David Attenborough, one of Britain's most trusted public figures and among the world's most recognizable voices for Earth's natural beauty, implored leaders to use the COP26 summit as a climate turning point, creating a more equitable world in the process.

The naturalist, whose narrative gravitas has focused attention on the planet's health for decades, was among the earliest speakers at the conference on Monday alongside world leaders and climate activists.

"If working apart we are force powerful enough to destabilize our planet, surely working together we are powerful enough to save it," said Mr. Attenborough, 95.

In his nature documentaries, Mr. Attenborough has guided viewers to the most beautiful corners of the planet, with his gentle but authoritative voice a comforting presence. But his work has never shied from politically thorny environmental issues, and he often speaks directly about the high stakes of climate change and the action necessary to address it.

On Monday, he focused his remarks on the concentration of carbon in the atmosphere, a measure that he said "defines our relationship with our world." In the last 10,000 years, as the number stabilized, he said, civilization was made possible and humans took advantage.

But he warned that this stability was now under threat.

"Perhaps the fact that the people most affected by climate change are no longer some imagined future generation but young people alive today — perhaps that will give us the impetus we need to rewrite our story," he said.