on the greatest challenges that threaten our tomorrow."
In a short and surreal skit, Bloomberg interviewed the Sesame Street muppet Oscar the Grouch on stage, securing a commitment that he give up on his dream of a "wasteful planet".
Hollywood A-lister Matt Damon also gave a brief speech, referencing the popular saying: "there is no planet B".
"I don't know if you've seen my movie The Martian," Damon quipped to laughter. "Spoiler alert - I spend like half the movie trying to grow a potato."
Other speakers included US actor Sam Waterston, Paris mayor Anne Hidalgo, and the Queen of Jordan Rania Al Abdullah.
