Prince William has warned the Earth is "dangerously close" to "critical tipping points"

He told delegates: "This, here at Cop30, is our moment. Let us not waste it. Our children and grandchildren are watching, and hoping.

"Let us use these inspiring surroundings here in the heart of the Amazon to rise to meet this moment, not with hesitation, but with courage. Not with division, but with collaboration. Not with delay, but with decisive commitment."

The 43-year-old royal praised his father's dedication to the environment over the years.

He said: "I have long believed in the power of urgent optimism: the conviction that, even in the face of daunting challenges, we have the ingenuity and determination to make a difference, and to do so now.

"I grew up with my father - the King - talking about the power of nature and the importance of harmony in the natural world.

"A subject he has championed for over five decades. It is a privilege to also represent him here today, as well as everyone else who has championed this cause, for so many years."

William noted melting ice and changing temperatures are no longer "distant threats" but are "fast approaching and will affect every one of us, no matter where we live".

He said: "All of us here today understand that we are edging dangerously close to the Earth's critical tipping points... thresholds beyond which the natural systems we depend on may begin to unravel."

The prince - who is in Brazil for his Earthshot Prize environmental competition - went on to call for "urgent optimism".

He added: "We must ask ourselves, what legacy do we wish to leave?

"Because the impact of all our choices will be felt by us all around the world, in the safety of their homes, the stability of their livelihoods, and the health of the natural world that sustains us all. The road ahead will be tough.

"We must transform the way we power our lives, produce our goods, move from place to place, and care for our land.

"But this is not just a challenge. It is a profound opportunity.

"An opportunity to build cleaner economies, restore nature and improve the health and wellbeing of communities everywhere.

"The science is clear - we must go further if we are to secure a liveable future for all. And we must go together. The time for partnership, protection and progress is now.

"We know what is at stake. We know what must be done. And we know that no country, no community, no individual can do it alone. Our children and grandchildren will stand on the shoulders of our collective action.

"Let us use these inspiring surroundings here in the heart of the Amazon to rise to meet this moment, not with hesitation, but with courage. Not with division, but with collaboration. Not with delay, but with decisive commitment.

"Let us honour the leadership of those who have long protected the planet - indigenous peoples and local communities - and walk forward together.

"Let us build a future where nature is valued, and where every child inherits a world of prosperity, not peril. Let us rise to this moment with the clarity that history demands of us.

"Let us be the generation that turned the tide - not for applause, but for the quiet gratitude of those yet to be born."