In November, the Indian city of Mumbai will host the sixth edition of William's 10-year project to recognise and reward ideas to help save the planet.
Writing in The Independent, the prince said a summer of "devastating" wildfires across Britain served as a "powerful reminder of the risks associated with a warming climate".
Provisional figures from the Met Office showed the northern summer of 2026 was the warmest in the UK since records began in 1884, with the average temperature sitting at 16.5C.
Multiple heatwaves led to wildfires which caused an estimated 2877 deaths in England, according to the UK Health Security Agency.
While William called the summer conditions "alarming", he said he believes that "urgent optimism" could craft a way forward for humanity.
"The crisis demands urgency. But without a belief that change is possible, its scale can leave us feeling overwhelmed," he said.
"Optimism gives us confidence that our actions can make a difference. We need both.
"This is what I mean by urgent optimism; seeing the danger clearly while believing in our ability to respond."
"For the first time in history, our greatest challenge is not inventing the answers," he wrote.
"It is deploying and scaling the solutions we already know work. It is not naivety or blind hope. It is optimism grounded in evidence."
"We can, and must, make the remainder of this decade count."
11°C