David Attenborough, the naturalist and broadcaster, sounded a dire warning in a speech Monday to the U.N. climate conference in Poland.
“Right now we are facing a man-made disaster of global scale, our greatest threat in thousands of years: Climate change,” Attenborough said as the international climate conference got underway with talks on how countries will implement the 2015 Paris Agreement limiting carbon emissions.
“If we don’t take action, the collapse of our civilizations and the extinction of much of the natural world is on the horizon.”
“I am only here to represent the voice of the people, to deliver our collective thoughts, concerns, ideas and suggestions,” Attenborough said.
He played a montage showing people from around the globe who participated in his speech by sending their own videos.
“The world’s people have spoken. Their message is clear. Time is running out,” Attenborough said. “They want you, the decision-makers, to act now.”
Attenborough also promoted the “ActNow.bot,” a Facebook campaign the U.N. is launching that will recommend actions people can take to protect the planet.
Attenborough, who has produced and narrated numerous nature documentaries, is a strong advocate for fighting climate change — but that wasn’t always the case.
“I am always cautious about crying wolf. I think conservationists have to be careful in saying things are catastrophic when, in fact, they are less than catastrophic,” he told The Independent in 2006. “Also, I’m not a chemist or a climatologist or a meteorologist; it isn’t for me to suddenly stand up and say I have decided the climate is changing. That’s not my expertise.”
The British environmental website Carbon Brief attributed Attenborough’s change in perspective to a lecture by American scientist Ralph Cicerone in 2004, in which Cicerone showed graphs of world temperature, global population and the make-up of the atmosphere.
“Now I do not have any doubt at all,” Attenborough said two years after that lecture. “One of the things I don’t want to do is to look at my grandchildren and hear them say: ‘Grandfather, you knew it was happening — and you did nothing.'”