British naturalist Sir David Attenborough has urged COP26 climate summit delegates to "turn tragedy into triumph" and tackle climate change.
In an impassioned speech which drew a standing ovation, he said the fate of future generations must give delegates the impetus "to rewrite our story".
The 95-year-old warned that humanity was "already in trouble" because of rising carbon levels in the atmosphere.
More than 120 world leaders are in Glasgow for the two week summit.
The COP26 conference is seen as crucial to limit global temperature increases, and changes to the climate.
The world is now about 1.2C warmer than it was in the 19th Century - and extreme weather events like heatwaves, floods and forest fires are already becoming more intense.
The 2015 Paris climate conference called for average temperatures to rise by well below 2C, and preferably only 1.5C, when compared to pre-industrial averages.
But unless more is done, the planet is already on track to warm by more than 2C by the end of this century.
'The greatest problem solvers'
Sir David spoke for seven minutes alongside screens showing a graph that tracked the rise of carbon concentration in the Earth's atmosphere.
That number - which Sir David said was "the clearest way to chart" the story of humanity - currently sits at close to 414 parts per million. According to the Greenhouse Gas Bulletin, that is now 149% of the pre-industrial level.
"Our burning of fossil fuels, our destruction of nature, our approach to industry, construction and learning, are releasing carbon into the atmosphere at an unprecedented pace and scale," he told the conference. "We are already in trouble."
He also criticised wealthier nations, saying this was also a story of inequality and that "those who've done the least to cause this problem are being the hardest hit."
The naturalist however said people were "the greatest problem solvers to have ever existed on Earth" and called on leaders to think of the younger generation as they work to address climate change.
"If working apart we are a force powerful to destabilise our planet, surely working together we are powerful enough to save it," he said, before concluding, "In my lifetime I've witnessed a terrible decline. In yours, you could and should witness a wonderful recovery."