Prince William gave his first ever TED Talk on Saturday, speaking about global warming from outside Windsor Castle.

“Growing up in my family gives you a certain sense of history,” said William, 38. “I’m simply the latest in a line that can be traced back generations. This oak tree is close to Windsor Castle, which has been home to my family for over 900 years. Thirty-nine monarchs have lived here and enjoyed these beautiful surroundings.”

“While these oaks have been growing, around 35 billion people have lived their lives on our planet. That’s 35 billion lifetimes worth of hope, love, fear and dreams,” he added, according to Yahoo News. “Over my Grandmother’s lifetime, the last 90 years or so, our impact has accelerated so fast that our climate, oceans, air, nature and all that depends on them are in peril.”

William went on to talk abut the lasting impact of global warming as he spoke in the free virtual conference.

“This oak has stood here for centuries. But never has it faced a decade like this. We start this new decade knowing that it is the most consequential period in history,” he explained. “The science is irrefutable. If we do not act in this decade, the damage that we have done will be irreversible and the effects felt not just by future generations, but by all of us alive today.”

William also talked about his Earthshot Prize, which will hand out five awards of $1.3 million each year, and will aim to promote at least 50 solutions to the greatest environmental issues around the world before 2030.

“I’ve long been inspired by President John F. Kennedy’s 1961 mission to put a man on the moon within a decade – he named it the moonshot,” William said. “It seemed crazy. We had only just launched the first satellite. Putting a man on the moon, that quickly, seemed impossible.”

“But now, rather than a moonshot for this decade – we need Earthshots,” the royal who is second in line for the British throne added. “We must harness that same spirit of human ingenuity and purpose and turn it with laser-sharp focus and urgency on the most pressing challenge we have ever faced – repairing our planet.”

“I’m determined to both start and end this decade as an optimist,” William concluded. “Whilst our generation represents just a blip in the lifetime of these magnificent oaks, we have the power and potential to ensure that they, and all life on earth, thrive for another thousand years and more. But only if we now unleash the greatest talents of our generation to repair our planet. We have no choice but to succeed.”