Jacinda Ardern has stood in for Prince William at an environmental summit in New York City, describing herself as an "exceptionally poor substitute".
The New Zealand prime minister was asked personally by the Prince of Wales to deputise in his place at the Earthshot Prize innovation summit, a sideline event at the United Nations General Assembly's leaders week.
Backed by the British royal family and beloved environmentalist David Attenborough, the Earthshot Prize grants huge sums to conservation leaders as a way to incentivise sustainability efforts.
Ms Ardern was introduced by former mayor of New York and billionaire Mike Bloomberg, who said the Kiwi PM was "a global leader on climate change" who had "devoted her life to building a better world".
"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," Ms Ardern said.
"My message today is one of gratitude and encouragement.
"As governments we have a responsibility to create the incentives and the space for you to flourish ... and the accountability that comes with guardianship.
"We think often of our challenges but imagine for a moment what can be achieved by channeling our potential."
Ms Ardern talked up her government's efforts to combat climate change, including legislating a platform to limit New Zealand's emissions to 1.5C, complete with an independent agency and plan to do so.
She also confirmed New Zealand's ambition to become "the first country in the world to price agricultural emissions".
The Kiwi leader is in New York this week to deliver New Zealand's address to the UN General Assembly, which she will do on Saturday morning (AEST).
Russia's invasion of Ukraine hangs over the global summit, with Ms Ardern telling journalists in New York more countries needed to condemn Vladimir Putin's war.
"What we need here is a rallying cry from the world what is happening here is illegal, it's immoral," she said.
"This whole false narrative around liberating Ukraine, you don't attack, and you don't threaten use of nuclear weapons over a country you claim to be liberating."
On Thursday, she will appear on a panel with her predecessor as New Zealand PM, Helen Clark, discussing pandemic readiness.
The Earthshot Prize takes its name from US President John F Kennedy's description of space travel as an audacious "moonshot," an ambition that led to the creation of other technologies.